Inhibition as a predictor of performance on an Old/New recognition memory task

1. UNIVERSITY OF KENTUCKY Inhibition as a predictor of performance on an Old/New recognition memory task Chase Kluemper1, Seth Kiser1, Yang Jiang1, Jane E. Joseph2, & Thomas H. Kelly1, 3 1Behavioral Science Department, University of Kentucky College of Medicine, Lexington, KY, USA, 2Dept. of Anatomy & Neurobiology, University of Kentucky Chandler Medical Center, Lexington, KY, 3Psychology Dept., University of Kentucky, Lexington, KY . Individual Impulsivity scores vs. New stimulus accuracy: Methods: Each subject studied a randomized set of 100 computer-displayed black and white line drawings for five seconds per drawing. The same study stimuli were then displayed for a second time, at random, also for five seconds apiece. Subjects were told to remember each drawing by relating it to themselves somehow. Retention of old stimuli was tested by a 20-stimulus practice task, and all subjects achieved a retention rate of >90% before beginning the task. During the task, subjects were presented with previously studied and unstudied stimuli, old and new respectively, and were instructed to discriminate between the two by pressing one of two buttons as quickly as possible upon stimulus presentation. Introduction: Inhibition is a personality dimension that conveys an individual’s relative willingness to pause and take into account potential consequences of behavior during the decision-making process. As a discrete component of the personality trait sensation seeking, inhibition plays a role in avoiding the initiation, escalation and development of problems associated with drug use (Kelly et al., 2006; Stoops et al., 2007). The purpose of this study is to investigate the neurobehavioral differences in individuals varying in inhibition and reward sensitivity, both separable components of sensation seeking. Here the study population was segregated based on risk due to lack of inhibition, and performance on a working memory task was evaluated. Electroencephalography and functional magnetic resonance imaging are both employed to gather comprehensive neurobehavioral data. Only behavioral data Is reported in this poster. Population: Twenty-four 18-30 yr-olds were individually assessed for inhibition using the Brief Sensation-Seeking Scale (BSSS) and segregated into two groups. The Low Risk group (N=14, 6 male, 8 female) showed a risk due to lack of inhibition that was less than the standard BSSS 50th percentile, indicating these individuals were more highly inhibited. The High Risk group (N=10, 6 male, 4 female) was assessed to have a risk due to lack of inhibition above the standard 50th percentile, indicating a general lack of inhibition. Accuracy Success on New/Old Recognition Task in High and Low Impulsive Subjects: Subject Impulsivity Score Accuracy Sample Images from the Old/New task • Conclusions: • Our data show that differences in impulsivity (or lack of inhibition) play a role in recognition memory task performance. It is unclear whether this difference has to do with encoding, retrieval, attention span, or some other component of memory. Analysis of EEG and fMRI imaging data associated with task performance will help determine the underlying neurophysiologic basis for differences in visual memory in these individuals varying in inhibition. Strategies for the prevention of high-risk behavior associated with a lack of inhibition may benefit from an understanding of this neurophysiologic basis as well as its behavioral correlates. Acknowledgements: • This study is supported by NIDA grant P50 05312 Stimulus Type Results: Response times were not different among the low and high impulsivity groups. In contrast, significant differences in accuracy were observed between low and high groups. The Low Risk group identified 97% of New stimuli and 96.19% of Old stimuli correctly, and the High Risk group demonstrated an accuracy of 89.9% on the New items and 92.8% on the Old items. In addition, individual subject impulsivity scores were inversely proportional to accuracy on the task. Analysis by two-way ANOVA confirmed the significance of the discrepancy in NEW stimuli accuracy (P=0.014) and suggested a near-significant trend (P=0.05) in OLD stimuli accuracy.