Behavior and electrical brain stimulation in the green iguana, Iguana iguana L. II. Stimulation effects.

Behavioral responses were electrically elicited in the brains of 21 green iguanas. At 518 stimulation sites, a limited number of behaviors could be reliably elicited. Except for some motor responses which had a forced appearance, they corresponded to the basic activity of green iguanas, exploratory behavior, display, defensive and escape-related behavior. Head-nodding displays were reliably elicited post stimulation when imminent escape was prevented experimentally but rarely during stimulation. Goal-directed behavior, i.e., feeding, drinking, mating and fighting behavior, were not elicited. The stimulation sites of frequently elicited behavioral responses revealed regional differences and some structural correlations. The majority of sites yielding defensive display responses were found in the hypothalamus, while dewlap display was more readily and widely elicited. Axial rotation and head-raising were elicited in a ventrothalamic zone extending into the tegmentum mesencephali. Tongue-flicking response sites were mostly concentrated in ventromedial areas of the tel-, di- and mesencephalon. Most escape-related responses were distributed unspecifically but the sites of violent flight responses were confined to the dorsal and lateral mesencephalon.