Cluster Analysis–Based Physiological Classification and Morphological Properties of Inhibitory Neurons in Layers 2–3 of Monkey Dorsolateral Prefrontal Cortex

Abstract

In primates, little is known about intrinsic electrophysiological properties of neocortical neurons and their morphological correlates. To classify inhibitory cells (interneurons) in layers 2–3 of monkey dorsolateral prefrontal cortex we used whole cell voltage recordings and intracellular labeling in slice preparation with subsequent morphological reconstructions. Regular spiking pyramidal cells have been also included in the sample. Neurons were successfully segregated into three physiological clusters: regular-, intermediate-, and fast-spiking cells using cluster analysis as a multivariate exploratory technique. When morphological types of neurons were mapped on the physiological clusters, the cluster of regular spiking cells contained all pyramidal cells, whereas the intermediate- and fast-spiking clusters consisted exclusively of interneurons. The cluster of fast-spiking cells contained all of the chandelier cells and the majority of local, medium, and wide arbor (basket) interneurons. The cluster of intermediate spiking cells predominantly consisted of cells with the morphology of neurogliaform or vertically oriented (double-bouquet) interneurons. Thus a quantitative approach enabled us to demonstrate that intrinsic electrophysiological properties of neurons in the monkey prefrontal cortex define distinct cell types, which also display distinct morphologies.

Noradrenergic Modulation of Electrical Coupling in GABAergic Networks of the Hippocampus

“…This type of cell is frequently encountered in stratum lacunosum-moleculare (Zsiros and Maccaferri, 2005), and may establish electrical connections with anatomically distinct groups of interneurons (Simon et al, 2005) as well as with other neurogliaform cells, with similar (Price et al, 2005) or distinct electrophysiological properties [Krimer et al (2005); Zsiros and Maccaferri (2005), their Fig. 7].…”

Distinct Firing Patterns of Identified Basket and Dendrite-Targeting Interneurons in the Prefrontal Cortex during Hippocampal Theta and Local Spindle Oscillations

“…Only 20 to 30% of neocortical neurons are GABAergic interneurons (Beaulieu and Somogyi, 1990;DeFelipe, 1993) with locally concentrated axons. Interneurons are heterogeneous in their postsynaptic targets, molecular expression, and temporal activity (Freund and Buzsaki, 1996;Kawaguchi and Kubota, 1997;Kisvárday et al, 1997;Swadlow et al, 1998;Cauli et al, 2000;Gupta et al, 2000;Markram et al, 2004;Tamas et al, 2004;Bacci et al, 2005;Földy et al, 2005;Krimer et al, 2005;Dumitriu et al, 2007;Kapfer et al, 2007;Ali and Thomson, 2008;Ascoli et al, 2008;Galarreta et al, 2008;Klausberger and Somogyi, 2008;Helmstaedter et al, 2009). Interneurons play a key role in regulating the organization and dynamics of cortical circuits.…”

Biophysical Support for Functionally Distinct Cell Types in the Frontal Eye Field

“…Cortical neurons have been distinguished by morphology (Kawaguchi 1995;Krimer et al 2005), neurotransmitter (Connors and Gutnick 1990), laminar distribution (Bullier and Henry 1979;Condé et al 1994;Dow 1974), molecular composition (Cauli et al 1997Martina et al 1998), functional property (González-Burgos et al 2005), and developmental origin (Letinic et al 2002). Differences between neuron types have typically been distinguished in vitro or intracellularly.…”