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HANDBOOK 1)1 PHYSIOLOGY 



NEUROPHYSIOLOGY HI 



ablating specific components of this 'pyriform- 

 amygdaloid-hippocampaJ complex," although the 

 precise delimitation of these particular structures 

 has not as yet been satisfactorily accomplished. 

 Indeed, a number of subsequent studies with mon- 

 keys have succeeded in demonstrating varying por- 

 tions of the Kliiver-Bucy complex as a function of 

 equally varied placements of limbic system lesions. 

 Thompson & Walker (365, 377), for example, 

 have confirmed the 'taming' effects of bilateral 

 lesions of the medial surface of the temporal lobe 

 apparently restricted to the amygdaloid complex 

 and hippocampus, although they have empha- 

 sized the temporary character of such changes (4 

 to 5 month duration) and affirm the fact that lesions 

 in other parts oi the inferior temporal cortex do not 

 produce these effects. Apart from this increased 

 docility and reduction in 'fear' responsiveness (all 

 these animals could still express 'anger' and 'rage' 

 to appropriate stimuli I, as well as a somewhat sur- 

 prising decrease in sexual activity, however, none 

 of the other Kliiver-Bucy symptoms could be demon- 

 strated, even though histological analysis of their 

 data seemed to support the implication that the 

 amygdala is primarily involved in the changes result- 

 ing from such lesions. Poirer (506) has also reported 

 finding fragments of the Kliiver-Buc) syndrome in 

 monkeys with somewhat more restricted lesions of the 

 temporal pole, although these observations have been 

 limited largely to the apparent 'apathy' and 'drowsi- 

 ness' of the operated animals without mention ol 

 other behavioral changes. 



Significantly, continuing attempts to analyze the 

 specific relationships in this temporal lobe-amygdala- 

 hippocampus syndrome have led investigators to a 

 wide variety of different animal species in their quest 

 for some basic understanding of this rather complex 

 motivational-emotional phenomenon. Pribram, Mish 

 kin and their collaborators (130, 283, 284, 309, 312), 

 foi example, have reported upon the effects ol lesions 

 involving the frontotemporal cortex, temporal pole 

 .mil amygdaloid complex in baboons and iIoljs, the 

 results confirming, for the most part, the 'taming' 

 and oral effects which follow involvement of these 

 structures. And Schreiner & Kling (332, 334) have 

 di cribed similar behavioral changes associated 

 with the amygdaloid complex and pyriform lobe 

 in c mis .mil K n\. In the cat preparations 

 (which were most extensively studied 1. refractoriness 

 to rage 01 anger-producing stimuli, exaggerated 

 01. il and vocal behavior, and marked hypersexuality 

 were observed, a iplex of changes similarly re- 



ported by Gastaut and his co-workers (141, ->88) 

 following amygdala lesions in the cat. The most 

 striking observation in the notably wild and intrac- 

 table agoutis and lynx studied by Schreiner & Kling, 

 however, was the dramatic conversion to virtually 

 complete (if somewhat temporary in the case of the 

 lynx, at least) docility following bilateral lesions in 

 the amygdala and pyriform lobe. 



It may be of some interest to note that at least the 

 state of hypersexuality produced by amygdalectomy 

 in Schreiner & Kling's cats can be abolished hv 

 castration and restored with substitution therapy 

 (333), suggesting the role of important neuroendo- 

 crine relationships involving the limbic system in the 

 elaboration of such motivational-emotional be- 

 havior patterns. Furthermore, these same authors 

 (332) have also reported that the characteristic. tllv 

 placid amygdalectomized cat can be readily con- 

 verted into a 'vicious,' 'rageful' animal by additional 

 superimposed lesions in the ventromedial nucleus 

 of the hypothalamus. And, in fact, one of the first 

 efforts to analyze quantitatively the behavioral effects 

 ol such limbic system lesions upon the acquisition 

 and retention of a conditioned avoidance response 

 by Brack et al. (55) involved many of these same 

 amygdalectomized cats. The avoidance technique 

 used in these experiments consisted of the animal's 

 passage through an open doorway separating the two 

 compartments of a conventional •double-grill' box 

 in response to the presentation of a 30-sec. conditioned 

 clicker stimulus, thus terminating the clicker and 

 avoiding the shocks which followed failure to respond 

 within the 30-scc. stimulus interval. Acquisition of 

 such a conditioned avoid. nice response was found 

 in lie significandy impaired in bilaterally amygdalec- 

 tomized cats, although virtually identical lesions 

 appeared to have little effect upon the retention of 

 precisely the same avoidance behavior in cats con- 

 ditioned prior to operation. Weiskrantz & Pribram 

 (386 388) have also undertaken similar efforts to 

 approach the "temporal lobe problem' in this some- 

 what quantitative fashion, and correspondingly 

 significant decrements were observed in conditioned 

 avoidance behavior following bilateral lesions in- 

 volving not only the amygdaloid complex in the 

 monkey, but other portions of the limbic system as 

 well (frontotemporal cortex, cingulate gyrus). 



\ considerably broader conception of limbic svs- 

 tem participation in emotional behavior would seem 



to be reflected, however, m the host of clinical and 



experimental observations which continue to emerge 



from more recent psychological and physiological 



