Motor cortical cell discharge during voluntary gait modification.

Kinematic and electromyographic data were recorded together with motor cortical cell discharge during a task which required the cat to modify its gait in order to step over 3 different types of obstacles fixed to a moving treadmill belt. In order to negotiate the obstacles the cat made large adjustments in limb trajectory which were associated with equally large changes in forelimb flexor muscle activity. Sixteen of 57 identified pyramidal tract neurones recorded from area 4 of two cats increased their peak discharge rate during this gait adjustment. It is suggested that the motor cortex plays a role in adjusting the flexor muscle activity to the requirements of the locomotor task.