Functional Connectivity During Reward Processing: Wavelet Coherence in a Gambling Task Chella Kamarajan, David Chorlian, Ashwini K. Pandey, Roopesh B. Nagaraj, Niklas Manz, Ramotse Saunders, Madhavi Rangaswamy, Bernice Porjesz Henri Begleiter Neurodynamics Laboratory, Department of Psychiatry, SUNY Downstate Medical Center, Brooklyn, NY, USA. Abstract The outcome related negativity (ORN), an event-related potential (ERP) component occurring around 200-250 ms, has been suggested to be an electrophysiological brain signature for the processing of loss and gain. This component has been suggested to involve theta band oscillations as a primary feature. The aim of the current study is to examine oscillatory activity and functional connectivity between frontal and parietal regions during the processing of monetary loss and gain. The sample consisted of 36 healthy individuals with an age range of 18-35 years. A 64-channel EEG was recorded continuously while the subjects performed a gambling task that prompted the subject to select one of two amounts, 10 and 50. Loss (-50) and Gain (+50) conditions were analyzed using a Wavelet coherence method for midline frontal (FZ) and parietal (PZ) electrodes. Time-Frequency representation and Power and Coherence were plotted and compared between loss and gain conditions. The loss condition had more power at FZ while the gain condition had maximum power at PZ. Wavelet coherence values were different between loss and gain in several frequencies at different time interval. The results tend to confirm the view that loss- and gain-related processing are mediated by separate and distinct cortical circuits. Introduction • Dynamic interplay among neurons within the local neuronal assembly and on the communication between different and often distant assemblies of neurons are essential for neural information processing (Engel et al., 2001; Pesaran et al., 2002; Schnitzler and Gross, 2005). • Wavelet Coherence (WC) is a new method of studying the functional connectivity network in normals (Zhan et al., 2006) and the dysfunctions in brain synchronization dynamics in neurocognitive disorders (Sakkalis et al., 2006). • The outcome related negativity (ORN), an event-related potential (ERP) component around 200-250 ms, has been suggested to be an electrophysiological brain signature for the processing of loss and gain (Gehring & Willoughby, 2002; Nieuwenhuis et al., 2004; Kamarajan et al., 2009). • ORN has been found to be composed of theta band oscillations (Gehring and Willoughby, 2004), with anterior activation more pronounced during loss and posterior during gain (Kamarajan et al., 2008). • The present study aims to examine the antero-posterior functional connectivity during the processing of loss and gain in a gambling task by using Wavelet Coherence. 1. 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Schnitzler A, Gross J (2005) Normal and pathological oscillatory communication in the brain. Nat Rev Neurosci, 6:285–96. 10. Zhan Y, Halliday D, Jiang P, Liu X, Feng J. Detecting time-dependent coherence between non-stationary electrophysiological signals--a combined statistical and time-frequency approach. J Neurosci Methods, 156:322-32. Acknowledgements In memory of Dr. Henri Begleiter, we acknowledge with great admiration his seminal scientific contributions to the field. We are indebted to his charismatic leadership and luminous guidance. This study was supported by the National Institutes of Health (NIH) Grants #5 RO1 AA02686 and AA005524 from the National Institute on Alcohol Abuse and Alcoholism (NIAAA). We are grateful for the valuable technical assistance of Arthur Stimus, Carlene Haynes, Joyce Alonzia, Chamion Thomas, Tracy Crippen, Glenn Murawski, Eric Talbert, Patrick Harvey, Cindy Lipper, Gaby Wurzel, Irina Kushnir, and Aleksandr Razran. We thankfully acknowledge A.Grinsted, J.C.Moore and S.Jevrejeva for the Wavelet Coherence software package for MatLab, available at the URL: http://www.pol.ac.uk/home/research/waveletcoherence/ . References Methods PARTICIPANTS: The sample consisted of 36 healthy individuals with an age range of 18-35 years. GAMBLING TASK: A Single Outcome Gambling Paradigm was used (see Figure 2) EEG RECORDING & ANALYSES: A 64-electrode EEG (Figure 3) was recorded as the subjects were performing the task. Wavelet coherence was computed. Background for Hypothesis We have reported that separate brain processes/circuitry may mediate loss and gain outcomes as indicated by the topography of amplitude and current density of ORN and ORP components (Kamarajan et al., 2009) and by the theta power during 200-500 ms after the outcome stimulus (Kamarajan et al., 2008). The current study explores the topographic differentiation of “frontal- loss vs. posterior-gain” and the functional link between frontal and parietal sites using Wavelet Power and Coherence between frontal and posterior sites. 0 250 500 750 ms +10 mV ORN (N2) ORP (P3) Next Trial 10 50 10 50 10 50 10 50 50 50 50 10 Choice Stimulus (CS) A) B) C) 10 50 10 50 10 50 10 50 10 50 10 50 10 50 10 50 10 50 10 50 10 50 10 50 50 50 50 50 Selection Window (800 + 200 ms) Analysis Window (200 + 800 ms) Outcome Stimulus (OS) Choice Stimulus (CS) . 800 ms 700 ms 800 ms 700 ms 800 ms Fig. 1. ORN and ORP Fig. 2. Gambling Task Fig. 3. EEG Montage Female Male -50 -10 +50 +10 N2 Potential -3 -2 -1 0 1 2 3 -3 -2 -1 0 1 2 3 -3 -2 -1 0 Male Female 5 10 15 20 25 2 A) B) P3 Potential N2 Z-score P3 Z-score Female Male Male Female -50 -10 +50 +10 –50 –10 +50 +10 M F A M F A θ –50 –10 +50 +10 Absolute Power Z-Scored Power -2 -1 0 1 2 5 10 15 20 Fig. 4. Topography of ORN and ORP Fig. 5. Topography of Theta Power Results for Evoked EROs 1) Time-Frequency Representation 2) Amplitude Envelope, Waveforms & Coherence of EROs Results for Total EROs Fig. 6. Evoked Power (Loss) Fig. 7. Evoked Power (Gain) CWT: FZ (Loss-50) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 0 10 20 30 40 CWT: FZ (Loss-50) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 -2 0 2 CWT: PZ (Loss-50) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 0 10 20 30 40 CWT: PZ (Loss-50) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 -2 0 2 Coh: FZ-PZ (Loss-50) Time (msec) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 0 0.5 1 Coh: FZ-PZ (Loss-50) Time (msec) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 -2 0 2 CWT: FZ (Gain-50) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 0 10 20 30 40 CWT: FZ (Gain-50) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 -2 0 2 CWT: PZ (Gain-50) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 0 10 20 30 40 CWT: PZ (Gain-50) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 -2 0 2 Coh: FZ-PZ (Gain-50) Time (msec) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 0 0.5 1 Coh: FZ-PZ (Gain-50) Time (msec) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 -2 0 2 Fig. 8. Evoked Power (Loss) Fig. 9. Evoked Power (Gain) 10 20 30 µ V Delta (1-3.5 Hz) -50 0 50 µ V Delta (1-3.5 Hz) 0 10 20 µ V Theta (3.5-7.5 Hz) -10 0 10 µ V Theta (3.5-7.5 Hz) 0 2 4 µ V Alpha (8-12 Hz) -5 0 5 µ V Alpha (8-12 Hz) 0 1 2 µ V Beta (13-28 Hz) -2 0 2 µ V Beta (13-28 Hz) -200 0 200 400 600 800 0 1 2 µ V Gamma (29-48 Hz) Time (msec) -200 0 200 400 600 800 -2 0 2 µ V Gamma (29-48 Hz) Time (msec) 0 20 40 µ V Delta (1-3.5 Hz) -50 0 50 µ V Delta (1-3.5 Hz) 0 5 10 µ V Theta (3.5-7.5 Hz) -10 0 10 µ V Theta (3.5-7.5 Hz) 0 5 10 µ V Alpha (8-12 Hz) -10 0 10 µ V Alpha (8-12 Hz) 0 1 2 µ V Beta (13-28 Hz) -2 0 2 µ V Beta (13-28 Hz) -200 0 200 400 600 800 0 1 2 µ V Gamma (29-48 Hz) Time (msec) -200 0 200 400 600 800 -2 0 2 µ V Gamma (29-48 Hz) Time (msec) Fig. 10. Coherence • Neural activity after the occurrence of the outcome stimulus (up to 500 ms) was dominated by low frequency oscillations. • Varying patterns of coherence were observed between loss and gain in different frequency bands. 3) Time-Frequency Representation 4) Amplitude Envelope, Waveforms & Coherence of EROs CWT: FZ (Loss-50) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 0 20 40 60 80 CWT: PZ (Loss-50) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 0 20 40 60 80 CWT: FZ (Loss-50) (Z) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 -2 0 2 CWT: PZ (Loss-50) (Z) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 -2 0 2 Coh: FZ-PZ (Loss-50) Time (msec) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 0 0.5 1 Coh: FZ-PZ (Loss-50) (Z) Time (msec) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 -2 0 2 CWT: FZ (Gain-50) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 0 20 40 60 80 CWT: PZ (Gain-50) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 0 20 40 60 80 CWT: FZ (Gain-50) (Z) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 -2 0 2 CWT: PZ (Gain-50) (Z) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 -2 0 2 Coh: FZ-PZ (Gain-50) Time (msec) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 0 0.5 1 Coh: FZ-PZ (Gain-50) (Z) Time (msec) Frequency (Hz) 0 200 400 600 1 2 4 8 16 32 64 -2 0 2 Fig. 11. Total Power (Loss) Fig. 12. Total Power (Gain) 30 40 50 µ V Delta (1-3.5 Hz) -50 0 50 µ V Delta (1-3.5 Hz) 10 20 30 µ V Theta (3.5-7.5 Hz) -10 0 10 µ V Theta (3.5-7.5 Hz) 10 20 30 µ V Alpha (8-12 Hz) -5 0 5 µ V Alpha (8-12 Hz) 5 10 15 µ V Beta (13-28 Hz) -2 0 2 µ V Beta (13-28 Hz) -200 0 200 400 600 800 5 6 7 µ V Gamma (29-48 Hz) Time (msec) -200 0 200 400 600 800 -2 0 2 µ V Gamma (29-48 Hz) Time (msec) 30 40 50 µ V Delta (1-3.5 Hz) -50 0 50 µ V Delta (1-3.5 Hz) 10 20 30 µ V Theta (3.5-7.5 Hz) -10 0 10 µ V Theta (3.5-7.5 Hz) 10 15 20 µ V Alpha (8-12 Hz) -10 0 10 µ V Alpha (8-12 Hz) 5 10 15 µ V Beta (13-28 Hz) -2 0 2 µ V Beta (13-28 Hz) -200 0 200 400 600 800 5 6 7 µ V Gamma (29-48 Hz) Time (msec) -200 0 200 400 600 800 -2 0 2 µ V Gamma (29-48 Hz) Time (msec) 0.8 0.85 0.9 Coh Delta (1-3.5 Hz) 0.5 0.6 0.7 Coh Theta (3.5-7.5 Hz) 0.5 0.55 0.6 Coh Alpha (8-12 Hz) 0.5 0.55 0.6 Coh Beta (13-28 Hz) -200 0 200 400 600 800 0.7 0.8 Coh Gamma (29-48 Hz) Time (msec) Fig. 13. Total Power (Loss) Fig. 14. Total Power (Gain) Fig. 15. Coherence In memory of Dr. Henri Begleiter, we acknowledge with great admiration his seminal scientific contributions to the field. We are indebted to his charismatic leadership and luminous guidance. This study was supported by the National Institutes of Health (NIH) Grants #5 RO1 AA02686 and AA005524 from the National Institute on Alcohol Abuse and Alcoholism (NIAAA). We are grateful for the valuable technical assistance of Arthur Stimus, Carlene Haynes, Joyce Alonzia, Chamion Thomas, Tracy Crippen, Glenn Murawski, Eric Talbert, Patrick Harvey, Cindy Lipper, Gaby Wurzel, Irina Kushnir, and Aleksandr Razran. We thankfully acknowledge A.Grinsted, J.C.Moore and S.Jevrejeva for the Wavelet Coherence software package for MatLab, available at the URL: http://www.pol.ac.uk/home/research/waveletcoherence/ . Acknowledgements • Comparison of Evoked vs. Total EROs offers information about specific contributions of particular frequency band(s) to produce specific ERP components. • High coherence between frontal and parietal sites are reflected in both low and high frequencies. Further studies are needed to confirm this finding. Absolute Z-scored Absolute Z-scored Absolute Z-scored Absolute Z-scored Amp Envelope Waveform Amp. Envelope Waveform Amp Envelope Waveform Amp. Envelope Waveform Loss vs. Gain Loss vs. Gain FPZ FP2 FP1 FZ F2 F4 F6 F8 F1 F3 F5 F7 AFZ AF2 AF8 AF1 AF7 FCZ FC2 FC4 FC6 FC1 FC3 FC5 C6 CZ C2 C4 C1 C3 C5 FT7 FT8 T7 T8 CPZ CP2 CP4 CP1 CP3 CP5 TP7 CP6 TP8 PZ P2 P4 P6 P8 P1 P3 P5 P7 POZ PO2 PO8 PO1 PO7 OZ O2 O1 LEFT TEMPORAL RIGHT TEMPORAL CENTRAL PARIETAL FRONTAL OCCIPITAL AF1 The author has requested enhancement of the downloaded file. All in-text references underlined in blue are linked to publications on ResearchGate. The author has requested enhancement of the downloaded file. All in-text references underlined in blue are linked to publications on ResearchGate.