SSA: Memories of touch: The role of higher order cortical areas in processing and remembering tactile textures.

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Humans mainly use the visual system to understand and interpret the world, making it difficult for us to imagine theworld of touch in any detail or understand its importance. Yet if we were unable to recognise objects from the waythey feel, we would then most likely realise the wealth of information yielded up by this vital sense. This studentshipproject is aimed at understanding how texture information is processed in the brain and how the brain adapts andlearns to attribute meaning to particular textures. To do this we will study texture processing in the rodent brain.Rodents are nocturnal animals and are therefore highly reliant on tactile information for identifying objects in theirenvironment. Rodents are experts at touch. In laboratory tasks, we have found that they preferentially use theirwhiskers to identify different textures. Remarkably, they are able to distinguish between surfaces that differ in particlesize by just 18um, a distance that is orders of magnitude smaller than the spacing between whiskers on the face.Building on the findings of an earlier BBSRC PhD studentship (Pacchiarin et al. 2017; 2020), we propose to extend ourinvestigation of how higher order somatosensory processing occurs in the cerebral cortex. We have established thatprimary somatosensory cortex (SI) is necessary for texture discrimination in freely moving mice by using chemo-genetic methods to inactivate temporarily SI during a whisker-dependent discrimination. Furthermore, using in vivo2-photon microscopy of dendritic spines, we have found that SI neurones undergo structural synaptic plasticity duringtexture discrimination, if and only if the mice learn the discrimination. The next step is to determine how textureinformation processing proceeds from SI to the hippocampus via the hypothesised ventral stream pathway. We willinitially study SII, which is strongly connected to SI, projects ventrally to Perirhinal cortex, and responds to tactiletextures. We will inactivate SII during the learning task using DREADDs and measure whether the mice still learn thetexture discrimination. These studies will lead to an understanding of how tactile sensory experience can be stored asmemories that are used to direct future choices.