8l2 



HANDBOOK OF PHYSIOLOGY 



NEUROPHYSIOLOGY II 



Parietal, Occipital and Temporal Cortex 



Mo\ements obtained by stimulation of the post- 

 central gyrus (areas i, 2 and 3) have already been 

 discussed (see page 801). Stimulation of parietal area 

 5 also produces mo\ements as first observed in man 

 bv Bartholow (40). This finding has been confirmed 

 both for man (149, 151, 439) and monkey (439), but 

 some authors did not succeed in producing move- 

 ment from this area (266). According to Dusser de 

 Barenne et al. ( i 26) movement of limbs is obtained, 

 when facilitated, from both areas 5 and 7. The con- 

 tro\-ersy seems to be settled by the comprehensive 

 studies of Fleming & Crosby (147) and Peele (354). 

 The first authors established that stimulation of area 

 5 produces motor responses of the head, trunk and 

 extremities which are not discrete but often are com- 

 bined and "resemble patterns of movements such as 

 running, turning and avoiding movement of a given 

 posture." These responses to stimulation were ob- 

 tained also after ablation of both precentral and post- 

 central gvri in disagreement with other authors (cf. 

 147). Epileptic attacks can originate from area 5 

 with convulsive movements of the opposite arm and 

 face and paresthesia (357). 



Small lesions in the sensory cortex (areas 3, 2 and 

 I) of the macaque have been tested for their effects 

 on discrimination by palpation, and associated effects 

 on dexterity and motor power (100). In all cases, 

 substantial or complete postoperative recovery oc- 

 curred. Although these lesions were not associated 

 with inaijililv to make movements, they may have 

 been accompanied by an initial unawarencss of the 

 movement made and with the limb then arrested in 

 an unusual position. In all cases there was a loss of 

 tactile sensation, with increased reliance on visual 

 cues. Cole & Glees (100) identified intimate connec- 

 tions between areas 3, i, 2 and 4 and consider that 

 these cortical areas form a unit essentially linked with 

 the thalamus and spinal cord but sending few fibers 

 into areas either further anteriorly or posteriorly. 

 Bender (44) has reported changes in sensory adapta- 

 tion time and after-sensation with lesions in the 

 parietal lobe. Peele (354) and Fleming & Crosby 

 (147) have examined the effects of acute and chronic 

 parietal lobe lesions in monkeys. Removal of area 3, 

 areas i and 2 and areas 5 and 7 individually, or of 

 areas i and 2 and 5 to 7 in combination, did not 

 result in paralysis but produced a loathness to move. 

 Removal of area 3 or of areas i and 2 affected the 

 contralateral arm and leg equally. Removal of area 



5 affected the leg particularly and of area 7, the arm 

 particularly. Hypotonia persisted for as long as one 

 year after operation and was greater in proximal than 

 distal muscles. Tendon reflexes were permanently 

 altered by an increase in threshold, a slowness of 

 execution and an increased excursion. Muscular 

 atrophy followed ablations of areas i and 2 and 5 to 7. 

 Peele concluded that the postcentral cortex was 

 essential for hopping and tactile placing reactions. 



Movements of the limb, trunk and face have been 

 observed following stimulation in the occipital cortex 

 of primates (149, 211, 262, 439). Penfield & Rasmus- 

 sen (358) do not mention, however, any motor re- 

 sponses from this cortical region. According to Brown- 

 .Scc|uard, confirmed in 1905 by Baer in an elegant 

 experiment with chronically implanted electrodes, 

 simultaneous stimulation of the motor area and of 

 the occipital convolutions of the dog and rabbit leads 

 to a lowered threshold in the occipital area with weak 

 currents now producing movements similar to those 

 obtained from the motor area (cf 27). 



Stimulation of the superior temporal gyrus has also 

 been reported to produce movements of the extrem- 

 ities, head and trunk, both in monkev- and man (151, 

 211, 262, 390, 439) even after ablation of the pre- 

 central motor cortex (484). They are different from 

 those elicited from the amygdaloid nuclei. The latter 

 are described in Chapter LMII by Gloor in this 

 work, while the role of amygdalostriatal interrela- 

 tionships in motor functions is discussed in a recent 

 review by Adey (4). 



Phenomenon of Suppression 



In igiq, \'os!t & \'ogt (43B) reported inhibition 

 of cortically-induced movements by stimulation of 

 cortical regions in the frontal lobe. Since then, inhi- 

 bitorv effects on movement have been reported from 

 stimulation of widely separated areas on the lateral 

 surface of the cerebral cortex (194, 250, 375, 419-421, 

 424). In 1937, Hines defined a strip of cortex between 

 areas 4 and 6 v\hich yielded inhibition of muscular 

 contractions of the opposite side of the l)ody (200). 

 Beginning in 1938, a series of publications on the 

 effects of strychninization or electrical stimulation of 

 certain points on the lateral surface monkey cortex 

 indicated a decrease in the spontaneous cortical 

 electrical activity, abolition of cortically induced 

 movements and relaxation of muscular contractions 

 (129, 130, 132, 134). These points were grouped as 

 'strips', designated 'suppressor areas' (33, 127), as 



