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NEUROPHYSIOLOGY III 



and in genera] enhance vigilance. Conversely, a high 

 temperature leads to somnolence and inactivity. 



Chemorcgulation likewise involves peripheral and 

 central receptors, and a general behavior pattern 

 and activity level appropriate to lack or surfeit of 

 external food supply. The important role of the 

 hypothalamic-pituitary system in these and other 

 regulations has been fully described (Stellar, Harris, 

 Ingram, Sawyer), and the special sensitivity of 

 hypothalamic and related neurons to chemical 

 influences has been noted. 



ooals. Closely related to drives and their associated 

 emotional tone are the problems of goals and feed- 

 back and the value hierarchy. As a given physio- 

 logical constant (or related equilibrium) is further 

 and further displaced from its equilibrium level, 

 more— and more powerful — homcostatic adjustments 

 are activated, and internal and external behaviors 

 become directed to the prepotent goal of restoring 

 this displacement. A stress is such a displacement, it 

 leads 10 irreversible damage only when the limits of 

 homeostatic tolerance are passed. The closer the 

 approach to the tolerance limit, the more vigorous 

 are attempts to correct the displacement and the 

 greater is the prepotency, or ■value,' of doing so. 

 Acclimatization can reset the physiological zero and 

 so alter the goal to which these adjustments strive, 

 the environment operates, via natural selection, on 

 such stress adjustments. 



In the psychological realm, the situation is similar. 

 The physiological zero for activity, alertness, vigilance 

 and behavior in general is not at the absolute zero 

 level of somnolence, sleep, inactivity and inattention. 

 It is somewhere between this equilibrium level and 

 the other pole of continued change, adjustment, 

 tension and vigilance. In the adult, tOO little environ- 

 mental challenge leads to boredom, restlessness, even 

 hallucinations; too intense a challenge leads to 



fatigue, anxiety and finally sleep. Presumably the 



adult mammal, at least, tends to regulate the physio- 

 logical neuron reserve at an optimal level of partial 

 ICtivation of neurons, which makes them easily 



iccessible, and with little over-reverberation or 

 over-synchronization, which lends to withdraw them 

 from the pool. It is impressive thai mankind, with 

 access in a variety of stimulanl and depressant 

 drugs, has tended to adopt both on a wide scale, but 

 with the stimulants dominating fin;, 144). 



Attention is directed to a considerable extent in 

 terms ol goals 01 'purposes'; so values perhaps just 

 'significance' must be 'givens' at any nine (cl 



MacLean). They have been established bv experience, 

 racial or individual, and arc related to survival. 

 Outcomes of action, rated 'good' or 'bad' on such 

 criteria, can reinforce or attenuate future acts — by 

 reasonably understood mechanisms, discussed later — 

 and so establish a hierarchy of choices embedded in 

 the nervous system. Much of this learning presum- 

 ably involves the diffuse sweep of evolution; more 

 altruistic goals have increased relative to more 

 selfish ones (66, 90, 99). Care of the young, sacrifice 

 for fellows, adherence to loyalties all mount with the de- 

 velopment of the neocortex (92); and monkeys raised 

 in a social group are cooperative, with many social 

 attributes, while those raised alone are hostile (132). 



Subjective and Objectiw 



Other behavioral consequences of neurophysio- 

 logical mechanisms have to do with the formation of 

 an interior brain model of the external world, with 

 categories and universals and particulars, with 

 memory and recall and forgetting, and with insight 

 and imagination and conceptualization. All these 

 have been touched upon earlier, along with tin- 

 problems of decision, of perception and attention, of 

 motor patterns and sequences and the development 

 of skills, and of concept formation. 



One last note is due on subjective experience and 

 objective behavior. The latter depends on efferent 

 nerve impulses to appropriate effectors. These neurons 

 are fired by impinging impulses from other neurons, 

 and so bv regresson to the afferent messages from 

 receptors. But it is clear that not all entering messages 

 or information bits find their way out in prompt 

 action, some, probably most, end bv altering the 

 material nervous system and become stored memories 

 or information. With reverberation and feedback 

 and synchrony, much can happen within the brain — 

 and presumably accompanied by some kind and 

 intensity of consciousness, including the unconscious — 

 with no immediately correlated behavior. Con- 

 versely, from this rich central store overt behavior 

 can How which is not immediately related to .mv 

 input. Such separation in time and type (and locus) 

 of stimulus and response gives the richness and 

 spontaneity of behavior experienced as volition and 

 rationalized as free will. Behaviorism is thus too 

 narrow a straight jacket comfortably to contain the 



mind, but the alternative is not the 'uncaused cause' 

 Of a choice bv the psvehe. Whatever the degree of 



contingency al each level or organization, there is 



no pi. lie lot a directed random event, and a general 



