PSYCHOSOMATICS 



735 



latter situation a spontaneous erection was noted on 

 one occasion. The same sexual manifestation has been 

 seen following chemical or electrical stimulation of 

 the anterior supracallossal cingulate and of the cortex 

 just above the posterior cingulate gyrus. The last- 

 mentioned observation calls to mind Erickson's case 

 (16) of hypersexuality in a 55-year-old woman who 

 had a tumor in the paracentral lobule which lies just 

 above the cingulate gyrus. 



There are also the following pertinent observations. 

 In 1909, von Bechterew (65) stated that his collab- 

 orator Pussep elicited penile erection in the dot; upon 

 stimulation in the region of the anterior thalamus. 

 Such stimulation might have involved the anterior 

 thalamic nuclei which are closely related to the 

 cingulate gyrus. In a recent analysis of their extensive 

 material, Hess & Meyer (25) found that the septum 

 was the region where stimulation was most commonly 

 followed by grooming. In 1939 Haterius (23) reported 

 that stimulation in the region of the septum induced 

 ovulation in rabbits." 



From the foregoing observations ii might be inferred 

 that a portion of the limbic system involving related 

 parts of the septum, hippocampus and cingulate g\ rus 

 is concerned with expressive and feeling states that 

 are conducive to sociability 7 and other preliminaries 

 to copulation and reproduction. In other words, this 

 portion of the limbic system, in contrast to the fronto- 

 temporal region, appears to bear on activities that are 

 directed for the purpose of preserving the species 

 rather than the self. 



The pleasure, grooming and sexual manifestations 

 that have been described lead one to wonder how 

 they are possibly related to the recent observations of 

 Olds & Milner (50) who found that rats with elec- 

 trodes implanted in the septum and other limbic 

 structures would repeatedly press a bar to obtain elec- 

 trical stimulation of the brain. This striking observa- 

 tion has been confirmed by Brady and others. The 

 reader is referred to Chapter LXIII of this Handbook, 

 by Brady, for further details. 



mass function of limbic svstem. When a seizure is 

 induced in the hippocampus by local chemical or 

 electrical stimulation, it has the tendency to spread 



throughout but to be largely confined to limbic and 

 perilimbic structures. As a consequence one has the 

 opportunity in waking and intact preparations to 

 observe the effects of a massive alteration of function 

 in the limbic system. To date such a 'functional abla- 

 tion' has provided the only means of deriving infer- 

 ences about the global contribution of limbic function. 

 It is to be emphasized that during hippocampal sei- 

 zures there may be no appreciable alteration of the 

 bioelectrical activity recorded from the neocortex 

 making up the outer convexity of the brain. 



During the stage of culmination of a carbachol- 

 induced seizure in the hippocampus, one has several 

 minutes to observe the effects of such a condition (38). 

 During this stage the behavior of an animal is remi- 

 niscent of that seen in the decerebrate preparation. The 

 animal appears semistuporous, shows lack of spon- 

 taneity of movement, and manifests an incapacitv for 

 directed appropriate action in response to various 

 stimuli. Generally there is underreactivitv to noxious 

 stimuli of moderate intensity, but intense noxious 

 stimulation elicits a state resembling sham rage that 

 is abrupib followed by the animal's assumption of 

 prolonged statuesque postures when such stimulation 

 is terminated. Basic postural, locomotor and viscero- 

 somatic reflexes arc retained. 



Conditioning procedures provide a means of obtain- 

 ing an objective measure of, in animal's psychological 

 impairment during propagated hippocampal seizures 

 (41). During brief electrically induced seizures, ani- 

 mals trained in a shuttle box to avoid a shock following 

 the sound of a buzzer fail to respond to the conditioned 

 stimulus, but will frequently direct their escape upon 

 receiving the shock. Relatively simple conditioned re- 

 flexes such as a leg withdrawal or changes in cardio- 

 respiratory activity are also abolished by hippocampal 

 seizures. The animal continues, however, to be 

 responsive to the noxious unconditioned stimulus. 

 There is evidence that when there is poor propagation 

 of the discharge to contralateral limbic structures, 

 there may be partial or complete retention of the con- 

 ditioned response. This suggests that there must be a 

 massive alteration of function in limbic structures of 

 both sides if the animal is to fail altogether in respond- 

 ing to the conditioned stimulus. 



6 Since this chapter was written, we have carried out ex- 

 periments on squirrel monkeys which have been specihcallv 

 concerned with the localization of genital function in the 

 brain. Points at which electrical stimulation elicits penile 

 erection have been found to follow a course from the septum 

 through the medial preoptic region to the medial forebrain 

 bundle. See Mac Lean (40). 



NATURE OF NEURAL APPARATUS INVOLVED IN EMOTION 



.1 natomical Differences 



The question next arises as to how cortical struc- 

 tures that have thus far been experimentally identi- 



