Study finds touch-processing brain layers can strengthen as we get older
New research shows that some layers of the human brain’s touch center actually become thicker with age, rather than thinning out. Using detailed MRI scans, scientists have found that while certain layers of the brain’s surface shrink as people get older, others remain stable or even increase in thickness. These findings reveal that the human brain stays adaptable much longer than previously believed, especially when it comes to processing touch.
Note: This article is intended for general information and educational purposes. It summarizes scientific research in accessible language for a broad audience and is not an official scientific press release.
The human brain changes over time, but new findings suggest that not all parts follow the same path. Scientists from the German Center for Neurodegenerative Diseases (DZNE), Otto von Guericke University Magdeburg, and their international partners have discovered that the brain’s touch-processing region remains surprisingly resilient as we age. According to their study, published in Nature Neuroscience on August 11, 2025, some layers of the brain’s cortex even grow thicker in older adults. The research involved nearly 60 healthy volunteers between the ages of 21 and 80, along with laboratory studies in mice.
What the Researchers Investigated
The research team set out to explore how different layers of the primary somatosensory cortex – the part of the brain responsible for the sense of touch – change with age. They aimed to find out if all layers thin equally, or if some might show greater resistance or even growth. To answer this, the scientists examined healthy people of different ages and also conducted detailed experiments in mice. According to the authors, their goal was to describe exactly how aging affects each layer of this brain region, both in structure and function.
As highlighted by Science Daily, the primary somatosensory cortex is only a few millimeters thick and arranged in numerous folds. It is located along a strip about a finger’s width wide across the top of the head and is crucial for processing tactile signals needed for everyday actions like picking up keys or opening a door. This part of the brain is directly involved in how we sense our own bodies and interact with our surroundings.
How the Study Was Conducted
About 60 healthy adults (men and women) between ages 21 and 80 participated in the human part of the study. They underwent ultra-high-resolution 7-Tesla MRI brain scans that focused on the primary somatosensory cortex. The scans allowed researchers to examine the brain in “layers,” similar to looking at the different levels of a cake. Volunteers also took part in simple tests of touch and hand movement, such as distinguishing textures and moving pegs.
According to Science Daily, the researchers used advanced MRI scanners that could capture brain structures as small as a grain of sand – allowing them to distinguish extremely thin layers within the cortex, each with its own unique architecture and function.
To compare results and investigate biological details, the researchers studied mice at different ages. Using special imaging and tissue analysis, they measured the thickness of brain layers, myelin content (which helps with nerve signal transmission), and the number of certain types of brain cells.
What Makes This Study New
As noted by the authors, earlier research usually described age-related thinning of the brain’s outer layer as a general loss across all layers. This study, however, was able to distinguish individual layers and showed that aging does not affect them all in the same way. Both the middle layer (which acts as a gateway for sensory signals) and the layers above it were found to be especially resilient, sometimes even thickening in older age.
The study is among the first to show that, in addition to the middle input layer, upper layers are also remarkably resistant to aging, which may help preserve function. The different layers were identified based on their myelin content, an essential factor for the transmission of nerve signals.
Key Findings from the Study
According to the study, researchers found the following:
- The overall thickness of the primary somatosensory cortex decreases with age, mainly due to thinning of the deep layers (layers V and VI).
- The middle layer (layer IV), which receives most sensory input, actually gets thicker and shows higher levels of myelin in older people compared to younger ones.
- The main borders between finger representations in the brain’s touch center stay clear in both younger and older adults. In other words, even in old age, the brain continues to clearly distinguish sensations coming from each individual finger.
- Upper layers are particularly involved in the interaction between neighboring fingers – important for coordinated movements.
- The findings in mice mirrored those in humans: older mice also showed increased thickness and myelination in the sensory input layers, along with changes in brain cell activity.
- Only the deeper layers showed significant age-related thinning, and these layers are involved in modulating sensory signals based on attention or context.
- Increased thickness and myelination in the input layer (layer IV) may help maintain sensory abilities as other parts of the cortex become thinner.
- The study did not find strong evidence linking changes in the thickness or myelin of specific layers to declines in touch or hand skills in older adults.
- There was a unique participant born with only one arm, who showed a thinner input layer on the corresponding side, suggesting the importance of sensory input for layer thickness.
Authors’ Conclusions
The authors conclude that the aging process in the brain’s sensory cortex is “layer-specific.” While the deeper layers shrink, the input layer and upper layers can grow thicker and more myelinated, which may help the brain adapt to changes in sensory input over time. As Science Daily points out, this supports the idea that the brain “preserves what is used intensively,” reflecting ongoing neuroplasticity.
At the same time, the researchers state that thinning of the deep layers may eventually contribute to decline in brain functions, especially in very old age. The results apply to healthy aging; more research is needed to see how these findings relate to brain diseases or other brain regions. According to the authors, it is important to study each layer separately to fully understand how the brain changes with age.
References
- Liu, P. et al. Layer‑specific changes in sensory cortex across the lifespan in mice and humans, Nature Neuroscience, Published: 11 August 2025. https://doi.org/10.1038/s41593-025-02013-1
- Scientists discover brain layers that get stronger with age. Science Daily, 12 August 2025. https://www.sciencedaily.com/releases/2025/08/250811104229.htm
The information in this article is provided for informational purposes only and is not medical advice. For medical advice, please consult your doctor.
