Combining mGRASP and Optogenetics Enables High-Resolution Functional Mapping of Descending Cortical Projections.

ABSTRACT: We have applied optogenetics and mGRASP, a light microscopy technique that labels synaptic contacts, to map the number and strength of defined corticocollicular (CC) connections. Using mGRASP, we show that CC projections form small, medium, and large synapses, and both the number and the distribution of synapse size vary among the IC regions. Using optogenetics, we show that low-frequency stimulation of CC axons expressing channelrhodopsin produces prolonged elevations of the CC miniature EPSC (mEPSC) rate. Functional analysis of CC mEPSCs reveals small-, medium-, and large-amplitude events that mirror the synaptic distributions observed with mGRASP. Our results reveal that descending ipsilateral projections dominate CC feedback via an increased number of large synaptic contacts, especiall

SUBMITTER: Song JH 

PROVIDER: S-EPMC6083038 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature