EXTERNAL REWARD FACILITATES VISUAL PERCEPTUAL LEARNING OVER A

EXTERNAL REWARD FACILITATES VISUAL PERCEPTUAL LEARNING OVER A NIGHT’S SLEEP Aaron V Berard, Tyler Barnes-Diana, Jose Nañez, Yuka Sasaki, Takeo Watanabe Laboratory for Cognitive and Perceptual Learning, Department of Cognitive, Linguistic, and Psychological Sciences, Brown University

Visual Perceptual Learning • Visual perceptual learning (VPL) is defined as a long-term performance improvement on a visual task as a result of visual experience • Plasticity in the visual system • Both sleep and reward play significant roles in VPL Karni et al. (1994); Mednick et al. (2003); Yotsumoto et al. (2009); Seitz et al. (2009); Arsenault et al. (2013); Kim et al. (2015)

Sleep and VPL • Both NREM and REM sleep may play significant roles in the consolidation of VPL Karni et al. (1994); Stickgold (2001); Yotsumoto et al. (2009) • Even a short 90 -minute nap has been shown to consolidate VPL Mednick et al. (2003)

Reward and VPL • In addition to sleep, reward has been found to enhance VPL Seitz et al. (2009); Arsenault et al. (2013); Kim et al. (2015)

The Problem of Sleep and Reward • In our studies that have shown the effect of reward on VPL, subjects slept after training Seitz, Kim, & Watanabe (2009); Kim et al. , (2015) • These studies have not clarified how sleep and reward interact on VPL

Predictions • Prediction 1: The effects of sleep and reward on VPL are independent • Prediction 2: The effects of sleep and reward on VPL are interactive

Aim of the Present Study • In order to test which prediction is correct, we employed an overnight vs. daytime VPL comparison, with and without reward

Design and Procedure • 4 independent groups were tested (n=48 in total) • Sleep group with reward (n=12) • Sleep group without reward (n=12) • Wake group with reward (n=12) • One subject excluded due to daytime napping • Wake group without reward (n=12)

Reward & Sleep No Reward & Sleep Training reward Training no reward Sleep Test reward Test no reward Reward & No Sleep No Reward & No Sleep Training reward Training no reward Wake Test reward Test no reward

Method • Subjects were trained on a texture discrimination task (TDT) 1. “ L or T ? ” 2. “ H or V ? ” Fixation Stimulus Blank Mask SOA Response Karni et al. (1991); Yotsumoto et al. (2009)

Method • Subjects in the reward groups received water as a reward upon correct discrimination response Seitz et al. (2009); Kim et al. (2015)

TDT Threshold • Results calculated to find the SOA at the 75% performance threshold • Plotted with a logistic function 75%

Results: Training Session • No significant group difference in threshold for the Threshold SOA (ms) training sessions 180 160 140 120 100 80 60 40 20 0 Reward No Reward Sleep No sleep (Wake)

Results: Performance Improvement • 2 -way (sleep vs. no sleep) x (reward vs. no reward) ANOVA Performance Improvement (%) • Significant interaction between sleep and reward (p<0. 05) 50 45 40 35 30 25 20 15 10 5 0 *** Sleep **** Reward + No Sleep (Wake) No Reward ****p<0. 001 ***p<0. 005 +p = 0. 06

Summary of Results • There was a significant interaction between the effects of sleep and reward on VPL • Without sleep, there was no significant effect of reward • With sleep, there was a significant effect of reward

Discussion • Our results suggest that reward if effective on VPL only after subjects sleep • No significant difference in performance of the training sessions suggest that the effect of reward is not shown before sleep • There are two possibilities: • The reward system effective on VPL is triggered by sleep • The reward system effective on VPL is inhibited during wakefulness

Acknowledgments • Laboratory for Cognitive and Perceptual Learning • NIH Support: • R 01 EY 015980 • R 01 MH 091801

Supplementary Slides Mednick et al. , 2003

Supplementary Slides Abe et al. , 2011

Supplementary Slides • Our findings suggest that sleep was necessary for VPL to occur, but not reward • Sleep VPL • Reward VPL • This leaves us with two possible models • Sleep Reward VPL • Reward Sleep VPL • Future directions include examining these models

Supplementary Slides • Additional models to consider for our results • Recursive properties of sleep and reward • Sleep/Reward VPL • Reward Sleep/Reward VPL

Supplementary Slides Interaction Model Sleep Independent Model Sleep VPL Reward