Comparative Neuroanatomical Study of the Amygdala and Fear Conditioning in Nigerian Breeds of Artiodactyla: Sheep (Uda) and Goats (Red Sokoto)

Abstract

Fear conditioning is a behavioural paradigm controlled by the amygdala, in which animals learn to distinguish safety cues from threats and thereby eliciting a range of defensive responses aimed at escaping from the threat. Defensive response to threat occurs either as an active coping strategy involving fight‐or‐flight response or a passive coping strategy involving immobilization‐or‐freezing response. Type of response elicited depends on the repertoire of the specie. This study hypothesized that there will be differences in the defensive response of goats and sheep to threat and these may be related to differences in the neuroarchitecture of the amygdala in these classes of artiodactyla. Fear conditioning was induced by associating the tone of a car horn (neutral stimuli) with water spray (aversive stimuli) and the response to the threat was determined by observation and measuring the flight distances. Furthermore, morphology and morphometry of the neurons in the amygdala was analysed using Toluidine blue and Golgi techniques. Results demonstrated that differences exist in their defensive responses and goats showed stronger active coping strategy with concomitant intense flight distances (p<0.001) compared to the sheep. Histologically, goats showed significantly more densely distributed spiny neurons and packed neuropil in the central amygdala while sheep showed more aspiny neurons in the basolateral complex. Morphometrically, sheep showed greater soma sizes of the pyramidal neurons than goats. These neuroanatomical differences in the amygdala were positively correlated with the defensive responses. This may be the basis for the higher incidence of the sheep in automobile accidents than goats in developing countries especially Africa.Support or Funding InformationStudy was supported by Ahmadu Bello Univesity.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.