Date of Award

Spring 5-11-2015

Degree Type

Thesis

Degree Name

MS Experimental Psychology

Department

Psychology

Advisor

Amy Silvestri Hunter, Ph.D

Committee Member

Marianne Lloyd, Ph.D

Committee Member

Amy Joh, Ph.D

Committee Member

Kelly M Goedert, Ph.D

Keywords

Ketamine, Object Recognition Memory, Adolescence, Chronic

Abstract

Prior research has demonstrated that ketamine causes deficits in object recognition and location memory following both acute and chronic administration (Pitsikas & Boultadakis, 2009; Venãncio et al., 2011). Although it is well established that abuse of many different kinds of drugs during the critical developmental period of adolescence can lead to impairments in cognition later in adulthood (Gilpin et al., 2012; Wagner et al., 2010), no research has investigated the effects of chronic ketamine administration during adolescence and its effects on behavior in adulthood. With recent research establishing that chronic ketamine during adolescence produces late-onset alterations in electrophysiology during adulthood (Featherstone et al., 2014), the current study examined the effect of chronic ketamine during adolescence on the object recognition (ORT) and location tasks (OLT). Additionally, the current study sought to clarify how the combination of natural neurodevelopmental processes and NMDA receptor antagonism affected both short- and long-term performance on both the object recognition and location tasks. Therefore, the animals received one injection of 25 mg/kg of ketamine daily for seven consecutive days during adolescence. Following drug administration, the animals were assessed in a locomotor assessment and subsequently in behavioral testing on the object recognition and location tasks. The animals underwent choice phases where they had to discriminate a novel object or location from a familiar object or location following a 15-minute and 24-hour delay during both adolescence and adulthood. Ketamine administration produced impairments in object recognition and location tasks at all time points tested (i.e., adolescence and adulthood, 15m and 24h delays). In addition, performance on the OLT was affected by both age and delay, with superior discrimination occurring in adult rats as compared to adolescent rats and at the 15-minute time point as compared to the 24-hour time point. There was also a trend toward an age by delay interaction on the ORT such that older rats were more impaired than younger rats, but only at the 24-hour delay. Taken together, the current findings expand the breadth of knowledge regarding the effects of ketamine on object recognition and location memory. Specifically, this study suggests that administration during adolescence induces deficits in how rats explore novel objects and locations in adolescence and that these deficits persist into adulthood.

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