Rats feel textures more sharply without light
People who are blind tend to have a finer sense of touch. But how does that work in the brain? New research in rats shows that the brain encodes touch signals very differently in darkness compared to light. That tells us something about how senses and brain ageing are connected.
When one sense is removed, the brain adapts. This phenomenon, known as sensory plasticity, has long been documented in behavioural experiments. But what exactly changes in the brain remained unclear. Rats were trained on a treadmill to distinguish textures: rough versus smooth. Electrodes recorded brain activity in the primary somatosensory cortex, the area that processes touch signals, under both light and dark conditions.
Touch signals become more distinct in the dark
The study, published in eLife, shows that the brain patterns for ‘rough’ and ‘smooth’ were more clearly distinguishable in the dark than in the light. In other words, the brain encoded touch more precisely when there was no visual input. Standard analyses looking at signal strength missed this difference entirely. Only a deep learning algorithm (a type of artificial intelligence that recognises patterns in complex data) could detect it.
That is methodologically significant: it suggests that many subtle brain adaptations remain invisible with classical measurement tools. The findings come from rats and do not automatically apply to humans.
Why this is relevant to longevity
As we age, the brain’s sensory plasticity declines. It becomes harder for the brain to compensate when a sense deteriorates, such as hearing loss or vision decline in later life. Understanding how the brain reorganises sensory processing is a step towards interventions that keep that adaptability intact for longer. That is still a long way off, but the mechanisms revealed here are relevant to the broader field of brain ageing.
Search terms to explore further: sensory plasticity somatosensory cortex, cross-modal compensation senses, neural coding texture perception