Deficient Event-Related Theta Oscillations in Individuals at Risk for Alcoholism: A Study of Reward Processing and Impulsivity Features.

Schematic illustration of the Monetary Gambling Task (MGT).Each trial starts with a choice stimulus (CS) (white boxes) which lasts for 800 ms and displays two amounts (10¢ or 50¢). The participant selects one of the amounts with a corresponding button press. An outcome of either gain (green box) or loss (red box) for the selected amount is shown by the outcome stimulus (OS). A trial with a gain of 50¢ and the next trial with a loss of 10¢ are illustrated. The ISI between the CS and the OS is 1500 ms. Participants were required to respond to the OS within 1000 ms (i.e., response window) by selecting one of the two amounts. ERO analysis was performed on trial epochs of 1000 ms post-stimulus period after the onset of the OS (i.e., analysis window).

Sixty-one electrodes using extended 10–20 system as recorded in the current study.Twelve electrodes (F3, FZ, F4, C3, CZ, C4, P3, PZ, P4, O1, OZ, O2) representing frontal, central, parietal and occipital regions were selected for statistical analyses (shaded).

Multiple comparisons of log-transformed theta power across risk group, gender and age group.Estimated marginal means and standard error (±1 SE) of pairwise comparisons between the risk groups (panel-sets A1 and A2), gender (panel-sets B1 and B2), and age groups (panel-sets C1 and C2) in loss and gain conditions have been plotted for each scalp region (F, frontal; C, central; P, parietal; and O, occipital). Bonferroni adjusted level of significance for each comparison is shown in asterisks (**p < 0.01, ***p < 0.001). [M = Male; F = Female; Yo = Younger Age Group (12–15 years); Ol = Older Age Group (16–25 years)].

Time-frequency (TF) plots of theta power.TF plots during loss at FZ electrode (middle panels on the left side) and gain conditions at PZ electrode (middle panels on the right side) for the younger (top two rows) and older male subjects (bottom two rows) are shown. Theta power differences between HR and LR subjects (HR < LR) were more robust in males (as shown in these plots) compared to females (not shown). In these panels, each TF plot is flanked by a topographic map of absolute values on the left side and z-scored values on the right side. The rectangle box inside the TF plots represents the Time Frequency Region of Interest (TFROI) of ERO theta band (3.5–7.5 Hz, y-axis) within 200–500 ms (x-axis). Loss condition with anterior maximum and gain condition with posterior focus are shown. Older groups displays more anterior activity than younger groups (“frontalization”).

Topographic maps of ERO theta activity.The maps illustrate absolute (Abs) and Z-scored (Zsc) CSD potentials across risk groups for the loss (left columns of panelset A) and gain condition (right columns of panelset B) in the younger (panelset A) and older group (panelset B). Uniform color scales for the absolute maps (μV/cm2) and for the Z-scored maps (from minimum to maximum) are shown at the bottom.

Comparison of impulsivity scores between LR and HR across subgroups.The mean and standard error (SE) of the BIS scores have been plotted. The error bars represent 1 SE. The significance levels have been marked with asterisks (*p < 0.05; **p < 0.01; ***p < 0.001).