WEBINAR LINK: https://mit.zoom.us/j/98084893382
Classical models of basal ganglia propose bidirectional regulation of thalamocortical motor circuitry, yet the principles of motor thalamus function are not well understood. We developed methods to record from basal ganglia-recipient thalamic neurons in awake behaving mice and assess their functional connectivity with the cortex. Using forelimb position during locomotion as a primary behavioral readout, we identified robust modulation of thalamic firing during locomotor stride, which varied depending on cortical projection target. Thalamic neurons projecting to anterior cortex (M2) showed less stride modulation, whereas thalamic neurons projecting more caudally (S1/M1) were more strongly stride modulated. Stride modulation of cortical units followed a similar pattern, and stride modulation in basal ganglia-recipient thalamus was largely dependent on cortical input. Together, our data argue for multiple, segregated loops between basal ganglia recipient motor thalamus and cortex, which are driven largely by cortical activity.