Brain Imaging Uncovers Uneven Aging Patterns in Sensory Regions

Researchers from the German Center for Neurodegenerative Diseases (DZNE), the University of Magdeburg, and the Hertie Institute for Clinical Brain Research at the University of Tübingen have found that the region of the brain responsible for processing touch does not age uniformly. The study, published in Nature Neuroscience, combined high-resolution brain scans from adults aged 21–80 years with comparative work in mice.

The cerebral cortex is a thin, folded layer of tissue that typically becomes thinner with age, often linked to the loss of neurons and a decline in certain abilities. In this study, researchers examined the “primary somatosensory cortex,” a strip of tissue on both sides of the head that processes tactile information from the body.

“This brain area is relevant for the perception of one’s own body and for interacting with the environment. When I pick up a key, grasp a door handle or even walk, I constantly need haptic feedback to control my movements. The corresponding stimuli converge in this area and are also processed here."

Dr. Esther Kühn.

Imaging at high resolution

Using magnetic resonance imaging (MRI) at a magnetic field strength of 7 tesla, the team was able to visualise this brain region in unprecedented detail, distinguishing tissue layers about the size of a grain of sand. They identified several distinct layers, each with specific structural and functional roles.

While the cortex overall became thinner with age, the middle and upper layers showed unexpected resilience. In some participants, these layers were even thicker in older age, suggesting that frequent use of certain neural pathways can help maintain their structure.

Different layers, different functions

The middle layer acts as a main entry point for tactile signals, while upper layers are involved in integrating information, such as coordinating input from neighbouring fingers during object handling. These layers appeared largely preserved across age groups.

By contrast, the deepest layers of the cortex, which are involved in adjusting sensory signals depending on context, showed clear thinning in older adults. This function, known as modulation, can explain why certain tasks, such as typing in a noisy environment, may become more difficult with age despite stable fine motor skills.

Signs of compensation

Although the deepest layers lost volume, they also showed an increase in myelin, a fatty substance that insulates nerve fibres and aids signal transmission. The researchers attribute this to a rise in certain neuron types that can enhance signal precision. Similar patterns were observed in the mouse experiments, although the compensatory changes appeared to diminish at very advanced ages.

Implications for sensory processing

The findings suggest that brain regions that remain highly active through frequent use may retain structural integrity for longer. Conversely, areas with reduced stimulation may be more vulnerable to decline. Variations in how layers age could help explain why some sensory and motor skills are preserved with age, while others are more affected.

Reference: Liu P, Doehler J, Henschke JU, et al. Layer-specific changes in sensory cortex across the lifespan in mice and humans. Nat Neurosci. 2025. doi: 10.1038/s41593-025-02013-1

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