Skip to main content
Open Access Publications from the University of California

UC Berkeley

UC Berkeley Previously Published Works bannerUC Berkeley

An Asymmetric Increase in Inhibitory Synapse Number Underlies the Development of a Direction Selective Circuit in the Retina


Neural circuits rely upon a precise wiring of their component neurons to perform meaningful computations. To compute the direction of motion in the visual scene, the direction selective circuit in the mouse retina depends on an asymmetry in the inhibitory neurotransmission from starburst amacrine cells (SACs) to direction selective ganglion cells (DSGCs). Specifically, depolarization of a SAC on the null side of a DSGC causes a threefold greater unitary inhibitory conductance than depolarization of a SAC on the preferred side. This asymmetry emerges during the second postnatal week of development, but its basis remains unknown. To determine the source of this asymmetry in inhibitory conductance, we conducted paired recordings between SACs and DSGCs at the beginning and end of the second postnatal week. We replaced calcium with strontium to promote asynchronous neurotransmitter release and produce quantal events. During the second postnatal week the quantal frequency but not the quantal amplitude of synaptic events increased more than threefold for null-side SAC-DSGC pairs but remained constant for preferred-side pairs. In addition, paired-pulse depression did not differ between SACs located on the null and preferred sides of DSGCs, indicating that all inhibitory SAC synapses onto a DSGC exhibit the same probability of release. Thus, the higher quantal frequency seen in null-side pairs results from a greater number of inhibitory synapses, revealing that an asymmetry in synapse number between SACs and DSGCs underlies the development of an essential component in the retina's direction selective circuit.

Many UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.

Main Content
For improved accessibility of PDF content, download the file to your device.
Current View