AbstractsPsychology

The modulation of attention and responding in the medial prefrontal cortex of rats

by Melissa Sharpe




Institution: University of New South Wales
Department: Psychology
Year: 2014
Keywords: Fear conditioning; Prelimbic cortex; Attention; Executive function; Infralimbic cortex
Record ID: 1050548
Full text PDF: http://handle.unsw.edu.au/1959.4/54083


Abstract

The present thesis examined the role of the prelimbic (PL) cortex in using associative history and contextual cues to change an animal’s response towards a stimulus. In the first set of experiments, we clarified the role of the PL cortex in attention. Here, we found that PL lesions disrupted the exhibition of the overshadowing effect whilst leaving the blocking phenomenon intact. Further, we found that rats with PL lesions demonstrated faster acquisition towards the blocked cue, suggesting they had not down-regulated attention towards the blocked cue. A deficit in down-regulating attention in PL-lesioned animals was confirmed using a blocking of unblocking procedure. These data demonstrated that the PL cortex is necessary to allow animals to change the degree of attention directed towards cues on the basis of their associative history. In a second set of experiments, we attempted to generalise the role of the PL cortex in modulating attention to the aversive domain. Here, we again found that animals with PL lesions exhibited a deficit in overshadowing but remain capable of demonstrating the blocking effect. Using functional inactivation, we found that the PL cortex is necessary during the conditioning phase of overshadowing, but not in the expression of this effect at test. This confirmed that the PL cortex is necessary to allow animals to modulate attention towards cues during the learning process to influence the development of learnt associations in an aversive procedure. In a final set of experiments, we investigated the role of the PL cortex in using contextual cues to modulate responding. Using an ABA renewal procedure, we demonstrated that rats without a functional PL cortex during the test phase failed to express the renewal of conditioned fear. This deficit was also accompanied by a lack of change in orienting towards a CS according to present contextual cues. Further, we also found that the PL cortex is also involved in the acquisition and expression of associations developed in a contextual bi-conditional discrimination. Taken together, these data demonstrate that the PL cortex is necessary for animals to use associative history and contextual cues to modulate both learning and performance.