Responses Evoked in Waking Cat by Electrical Stimulation of Motor Cortex

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Abstract
[longdash]Functions of the superficial and hidden motor cortex were studied in unrestrained, unanesthetized animals by use of implanted electrodes. Characteristics of stimulation stability of responses, latency, extend and organization of the movements were similar in both superficial and hidden motor cortex. Activation of the motor cortex by spontaneous activity or by electrical stimulation seems to have a similar functional value. Obstacles interposed in ''the path of evoked movements, caused the animals to act in a logical and adequate manner for avoiding the obstacles in trying to attain the goal imposed by the stimulation. Some responses, as licking, were directed by the animals towards different objectives, e.g., its body, the floor or the experimenter''s hands. Drinking and ingestion of milk were evoked by electrical stimulation of the medial part of the presylvian sulcus. In this way the animals were forced to take a supplementary amt. of food. Stimulation of the motor cortex did not appear to cause pain, disagreeable sensations or emotional disturbance of the animals. This is in striking contrast with emotional changes associated with stimulation of some areas of the temporal lobe. Excitation of the motor cortex generally did not disturb the postural reflexes of the animal. On the other hand, when high intensities of stimula- tion of some cortical points were used disturbances of equilibrium appeared. Arrest reaction was evoked by electrical stimulation of some points of the hidden cortex.