CINGULATE, POSTERIOR ORBITAL, ANTERIOR INSULAR AND TEMPORAL POLE CORTEX 136^ 



rage reactions. The different effects obtained in these 

 two studies were considered to be due to species 

 differences. This explanation is not entirely compat- 

 ible with the somewhat 'paradoxical" results obtained 

 by Spiegel et al. (242) who observed both rage reac- 

 tions and cataleptic symptoms following bilateral 

 lesions of the amvgdaloid region in one and the same 

 species of animal (cats). Docile cats as a result of such 

 lesions have also been reported by Schreiner & Kling 

 (217) and Brady et al. (30). It seems more likely that 

 the structures removed are not completely analogous 

 in all these experiments. Lesions of the anterior por- 

 tion of the temporal lobe may include in varying 

 degrees such diverse structures as the pre- and peri- 

 amygdaloid cortex, the entorhinal area, juxtallocorti- 

 cal and neocortical zones or their efferent or afferent 

 projections, olfactory pathways, the amygdaloid 

 nuclear complex (with its at least six subdivisions with 

 different projections), and more or less the temporal 

 portion of the hippocampus proper. Apparently, our 

 "present knowledge and techniques do not permit 

 sufficiently accurate pinpointing of crucial structures" 



(197, P- 59)- 



The results of Kliiver & Bucy (143) and more 

 recent ones (180, 248) ascribe more importance to 

 the medial temporal structures than to the lateral 

 temporal cortex. Various manifestations of the Kliiver- 

 Bucy syndrome have been reproduced in monkeys 

 (179, 183, 200, 248), cat (30, 217) and man, where it 

 includes memor^^ loss (97, 216, 220, 247) when the 

 bilateral lesions are mainly restricted to the antero- 

 ventral portion of the temporal lobe. It is not clear, 

 however, which basic functions have been disturbed 

 by the various lesions. Recent attempts to analyze 

 the complex syndrome associated with large bitem- 

 poral lesions through the use of a battery of behavioral 

 observations and tests and more rigidly controllai)le 

 techniques of experimental psychology seem promis- 

 ing (30, 179, 180, 200). According to Pribram & 

 Bagshaw (200), such measures have related the poste- 

 rior orbital surface to locomotor activity, the anterior 

 insula to taste, and the temporal polar and amygda- 

 loid region to food intake, temperature regulation and 

 'hypermetamorphotic' behavior. Visual discrimina- 

 tion ability is unaffected either by such lesions (200) 

 or by hippocampectomy but depends on the integrity 

 of the medial occipitotemporal region (43, 179, 180). 



It is still a matter of controversy exactly which 

 lesions are responsible for increased rage reactions. 

 Lesions of the basal structures just rostral to the optic 

 chiasma (77, 78), the olfactory tubercles (242), 

 amygdala (27, 242), or the hippocampal-fornix sys- 



tem in cats with absent neocortex (212) have all 

 lowered the rage threshold. However, either no effects 

 or opposite effects, such as increased tameness and 

 docility, ha\e been observed after bilateral lesions of 

 the amygdaloid complex (g, 30, 212, 217, 242, 275), 

 the hippocampus-fornix (26, 27, 212, 272) or the 

 junction of the tail of the caudate and putamen (256). 

 None of the increased rage responses produced after 

 cortical, amygdaloid or hippocampal lesions, how- 

 ever, is comparable to the savage behavior of extreme 

 type which follows lesions of the \entromedial hy- 

 pothalamic nucleus (272). 



Further consideration of behavioral changes fol- 

 lowing temporal lesions are found in the two succeed- 

 ing chapters on the hippocampus and amygdala. 



PHYSIOLOGICAL SIGNIFIC-^NCE 



Olfaclion 



It appears at present widely accepted that onlv 

 more restricted anterior basal areas of Broca's grand 

 lobe limbique (a portion of the pyriform cortex together 

 with parts of the amygdala, olfactory tubercle, bed 

 nucleus of the stria terminalis and other regions) are 

 implicated in important olfactory functions. This 

 applies both to the detection and discrimination of 

 olfactory impressions and to olfactory reflexes and 

 associated feeding reactions (2, 36, 37, 1 76, 202). 

 (Chapter XXI by Adey in this Handbook is devoted 

 to this topic.) The functional terms "olfactory brain' 

 and "rhinencephalon' therefore should not be used in 

 the wider sense as identical with the 'limbic lobe' 

 because these terms suggest that there is a particular 

 function common to all formations included in this 

 portion of the ijrain, an assumption which is not sup- 

 ported by experimental evidence. The main functions 

 of the other parts of the 'limbic lobe" must be sought 

 in other spheres of activity. 



I'isceral Functunu 



In spite of the extensive physiological, anatomical 

 and clinical data that have accumulated in the past 

 decade nothing conclusive can as yet be said about the 

 functional significance of these other formations of 

 the 'limbic lobe.' It has recently become customary 

 to speak of the 'visceral brain' (10, 162, 163, 165, 197) 

 as synonymous with the 'limbic lobe,' thus imputing 

 to this entire brain area another specific common 

 function. However, thus far all of the experimental 



