Functionally distinct GABAergic amacrine cell types regulate spatiotemporal encoding in the mouse retina

GABA (γ-aminobutyric acid) is the primary inhibitory neurotransmitter in the mammalian central nervous system. GABAergic neuronal types play important roles in neural processing and the etiology of neurological disorders; however, there is no comprehensive understanding of their functional diversity. Here we perform two-photon imaging of GABA release in the inner plexiform layer of male and female mice retinae (8–16 weeks old) using the GABA sensor iGABASnFR2. By applying varied light stimuli to isolated retinae, we reveal over 40 different GABA-releasing neuron types. Individual types show layer-specific visual encoding within inner plexiform layer sublayers. Synaptic input and output sites are aligned along specific retinal orientations. The combination of cell type-specific spatial structure and unique release kinetics enables inhibitory neurons to sculpt excitatory signals in response to a wide range of behaviorally relevant motion structures. Our findings emphasize the importance of functional diversity and intricate specialization of GABAergic neurons in the central nervous system. GABA is the primary inhibitory neurotransmitter in the central nervous system. Using two-photon GABA imaging, Matsumoto et al. reveal over 40 GABA neuron types in the mouse retina, each uniquely filtering visual features.