R. W. DOTY AND C. GIURGEA 147 



often appeared spontaneously at about the same tune that CRs were first 

 noted. The threshold of the neural heirarchy controlling the complex CR 

 thus seems to have been lowered. The frequent generalization of these 

 CRs to other stimuli supports this view and m Doo Epsiloii and Cat 48g 

 it was observed that convulsions induced accidentally by high-current 

 CS began with remarkably prolonged CRs. 



Some animals seem to have inherently low thresholds for particular 

 movement complexes so that stimulation at widely separated points with- 

 in the nervous system will evoke the same response. For instance in Cat 

 ^23 stimulation in sensorimotor cortex, posterior ectosylvian and middle 

 suprasylvian gyri, and the caudate nucleus produced an abrupt turning of 

 the head which was Inghlv similar for the different stimulus points. 

 Stimulation in middle ectosylvian gyrus, ventral anterior and ventral 

 posterolateral nuclei did not produce this effect but a convulsion elicited 

 from middle ectosylvian gyrus began with prolonged turning of the head 

 r8o^ to the rear. In Cat j,C\^ flexion and, at higher currents, attack move- 

 ments of the foreleg could be elicited by stimulation in the anterior portion 

 of the caudate nucleus, septal region, ventral hippocampus, and periaque- 

 ductal grey. This motor response was not correlated with the motivational 

 effects of this stimulation since caudate and septal stimulation increased 

 lever-pressing, periaqueductal stimulation was avoided and hippocampal 

 stimulation was 'neutral'. Stimulation of the median forebrain bundle, 

 pyriform area and habenula which produced aversive effects in this 

 animal did not elicit the foreleg attack movement. 



The data are too limited to know whether electrodes in these areas in 

 any cat would give these responses. The impression is gained, however, 

 that they would not and that somehow a particular type of movement has 

 in a given individual come to be 'prepotent' over others. The stimulating 

 electrodes may thus be revealing the existence of 'individually acquired 

 reflexes' (Beritoff", 1924) established through the animal's own activities. 

 At least they are not different from the individually acquired reflexes 

 deliberately given the animal by the stimulating electrodes during the 

 course of our experiments. However, the relation, if any, between these 

 phenomena must, as so many questions raised by these experiments, 

 await further experimental analysis. 



GROUP DISCUSSION 



Segundo. I shall first comment on the finding that motor cortical stimulation is 

 relatively 'indifferent'. It agrees with other observations, for excitation ot tlus 

 region in the sleeping monkey produced no arousal unless a generalized seizure 



L 



