The Organization and Development of Cortical Interneuron Presynaptic Circuits is Area Specific

Abstract

Parvalbumin and somatostatin inhibitory interneurons gate information flow in discrete cortical areas that compute sensory and cognitive functions. However, despite the considerable differences between cortical regions, both of these interneuron subtypes are genetically invariant and are thought to form similar canonical circuits regardless of which cortical region they are imbedded in. Here we investigate the hypothesis that this is achieved through selective and systematic variations in the afferent connectivity of inhibitory interneurons during development. To this end, we examined the development of the inputs impinging upon parvalbumin and somatostatin interneurons within distinct cortical areas. We found that interneuron afferents showed little evidence of being globally stereotyped. Rather, each cell-type displayed characteristic regional connectivity and distinct developmental dynamics by which this is achieved. Moreover, afferents dynamically regulated during development are disrupted by early sensory deprivation or in a model of Fragile X syndrome. These data provide a comprehensive map of interneuron afferents across cortical areas and reveal the region-specific logic by which these circuits are established during brain development.