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HANDBOOK OF PH'iSIOLOG^ 



NEMROPHYSIOLOGV U 



bilateral anterior cingulatc removal in monkeys (91, 

 266). 



Using rats with bilateral lesions in the area of the 

 anterior cingulate gyrus, Peretz (191 ), quite recently, 

 has shown that they took significantly longer than 

 normal animals to learn an avoidance response when 

 motivated by fear of electric shock. This latter experi- 

 ment included a series of control procedures which 

 indicated that the results could probably not be 

 accounted for in terms of lessened sensitivity to elec- 

 tric shock, general reduction of all motivation or 

 intellectual deficit. 



The earlier observations that apprehensiveness 

 and anxiety seem to disappear after cingulate abla- 

 tions have led several neurosurgeons to remove this 

 region in agitated, aggressive and overactive psy- 

 chotic patients and in anxiety and obsessional states 

 (28, 138, 149-151, 157, 219, 251, 253, 267, 273, 274). 

 According to the earlier as well as to subsequent 

 reports the results appear promising when the proce- 

 dure is applied to carefully selected cases. No intellec- 

 tual impairment has been reported to follow such 

 ablation (75, 126, 150, 206). 



After liilateral cingulate ablations in the cat 

 Kennard (137) has recently observed confused, per- 

 severative, obsessive behavior, a plasticity of posture 

 and a slight increase in rage reactions. It is stated that 

 in these cingulate ablations the only area removed 

 was that lying in the region called area 24 in monkey 

 and man. It appears from the illustration, however, 

 that the ablations have mainly included the posterior 

 granular subdivision of primates, area 23 or the 

 'cingular area' (Cg. in fig. jE) in Rose & Woolsey's 

 terminology (209), whereas the area corresponding to 

 the agranular anterior cingulate cortex of primates 

 (area La. in fig. jE) was spared in most animals. 

 Kennard's syndrome, which in many respects re- 

 sembles that seen in destructive lesions involving the 

 cingulate gyrus in man (7, 8, 28), may perhaps be due 

 to a lesion of the granular posterior cingulate cortex. 

 It should be emphasized that in the cat as well as in 

 primates the most profound autonomic and somato- 

 motor effects of stimulation are elicited from the pre- 

 and subcallosal region of the cingulate cortex. 



Posterior Orbitid Cortex 



The most marked behavior change which follows 

 ablation of this region in monkeys is motor restless- 

 ness (71, 159, 213). According to Ruch & Shenkin 

 (213), this hyperactivity appears to be a fairly specific 

 phenomenon, manifested chiefl\- in locomotion. 



whereas other motor activities, such as expressivity, 

 were rather reduced in variety and quantity. The 

 hyperactivity possibly represents a release phenome- 

 non, consequent on removal of the inhibitory influ- 

 ence on somatic movements e.xerted by the posterior 

 orbital cortex, as well as by other areas ablation of 

 which yields motor hyperactivity (126, p. 249). These 

 changes in spontaneous motor activity have not fol- 

 lowed similar posterior orbital lesions in man (218, 

 222). According to Davis (52) and Turner (256), the 

 hyperactivity in monkeys after posterior orbital abla- 

 tion is profound only if the subjacent head of the 

 caudate nucleus has been damaged. 



In line with these observations in monkeys Dax & 

 Radley-Smith (53) emphasized that in performing 

 frontal leucotomy in man the lower and posterior 

 sections should be avoided in very excited and rest- 

 less patients. Orbital undercutting or orbital ablation 

 has been recommended for depressions and catatonic 

 stupors with subnormal psychomotor activity [see 

 {75) for references]. A number of other clinical papers 

 deal with these problems (68, 69, 72, 174, 175, 196, 

 214, 218, 221, 222, 252). 



Anterior Temporal Region 



Unilateral anterior temporal resections in animals 

 and man apparently cause no appreciable defects as 

 shown, for instance, by the several hundred such abla- 

 tions which have been carried out in epileptics for the 

 relief of psychomotor seizures (17, 19, 20, 64, 89, 177, 

 181, 186, 189). On the other hand, bilateral removal 

 of the anterior portion of the temporal lobe in pri- 

 mates and of the homologous areas in subprimates 

 causes profound changes in Ijehavior. On several 

 points, however, the various reports are somewhat 

 contradictory. The effects of bilateral remo\al of the 

 temporal lobes, including most of the uncus, amyg- 

 dala and hippocampus in monkeys, were described by 

 Kliiver & Bucy in 1937 (141) as "'the most striking 

 behavior changes ever produced in animals." These 

 behavior changes consisted of a) 'psychic blindness' 

 or 'visual agnosia'; h) "hypermetamorphosis' or exces- 

 sive tendency to examine objects visually, tactually 

 and orally; c) a remarkable decrease of aggressive 

 behavior and loss of fear reactions; d) bizarre sexual 

 behavior; and e) considerable changes in dietary 

 habits (139, 142, 143). On the other hand. Bard & 

 Mountcastle (27) demonstrated that ijilateral remo\al 

 of apparently the same structures in cats, particularly 

 of the amygdala and of much of the pyriform cortex, 

 produced savageness and a considerable increase in 



