A research group at Nagoya University and others has clarified the mechanism by which tactile (somatosensory) ability is enhanced in blinded mice.
Normally, visual information is processed in the visual cortex in the brain, but when sight is lost, the visual cortex will instead process other sensory information such as hearing and touch (somatosensory), resulting in A phenomenon called “intersensory plasticity” occurs, in which auditory and tactile sensations become sharper.It is known that the visual cortex of mice also responds to somatosensory information from whisker stimulation after visual deprivation, but the mechanism of this heterosensory plasticity has not been elucidated.
In this study, we first found that there is a potential transmission pathway from the somatosensory cortex that processes tactile information from the whiskers of mice to the higher visual cortex, but it is suppressed under normal conditions. .However, in mice whose vision was blocked soon after birth, microglia, one of the glial cells in the higher visual cortex, suppressed inhibitory neurons (parvalbumin-positive neurons) to excitatory neurons (pyramidal cells). removed the sex synaptic input.As a result, the inhibitory system of the transmission pathway from the somatosensory cortex to the higher visual cortex is released, and the higher visual cortex of visually deprived mice responds to somatosensory information from whisker stimulation.In addition, we also identified the mechanism by which microglia release and remove inhibitory synapses by dissolving the extracellular matrix using a molecule called matrix metalloproteinase 9.
The somatosensory abilities of visually deprived mice, tested by sensory training learning, were improved over normal mice.However, when the neural activity was restricted to the higher visual cortex, it decreased to the same level as in normal mice.In other words, the reorganization of neural circuits in the higher visual cortex by microglia after visual deprivation is, so to speak, ``removing the stopper and processing non-specialized information,'' increasing neural responses to somatosensory perception. , contributes to the improvement of remaining somatosensory functions.
The results of this research are expected to lead to the proposal of a new mechanism related to the integration and classification of various sensory information in the brain.
Paper information:[Cell Reports] Microglia Enable Cross-Modal Plasticity by Removing Inhibitory Synapses
