Thalamocortical (TC) interactions are a key component of normal brain functions both in sensory and motor areas. In the motor system, impairment in information flow through this pathway leads to severe motor deficits, yet little is known about the mechanism through which thalamic input is integrated by the local cortical circuitry. The fact that thalamocortical connectivity is excitatory has led to the suggestion that their main role is positively driving motor cortical activity. Here we show that the motor thalamus has contrasting, area-dependent interactions with cortical sites, such that it can either enhance or suppress motor cortical variability. The TC interactions with the primary motor vs. the premotor cortex put the motor thalamus in an ideal position to promote the transition from a motor plan to motor action and serve as an important driver of movement initiation.
