EMOTIONAL BEHAVIOR 



'533 



can be safely attributed to Goltz (156) and to Wood- 

 worth & Sherrington (401) in their analysis of the 

 'pseudoaffective' behavioral reactions which are 

 observed to follow transection of the brain stem at 

 the intercollicular level in laboratory carnivores. 

 Nociceptive stimulation of the skin in such prepara- 

 tions can be seen to elicit mimetic expressions of 

 apparent 'anger' and 'rage' in the form of growling, 

 barking, opening of the mouth, retraction of lips 

 and tongue, snapping of jaws, snarling, lowering 

 of the head as if to attack, and increase in arterial 

 pressure. All such responses are extremely brief and 

 do not outlast stimulation, however, and the normal 

 emotional repertoire of such preparations appears 

 severely circumscribed, especially with respect to the 

 more positive types of affective expression usually 

 present in unoperated members of these species (ap- 

 parent 'joy' or 'satisfaction,' and sexual behavior). 

 Indeed, many later observations have confirmed 

 the general appearance of a poorly organized 'rage' 

 response of but brief duration in the decerebrate 

 preparation, along with a number of associated 

 sympathetic reactions, although in not all cases does 

 there seem to be a complete absence of pleasurable 

 reaction (19, 208, 323, 328). The main point of in- 

 terest to be derived from these observations, how- 

 ever, is that at least some primitive 'pseudoaffective' 

 behavioral expressions of emotion can be readily 

 elicited at this midbrain level even in the absence 

 of all other forebrain structures. Section of the brain 

 stem below this level, however, has been reported 

 by Bard (11) to abolish such behavior and strongly 

 suggests involvement of the midbrain reticular forma- 

 tion in the mediation of at least these rather funda- 

 mental aspects of emotional expression. Certainly, a 

 host of important subsequent experimental observa- 

 tions (16, 96, 127, 211, 251) have continued to draw 

 attention to reticular influences in many basic 

 features of the emotional behavior pattern and in 

 the maintenance of 'aroused affective states.' Linds- 

 ley (248) has recently proposed an 'activation theory 

 of emotion' which assigns critical executive functions 

 to the reticular formation of the brain stem. 



Diencephalic Partit ipation 



The more classic theoretical conceptions relating 

 emotional behavior and the nervous system can be 

 seen to have developed around experimental empha- 

 sis upon cortical-diencephalic interrelationships. The 

 early experiments of Dusscr de Barenne (112) and 

 Cannon & Britton (73), using decorticate prepara- 



tions and the now famous 'sham-rage' phenomena 

 characteristic of such animals, did indeed provide an 

 early focus for this continuing emphasis upon fore- 

 brain mechanisms in emotional expression. By 

 comparision with the more drastic Sherringtonian 

 decerebrates, the decorticate preparations can be 

 observed to respond even more readily and in a 

 somewhat more intense, better organized fashion to 

 ordinary handling and care, although the behavior 

 remains poorly directed and short-lived. As a matter 

 of fact, subsequent experimental analysis by Bard and 

 Rioch (10-13, 17, 319) clearly demonstrated that 

 such sham-rage behavior (described in some detail 

 by these authors as involving lowering of the head 

 and body in crouch, raising the back, drawing back 

 the ears, loud angr\ growling, hissing, biting, striking 

 with claws unsheathed, erection of hair, pupillodilata- 

 tion, retraction of nictitating membrane, and widen- 

 Lng of palpebral fissures) could still be elicited after 

 removal of all cerebral tissue rostral, dorsal and 

 lateral to the hypothalamus (including virtually all 

 of the paleocortex, juxtallocortex and major portions 

 of the related subcortical structures). This vigorously 

 patterned but poorly directed activity involving 

 both somatic and visceral components failed to de- 

 velop, however, following truncation of the brain 

 stem it ,m\ level below the caudal hypothalamus, 

 a consideration suggesting both the central executive 

 and facilitatory functions of these diencephalic 

 regions in the elaboration of emotional behavior, as 

 well as the possible inhibitory role of more rostral 

 neocortical and paleocortical forebrain structures. 

 It is interesting to note in this connection that even 

 a somewhat broader range of affective expression, 

 including 'fear' and 'sexual excitement,' in addition 

 to the sham-rage response, was also described by 

 Bard and Rioch as being elicitable from such prep- 

 arations with extensive forebrain damage. More re- 

 tent observations by Bromiley (61), in the course of 

 discrimination learning experiments with the de- 

 corticate dog, seem to indicate that the capacity for 

 affective expression in such preparations can be 

 maintained over relatively long periods of time even 

 in the absence of extensive forebrain influences. 

 Barking, growling, snarling and snapping as charac- 

 teristic components of the sham-rage response to 

 mere cage manipulation or gentle handling persisted 

 over an extended period of almost 3 years in the 

 Bromiley decorticate preparation. Clearly this im- 

 portant combination of experimental inquiries points 

 up the striking facilitatory role exerted by the addi- 

 tion of limited (although obviously critical) hv- 



