EMOTIONAL BEHAVIOR 



J539 



strongly suggested that the amygdaloid complex or 

 cingulate gyrus, or both, might be specifically involved 

 in the mediation of this restraining influence in the 

 absence of the neocortex since rather striking in- 

 creases in emotional reactivity followed removal 

 of these subcortical and juxtallocortical structures in 

 the previously neodecorticate preparation. More 

 recently, Rothfield & Harman (322) have confirmed 

 the placidity and emotional unresponsiveness result- 

 ing from neocortical ablation sparing the limbic sys- 

 tem in cats, and have further demonstrated that the 

 fornix (distributing important hippocampal fibers 

 to the septal region, diencephalon and rostral mid- 

 brain) may figure prominently in the mediation of 

 such restraining influences. Interruption of the fornix 

 in their neodecorticate preparations resulted in a 

 significant lowering of the rage threshold. 



Bard & Mountcastle (15) further analyzed the 

 effects of relatively discrete paleocortical, juxtallo- 

 cortical and related subcortical lesions in otherwise 

 intact cats in an attempt to delimit more precisely 

 the character of limbic system participation in such 

 behavioral phenomena. Although bilateral removal 

 of the hippocampus and presubiculum produced 

 little demonstrable alteration in affective expression 

 (with the possible exception of slight increases in 

 pleasureable reactions), bilateral removal of the 

 pyriform lobe and amygdaloid complex (sparing 

 other limbic structures) resulted in dramatic, if 

 somewhat delayed, behavioral changes. In this par- 

 ticular case, the cats were observed to develop a 

 markedly lowered rage threshold within (> to 8 

 weeks following surgery, although subsequent reports 

 by Gastaut and his collaborators (141, 288) and by 

 Schreiner & KJing (332, 334) describe changes more 

 in the direction of the Kluver-Bucy effect (218, 219) 

 consequent upon similar (but obviously not pre- 

 cisely the same) destruction of the pyriform-amyg- 

 daloid complex in the cat. Certainly, these rather 

 gross differences in observed emotional changes (pre- 

 sumably related to what appear to be only minor 

 variations in the anatomical substrate involved in 

 these somewhat conflicting; studies) may serve to 

 point up even more sharply the delicately balanced 

 relationships which characterize limbic system par- 

 ticipation in affective processes 



At least one additional contribution of the Bard 

 and Mountcastle research program, however, was 

 to call attention to the somewhat complicated role 

 of the cingulate gyrus in the elaboration of such ob- 

 viously complex motivational-emotional behavior 

 patterns. Although the removal of this juxtallocor- 



tical structure in neodecorticate preparations was 

 observed to lower the rage threshold in their earlier 

 experiments, these investigators found that cingulate 

 ablation in otherwise intact cats tended to raise this 

 threshold and produce emotionally less responsive 

 animals (15). Indeed, several authors (151, 350, 

 381) have referred to similar consequences of cingu- 

 lectomy ("loss of fear,' 'social indifference') in an 

 attempt to define the role of this juxtallocortical 

 portion of the limbic system in emotional behavior, 

 and although Pribram & Fulton (310) have empha- 

 sized the rather limited extent and duration of 

 such changes, their observations generally confirm 

 the character and direction of these effects. 



Undoubtedly, however, what has now come to be 

 known as the 'Kluver-Bucy syndrome' (363) appears 

 to have suggested the most stimulating lead for a 

 host of subsequent research efforts to unravel the 

 somewhat complicated role of limbic system com- 

 ponents in the elaboration of emotion.il behavior. 

 In a paper presented 10 the American Neurological 

 Association in 1949, for example, Fulton and his 

 colleagues (1371 reported that bilateral ablation of 

 the frontotemporal portion of the juxtallocortex in 

 monkeys can produce alterations in emotional be- 

 havior similar to, but apparently nut ,is extensive .is, 

 those found bv kltivcr and Bucy following temporal 

 neocortical and paleocortical lesions Compulsive 

 oral behavior and apparent lack of emotional re- 

 sponsiveness to aversive stimuli were observed in 

 these Irontotemporal preparations, but no alterations 

 in sexual behavior seem to have appeared. As a 

 matter of fact, the affective character of such changes 

 .ire ol .111 even more limited scope when the lesions 

 are restricted to the lateral surface of the temporal 

 lobe and preoccipital cortex, although Blum el al. 

 (29) have observed following such lesions in monkeys 

 some deficits in complex visual tasks and learned 

 discriminative performance which they believe to be 

 at least somewhat related to motivational-emotional 

 effects. 



When, however, experimental lesions are carefullv 

 restricted to the pyriform lobe, amygdaloid complex 

 and hippocampus (sparing neocortical regions for 

 the most parti in the monkey, Smith (351 ) has con- 

 firmed the appearance of very striking portions of the 

 Kluver-Bucy syndrome (loss of 'fear' and 'anger' 

 responses, docility, compulsive oral behavior) with- 

 out gross motor or sensory deficits. In addition, this 

 same report would seem to indicate that the docility 

 and loss of fear can be produced in such animals 

 without the compulsive oral behavior bv selectively 



