The effect of kindling different nuclei in the left and right amygdala on anxiety in the rat

Morgan, Hywel David (1992) The effect of kindling different nuclei in the left and right amygdala on anxiety in the rat. Masters thesis, Memorial University of Newfoundland.

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Abstract

The effects on rodent anxiety of kindling in the medial, lateral and central amygdaloid nuclei were measured using the hole board and elevated plus maze tests. Kindling has been suggested to model complex partial epilepsy with secondary generalization in humans. Kindling permanently increases the epileptic response of an animal to intracranial stimulation by repeated adminstration of high frequency electrical stimulation. The animals were kindled in medial or lateral amygdalas, of the left and right hemispheres, or in the right hemisphere Central amygdala. Controls had electrodes implanted but were not kindled. Post experimental analysis of electrode location showed that some of the animals were kindled in none of the above nuclei. These animals were labelled ‘Outliers'. Kindling of the Medial/Lateral amygdala in the left hemisphere decreased anxiety in the elevated plus maze for at least one week after the last kindled seizure. Right hemisphere Medial/Lateral kindling did not affect anxiety significantly, though there was a trend toward an anxiogenic effect. The ‘Outlier' kindled rats were less anxious than their controls regardless of hemisphere one week after their last kindled seizure. Central amygdala Kindled animals did not differ from their controls. Previous findings suggest that kindling of specific loci in the right hemisphere may be anxiogenic. Clear anxiogenic effects were likely not seen in the right hemisphere in this study because of electrode locations. Correlations between anxiety and electrode location further pointed to the importance of kindled focus in the amygdala for behavioral effect. Future research should carefully control the location of kindled foci when investigating effects of amygdala kindling on anxiety and other behaviors.

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