Interactions between motor thalamic field potentials and single unit spiking predict behavior in rats

Abstract

19The thalamus plays a central role in generating circuit-level neural oscillations believed 20 to coordinate brain activity over large spatiotemporal scales. Such thalamic influences are well-21 documented for sleep rhythms and in sensory systems, but the relationship between thalamic 22 activity, motor circuit local field potential (LFP) oscillations, and behavior is unknown. We 23 recorded wideband motor thalamic (Mthal) electrophysiology as healthy rats performed a two-24 alternative forced choice task. The power of delta (1-4 Hz), beta (13-30 Hz), low gamma 25 (30-70 Hz), and high gamma (70-200 Hz) oscillations were strongly modulated by task 26 performance. As in cortex, delta phase predicted beta/low gamma power and reaction time. 27Furthermore, delta phase differentially predicted spike timing in functionally distinct populations 28 of Mthal neurons, which also predicted task performance and beta power. These complex 29 relationships suggest mechanisms for commonly observed LFP-LFP and spike-LFP interactions, 30as well as subcortical influences on motor output. 31 amplitude-amplitude coupling, these results argue that delta-beta/low gamma PAC does not 131 result simply from common responses to behavioral events. 132