i?3° 



HANDBOOK OF PHYSIOLOGY -^ NEUROPHYSIOLOGY III 



stem caudal to the anterior neuropore is essentially 

 similar in all vertebrates. Physiological studies have 

 shown that this neural chassis contains the basic 

 neural apparatus required for posture, locomotion 

 and the integrated performance of mechanisms in- 

 volved in self-preservation and the preservation of the 

 species. It has long been established that the hy- 

 pothalamus has neural control over all the interofec- 

 tivc systems that account for the visceral and vis- 

 cerosomatic manifestations which are seen as an 

 accompaniment of emotional behavior. It has been 

 postulated that its neural organization permits the 

 principle of ieciprocal innervation to apply to its reg- 

 ulation of sympathetic and parasympathetic activity. 

 In recent years it has been demonstrated that the hypo- 

 thalamus also exerts a control over the release of pitui- 

 tary hormones the influence of which on the endocrine 

 systems is so vital to self-preservation and procreation. 

 1 1 is therefore logical to begin a consideration of 

 central mechanisms of emotion with an evaluation of 

 the emotional capacities of an animal with only its 

 basic neural chassis intact, and an analysis of pertinent 

 materi.il from the standpoint of functional locali- 

 zation. 



decerebrate preparations. There has been no suc- 

 cess in producing chronic preparations of this kind in 

 animals higher than carnivores. Many experiments 

 on carnivores, however, have been complicated by 

 the fact that the preparation had attached remnants 

 of forebrain. Perhaps cat 228 in Bard & Rioch's stuck 

 (4) comes as close as any to being suitable for the 

 present analysis. Its behavior was reminiscent of 

 Ferrier's classical descriptions (17) of the decerebrate 

 frog, bird, and rabbit. The observation that stands 

 out in such descriptions pertains to the animal's lack 

 of spontaneity of movement and its failure to investi- 

 gate its surroundings and to seek nourishment. It 

 resembles nothing so much as an idling mechanism 

 temporarily devoid of ii^ driver. In the case of du- 

 cat in question it showed the tendency to remain 

 standing, siding or crouching for long periods of time, 

 and would Fail to <-at unless presented with food. There 

 was [hi grooming nor an) signs of tear or pleasure. 

 1 ndirected angry behavior could be provoked upon 

 noxious stimulation. Characteristically in the de- 

 cerebrate, the angry behavior is nol enduring. I ' p< >i 1 

 cessation of the provoking stimulus the animal will 



1 lenly assume a statuesque posture. 



I In- decerebrate animal shows evidence of sleeping 

 and waking, h will spontaneously assume an appro- 

 [ni.iii aiiiiudi ibi defecation and urination. Although 



it will not seek out a partner, it will submit to sexual 

 excitement and perform the copulatory act. If the 

 neuraxis as far forward as the superior colliculus is 

 left intact the female cat is able to manifest estrous 

 behavior, including vocalization and the rest of the 

 'afterreaction' that occurs following intromission (2). 



HYPOTHALAMUS and midbrain. Except for the angry 

 and sexual manifestations, it is evident that there is 

 very little in the behavior of a decerebrate animal that 

 can be construed as emotional in character. There is 

 experimental evidence that the structures most crucial 

 to integrating the performance of angry and sexual 

 behavior lie in the hypothalamus and in the central 

 gray and reticulum of the midbrain. More is known in 

 regard to angry behavior. Elements of such behavior 

 have a scattered representation throughout the region 

 in question ( 28). The classic studies of Bard ( 1 1 showed 

 that in decerebrate preparations the posterior hypo- 

 thalamus must be intact in order to obtain the fully 

 integrated manifestations of rage. As will be indicated, 

 the same requirement does not appear to hold under 

 other experimental conditions. The work of Hess and 

 of Hunsperger has shown that there are principally 

 two regions in the brain stem from which one can 

 elicit full-blown angry behavior in intact preparations. 

 One is in the perifornical region of the hypothalamus 

 (24), the other in the central gray of the midbrain 

 (26). If the latter region is destroyed, the rage re- 

 sponse ordinarily elicited by stimulation of the hy- 

 pothalamus is abolished. On the contrary, destruction 

 of the hypothalamus does not modify the form of the 

 response obtained from the central grav (26). In 

 intact preparations ii has been found that chemical 

 Stimulation in the region of the central grav will elicit 

 a prolonged state of fury in which the animal will 

 viciously direct his attack (^8). From his clinical 

 studies on encephalitis lethargic.!, von Economo (66) 

 concluded that this region is fundamental to emo- 

 tional processes. 



The decerebrate animal presents a thorny problem 

 in regard to inferences aboul its subjective state. Can 

 one infer that it is aware and in addition capable of 

 feeling emotion? The angry behavior of such an ani- 

 mal is commonly referred to as -sham" or 'pseudo- 

 alfcctivc' because il is undirected and because ii i^ 

 assumed to be unaccompanied bv the "feeling' of 

 anger. Il must be admitted, however, that the be- 

 havior of the decerebrate animal in general reveals 

 several characteristics that are recognized as ele- 

 ments of awareness. From the experiments of Magoun 

 and others il can be inferred that the neural apparatus 



