Tag Archives: hypothalamus

The Male Brain: Demystifying the Divinely Devised Differences

Male Brain. While women don’t often understand or agree, men have—since the dawn of time—had different instincts, emotions, and approaches to situations. Although these approaches can (arguably) be questionable, the varying innate reactions are simply different than those of women: not better, not worse. While both sexes come with their own strengths and weaknesses, we have to wonder: what biological structures underlie the instincts and actions of the male brain? Why are there differences between the male brain and the female brain? And how do the neurophysiological structures within the male brain attribute to the behavior we see in everyday life? Find out more below. 

Male Brain

The Male Brain

Historically, social differences between men and women centralized around physical characteristics and social constructs that defined each gender. As our modern society has progressed to challenge the social roles and labels that have, for centuries, defined men and women, research over the past twenty years has zeroed in on sex-based differences that classify neurological differences between the sexes. While the emerging biological discoveries underline the strengths and weaknesses of both the male and female brain, the overarching goal of research aims to emphasize the divine differences that distinguish sexes—rather than imply inferiority—to better understand how anatomical differences influence behavioral differences between sexes.

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While the natural behavioral tendencies of both males and females seem to be unpredictable and bewildering, understanding the neurophysiological dissimilarities between sexes links behavioral differences to a structural root. Although, at times, it seems as though the men and women are from two entirely different planets—as the saying goes:

“men are from Mars, women are from Venus”

Understanding the male brain is fundamental for discovering the neurological and behavioral differences that distinguish the innate tendencies people have based on their biology.

The Male Brain: How It All Started

As a trailblazer in the investigation of behavioral differences between sexes, Nirao Shah, spearheaded research to biological differences in 1998 as he began his postdoctoral fellowship.  While Shah observed the behaviors essential for the survival of each sex, he investigated how this innate behavior is biologically wired in the brain. He hoped to find the root of behaviors by identifying neuronal circuitry unique to each sex, he has since inspired researchers to unearth the inherent differences that distinguish the male brain from its female counterpart.

The Male Brain: Structural and Functional Differences

A Question of Grey Matter and White Matter in the Male Brain

The most obvious difference between the male and female brain is the distinctly larger crania of males. Due to the proportionally larger body size of males, larger craniums allow for a larger brain to develop amongst male brains. While the presence of a larger brains lacks correlation for heightened intelligence, a fundamental size difference is present between the male and female brain.

As research has found that the male and female brain are wired differently, it has been determined that the male brain operates on intrahemispheric communication, contrasting that of the female brain which optimally operates through inter-hemispheric communication. This insinuates that the male brain has stronger connections within a single region of the brain, whereas females have stronger connections between the left and right hemispheres. While this puzzling difference seems to be without reason, the cellular composition of brain tissue accounts for the wiring that makes the male brain unique.

As a result of an MRI study at the University of Pennsylvania, it has been confirmed that male brains have higher percentages of white matter. Found within the cerebellum, which is split into the right and left hemisphere, two types of tissue of the central nervous system are found: grey matter and white matter. The outer layer of the cerebellum, composed of grey matter folds, is made up of tightly packed dendrites, cell bodies, and axon terminals.

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These tightly folded regions are specialized to regulate memory, language, perceptual awareness, and attention—ultimately containing the synapses that communicate messages. White matter, in contrast, is made up of axons—connecting grey matter to one another—creating a fast communication network, like a metro system. White matter makes up important structures, like the thalamus and hypothalamus, which ultimately relay information from the body to the cerebellum.

Together, these tissues work to allow the white matter to communicate between grey matter areas, and for the grey matter to communicate with the rest of the body. While the researchers at the University of Pennsylvania speculated that the higher volumes of white matter are found amongst larger brains because of the further distance for information transference, the research team concluded that the greater amounts of grey matter amongst the female brain facilitates inter-hemispherical computation of information in a smaller amount of space (e.g. a smaller brain).

During development, the male brain is structured to increase activity and connectivity within each hemisphere by creating communication networks that are modular and direct. While this within-hemispheric processing allows linkage of perception to action along the posterior tract of the cerebellum, it also allows the mediation of motor action ipsilaterally. By way of strong within-hemispheric processing and connectivity, the divinely designed male brain allows for strong coordination of actions in males.

As research and functional imaging have suggested, white matter tracts are activated while working memory is in use. Because of the high percentage of white matter within the male brain, it comes as no surprise that men are better equipped to juggle items within their working memory.

The Male Brain and the Corpus Callosum

The Bridge of the Brain

Extending from the University of Pennsylvania study in 2014, the corpus callosum—a white matter cable that connects the right and left hemisphere—is smaller in the male brain. This also led to the observation of heightened bilateral symmetry amongst the brain in females compared to males: as communication between hemispheres increases, greater symmetry in muscle tissue arises. From these observations, the larger corpus callosum in the female brain can account for the greater inter-hemispherical communication observed in females, and why, biologically, the male brain tends to reflect the success of intrahemispheric communication. This anatomical explanation helps debunk why men are easily frustrated when asked to multitask: because the female brain allows multiple tasks and an abundance of information to flow simultaneously, the smaller corpus callosum in men inhibits the same task juggling ability that the female brain facilitates.

The Male Brain and the Limbic System

The Emotions of a Man

Areas of the Brain

Comprised of the hypothalamus, hippocampus, amygdala, and various other surrounding areas, the limbic system is heavily involved in emotional regulation. In an issue of the Journal of Neuroscience, which was solely dedicated to sex differences within the nervous system, Larry Cahill discussed how the amygdala in the male brain—which experiences and recalls emotional events—is larger than the amygdala in the female brain. Even as infants, MRI research shows that the male brain has higher activity within the limbic system than the female brain. While men are often stereotyped as “unemotional creatures,” this natural, anatomical difference supports the idea that men are, in fact, more emotional than women, but nurture leads to the masking of emotional expression.

Thought to attribute to learning differences between sexes, neurochemical and anatomical differences between the hippocampi of men and women have also been discovered. Contrasting the left hippocampus activation in females, the right hippocampus has increased activation in the male brain; these findings suggest that when presented tasks that require cognitive thinking, males use fewer verbal strategies than women.

Additionally, despite the stereotype that men think about sex more than women, the limbic system— specifically, the hypothalamus—is responsible for this biological drive for sexual pursuit. While the hypothalamus within the male brain is nearly two and a half times larger than the female brain’s hypothalamus, testosterone fertilizing the Y gene (aka the male gene) attributes to this size discrepancy. This is why males report thinking about sex three times more often than females. While this research serves as a biological basis of male behavior, it does not negate an ability to learn to be civil and controlled. (Just because a man has an urge to act, it doesn’t mean he can’t control it!)

The Male Brain and Visuospatial Skills

The male brain tends to surpass the skills of the female brain when it comes to visuospatial skills that allow them to analyze and mentally manipulate objects. Seen from early stages of development, the superior visuospatial abilities of the male brain exceeds the female brain’s ability when it comes time to track moving objects, aim projectiles at targets, and visualize the rotation of two- or three-dimensional objects. While females exceed at other tasks, such as recalling word lists, the differing brain development between sexes explains the heightened accuracy of males in certain skills, such as spatial tasks and motor skills. In everyday life, these surpassing abilities can be seen in navigational skills: males better calculate their position by direction and relative distance traveled, whereas the female brain relies on landmarks to distinguish location.

The Male Brain and Chemical Differences

While we often attribute the prominence of aggression amongst males with their increased levels of testosterone, there are a variety of uses of testosterone throughout the body. Notably, testosterone, in the male brain, impairs impulse-control and ignites libido. While so many questions where they stand with their partner when they see him checking out the supermodel walking by, rest assure that it is just biology at play! Because of the dampened impulse control and revved libido, it makes it harder for men to suppress their impulse to scope the gorgeous woman walking by.

Questionably unfaithful behavior can also be attributed to the presence of the hormone vasopressin. In a study of mole rats, a species containing the vasopressin gene were more monogamous and committed than their cousin species: the cousin species of mole rats that lacked the vasopressin gene were more promiscuous. When the vasopressin gene was injected into the brain of the promiscuous mole rat, the transient tendencies subsided and the mole rats became monogamous. While we are not claiming that men are (always) like rats, a higher presence of vasopressin in the male brain is attributed to more committed, faithful relationships.

While it often seems that male behavior is dominated by their natural abundance of testosterone, the male brain changes when they become a dad-to-be. Similar to the changing chemicals of an expecting mother’s brain, the male brain decreases testosterone and increases bonding hormones, such as prolactin and oxytocin, ultimately equipping them with more bonding hormones to make them better dads.

In terms of stressful situations, male brains have a unique increase of dopamine, serotonin, and norepinephrine in the basolateral amygdala, while female brains don’t. In the onset of stress exposure, chemical levels change within the male brain, particularly influencing the prefrontal cortex and hippocampus, which are associated with spatial and nonspatial memory. This helps to explain why the onset of stressful situations impairs the male brain’s ability of object recognition.

The Male Brain is Different From the Female Brain: Why?

Biologically speaking, the male brain has different sex-steroid hormones than women’s. While females have high levels of estrogen and progesterone, males are dominated by testosterone and androgens. During in-utero development, the male brain becomes heavily influenced by the high levels of testosterone, which are responsible for their masculine body plan; while this naturally attributes to physical characteristics, the surging testosterone naturally shapes the brain, too. Regions, like the amygdala and hippocampus, have an abundance of receptors specific for sex hormones, explaining why these regions differ in size between the male brain and the female brain.

In terms of evolution, researchers break down the neural differences as a result of adaptation to the actions of neurotransmitters and hormones that appease our sense organs and brain. As the female brain has adapted to childbearing and education, the female brain is better adapted for verbal sharing and communication. Evolutionarily, the male brain, in contrast, is adapted for hunting and fighting; as men roamed the land for hunting, their silent pursuits and navigational skills required heightened visuospatial skills and a decreased need for verbal sharing.

Although some behaviors of men are confusing and, at times, unforgivable, nature has equipped men with biological predispositions that are simply different from those of females. Debunking the differences between the biological structures of the male and female brain helps to understand what motivates behaviors. Although testosterone fuels the male brain to strive for sexual pursuit, differing structures between the male and female brain attribute to functional and behavioral differences. While subtle deviations are seen anatomically between the male and female brain, the emerging research of sex-based neurological differences attempts to explain how the male brain approaches life.

Consider checking out an in-depth look at the female brain and how the structural differences result in different behaviors.

Feel free to comment below!

References

Madhura, l., Alex, S., Drew, P., Theodore D., S., Mark A., E., Kosha, R., & … Ragini, V. (2014). Sex differences in the structural connectome of the human brain. Proceedings Of The National Academy Of Sciences Of The United States Of America, (2), 823.

Goldman, Bruce, and Gérard DuBois. “Two Minds: How Men’s and Women’s Brains Are Different.” Stanford Medicine, stanmed.stanford.edu/2017spring/how-mens-and-women’s-brains-are-different.html.

Fear: Everything you need to know about being scared

In the famous words of Franklin Roosevelt, “The only thing we have to fear is fear itself!”,  but what exactly is fear, what does it look like, and how does it work? What are the different kinds? Can you actually be scared to death? What happens to our bodies and brains when we feel scared and how can it be managed? What are some tips to deal with being scared?

Fear

What is fear?

Fear is the response to something dangerous- whether emotionally or physically. Defined by the Cambridge dictionary as:

“an unpleasant emotion or thought that you have when you are frightened or worried by something dangerous, painful, or bad that is happening or might happen.”

It’s essential for us to feel it because if we didn’t have it, we wouldn’t be protected against potential threats. It is adaptative. Fear stems from our fight-or-flight mode which comes from our sympathetic nervous system. Fear should be distinguished from anxiety– the response that occurs when a threat seems unavoidable or uncontrollable.

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What does fear mean?

Traits and behaviors of fear

Fear can make us do just about anything… buy that hotel room online because “6 other people are looking at this room right now”, buy that home security system that has everything included, or inspecting a dark attic while holding a baseball bat because your wife heard a noise. Humans are wired to feel fear and behave accordingly.

The tell-tale signs of fear are what put our body into its flight-or-flight mode. The signs include hyperventilation (a higher heart rate), the constriction of peripheral blood vessels, dilation of the central blood vessels (this causes blushing), piloerection (making a cold person warmer, making a scared animal look more impressive), muscle tension increases (this causes goosebumps), sweating, hyperglycemia (increased blood sugar levels), dyspepsia (the feeling of butterflies in the stomach), and increased serum calcium. When all of these functions happen, our brain realizes that there is danger, and the result is fear.

Can you die from fear?

Yep, it’s possible to be scared to death! When people feel quite scared, their fight-or-flight mode turns on giving them a large rush of adrenaline. This increased level of adrenaline can be damaging to the heart and triggers calcium channels in the heart to open up. When calcium goes into the heart cells, the heart muscles contract forcefully.

Essentially, the calcium doesn’t stop because the adrenaline doesn’t stop, and the heart muscles can’t relax. This can lead to the development of a heart arrhythmia known as ventricular fibrillation– when the heartbeat isn’t regular. This arrhythmia leads to a drop in blood pressure which, if strong enough, cause the brain to cease blood flow and consciousness is lost.

Causes of fear

Fear can be learned, cultural, natural, and evolutionary. If a kid has a bad experience with clowns, he might have a phobia of them later on in life. Culturally, different cultures it different phenomena. Fear is embedded into our nature- we can’t survive without it. Scientists believe that the phobia of heights is something embedded in us and that came out during the Mesozoic period of time. Since then, most of us evolved to have a slight phobia of tall heights.

Fear is characterized by rational or appropriate and inappropriate or irrational. An irrational fear is also called a phobia. It’s a twist of the normal response to fear. “Phobia” is the Greek stem for “fear of”. Some of the most common phobias are public speaking, heights, needles, spiders, snakes, ghosts, tight/enclosed spaces, and rejection.

People who suffer from a fear of fear, also known as anxiety sensitivity, are likely to have a personality or identity issue to begin with which is what helps the fear phobia develop. Many people also develop an affect phobia– a phobia of negative feelings. It’s not uncommon for those with anxiety disorders to develop a fear of phobia. This is because they perceive a fear response as negative and will do everything in their power to avoid that response. Phonophobia is the technical term for the fear of phobias.

Fear

Psychological theories of fear

Some psychologists have suggested that there are only a small set of innate and basic emotions that the rest of our emotions stem from. Of those include anger, angst, acute stress reaction, anxiety, horror, fright, panic, happiness, sadness, and fear. They believe that fear comes from a behavioral response and has been preserved through evolution.

Others suggest that the feeling of being scared isn’t only dependent on the nature of a person, but by their social and cultural interactions which help guide them to know what is scary. For example, being scared of the monster under the bed or having a parent look in the closet for the Boogeyman.

The psychoanalytic theory of fear comes from Sigmund Freud. He believes that the scary object/idea is not the original subject of fear. For instance, while I may be scared of clowns, it’s because when I was smaller, I was bitten by a dog while watching a clown.

The learning theory combines cognitive theory and behaviorism. This theory means that a phobia develops when the fear response is punished or reinforced- in either a positive or negative way.

There is also the option of a biological basis with the focus mainly on neuropsychology- mental disorders are caused by physiological factors. Neuropsychologists have found that there are some genetic factors that could play a role in phobia development. They’ve also found that certain medications that affect brain chemistry are useful in helping to treat phobias- mainly medication that raises serotonin levels.

How does fear affect the brain?

Fear neurocircuits in mammals

When fright is felt (via any of the five the senses), three main areas of the brain are affected. First, the thalamus collects the data from the senses. Second, the sensory cortex takes the data from the thalamus and begins to process and interpret it. After, the sensory cortex takes the processed information and spreads it throughout the two amygdalae (fear), hypothalamus (fight-or-flight), and the hippocampus (memory). However, it has also been found that when people are presented with a scary face, the occipital cerebellar regions of the brain are activated. Those include the fusiform gyrus, inferior parietal, and the superior temporal gyri. People who have damage to their amygdala might be unable to experience feeling scared.

The response to fear is automatic and we won’t know it’s going on until it’s over and has run its course. The main part of the brain where the feeling of scared is really felt is in the amygdala. It’s essential for our adaptation to emotional learning memory and stress. Our brain has two amygdalae and each one forms a part of our circuitry of fear learning. When we feel a threat, our fight-or-flight response begins. Essentially, this means that the amygdalae produce a secretion of hormones that influence both feeling scared and aggression.

Once the feeling of fear or aggression has started, the amygdala release hormones into the body in order to keep the human alert so they may be ready to run, fight, and move at any moment. Some of these hormones include norepinephrine (increases heart rate, blood flow, and glucose release for energy), epinephrine (regulates heart rate and metabolism, dilates air passages and blood vessels), and cortisol (increases blood sugar and the feeling of stress). Once the threat and reason for terror has subsided, the amygdala sends this information to the medial prefrontal cortex (mPFC) in order to have it stored for the future. This is known as memory consolidation and happens through a process known as synaptic plasticity.

This synaptic plasticity occurs because the amygdalae and the hippocampus work together to create memories surrounding the situation. Stimulation of the hippocampus causes the person to remember specific details about the scary situation. Neuron stimulation in the amygdalae generates memory formation and plasticity. When this process occurs frequently, known as fear conditioning, it can lead to having a phobia or post-traumatic stress disorder (PTSD).

Some MRI scans have shown that the amygdalae in people who have been diagnosed with panic disorders or bipolar disorder are larger overall and more wired to have a higher level of fright.

Fear pheromones

As mammals, like other birds, reptiles, insects, and aquatic organisms, we release an odor called pheromones. Also known as alarm substances, fear pheromones are signals that are chemical and meant to defend oneself from danger. For example, think of a skunk or a stink bug. When they feel scared, they release an odor- their pheromone- to try and make the danger go away via the foul smell. In many animals, the release of the pheromones is meant to let other members of the species around them know that there is danger. This pheromone-alarm can lead to a change such as defensive behavior, dispersion, or freezing depending on the species and situation. For example, it’s been found that rats can release pheromones that cause the rats around them to move away from the rat releasing pheromones.

Humans work slightly differently than animals in that respect. When we feel scared, other humans naturally react differently than how the rats acted in the scenario above. Unlike in animals, humans’ alarm-pheromones haven’t been chemically isolated yet- but we know they exist. Androstadienone is a steroid in the form of an odor that comes from deep within the human body and is found in human sweat, hair, and plasma. Androstenone is another related steroid that is used to communicate dominance, competition, or aggression. One study found that terror responses may be gender specific.

Fear

Is fear contagious?

Can it be contagious, though? An interesting study found that it’s possible to smell the difference between human exercise-induced sweat and human feeling scared/nervous/anxiety-induced sweat. This means that we can literally smell terror and that, yes, it can be contagious. When someone is scared, the other people around them can feel it. If those other people are sensitive enough, they might begin to feel it as well. This is a simple survival instinct. When one member of the gazelle herd feels scared because of a lion running towards them, the other members should, too. Unlike animals who use smell to communicate, humans usually communicate by language, both verbal and body. However, humans are able to communicate some emotions via smell and fear is one of them.

Fear isn’t just contagious via smell, but also via genetics. One study showed that a generation of lab rats who were trained to associate cherry blossoms with electric shock had children and grandchildren who were all nervous about the cherry blossom even though the younger generations had never experienced any shock association with cherry blossoms. In their brains, the areas known for smell were bigger- likely to be able to smell the cherry blossom and avoid what their ancestors were wary of. Known as epigenetics, the genetic code gets modified and turns off/activates certain genes.

Fear within society

According to a Gallup Poll done in 2015, within the U.S., the top 10 fears people have (not in any order) are:

  • Terrorist attacks
  • War
  • Gang violence
  • Criminal violence
  • Failure
  • Death
  • Spiders
  • Being alone
  • Nuclear war
  • The future

In 2008, one author analyzed the top words on the internet that followed the phrase “fear of…” and found that the top ten were:

  • Snakes
  • Failure
  • Clowns
  • Flying
  • Death
  • Heights
  • Intimacy
  • Driving
  • People
  • Rejection

Management and treatment

Pharmaceutically, fear conditioning (PTSD, phobias) has been proven to be manageable using glucocorticoids. This is because the glucocorticoids prevent the fear-conditioned behavior. Psychologically, cognitive behavior therapy (CBT) is successful to help people overcome what they’re scared of.

CBT is useful through exposure therapy because people are able to confront what they are scared of in a safe way that helps them learn how to suppress the fear-triggering stimulus or memory. One study has shown that up to 90% of people who try exposure therapy for phobias are able to decrease the phobias overtime. Another study showed that our brains can overwrite bad, scary memories with stimulation of the amygdala.

True facts about fear

  • Fear is contagious and we can smell it! A group of women who smelled the shirts of men- half with anxiety induced sweat and half with exercise-induced sweat- could smell the difference between the two types of sweat.
  • We remember being scared. When we are scared, our brains save the situation in our memory so we can remember not to repeat the situation.
  • Our brains can overwrite fear!
  • It’s possible to be scared to death. When our bodies produce to much adrenaline, our hearts become overworked and we can collapse unconscious.
  • Fear is genetic! Epigenetics is real and our genetic makeup can warn us to be scared and wary of something.
  • The fear gene, known as stathmin, is stored in the amygdala and is what groups us into people who can jump off cliffs and those who can’t get near one.
Fear

Tips to overcome fear

  • Be aware that you’re feeling scared. You can’t fix what you don’t know. You aren’t what you’re scared of- you’re the awareness that is experiencing it.
  • Identify what’s making you scared.
  • Find the root of it.
  • Therapy. Cognitive Behavior Therapy and exposure therapy are both forms of therapy that are helpful in overcoming phobias.
  • Hypnosis is a common method to help people overcome some phobias.
  • Yoga can help release any bad energy and anxiety in the body. By releasing some negative energy, the scared feelings can become less powerful.
  • Read books or watch movies on your phobia. Sometimes you’ll find helpful hints or interesting facts about your phobia that will help alleviate it.
  • Be grateful. Rather than being scared about having to speak publicly, think about what a great opportunity it is to be able to share what you’re going to say. Switch the situation around.

Let us know what you think in the comments below!

Limbic System Functions: Limbo With Your Limbic System

Your limbic system functions range from regulating your emotions to storing your memories to even helping you to learn new information. Your limbic system is one of the most essential parts of the brain that help you live your daily life. The primary structures that work together in your limbic system are the amygdala, the hippocampus, the thalamus and hypothalamus, the cingulate gyrus, and the basal ganglia. All these parts help you to be active in society, engage in social relationships, and be a well-rounded person. To learn more about the interesting ways your limbic system impacts your life, sit back and get in-tuned with all of its hard-working employees!

Limbic System Functions

1. What is another name for your amygdala?
  • Your amygdala is essential for controlling the emotions that you express. That is why it is called ''the emotional center of the brain.''

2. What is your basal ganglia involved with?
  • Your basal ganglia is the main structure that controls all of the voluntary movements your body performs

3. Where do hormones originate in the brain?
  • Your hypothalamus is controlled by the pituitary gland which regulates how many and what hormones are released throughout your body (this is all under the endocrine system)

Limbic System Functions

Limbic System Functions

Interconnected nuclei and cortical structures located in the telencephalon and diencephalon have different functions that are related to the limbic system. These nuclei main functions are of self-preservation. They regulate our autonomic and endocrine function especially as a response to emotional stimuli.

Many of the areas are related to memory and with arousal levels involved in motivation and reinforcing behaviors. Since it’s related to self-preservation, many of the areas are related to the sense of smell, since it is critical for survival.

The areas critical for functions in the limbic system are two:

  • Subcortical structures include the olfactory bulb, hypothalamus, amygdala, septal nuclei and thalamic nuclei.
  • Cerebral Cortex also is known as the limbic lobe it includes the hippocampus, insular cortex, subcallosal gyrus, cingulate gyrus and parahippocampal gyrus.

Here are some of the different parts of the limbic system and how they affect you:

Limbic System Functions: The Amygdala

Shaped like a small almond, the amygdala is located in each of the left and right temporal lobes. It’s known as  “the emotional center of the brain,” because it is involved in evaluating the emotional intake of different situations or emotional intelligence (for example, when you feel happy because you received an awesome grade on your math exam or when you might be frustrated because the heavy traffic is making you late for work). The amygdala is what makes the brain recognize potential threats (like if you are hiking in the lone woods and suddenly you hear the loud footsteps of a bear coming toward you). It helps your body prepare for fight-or-flight reactions by increasing your heart and breathing rate. The amygdala is also responsible for understanding rewards or punishments, a psychological concept known as reinforcement coined by the classical and operant conditioning experiments of Ivan Pavlov.

The amygdala works by being stimulated through the electrical forces of neurotransmitters (understand the different types of neurotransmitters). Many times, when this stimulation is very high, we show physical acts of aggression, like throwing tantrums, screaming, or hitting objects. If the amygdala was removed from the human brain, then we would all become extremely tame and no longer respond to things that previously caused us frustration or annoyance. Also, we would become indifferent to all forms of external stimuli, especially those related to fear and sexual responses.

Limbic System Functions: The Hippocampus

This part of the brain is found deep within the temporal lobe and is shaped like a seahorse. The exact role of the hippocampus is disputed between psychologists and neuroscientists, but we generally know that it is essential in forming new memories about past experiences. The three major stages of memory forming in the brain are:

1. Sensory input from your peripheral nervous system sending neurotransmitters to your brain

2. Your brain storing those stimuli in its “short-term memory,” which holds the information for about 3-5 minutes

3. If 5 minutes has elapsed and you are still thinking about that memory, then it will enter into your long-term memory, where it will stay for virtually an endless period of time.

Your hippocampus is the main brain portion responsible for going from stage 2 to stage 3, or converting short-term memories to long-term memories.

Researchers suggest that the hippocampus is responsible for “declarative memory,” which is the ability for one to explicitly verbalize their memories (i.e. episodic memories and semantic memories).

Limbic System Functions

If the hippocampus is damaged, then a person will not be able to build new memories (known in neuropsychology terms as anterograde amnesia) although he or she might be able to hold onto older memories. This individual would instead live in a very strange world where everything they experience and everyone knew whom they meet just fades away. A classic example of this is seen in the movie 50 First Dates, where Drew Barrymore plays the lead role of a girl with short-term memory who loses memory every night being with her beloved during the day.

Limbic System Functions: The Thalamus

These structures are both associated with changes in emotional reactions. The thalamus is known as the “way-station” of the limbic system because it aids in communicating what is going on in the system with the rest of the brain. It connects areas of the cerebral cortex that are involved in sensory perception and movement with other parts of the body associated with sensation and movement. It has control over your peripheral nervous system, which moves sensations from the body through the spinal cord into the brain. Specifically, it works alongside these major lobes in the brain:

  1. The parietal lobes – it sends sensory touch information to the somatosensory cortex located here
  2. The occipital lobes – it sends visual information to the visual cortex here
  3. The temporal lobes – auditory signals are sent to the auditory cortex here

The thalamus has other functions for your body as well, like controlling your sleep and awake states of consciousness. It sends signals from the brain to the rest of the body to reduce your perception of sensory information while sleeping, which is why you wouldn’t necessarily feel if an ant was crawling on you or someone put their hand on your arm gently while you were sleeping. The thalamus also is involved in motor controls, relaying sensory signals to the cerebral cortex, forming memories and expressing emotions, and perceiving pain.

Limbic System Functions: The Hypothalamus

The hypothalamus is a small piece located just below the thalamus and has lesions on it that are the driving forces behind our major unconscious activities, like respiration and metabolism. One of its central functions is homeostasis for the body, which is returning it from either too much excitement or too little pleasure to a calm “set-point” from which we behave “normally.” It is one of the busiest parts of the brain because it also helps drive other motivated behaviors like hunger, sexuality, and aggression. The lower side of the hypothalamus seems to be involved with pleasure and rage, while the middle section is associated with displeasure, aversion, and uncontrollable and loud laughter. Because the hypothalamus also regulates the functions of your autonomic nervous system, it controls things like your pulse, blood pressure, breathing, and arousal response to emotional circumstances.

Recent biological studies have shown that when we overeat, a protein called leptin is released by fat cells in our bodies. The hypothalamus is the first part of the brain to sense these high levels of leptin in the bloodstream so it will respond by decreasing our appetites. Some research suggests that some people have a mutation in the gene which produces leptin, so their hypothalamus is unable to recognize that they are overeating. However, there are many overweight individuals studied who do not have this mutation, so work is still being done in this research idea.

The hypothalamus also works in coordination with the pituitary gland, known as the “master gland.” It is chemically and neurally related to the pituitary gland, which as a result of its control, pumps hormones called releasing factors into the bloodstream. The pituitary gland has the central control over your endocrine system, so it releases hormones that are essentially important to regulating growth and metabolism for you.

 Limbic System Functions: The Cingulate Gyrus

This part is located in the middle of your brain next to the corpus callosum. Not much is known about the cingulate gyrus, but researchers suggest that this is the area that links smell and sight with pleasurable memories of previous experiences and emotions because it provides a pathway from the thalamus to the hippocampus. This area is involved with your emotional reaction to pain and how well you regulate aggressive behavior.

The anterior cingulate gyrus deals with the vocalization of emotions. It has connections with speech and vocalization areas of the frontal lobe, which includes Broca’s area, a brain piece that controls motor functions involved with speech production. People with Broca’s aphasia, or an impairment in their Broca’s area, are unable to fluently produce speech to convey what exactly is in their mind but they are able to fully comprehend the speech and writing of others.

The cingulate gyrus also is involved in the emotional bonding and attachment between a mother and her child because of the frequent vocalization that takes place between mothers and their infants, so children feel deeply attached to the voices of their mothers. Because the cingulate gyrus is connected with the amygdala, it processes emotions and is responsible for fear conditioning and relating memories to sensory information received from the thalamus.

Limbic System Functions: The Basal Ganglia

This area is an entire system within itself located deep in the frontal lobes. It organizes motor behavior by controlling your physical movements and inhibiting your potential movements until it gets the instructions to carry them out, based on the circumstances that you are in. The basal ganglia also participate in rule-based habit learning; choosing from a list of potential actions; stopping yourself from undesired movements and permitting acceptable ones; sequencing; motor planning; prediction of future movements; working memory; and attention.

In general terms the limbic system functions are as follows:

  • The sense of smell: the amygdala directly intervenes in the process of olfactory sensation.
  • Appetite and eating behaviors: The amygdala and the hypothalamus both act in this behavior. The amygdala helps in food choice and emotional modulation of food intake. Meanwhile, the hypothalamus controls the intake of these foods.
  • Sleep and dreams: While dreaming, the limbic system is one of the most active brain areas according to different neuroimaging techniques. The hypothalamus also intervenes in this case particularly the suprachiasmatic nucleus of the hypothalamus that controls the sleep-wake cycle through circadian rhythms.
  • Emotional Responses: Limbic system functions include modulating emotional responses of fear, rage and endocrine responses of fight or flight responses. In these responses, the amygdala, the hypothalamus, the cingulate gyrus and even the basal ganglia’s motor tasks work together.
  • Sexual Behavior: The limbic system also takes part in the sexual behavior through the hypothalamus and different neurotransmitters, specifically dopamine.
  • Addiction and motivation: Addiction is highly related to your reward system which in part is controlled by the amygdala. Therefore it’s important to know this when treating addicts. Relapse is usually related to the release of excitatory neurotransmitters in brain areas such as the hippocampus and the amygdala.
  • Memory: As we mentioned before emotional responses are related to the limbic system. Emotions are is also involved in the retrieval and consolidation of memory, therefore one of the limbic system functions is the emotional memory. Other memories that have influence from the limbic system are medial temporal lobe memory system in charge of making and storing new memories. As well as, Diencephalic memory system related to the storage of a recent memory, a dysfunction of this circuit results in Korsakoff’s Syndrome.
  • Social Cognition: This refers to thought processes involved in understanding and dealing with other people. Social cognition involves regions that mediate face perception, communication skills, emotional processing, and working memory. They help the complex behaviors necessary for social interactions. Limbic structures involved are the cingulate gyrus and amygdala.

To end this fantastic article we leave a video with a song to learn the limbic system functions. Hope you enjoyed the article and feel free to leave a comment below.

https://www.youtube.com/watch?v=B-RLFEWTqsY

Korsakoff Syndrome: inventing memories to compensate forgetfulness

Korsakoff syndrome is a memory problem that is usually due to alcohol abuse or overly restrictive diets that lead to vitamin deficiency. Find out here what it consists of, what are its main symptoms, causes, treatment and how we prevent it.

Korsakoff Syndrome

What is the Korsakoff Syndrome?

Korsakoff syndrome is a chronic memory disorder due to severe deficiency of thiamine, or vitamin B1.

Thiamin helps the brain produce energy from sugar. When levels fall drastically brain cells can’t generate enough energy to function properly and as a result, Korsakoff syndrome can develop.

It is believed that this deficiency causes damage to the thalamus and mammillary bodies of the hypothalamus. Mammillary bodies are brain parts or small structures with many connections to the hippocampus (an area closely related to memory). There is also general brain atrophy, loss, and neuronal damage.

Research has shown that this deficiency alters the substances responsible for transmitting signals between brain cells and storing memories. These alterations can destroy neurons and cause bleeding and microscopic scars throughout the brain tissue.

This syndrome is often, but not always, preceded by an episode of Wernicke’s encephalopathy. This consists of an acute reaction of the brain due to a severe lack of thiamine. Wernicke’s encephalopathy is a medical emergency that causes severe life-threatening brain disturbance, mental confusion, uncoordinated movement and abnormal and involuntary eye movements. Because Korsakoff syndrome is commonly preceded by an episode of Wernicke’s encephalopathy, the chronic disorder is sometimes called Wernicke-Korsakoff syndrome. However, Korsakoff can develop without a previous episode of this encephalopathy.

Korsakoff Syndrome Symptoms

Korsakoff is characterized by memory problems but retaining consciousness. This may give the impression during conversations that he is in full possession of his faculties.

However, he has severe alterations in recent memory. The person will ask the same questions over and over again, read the same page for hours, and is not able to recognize the people they have seen several times in the course of his illness.

Memory problems can be very severe, both short-term memory and long-term memory with many memory gaps or memory loss, while other skills such as social or thoughts may be relatively intact.

The main symptoms are:

  • Anterograde amnesia: inability to form new memories or learn new information.
  • Retrograde amnesia: severe loss of existing memories, prior to the beginning of the disease.
  • Confabulations: invented memories that are believed by the individual himself as real because of memory gaps.
  • Conversation with low content.
  • Lack of introspection.
  • Apathy.

Individuals with Korsakoff syndrome may show different symptoms. In some cases, a patient may continue to “live in the past”, convinced that his life and the world remain unchanged since the beginning of the disorder.

Others may display a wide variety of confabulations. Retrograde amnesia does not happen to all memories alike but affects more in recent events. The older the memories, the more they remain intact. This may be because recent memories are not fully consolidated in our brains, therefore, being more vulnerable to their loss.

Confabulations in Korsakoff Syndrome

One of the most characteristic symptoms of people with Korsakoff syndrome is the confabulations. They often “collude” or invent information they can’t remember. It is not that they are “lying”, but actually believe their invented explanations. There is still no agreed scientific explanation as to why this happens.

Korsakoff Syndrome-Confabulations

Some people may show constant, even frenetic, conspiracies. They continually invent new identities, with detailed and convincing stories that support them, to replace the reality they have forgotten.

Causes of Korsakoff Syndrome

We know that excessive intake of alcohol can harm our nervous system. In fact, in most cases, Korsakoff’s syndrome is due to alcohol abuse and its consequences on our brain.

Research has identified some genetic variations that may increase the risk of this disorder. In addition, poor nutrition can also be an important factor.

Korsakoff syndrome can also be caused by eating disorders, such as anorexia, overly restrictive diets, starvation, or sudden weight loss after surgery. Also by uncontrolled vomiting, HIV virus, chronic infection or cancer that has spread throughout the body.

Treatment of Korsakoff Syndrome

Intervention for Korsakoff syndrome should be approached from a multidisciplinary point of view, in which doctors, psychologists, and neuropsychologists will work to achieve the best results.

Some experts recommend that people who consume large amounts of alcohol or have other risks of thiamine deficiency, take oral supplements, always under the supervision of a doctor.

It is also recommended that anyone who has had a history of alcohol abuse or symptoms associated with Wernicke’s encephalopathy be injected with thiamine. For people who develop Korsakoff Syndrome, treatment with oral thiamine, other vitamins and magnesium may increase the chances of symptoms improving.

A psychological intervention will revolve around maintaining alcohol abstinence. From the neuropsychological point of view, it will help to compensate for their deficits, so that the patient can integrate socially and lead a life as normal as possible. CogniFit is a tool that trains different cognitive skills affected by Korsakoff Syndrome. 

Prognosis of Korsakoff syndrome

Some data suggest that about 25 percent of people with Korsakoff syndrome recover, half improve but don’t fully recover, and another 25 percent remain the same.

According to these researchers, the mortality rate is high, between 10 and 20%. This is mainly due to lung infection, septicemia, liver decompensation disorder and an irreversible thiamine deficiency state.

Early attention and treatment for Korsakoff symptoms is very important. Early treatment of Wernicke’s encephalopathies may improve prognosis and prevent Korsakoff’s syndrome. For example, eye problems begin to improve in hours or days, motor problems, in days or weeks. Although some 60% of patients may have some residual symptoms.

According to these authors, once the Korsakoff syndrome has been established, the prognosis is quite pessimistic. Approximately 80% of patients are left with a chronic memory disorder. These can get to learn simple and repetitive tasks that involve procedural memory (motor memory).

Cognitive recovery is slow and incomplete and reaches its highest level of recovery after one year of treatment. Although recovery may occur, it depends on factors such as age or alcohol withdrawal.

Tips for Preventing Korsakoff Syndrome

Tips for Preventing Korsakoff Syndrome

The primary advice is to reduce your alcohol intake to a minimum. The less alcohol, the better. Although we think that drink very little, the fact is that even in small amounts, we are already damaging our body.

  • A healthy and non-restrictive diet will ensure the synthesis of the vitamins needed to function properly and in particular thiamine or B1.
  • Go to the doctor whenever we detect memory problems. He will establish if it is a problem associated with normal aging or some kind of dementia.
  • Maintain a good support system, since loved ones will be of help in case any disturbing symptoms appear.
  • If you think you drink more than you do and don’t know how to quit, go to a professional who will help you reduce your alcohol intake.

Feel free to leave a comment below.

This article is originally in Spanish written by Andrea García Cerdán, translated by Alejandra Salazar.

Hippocampus: the orchestra director in the deepest part of our brain

Hippocampus. Have you ever gone blank and forgotten what you were going to say? Our brain is full of important data and information that we have stored over the years. Sometimes we have so much information that we force our brain to get rid and ignore some data. The part of the brain in charge of such important functions as memory and learning is the hippocampus. Without this brain structure, we would lose the ability to remember and feel the emotions associated with memories. You want to know more? Keep reading!

Hippocampus

What is the Hippocampus?

The hippocampus is named after the anatomist Giulio Cesare Aranzio who in the 16th century observed that this brain structure bears a great resemblance to a seahorse.

The word hippocampus comes from the Greek Hippos (horse) and Kampe (crooked). In his discovery, this part of the brain was related to the sense of smell and he advocated the explanation that the hippocampus’ main function was to process the olfactory stimuli.

This explanation was defended until in 1890 when Vladimir Béjterev demonstrated the actual function of the hippocampus in relation to memory and cognitive processes. It is one of the most important parts of the human brain because it is closely related to memory functioning and emotions. It is a small organ located within the temporal lobe (approximately behind each temple), which communicates with different areas of the cerebral cortex in what is known as the “hippocampus system.” It is a small organ with an elongated and curved shape. Inside our brain, we have two hippocampi, one in each hemisphere (left and right).

The hippocampus is known as the main structure in memory processing.

Where is the Hippocampus?

It is very well located, connected to different regions of the brain. It is located in the middle temporal lobe.

The hippocampus along with other brain structures such as the amygdala and hypothalamus form the limbic system and are responsible for managing the most primitive physiological responses. They belong to the most “ancient, deep and primitive” part of the brain, in a part of the brain known as “archicortex” (the oldest region of the human brain) that appeared millions of years ago in our ancestors to meet their most basic needs.

The blue part is the hippocampus

What does the Hippocampus do?

Among its main functions are the mental processes related to memory consolidation and the learning process. As well as, processes associated with the regulation and production of emotional states and spatial perception. How does the brain learn?

Some research has also linked it to behavioral inhibition, but this information is still in the research phase as it is fairly recent.

Hippocampus and Memory

The hippocampus is primarily related to emotional memory and declarative memory. It allows us to identify faces, to describe different things and to associate the positive or negative feelings that we feel with the memories of the lived events.

It intervenes in forming both episodic and autobiographical memories from the experiences we are living. The brain needs to “make room” to be able to store all the information over the years and for this, it transfers the temporal memories to other areas of the brain where memory storage takes place in the long term.

In this way, older memories take longer to disappear. If the hippocampus were damaged, we would lose the ability to learn and the ability to retain information in memory. In addition to allowing the information to pass into long-term memory, it links the contents of the memory with positive or negative emotions that correspond depending on whether the memories are associated with good or bad experiences.

There are many types of memory: semantic memory, visual memory, working memory, implicit memory, etc. In the case of the hippocampus, it intervenes specifically in declarative memory (it covers our personal experiences and the knowledge we have about the world), managing the contents that can be expressed verbally. The different types of memory are not governed solely by the hippocampus but are formed by other brain regions. It does not take care of all the processes related to memory loss but it covers a good part of them.

Hippocampus and Learning

It allows learning and retention of information since it is one of the few areas of the brain that have neurogenesis throughout life.

That is, it has the ability to generate new neurons and new connections between neurons throughout the life cycle. Learning is acquired gradually after many efforts and this is directly related to it. For new information to be consolidated in our brains, it is vitally important that new connections are formed between neurons. That is why the hippocampus has a fundamental role in learning.

Curiosity: Is it true that the hippocampus of London taxi drivers is bigger or more developed? Why? London taxi drivers must pass a hard memory test where they must memorize a myriad of streets and places to get the license. In the year 2000, Maguire studied London taxi drivers and observed that the posterior hippocampus was greater. He also noted that the size was directly proportional to the time the taxi drivers were working. This is because of the effect of training, learning and experience changes and shapes the brain.

Spatial perception and its relationship with the hippocampus

Another important function in which the hippocampus stands out is the spatial orientation, where it plays a very important role.

Spatial perception helps us to keep our mind and body in a three-dimensional space. It allows us to move and helps us interact with the world around us.

There have been different studies with mice where it is stated that it is an area of vital importance for orientation capacity and spatial memory.

Thanks to its correct functioning, we are capable of performing acts such as guiding us through cities we do not know, etc. However, the data concerning people are much more limited and more research is needed.

What happens when the hippocampus is disturbed?

An injury to the hippocampus can mean problems generating new memories. An brain injury can cause anterograde amnesia, affecting specific memories but leaving intact learning skills or abilities.

Lesions can cause anterograde or retrograde amnesia. Non-declarative memory would remain intact and uninjured. For example, a person with a hippocampal injury may learn to ride a bicycle after the injury, but he would not remember ever seeing a bicycle. That is, a person with the damaged hippocampus can continue to learn skills but not remember the process.

Anterograde amnesia is memory loss that affects events occurring after the injury. Retrograde amnesia, on the other hand, affects the forgetfulness generated before the injury.

At this point, you will wonder why the hippocampus is damaged when there are cases of amnesia. It is simple, this part of the brain acts as a gateway to brain patterns that sporadically retain events until they pass to the frontal lobe. One could say that the hippocampus is key to memory consolidation, transforming short-term memory into long-term memory. If this access door is damaged and you can’t save the information, it won’t be possible to produce longer-term memories. In addition to losing the ability to remember, when injuries or damage to the hippocampus occurs, you may lose the ability to feel the emotions associated with such memories, since you would not be able to relate the memories to the emotions that evoke it.

Why can the Hippocampus be damaged?

Most of the alterations that may occur in the hippocampus are produced as a result of aging and neurodegenerative diseases, stress, stroke, epilepsy, aneurysms, encephalitis, schizophrenia.

Aging and dementias

In aging in general and dementias such as Alzheimer’s disease in particular, the hippocampus is one of the areas that has previously been damaged, impairing the ability to form new memories or the ability to recall more or less recent autobiographical information. Memory problems, in this case, are associated with the death of hippocampal neurons.

Most of us know of someone who has suffered or suffers from some kind of dementia and has experienced memory loss. It is curious how the memories that remain are childhood memories or the oldest memories. You may wonder why this happens if the hippocampus is supposed to be damaged.

Well, although it is severely damaged (whether by dementia or any other type of illness), the most common memories are the oldest and they are also the most relevant to the life of the person. This is because over time these memories have been “becoming independent” of the hippocampus to be part of other structures related to long-term memory.

Hippocampus and stress

This region of the brain is very vulnerable to periods of stress because it inhibits and atrophies the neurons of this structure.

Have you noticed that when we are very stressed and we have a billion things to do sometimes we feel forgetful?

Stress and specifically cortisol (a type of hormone that is released in response to stressful moments) damage our brain structures sometimes causing neuronal death. That is why it is fundamental that we learn to remain calm and manage our emotions to get our hippocampus to remain strong and continue to exercise their functions optimally.

To know more watch the following video.

If you like this super interesting subject about memory, I recommend you watch the movie “Memento”. I’ll leave the trailer here so you can see what it’s about.

If you liked this post, leave your comment below. I will be happy to read it and answer your questions :).

This article is originally in Spanish written by Mairena Vázquez, translated by Alejandra Salazar.

Hypothalamus: the importance of hormones in the brain

What is the hypothalamus? Let’s start by painting a picture: Your stomach starts churning. It’s been hours since you last ate and you can feel the hunger intensely. You start craving every food available and it starts to become difficult to concentrate. The only thing you can think about is food and it becomes too uncomfortable to bear so you decide to eat. Does this sound familiar?

If you want to learn in depth about the hypothalamus don’t miss “the extend further” section at the end of this article!

The responsible of this whole process is the hypothalamus, a small sub-cortical structure located in the center of the brain. Being only the size of a pea, the hypothalamus is in charge of regulating different functions that are essential to our day to day life, such as eating and homeostasis. If it weren’t for the hypothalamus, we wouldn’t know when we needed to eat and we would end up dying of hunger.

It modules the food intake by increasing or decreasing hunger and satiation awareness. – Ali Inay on Unsplash

What is the Hypothalamus?

The hypothalamus and the thalamus are part of the diencephalon. They are part of the limbic system and contain the main diversity in neurons of the whole brain. It’s in charge of the autonomic nervous system and the endocrine system. It’s an endocrine gland that releases hormones in charge of modulating behaviors relating to species maintenance. It also regulates hormone secretion of the hypophysis (pituitary gland) with whom it shares the hypothalamic-pituitary-adrenal axis. It’s made of two different secreting neurons: The parvocellular (who secrete peptidic hormones) and the magnocellular (which secrete neurohypophysial hormones).

Where is the Hypothalamus located?

Having a perfect spot in the brain is important. It is located in a brain part just beneath the thalamus (from there the name) and right above the brainstem. It connects with the hypophysis through the pituitary stalk. The hypothalamus central position allows it to communicate perfectly, receiving information from different body structures and sending information to others.

What does the Hypothalamus do? How does it keep us alive?

Its functions are essential to our daily life. It is responsible for maintaining the body’s systems, including body temperature, body weight, sleep, mating, levels of aggression and even emotional regulation. Most of these functions are regulated by a chain of hormones that inhibit or release between themselves.

  • Hunger: when our body detects that we have don’t have enough energy saved, it sends Ghrelin (hunger hormone) to the hypothalamus, telling us we need to eat. It then releases a neuropeptide that produces the hunger feeling in our body. In the painted picture above our body is producing so many neuropeptides that we feel overwhelmed by hunger.
  • Satiation: when we have eaten enough, our body has to tell our brain that we don’t need any more food and that we need to stop eating. While we are eating our body produces insulin which in turn increases the production of a hormone called Leptin. Leptin travels through our blood until it reaches the ventromedial nucleus of the hypothalamus. This inhibits the production of neuropeptides, therefore, stopping the hunger sensation.
  • Thirstiness: Similar to hunger, when the body is thirsty it releases an antidiuretic hormone (vasopressin) that allows for the body not to lose water and stimulate drinking more.
  • Temperature: The blood temperature when it arrives at the hypothalamus will determine if we need to reduce or increment our body temperature. If the temperature is too high, we need to lose heat, therefore, the anterior portion with inhibit the posterior, producing certain events such as sweating, in order to lower heat. On the other hand, when the temperature is too low, the posterior portion will inhibit the anterior. This will enable the release of a thyroid stimulating hormone (TSH) and the adrenocorticotropic hormone (ACTH), both helping heat conservation.
  • Sleep: The reason why it’s so difficult to sleep with the light on is because of the hypothalamus. The sleep cycle is regulated by circadian rhythms, which in turn are managed by a set of neurons in the medial hypothalamus called the suprachiasmatic nucleus. This nucleus receives information from ganglion cells in the retina through the optic nerve tract. This way the retina is capable of detecting a change in lighting and sends the information back to the hypothalamus. The set of neurons process the information and then it is sent to the pineal gland. If there is no light, the pineal gland will secrete melatonin (sleep hormone). If there is light, the gland reduces melatonin levels which promotes wakefulness.
  • Mating and Aggression: Even though these behaviors are opposites they are highly related in the animal world and are also regulated by the hypothalamus. Some neurons are stimulated when there is mating behavior present while others when there is aggression. However, there are other neurons that happen to respond to both scenarios. The amygdala sends in information related to the aggressive area in the hypothalamus so that it can release important and pertinent hormones depending on the situation.
  • Emotions: when we experience an emotion this comes with many physiological changes. For example, when walking in a dark alley by yourself the natural response is to feel fear. Therefore the body has to prepare to respond appropriately given the circumstance. So, the hypothalamus sends information to the different parts of the body (increasing our breathing rate, contraction of the blood vessels, pupil dilation and muscle contraction). This way, the hypothalamus allows us to detect threats and run if necessary away from it. That being so, it enables the physical response to the emotion.

What relationship does the hypothalamus have with love?

One of the most important brain functions is processing emotions. These emotions are processed in the limbic system. The hypothalamus is a big part of this system since it’s in charge of letting the whole body know what emotion the brain is feeling. How emotions work in the brain is a complex task, nevertheless, the hypothalamus is responsible for how we feel love. The hypothalamus produces phenylethylamine, a type of neurotransmitter with similar effects to amphetamines. This is the reason why when we fall in love we feel happy and euphoric. This neurotransmitter also leads to an increase in adrenaline and noradrenaline, which rises the heartbeat, oxygen levels and blood pressure (triggering the sensation of your “heart skipping a beat”).

On the other hand, the brain also produces dopamine and serotonin, which allows us to focus our attention on the person that makes us feel these emotions and regulate our emotions accordingly. Consequently, the hypothalamus is very important since without it, we wouldn’t be able to fall in love.

Without the it, we wouldn’t be capable of falling in love.

What link is there between the hypothalamus and the hypophysis (pituitary gland)?

The hypothalamus regulates the emission of hormones from the hypophysis. The hypophysis is also an endocrine gland and its under the hypothalamus, protected by the sella turcica (bone structure in the base of the cranium). The pituitary gland function is to secrete hormones, under the hypothalamus command, through the blood that our body needs to maintain homeostasis (level our temperature or balance different hormones). Their relationship is so close that they form the hypothalamic-pituitary-adrenal axis and they couldn’t work separately. The hypophysis allows for the hypothalamus to extends its effects to the rest of the body.

What happens when the hypothalamus is disturbed? In what disorders o diseases is the hypothalamus involved?

Given the relevance of the hypothalamus, an injury in any of the hypothalamus’ nuclei can be fatal. For example, if the satiation center is damaged (not being capable of being satiated), we wouldn’t stop eating and therefore eat non-stop with a high risk to what this conveys. Some of the most frequent pathologies are:

  • Diabetes insipidus: It is when the supraoptic, paraventricular and the supraoptic hypophysial fasciculus nuclei are injured. Due to low production of ADH, there is more liquid intake and more urine output.
  • Injury in the caudolateral hypothalamus: If this region is damaged all sympathetic activity of the nervous system will diminish including body temperature.
  • Injury in the medial hypothalamus: all parasympathetic activity of the nervous system will be damaged but the body temperature will rise.
  • Korsakoff Syndrome: with the mammillary nucleus (related to the hippocampus) altered, there will be anterograde amnesia, the person will have difficulty remembering new information in long-term memory. Since remembering is difficult, people with this syndrome tend to use fabrications to fill the gaps. This disorder is usually associated with chronic alcoholism it can also happen as an alteration in the mammillary tubers and their connections.

To extend further…

What hormones are produced in the hypothalamus?

The hypothalamus function is through hormone release. Some of the hormones are:

  • Neurohormones: Antidiuretic hormone and oxytocin.
  • Hypothalamic factors: The hypothalamus uses corticotropin-releasing hormone (CRH or corticoliberin), thyrotropin-releasing hormone (TRH), gonadotropin-releasing hormone (GnRH or gonadoliberin), growth hormone–releasing hormone (GHRH or somatoliberin).

Of what nuclei is the hypothalamus made of and what is their purpose?

Each nuclei has a main purpose:

  • Arcuate nucleus: it’s part of the emotional function of the hypothalamus. Its endocrine function consists of synthesizing hypothalamic peptides and neurotransmitters. In charge of liberating the gonadotropin hormone.
  • Anterior hypothalamic nucleus: it’s in charge of releasing the heat when sweating. It’s also in charge of liberating thyrotropin in the hypophysis.
  • Posterior hypothalamic nucleus: Its function is to keep the heat inside the body when it’s cold.
  • Lateral hypothalamic nucleus: it regulates thirst and hunger. When it detects a lack of sugar or water it tries to find homeostasis.
  • Mammillary nucleus: given its connections with the hippocampus, it’s related to the memory.
  • Paraventricular hypothalamic nucleus: It regulates hormone release from the hypophysis (oxytocin, vasopressin, and corticotropin).
  • Preoptic Nucleus: it influences functions such as nutrition, locomotion, and mating.
  • Supraoptic nucleus: It regulates arterial pressure and liquid equilibrium through the antidiuretic hormone.
  • Suprachiasmatic nucleus: In charge of hormones relating to circadian rhythms.
  • Ventromedial nucleus: its role consists of regulating satiation.

From where does the hypothalamus receive information? Where does it send it?

The hypothalamus has great different connections due to the brain area where it’s located. On one side, it receives information from other structures (afferent) and then sends information to other parts of the brain (efferent).

Afferents

  • Reticular cephalic flexure: From the cephalic flexure to the lateral mammillary nucleus.
  • Median prosencephalic fasciculus: from the olfactory region, septal nuclei and amygdala region to the preoptic lateral and lateral hypothalamus.
  • Stria terminalis: from the hippocampus to the septum and mammillary nucleus.
  • Precommissural fornix fibers: connect with the dorsal hypothalamic area, septal nuclei and preoptic lateral nucleus.
  • Postcommissural fornix fibers: takes the information to the medial mammillary nucleus.
  • Retinohypothalamic fibers: Take information from the amount of light in the retina and sends it to the suprachiasmatic nucleus for circadian rhythm regulation.
  • Cortical projections: receives information from the cerebral cortex and sends it to the hypothalamus.

Efferents

  • Dorsal longitudinal fasciculus: from the medial and periventricular regions of the hypothalamus to the grey matter.
  • Mammillary efferent fibers: From the medial mammillary nucleus to the anterior thalamic nuclei, and also from the mesencephalon to the ventral nuclei.
  • Supraoptic nucleus: from the supraoptic nuclei to the posterior lobe of the hypophysis.
  • Tuberohypophyseal: from the nuclei arcuati to the infundibular stalk.
  • Descendent projections to the brainstem and spinal cord: from the paraventricular nucleus to the solitary nucleus and the ventrolateral regions of the medulla oblongata.
  • Efferent projections to the suprachiasmatic nucleus: it connects directly with the pineal gland.

Questions? Leave a comment below 🙂

This article was originally written in Spanish by David Asensio Benito, translated by Alejandra Salazar.