Fig. 2: Inhibitory subclasses and the inhibition of inhibition.
From: Inhibitory specificity from a connectomic census of mouse visual cortex
a, Example of an inhibitory axon making synaptic outputs (green dots) onto specific locations on a target pyramidal cell (purple). b, Dendritic compartment definitions for excitatory neurons. c, Cartoon definition for a multisynaptic connection (left) and the synapses in the multisynaptic connection considered ‘clumped’ along the presynaptic axon (right). d, Targeting features for all inhibitory neurons, measured as fraction of synapses onto column cells (for fraction clumped only: synapses in multisynaptic connections). e, Relationship between anatomical connectivity categories (top), typical associated classical cell categories (middle) and anatomical examples (bottom) of the inhibitory subclasses. Dendrite is darker, axon lighter. f, Adjacency matrix for inhibitory neurons. Each dot represents a connection from a presynaptic to a postsynaptic cell, with dot size proportional to synapse count. Dots are coloured by presynaptic subclass and ordered by subclass, connectivity group (Fig. 5) and soma depth. g, Standard model of inhibition of inhibition between molecular subclasses. h, Mean number of synaptic inputs a postsynaptic cell received from all cells of a given presynaptic subclass. i, Potential InhTC targets. j, Synaptic output fraction each InhTC (columns) places onto target subclasses (rows). InhTCs are clustered into two subtypes: one targeting DistTCs (InhTCdist) and another targeting PeriTCs (InhTCperi). k, Connectivity diagram for InhTCperi suggested by data. l, Morphology of example InhTCdist. m, Morphology of all InhTCperi. n, Median synapse size (arbitrary units measuring voxels in segmented cleft) from InhTCdist (left) and InhTCperi (right) onto inhibitory subclasses. Error bars indicate 95% confidence interval. T-test P-values indicated: *, P < 0.05; ***, P < 0.005 after Holm–Sidak correction. o, Distribution of synapses per connection for InhTCperi and InhTCdist onto their preferred and non-preferred targets. Scale bars, 500 µm. CCK, cholecystokinin; frac, fraction; multisyn, multisynaptic; no, number of.
