Agonistic Behavior Elicited by Electrical Stimulation of the Brain in Western Collared Lizards, <i>Crotaphytus collaris</i>

Abstract

Western collared lizards, Crotaphytus collaris, were tested in three experiments using electrical stimulation of the brain. In experiment 1, agonistic behavior (defensive, aggressive and escape) responses were elicited in free-moving unanesthetized lizards. In experiment 2, areas were localized from which gular extension, a common component of defensive and aggressive behavior, could be evoked in anesthetized animals. Experiment 3 was carried out to demonstrate that defensive and aggressive behavior could be elicited from the same stimulation sites both in anesthetized and unanesthetized lizards. Initially, gular extension was evoked while the animal was anesthetized and later the animal was tested while freely moving and unanesthetized. Based on a combined plot of the sites from which defensive and aggressive behavior was evoked in experiments 1–3, the higher threshold sites (51–750 µA) were in the dorsal ventricular ridge anterior, amygdaloid complex, septal and preoptic areas, hypothalamus, thalamus and adjacent to the nucleus profundus mesencephali (NPM) and reticular formation. Lower threshold sites (up to 50 µA) are found in the NPM and the reticular formation. Escape behavior can be evoked from stimulation sites within or adjacent to areas from which defensive and aggressive behavior can be elicited.

Steroid hormones alter neuroanatomy and aggression independently in the tree lizard

“…For detailed descriptions of brain nucleus localization, see Kabelik et al [35]. Six of these nuclei were chosen because of their previous implication in the control of aggression [49][50][51][52] and/or the presence of steroid receptors [46][47][48]53]. The habenula (HAB) was chosen as a control nucleus because it is easily quantifiable and devoid of steroid receptors.…”

Evolution of the Amygdala: New Insights from Studies in Amphibians

“…The thalamic sensory input to the ADVR is segregated across modalities, as opposed to the multimodal input to the PDVR, which is expected for a limbic associative component ; see also Striedter, 1997 andNovejarque et al, 2004]. Interestingly, the PDVR of reptiles appears to be involved in emotional behavior, as shown by experimental lesion or stimulation of the reptilian amygdala [Tarr, 1977;Distel, 1978;Sugerman and Demski, 1978]. However, the thalamic sensory input to the lateral nucleus of mammals is also largely segregated across modalities [Linke et al, 2000].…”

Behavioral Studies of Telencephalic Function in Reptiles

“…One final experiment of this group is that of Sugerman (1974;Sugerman and Demski, 1978) who studied agonistic behavior in the iguanid lizard Crotaphytus collaris following electrical stimulation of several sites within the telencephalon. Using both anesthetized and free-ranging animals with monopolar stimulation (2-ms biphasic square waves, 50Hz, 10 to 750 JLA), he elicited "defensive or agressive behavior" (e.g., gular extension) from the septum and nucleus sphaericus.…”