This thesis investigates the roles of the amygdala and hippocampus in Pavlovian conditioning. Three questions are addressed. First, what is the involvement of discrete sub-nuclei of the amygdala in Pavlovian conditioning? Second, what molecular processes accompany the retrieval of Pavlovian associations? Third, what changes in gene expression are induced during the acquisition of a Pavlovian association? The basolateral region of the amygdala (BLA) is widely believed to represent the site of CS-US association in Pavlovian conditioning. Recent experiments have however suggested that the BLA may play a more restricted role in Pavlovian conditioning, and that other nuclei and within and outside the amygdala can support the formation of Pavlovian associations. In a first series of experiments the effect of BLA lesions on aversive Pavlovian conditioning were investigated. Lesions of the BLA were found to disrupt conditioning to both discrete and contextual stimuli, as assessed by conditioned freezing, but the effect of BLA lesions on contextual conditioning was ameliorated by additional training. In a second group of experiments the effect of amygdala lesions on the ability of Pavlovian cues to motivate instrumental responding (Pavlovian to instrumental transfer, PIT) was studied. Lesions of the BLA were found to be without effect on PIT, but lesions of the central nucleus of the amygdala (CeN) abolished this effect, as did lesions of the nucleus accumbens (NAcc) core. These results demonstrate that there are dissociable roles of the BLA and CeN within Pavlovian conditioning, and suggest that the CeN and NAcc core interact in PIT.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:599869 |
| Date | January 2000 |
| Creators | Hall, J. |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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