Abstract
Behavioral phenomena consisting of approach (self-stimulation, SS), flight and ambivalence (approach-flight) elicited by intracranial stimulation (ICS) along the neuraxis from the forebrain to the hindbrain were filmed and analyzed. The main findings were: (1) approach, flight and ambivalence could be obtained from all levels of the brain; (2) no single fixed behavioral pattern was common to approach or ambivalence; (3) there were instead different patterns which varied according to the area but some of the individual features of these patterns were at times common to several brain areas; (4) exploration with sniffing was found to be the most frequent behavior accompanying both approach and ambivalence. For SS, exploration was organized in the following topographical manner: nonsystematically at the level of the dorsal pons, diffused at the raphé, scattered at the level of the ventromedial mesencephalon (VMT), and focalized at the level of the lateral hypothalamus; (5) the highest intensities of SS, flight and ambivalence were found in the more caudal areas, namely the VMT for approach, the posterior mesencephalic reticular formation for ambivalence and the ventral region of the reticularis pontis caudalis (RPC) for flight; (6) in approach behavior for SS, when the point of stimulation was changed from the medio-frontal cortex to the posterior hypothalamus and VMT, an orderly change from depression to excitation of locomotor activity appeared. However, in the case of the locus coeruleus (LC) and adjacent dorsal tegmentum, SS by bursts was correlated with either intense motor activity or transitory periods of adynamia followed eventually by progressive ambivalence after bursts of SS; (7) approach and ambivalence elicited from areas known or believed to be involved in sleep regulation (midbrain raphé, LC and proximal dorsal pontine areas) were accompanied by what at first appeared as disruptive behaviors; but other complex behaviors were noted which suggest that during alertness, these areas may be involved in behaviors that are phylogenetically important for the development of motor and cognitive functions and most likely also in the behavioral manifestations of major psychiatric illnesses.
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