A beta2-frequency (20–30 Hz) oscillation in nonsynaptic networks of somatosensory cortex

TLDR

Beta2 (20–30 Hz) oscillations are observed over somatosensory and motor cortices during motor preparation and can synchronize with muscle activity. The study reports a beta2 oscillation in vitro within layer V pyramidal cell networks, the corticospinal tract’s origin. The oscillation relies on gap‑junction coupling, persists after layer 4 removal and after AMPA or GABA(A) receptor blockade, and its period is set by M‑type K⁺ currents, indicating it is independent of apical dendritic electrogenesis.

Abstract

Beta2 frequency (20-30 Hz) oscillations appear over somatosensory and motor cortices in vivo during motor preparation and can be coherent with muscle electrical activity. We describe a beta2 frequency oscillation occurring in vitro in networks of layer V pyramidal cells, the cells of origin of the corticospinal tract. This beta2 oscillation depends on gap junctional coupling, but it survives a cut through layer 4 and, hence, does not depend on apical dendritic electrogenesis. It also survives a blockade of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors or a blockade of GABA(A) receptors that is sufficient to suppress gamma (30-70 Hz) oscillations in superficial cortical layers. The oscillation period is determined by the M type of K+ current.