Abstract
The rules by which neurons in neocortex choose their synaptic partners are not fully understood. In sensory cortex, intermingled neurons encode different attributes of sensory inputs and relay them to different long-range targets. While neurons with similar responses to sensory stimuli make connections preferentially, the relationship between synaptic connectivity within an area and long-range projection target remains unclear. We examined the local connectivity and visual responses of primary visual cortex neurons projecting to anterolateral (AL) and posteromedial (PM) higher visual areas in mice. We found that layer 2/3 neurons preferentially connected to those projecting to the same long-range target and avoided connecting to cells projecting to different targets. Although AL and PM projection neurons differed in their visual responses, these differences were not sufficient to explain the lack of connectivity between them. Thus, projection target, alongside response similarity, is a key determinant of local synaptic connectivity in cortical microcircuits.
