.368 



HANDBOOK OF PHYSIOLOGY 



NEUROFHVSIOLOGV II 



data have confined the areas of the 'hmbic lobe" which 

 hifluence autonomic activities to a rather limited 

 portion of its rostral part, comprising the anterior 

 cingulate, orbitoinsulotemporal polar region and the 

 amygdala. There is at present no evidence, either 

 from stimulation or from ablation experiments, to 

 justify the application of this term to the posterior 

 portions of the cingulate and hippocampal gyri or to 

 the hippocampus-fornix system (126, 202). Further, 

 the rich variety of autonomic and soinatomotor 

 responses evoked from the rostral alio- and juxtallo- 

 cortical areas and amygdala are all independent of 

 the hippocampus-fornix (126). Even if the term 

 'visceral brain' is confined to these rostral mediobasal 

 areas it becomes somewhat misleading since somatic 

 responses from the same areas appear to be just as 

 prominent as the visceral ones. 



Emotion 



Two decades have passed since Papez (184) pro- 

 posed the now famous and much quoted theory that 

 the hypothalamus, the anterior thalamic nuclei, the 

 gyrus cinguli, the hippocampus and their interconnec- 

 tions possibly constitute the central anatomical sub- 

 strate for emotion. This hypothesis seemed to find 

 support in the emotional changes resulting from 

 Kliiver & Bucy's (141-143) temporal and Smith's 

 (238) and Ward's (266) anterior cingulate ablations 

 in monkeys. The more recent temporal ablations, 

 referred to above, tend to relate the changes in emo- 

 tional behavior to lesions in the amygdaloid region 

 rather than to the more posterior temporal cortex 

 and hippocampus. Further, as regards the anterior 

 cingulate region, renewed studies find as yet no con- 

 clusive evidence to substantiate the earlier claims of 

 the iinportance of this area in emotion. One might 

 also question whether the anterior cingulate area 

 actually represents an essential integrative part of the 

 postulated hippocampal-cingulate "circuit,' since in 

 the phylogenetic scale the anteromedial thalamic 

 nucleus (projecting upon the anterior cingulate area) 

 is considerably reduced (226, 250) whereas the antero- 

 ventral nucleus, which in higher mammals receives 

 the bulk of fillers from the mammillary bodies, shows 

 a progressive development similar to that of the hippo- 

 campus, fornix, mammillary bodies, mammillo- 

 thalamic tract and most of the cingulate gyrus (211). 

 These phylogenetic data together with the essentially 

 negative results of stimulation and ablation in animals 

 might indicate, as previously suggested (126, p. 258), 

 that these structures are concerned in higher psychic 



functions rather than in physiological acti\ities of a 

 primitive elementary type. Data are at present 

 accumulating which tend to show that the hippo- 

 campal-cingulate system possibly might ije critically 

 concerned in memory function (122). Whether these 

 structures, or parts of them, are in any way primarily 

 involved in emotional behavior can be resolved only 

 in future experiments. Potentials have been recorded 

 by several authors from the pyriform cortex, amyg- 

 dala, hippocampus and cingulate gyrus in response to 

 various types of sensory stimulation (visceral, audi- 

 tory, visual, olfactory, gustatory and .somatic). It has 

 been suggested that these latter potentials are pos- 

 sibly related to emotional experience (164). There are, 

 however, at present several discrepancies in the find- 

 ings of the various authors and more information is 

 needed before anything can be said about the func- 

 tional significance of these sensory impulses. 



More recently Turner (255, 256) has introduced the 

 term "thymencephalon' for much the same structures 

 as contained in the 'rhinencephalon,' 'limbic lobe' 

 or 'visceral brain" in order to denote the affective or 

 temperamental part of the brain {thymos: mind, spirit, 

 soul, passion). However, of all the structures included 

 in these terms only the amygdala and the orbito- 

 insulotemporal polar cortex and possibly the sub- 

 callosal and septal regions appear to be related to 

 emotional behavior (202). (Emotion is considered in 

 Clhapter LXIII by Brady in this Handbook.) 



'Attention or 'AroiisaP Response 



The significance of the behavioral and EEG- 

 "arousal' or 'attention' response — which rather exten- 

 sive parts of the cingulate and orbitoinsulotemporal 

 polar regions and part of the amygdala and hippo- 

 campus share with neocortical area.s — is not clear. 

 -Mthough these diverse cortical zones seem to have 

 some common functions related to the arousal re- 

 sponse, it is extremely unlikely, as also emphasized 

 by French et al. (70), that all influences mediated by 

 them are identical or that these are the only functions 

 they subserve. It appears likely that alertness asso- 

 ciated with functional activity of the difTerent cortical 

 areas may be related to different patterns of general 

 behavior. In this respect, it should be mentioned that 

 if subsequent findings indicate that the medial-basal 

 cortical areas in some way are concerned with emo- 

 tional behavior, it would be extremely reasonable to 

 find 'arousal" responses elicited from these as well. 



It may also be of significance that most of the corti- 



