Alcohol intoxication effects on visual perception: an fMRI study

Abstract

We examined the effects of two doses of alcohol (EtOH) on functional magnetic resonance imaging (fMRI) activation during a visual perception task. The Motor-Free Visual Perception Test-Revised (MVPT-R) provides measures of overall visual perceptual processing ability. It incorporates different cognitive elements including visual discrimination, spatial relationships, and mental rotation. We used the MVPT-R to study brain activation patterns in healthy controls (1) sober, and (2) at two doses of alcohol intoxication with event-related fMRI. The fMRI data were analyzed using a general linear model approach based upon a model of the time course and a hemodynamic response estimate. Additionally, a correlation analysis was performed to examine dose-dependent amplitude changes. With regard to alcohol-free task-related brain activation, we replicate our previous finding in which SPM group analysis revealed robust activation in visual and visual association areas, frontal eye field (FEF)/dorsolateral prefrontal cortex (DLPFC), and the supplemental motor area (SMA). Consistent with a previous study of EtOH and visual stimulation, EtOH resulted in a dose-dependent decrease in activation amplitude over much of the visual perception network and in a decrease in the maximum contrast-to-noise ratio (in the lingual gyrus). Despite only modest behavior changes (in the expected direction), significant dose-dependent activation increases were observed in insula, DLPFC, and precentral regions, whereas dose-dependent activation decreases were observed in anterior and posterior cingulate, precuneus, and middle frontal areas. Some areas (FEF/DLPFC/SMA) became more diffusely activated (i.e., increased in spatial extent) at the higher dose. Alcohol, thus, appears to have both global and local effects upon the neural correlates of the MVPT-R task, some of which are dose dependent.

Figure 1

Timeline of the MVPT‐R fMRI paradigm. Figures were presented with an inter‐stimulus interval of approximately 17 sec. The participants were asked to indicate which of the four lower figures contained the upper figure by pressing 1, 2, 3, or 4, after which an asterisk was presented until the next figure appeared. The correct answer for this figure is 2.

Figure 2

Main effect group maps for (mean) sober, low‐dose, and high‐dose conditions. T‐maps are displayed over the T₁‐weighted template. Images were thresholded at P < 0.05 (corrected for multiple comparisons). All colored regions in the figure represent activations and are color‐coded to discriminate the alcohol dosing level. The main effect SPM group analysis for (1) (mean) sober (colored red/orange), (2) low‐dose (colored blue/cyan), and (3) high‐dose (colored green/yellow) are displayed on the same image for clarity. Alcohol dose results in a global decrease in contrast‐to‐noise and also that there are some localized increases and decreases.

Figure 3

Graphic view of contrast‐to‐noise ratio (CNR) differences detected in the main effects analysis. Bar graph comparison of CNR‐by‐area in the (mean) sober, low‐dose, and high‐dose studies. Visual areas demonstrate a clear dose‐dependent decrease in CNR whereas frontal regions appear to be higher in the low‐dose condition and then lower in the high‐dose condition.

Figure 4

EtOH blood alcohol content correlation maps and plots. Comparison of the amplitude difference between the sober (S) and drug (D) conditions for the high (H) dose with the amplitude difference between the sober and intoxicated conditions for the low (L) dose, that is (Δ_H+L [D‐S]). T‐maps are displayed over one of the normalized EPI images. Images were thresholded at P < 0.05 and a cluster size of 50 voxels. Dose‐dependent decreases are depicted in blue/cyan whereas dose‐dependent increases are depicted in red/orange.