Chase Kluemper 1 , Chelsea Black 1 , Yang Jiang 1 , Jane E. Joseph 2 , & Thomas H. Kelly 1, 3

1. UNIVERSITY OF KENTUCKY Recognition memory amongst individuals varying in the personality dimensions of Reward Seeking and Impulsivity Chase Kluemper1, Chelsea Black1, Yang Jiang1, Jane E. Joseph2, & Thomas H. Kelly1, 3 Departments of Behavioral Science1, Anatomy & Neurobiology2, and Psychology3 University of Kentucky, Lexington, KY Results Introduction TIME (ms) Reward Seeking x Electrode interaction, greatest at FPZ (P<0.001) • Sensation Seeking is a personality trait that is associated with the initiation, escalation and development of problems associated with drug use. The efficacy of prevention interventions targeting high sensation seekers are enhanced by presenting persuasive messages in unfamiliar and unexpected high sensation value contexts. Previous research by our group has established sensation seeking group differences at the N200 component of the ERP waveform during Old/New recognition memory task performance, reflecting individual differences in automatic stimulus novelty and orienting processes. The purpose of this study was to examine the role of impulsivity and reward seeking dimensions of sensation seeking in response to novelty. • Participants: • 81 healthy 18-30 yr-olds • Right-handed, English-speaking, and not regular drug users • Each subject was categorized on Reward Seeking and Impulsivity using uncorrelated impulsivity and sensation-seeking items from the impulsive sensation-seeking scale of the Zuckerman-Kuhlman Personality Questionnaire (median split into 4 groups): Impulsivity x Electrode interaction, greatest at PZ (P=0.06) Behavioral Data: ACTIVATION (uV) Reward Seeking x Impulsivity x Stimulus interaction (P=0.002) greatest for New items * Mean + SE EEG Data: • P100 Latency: Impulsivity x Electrode interaction (P=0.06). Impulsivity group differences were greatest at posterior sites, with maximum effect at Electrode PZ. • N200 Peak Value: Reward Seeking x Impulsivity x Electrode interaction (P=0.07). Differences were significant at electrode FPZ only. • N200 Latency: Reward Seeking x Impulsivity x Electrode interaction (P=0.05). Latency differences were observed at posterior electrodes, and maximum effect was seen at PZ. • FN400 Peak Value: Reward Seeking x Electrode interaction (P=0.001). Group differences in Reward Seeking occurred only at the FPZ site. • Late Positive Component (LPC) Peak Value: A Main effect of stimulus was shown by all four groups, a hallmark of the Old/New task ERP waveform. • Late Positive Component (LPC) Latency: Reward Seeking x Impulsivity x Stimulus interaction (P=0.002). Greatest differences were observed for New stimuli. This analysis also uncovered a Reward Seeking x Impulsivity x Electrode interaction (P<0.0001). This interaction was most prevalent among frontal electrodes, and maximum effect was seen at FPZ. Methods N200 Peak FN400 Peak LPC Latency P100 Latency N200 Latency LPC Latency Reward Seeking x Impulsivity x Electrode interaction, greatest at FPZ (P<0.001) Reward Seeking x Impulsivity x Electrode interaction, greatest at PZ (P=0.05) Reward Seeking (RS) Low High Conclusions Low High Impulsivity (Imp) Task Design: • Study Phase: • 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 or a personal memory. 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. • Test phase: • Subjects were presented with studied (70) and unstudied (70) stimuli, old and new respectively, presented in random order and were instructed to discriminate between the two by pressing one of two buttons as quickly as possible upon stimulus presentation. • Recordings: • 64 channel EEG (NeuroscanSynamp 2, event-related potentials, 0.05 – 40 Hz band pass) The personality dimensions of reward seeking and impulsivity are associated with individual differences in automatic stimulus novelty and orienting processing. Task performance (reaction time, accuracy) was comparable across groups. The Impulsivity x Electrode interaction observed at the P100 component may represent visual attention differences across groups, since the maximum effect was observed at electrodes in proximity to ocular processing. The N200 component, which has been implicated in novelty processing, is influenced by Reward Seeking and Impulsivity. FN400, associated with familiarity, was influenced by Reward Seeking status, only. These results suggest that the influence of the sensation-seeking sub-dimensions of Reward Seeking and Impulsivity may vary as a function of novelty- and familiarity-processing. The expected old/new task stimulus effect, observed in the LPC component associated with memory and contextual processing, was influenced by both Reward Seeking and Impulsivity. An understanding of the neurophysiologic basis of information processing in individuals at risk for drug abuse may help target appropriate prevention strategies. STUDY PHASE (100 OBJECTS): Electrode Location:    FPZ TEST PHASE (140 OBJECTS): Axial PZ OLD NEW OLD NEW OLD NEW This project is supported by NIDA grant P50 05312-15 to the Center for Drug and Alcohol Research Translation at the University of Kentucky OLD NEW OLD NEW Saggital