This experiment will examine the extent to which actual damage to amygdaloid tissues may account for symptoms of reduced intake and lowered body weight following lesions in the amygdala itself to lesions invading striatal tissues dorsal to the amygdala.
Subjects – one hundred rats, weighing approximately 270g at the beginning of the experiment will be used. The pregnant rats will undergo testing at the beginning of their pregnancy so they will not weigh significantly more than subjects in other groups. Twenty-five will be roughly 6 weeks old (not sexually mature), 25 will be 4 months old and in usual reproductive cycle, 25 will be pregnant, and 25 will be nursing at the time of testing.
Subjects will be randomly assigned to 4 surgical groups or a control group (anaesthetized only). Lesions in surgical groups:
1. Lateral amygdala
2. Medial amygdala
3. Amygdala-striatal transition zone
4. Striatum
There will consequently be 5 rats (of different sort) randomly assigned to one of the surgical groups or the control group. The procedure for this experiment will also be carried out as dictated in Schoenfeld & Hamilton’s article (p. 568).
References:
Box, B. M., & Mogenson, G.J. Alterations in ingestive behaviours after bilateral lesions of the amygdala in the rat. Physiology and Behaviour, 1975, 15, 679-688
Dacey, D.M., & Grossman, S.P. Aphagia, adipsia, and sensory-motor deficits produced by amygdala lesions: a function of extra-amygdaloid damage. Physiology and Behaviour, 1977, 19, 389-395.
Fonberg, E. The relation between alimentary and emotional amygdalar regulation. In D. Novin, W. Wyrwicka, & G.Bray (Eds.) Hunger: Basic mechanisms and clinical implications. New York: Raven Press, 1976.
Klüver, H., & Bucy, P.C. Preliminary analysis of functions of the temporal lobes in monkeys. Archives of Neurology and Psychiatry, Chicago, 1939, 42, 979-1000
Nachman, M., & Ashe, J.H. Effects of basolateral amygdala lesions on neophobia, learned taste aversion, and sodium appetite in rats. Journal of Comparative and Physiological Psychology, 1974, 87, 622-643.
Phaff, D.W., & Keiner, M. Estradiol-concentrating cells in the rat amygdala as part of a limbic-hypothalamic hormone-sensitive system. In B.E. Eleftheriou (Ed.), The neurobiology of the amygdala. New York: Plenum Press, 1972.
Schoenfeld, T.A., & Hamilton, L.W. Disruption of Appetite but not Hunger or Satiety following small lesions in the Amygdala of Rats. Journal of Comparative and Physiological Psychology, vol. 95, No.4, 565-587.