Basal Ganglia and 5-HT in Ritualistic Social Displays

University Of Florida, Gainesville FL

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Abstract

DESCRIPTION (provided by applicant): Ritualistic displays of social/territorial status are important regulators of intra-species interactions, reducing costs of competition for both individuals, and the group. Such ritualistic behaviors have similar forms across a wide range of land vertebrates (anmiotes). When the brain mechanisms mediating them dysfunction in man, the result may be certain psychopathologies, such as those characteristic of obsessive compulsive disorder (OCD), Tourette's disorder (GTS), social phobia, and some mood disorders. Functional neuroimaging studies by the Principal Investigator and others suggest that cortico/limbic-basal ganglionic-thalamic (=BG) systems mediate symptoms seen in OCD and related depressions. Work with Anolis lizards suggest that amniote- generic dorsolateral (DL) vs. ventro-medial (VM) BG systems mediate generic dominant vs. submissive social displays, respectively. This work has also demonstrated an acute role for serotomn (5-HT) in determining whether dominant or submissive behaviors are expressed in a given context, and strongly suggest that Anolis 5-HTIB receptors determines the differential 5-HT flux related to dominant vs. submissive behavior. Our human and lizard findings together have lead to a thesis that BG systems are organized as cross-inhibitory DL vs. VM subsystems that interact to bias behavior toward generic dominant vs. submissive behavioral routines. When DL/VM BQ subsystem interactions dysfunction in humans, the result may be fixed, context-inappropriate behaviors, as seen in OCD/depressions (submissive/ defeat), thus explaining the human PET findings. Conversely, aggressive states with stereotypic displays of dominance behavior (e.g., mania ,QTS), might have reciprocal BG system dysfunctions. Thus, a fuller understanding of how BQ systems interact and are regulated by 5-HT functions to mediate social/territorial display behaviors in an appropriate, easily manipulated model system is of value. By using pharmacological challenges, in vivo functional autoradiography, and in situ hybridization, we propose to elucidate the proximate BG mechanisms by which male Anolis lizards are vectored to display dominant vs. subordinate social/territorial behavioral routines, and how these behaviors and their mediating brain functions are switched between these poles of status as a result of social/conflict experience.