EMOTIONAL BEHAVIOR 



!535 



Although precise anatomical localization of specific 

 diencephalic regions tends to be far from satisfactory 

 under such conditions, various manifestations of 

 affective changes including "terror,' "rage," "anxiety" 

 and even some of the more "pleasant moods' ('witty,' 

 'jocular,' 'obscene') have been reported following 

 hypothalamic involvement in the human (1,80, 

 82, 85, 87, 124, 134, 385, 395). And indeed, both 

 experimental and clinical observations over the 

 past three decades have made it abundantly clear 

 that many other important biological motivations 

 intimately related to emotional expression, including 

 hunger, thirst, sleep, sex and activity, bear a critical 

 dependence upon the functional integrity of rela- 

 tively specific hypothalamic components (2, 14, 58, 

 62-64, 85, 134, 184, 294, 314, 316, 375, 385). This 

 diencephalic emphasis has, as a matter of fact, 

 found most recent expression in Stellar's (360) 

 presentation of a 'physiological theory of motivated 

 behavior' which places a heavy explanatory burden 

 upon hypothalamic excitation in accounting for a 

 wide range of motivational-emotional behavior 

 patterns. 



The weight of available evidence, then, would 

 certainly seem to indicate that at least some primi- 

 tively organized, relatively undifferentiated patterns 

 of emotional behavior may be elaborated within 

 limited reticular and hypothalamic levels of neural 

 organization. The emergence of homeostatic and 

 adaptive autonomic functions, as well as important 

 somatomotor activities basic to such affective proc- 

 esses, would seem to depend critically upon the 

 unique and direct integration of such brain-stem 

 components with peripheral effector mechanisms. 

 But the functional limitations of such gross react ton 

 patterns contrast sharply with the more delicately 

 balanced and restrained discriminative emotional 

 behavior of which the normal organism is seen to be 

 capable. Quite obviously, important influences from 

 more advanced forebrain levels of integration con- 

 tribute significantly to the elaboration and refine- 

 ment of complexly organized and finely differentiated 

 emotional response repertoires. Indeed, the early 

 writings of Head (167) and the subsequent theo- 

 retical formulations of Cannon (69, 72) suggested 

 an important role for the more rostral thalamic nuclei 

 in the elaboration of these affective processes, and 

 several clinical and experimental inquiries over the 

 past two decades have clearly justified this specula- 

 tive focus. 



Spiegel and his collaborators (356, 357), for ex- 

 ample, have reported changes in emotional behavior 



in both experimental animals and human patients 

 following various thalamic lesions, involving prin- 

 cipally the dorsomedial nuclei. Such ablations 

 appear to reduce "anxiety,' 'tension,' 'agitation' 

 and 'aggressive or assaultive behavior' in psychiatric 

 patients, and at least a transitory reduction in emo- 

 tional reactivity was presumably observed in simi- 

 larly operated animals. More extended observations, 

 however, by Schreiner et al. (335) on such animal 

 preparations (cats) with lesions rather carefully 

 restricted to the thalamic dorsomedial nuclei, demon- 

 strate emotional changes in the direction of 'increased 

 irritability and rage,' even though there has been 

 some confirmation of an 'amelioration of neurotic 

 patterns' in some of the same animals (275, 303). 

 Of course, many of these same experimental studies 

 have implicated more extensive regions of the thala- 

 mic, including the anterior and intralaminar nuclei 

 (275, 335)1 and even some of the more posterior 

 nuclear groups 1 156) in the elaboration of emotional 

 change, although reports of negative findings have 

 likewise made important contributions (79). Del- 

 gado (99), however, lias recently reported elicitation 

 of 'conditioned anxiety, defensive and offensive 

 movements, vocalizations, and autonomic mani- 

 festations' in both cats and monkeys electrically 

 stimulated in the posteroventral nucleus of the 

 thalamus. Olds (300) also finds at least some mildly 

 rewarding effects .1- .1 result of intracranial self- 

 stimulation in the rat from such diverse thalamic 

 placements as the habenula, and the lateral, ventral 

 and ventromedial nuclei. 



The anterior nuclei, however, appear to have 

 invited at least some special attention in the ex- 

 perimental quest lor thalamic participants in emo- 

 tional behavior. For the most part, lesions in this 

 region of the thalamus in the cat are reported to 

 produce marked reductions in emotional respon- 

 siveness (8, 275, 335), while the effects of direct 

 electrical stimulation in the anterior thalamus ap- 

 pear to be at least 'alerting' in the cat (8) and 

 highly rewarding in the rat (300). The range of 

 these emotional changes following thalamic involve- 

 ment suggests the possibility of a limited modulation 

 of affective procc^^ .it this diencephalic level, 

 even though the intimate relationship of these tha- 

 lamic nuclei with more advanced paleocortical, 

 juxtallocortical and neocortical systems must pro- 

 vide for the more refined and integrative behavioral 

 expression. Certainly, both the structural and 

 functional interaction between the mediodorsal 

 thalamus and the frontal neocortex on the one hand, 



