Summary: Researchers report that the brain’s touch-processing region ages in a layer-specific pattern: some cortical layers remain robust while others thin with age. High-resolution 7T MRI scans show that the middle and upper layers of the primary somatosensory cortex often remain stable or even thicken, likely reflecting continued sensory use, while deeper layers that modulate touch tend to thin. The findings point to ongoing neuroplasticity and suggest that sustained sensory engagement may help preserve function.
A collaborative study by scientists at DZNE, the University of Magdeburg, and the Hertie Institute for Clinical Brain Research at the University of Tübingen combined advanced human imaging and animal experiments to examine how sensory cortex structure and function change over the lifespan. The results, published in Nature Neuroscience, clarify how layered cortical architecture relates to age-related changes in sensory processing.
Key points
- Layer-specific aging: Middle and upper cortical layers are relatively preserved with age, whereas deep layers show thinning.
- Use-dependent preservation: Continual sensory input appears to help maintain structure, providing evidence of neuroplasticity in older adults.
- Compensatory changes: Deep-layer myelination can increase with age, suggesting partial compensation for structural loss.
Primary somatosensory cortex: a processor for touch
The primary somatosensory cortex, located along the top sides of the head, is the main cortical area where touch signals are received and processed. It plays a central role in perceiving the body and guiding interactions with the environment—everything from grasping a key to sensing surface textures. Because this region integrates continuous tactile input, the researchers chose it as an ideal target to study layer-specific aging.
High-resolution imaging reveals layered changes
Using 7 Tesla MRI, the team mapped the primary somatosensory cortex at submillimeter resolution, capturing the distinct, thin cortical layers that standard scanners cannot resolve. About 60 healthy adults aged 21 to 80 participated in the study. The high-field scans allowed the investigators to distinguish layers by their myelin content and to combine structural measures with functional MRI and behavioral tests of tactile sensitivity and hand motor skills.
Contrary to the expectation that the cortex uniformly thins with age, the study found a nuanced, layer-specific pattern. The input layer (middle layer IV) and the layers above it were often stable or even more myelinated in older adults, features associated with extended sensory input signals and robust processing of tactile information. These observations suggest that regions heavily and continually stimulated by touch may retain structure and function longer than other parts of the cortex.
Deep layers: thinning with partial compensation
In contrast, the lowest cortical layers showed age-related thinning. Those deep layers are responsible for modulating incoming tactile signals—amplifying or suppressing them depending on attention and context. Reduced thickness in these layers could explain why older individuals have more difficulty filtering distracting stimuli: for instance, an older person may struggle to ignore background noise or competing tactile inputs while performing a task.
Despite the structural thinning, the researchers observed increased myelin content in the deep layers of older participants. Parallel experiments in mice showed similar layer-specific trends and indicated that increases in certain neuron types—cells that help sharpen or regulate signals—may underlie this myelination rise. These compensatory mechanisms may partially offset the effects of cellular loss, at least until very advanced age.
Use it and preserve it
The study supports the idea that cortical circuits exposed to frequent stimulation maintain greater integrity over time. The research team reports anecdotal evidence from a participant born with a missing limb: the corresponding sensory input layer for that absent limb was comparatively thinner, consistent with long-term reduced input. More generally, sensorimotor abilities that are practiced repeatedly—such as typing—can remain stable into older age, while tasks requiring flexible modulation in noisy or distracting environments become harder as deep-layer function declines.
Implications for aging and prevention
Findings highlight both vulnerability and resilience within cortical architecture. The preservation of input and upper layers points to enduring plasticity, while depth-layer thinning and subsequent compensatory myelination reveal complex adaptive responses. The authors suggest these mechanisms might be targets for interventions that promote sensory engagement and potentially strengthen compensatory processes, though further research is needed to determine if and how such approaches could be applied in humans.
About this research
Author: Marcus Neitzert
Source: DZNE
Contact: Marcus Neitzert – DZNE
Image credit: Neuroscience News
Original research: “Layer-specific changes in sensory cortex across the lifespan in mice and humans” by Esther Kühn et al., published in Nature Neuroscience. The study used multimodal imaging and histology to compare layer-specific structural and functional changes across ages and species.
Abstract summary
Cortical layers segregate processing across species, but how layer architecture changes with age and how those changes affect sensory function remain unclear. Layer-specific 7T MRI of the primary somatosensory cortex in younger and older adults revealed enlargement and increased myelination of the input layer (IV) in older adults, along with extended sensory input signals. Age-related cortical thinning was driven primarily by deep layers and accompanied by increased myelination, with no clear evidence of reduced inhibition. Mouse calcium imaging and histology supported increased sensory-evoked activity and changes in parvalbumin expression, plus dynamic layer-specific myelination across age groups. Multimodal imaging demonstrates that middle and deep layers show specific sensitivity to aging across species.