It is well known that attention sharpens and increases sensory perception. Similarly, attention is critical for the completion of complex motor tasks, but the neural mechanisms of this are unknown. In sensory systems, corticothalamic modulation of thalamic activity is a significant substrate for these increases in perception. Comparable circuits also exist in the motor system, suggesting that corticothalamic inputs at the thalamus can increase the gain of motor systems. Moreover, there are significant inputs from the frontal cortex to the origins of these corticothalamic axons, suggesting that executive control areas may exert control over cerebellar outputs at the thalamus. Successful completion of this project will extend attentional mechanisms to the motor system and advance our understanding of corticothalamic modulation of subcortical computations.