Featured Finding Figure
In neocortex, GABAergic interneurons that contain the calcium binding protein parvalbumin (PV) constitute the fast-spiking (FS) electrophysiological subclass. In schizophrenia, this class of interneurons exhibits reduced levels of PV expression. PV is an intracellular calcium buffer protein which affects the response of GABAergic synapses to repetitive stimulation. In the monkey dorsolateral prefrontal cortex (PFC) in vivo, FS interneurons fire repetitively during working-memory tasks. To gain further understanding of the functional role of monkey PFC FS neurons, we described the in vitro electrophysiological properties of FS interneurons and their synaptic connections with pyramidal cells in layers 2/3 of areas 9 and 46. As shown in Figs. A-B, we found that FS neurons could be divided into two main morphological groups, chandelier (Fig. A) and basket neurons (Fig. B), with very similar electrophysiological properties but significantly different horizontal spread of the axonal arborization. In paired cell recordings, unitary inhibitory postsynaptic potentials (IPSPs) elicited by FS neurons in pyramidal cells had rapid time course, small amplitude at resting membrane potential, and were mediated by GABAA receptors. Repetitive FS neuron stimulation, partially mimicking the repetitive firing of interneurons in vivo, produced short-term depression of the unitary IPSPs (Figs. C-D), present at connections made by both basket and chandelier neurons and due at least in part to presynaptic mechanisms. These results suggest that FS neurons and their synaptic connections with pyramidal cells have homogeneous physiological properties. Thus, different functional roles of basket and chandelier neurons in the DLPFC in vivo must arise from the distinct properties of the interneuronal axonal arborization or from a different functional pattern of excitatory and inhibitory connections with other components of the DLPFC neuronal network.
Konopaske GT, Dorph-Petersen KA, Sweet RA, Pierri J, Zhang W, Sampson A, and Lewis DA: Effect of chronic antipsychotic exposure on astrocyte and oligodendrocyte numbers in macaque monkeys. Biological Psychiatry 32: 1216-1223, 2007.

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David A. Lewis, M.D. | Department of Psychiatry | University of Pittsburgh
3811 O'Hara Street, Biomedical Science Tower W1654
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