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. Author manuscript; available in PMC: 2015 Mar 1.
Published in final edited form as: Mol Psychiatry. 2014 Jul 22;19(9):966–977. doi: 10.1038/mp.2014.68

Figure 2. Inhibitory neuron identity and local circuit regulation of excitatory pyramidal cell function in controls and major depression.

Figure 2

(A) Pyramidal neurons (PYR) receive inhibitory input on dendrites from SST-positive GABA neurons, and in the perisomatic region from PV-positive GABA neurons. Excitatory signal input is therefore regulated by SST neurons whereas PV neurons regulate excitatory signal output. Furthermore, PV-neurons are reciprocally connected by inhibitory input, and are critical in the generation of synchronous firing in the gamma range (sawtooth symbols), mediating propagation of information across ensembles of neurons. (B) In PACC, reduced expression of markers for SST and PV neurons and of GABA synthesis genes suggests reduced inhibition of input and output of information (and potentially less synchronous) in MDD. (C) In DLPFC selective reduction in the expression of markers for SST neurons suggests reduced inhibition of input, but intact output, potentially resulting in overall increased information transfer (however see section PACC and DLPFC reciprocal inhibition for a putative overriding effect of increased PACC activity on DLPFC activity under resting state condition). Red codes for excitatory signal, and blue and green for inhibitory signals.