SYNAPTIC DIVERSITY SIGNATURES OF SENSORY EXPERIENCE IN THE CORTEX

Sensory cortices share common organisational and functional principles, featuring remarkable capacity for plasticity, whereby one sensory cortex can partially assume the function of another when typical input is lost. At the same time, these regions appear specialised for their respective sensory modalities, exhibiting distinct anatomical features, developmental trajectories, cytoarchitecture, and input pathways that supports modality-specific perception. While such circuit- and cell-type differences are well described, it remains unclear how sensory input may shape region-specific specialisation of synapse populations, or how the absence of input may remodel these synapses.
To address this, we use synaptome mapping which enables us to visualise and classify billions of individual synapses based on their molecular and structural features, revealing synapse diversity at a brainwide scale. Currently we are mapping synapse types and subtypes across the primary somatosensory, visual, and auditory cortices in the mouse. Our preliminary analysis reveals region-specific differences in synapse subtype distributions, with the strongest divergence in the thalamoreceipient layer 4, consistent with input-driven specialisation. Moving beyond canonical regional boundaries, we are employing binning analysis to generate high-resolution cortical maps of synapse distribution patterns that uncover continuous gradients of synaptic parameters across layers and cortical space.
Building on these findings, we will test how sensory input and its absence reshapes synaptome architecture using models of deafness and auditory stimulation. We aim to define how altered auditory experience reprograms synapse populations within and beyond auditory circuits, identify synapses selectively associated with hearing, and determine how cortical synaptic gradients are perturbed by sensory deprivation.