Date of Award
Kinesiology and Health Science
Learning and memory abilities are altered in disorders of the serotonergic system, in disorders such as such as depression, phobias, and post-traumatic stress disorder (PTSD). Among the processes impaired by emotional distracters, and whose dysregulation is documented in affective disorders, is the ability to time in the seconds-to-minutes range, i.e., interval timing. Presentation of distracters during timing tasks result in delays in responding suggesting a failure to maintain subjective time in working memory, as proposed by the Relative Time-Sharing (RTS) model. We investigated the role of the prelimbic cortex in the detrimental effect of anxiety-inducing distracters on the cognitive ability to interval time, using local infusions of selective serotonin reuptake inhibitor (SSRI) fluoxetine in a modified peak-interval procedure with neutral and anxiety-inducing distracters. Given that fluoxetine has beneficial effects on decreasing emotional responses to negative events, we hypothesized that fluoxetine would improve working memory in trials with distracters. Our results revealed a dissociation of the effects of fluoxetine infusion in the pre limbic cortex on interval timing and resource allocation (working memory for time), when neutral and anxiety-inducing distractions occurred. Fluoxetine was effective only during trials with distracters, but not during trials without distracters. Moreover, fluoxetine reduced the harmful effect of the distracters not only when the distracters were anxiety-inducing, but in fact exacerbated their detrimental effects on working memory when they were neutral. Results are discussed in relation to the brain circuits involved in RTS of resources, and the pharmacological management of affective disorders.
Christensen, Chance, "Dissociation of the Effects of Serotonin Reuptake Inhibitor Fluoxetine in Prelimbic Cortex on Disruption of Timing and Working Memory for Time by Neutral and Negative Emotional Events" (2014). Undergraduate Honors Capstone Projects. 505.
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