Neural correlates of a Go/NoGo task with alcohol stimuli in light and heavy young drinkers

Abstract

Inhibitory processes are highly relevant to behavioral control affecting decisions made daily. The Go/NoGo task is a common task used to tap basic inhibitory processes important in higher order executive functioning. The present study assessed neural correlates of response inhibition during performance of a Go/NoGo task in which NoGo signals or tests of inhibitory control consisted of images of beer bottles. Group comparisons were conducted between 21 heavy and 20 light drinkers, ranging in age from 18 to 22. Behaviorally, overall performance assessed with d-prime was significantly better among the lighter drinkers. On a neural level, the heavy drinkers showed significantly greater activity in the right dorsolateral prefrontal cortex, medial frontal cortex and cingulate relative to the light drinkers during the NoGo trials. These regions are implicated in reflective or control processing of information. Further, heavy drinkers showed significantly greater activity in the insula relative to light drinkers during NoGo trials, a neural region implicated in habit circuitry and tied to cue induced urges and emotional memories of physical effects of drugs. These results suggest that the heavier drinkers may have experienced increased working memory demand and control efforts to withhold a response due to poorer inhibitory control from enhanced salience of alcohol cues on the beer NoGo trials, which also engaged insula mediated effects.

Keywords: Alcohol; Dorsolateral prefrontal; Go/NoGo; Response inhibition; fMRI.

Figure 1. Temporal layout of task

The paradigm consisted of 160 Go trials and 40 No/Go trials (4:1 ratio). Go trials consisted of 80 coke bottles and 80 water bottles while NoGo trials consisted of 40 beer bottles. A fixation point (plus symbol) was presented before and after each image. Cue exposure occurred for a maximum of 1.5 seconds, and mean exposure for fixation was 2 seconds. Total trial duration was between 1.5 – 4.5 seconds.

Figure 2. Right Dorsolateral Prefrontal (32, 44, 38)

Percent signal change and activation of the right dorsolateral prefrontal cortex (32, 44, 38): Sagittal and coronal views (t=3.89, p<.001, uncorrected, voxels >10) showed significant activation during NoGo trials among heavy drinkers relative to light drinkers. Graph provides the plots of % signal change for the dorsolateral prefrontal cortex. Error bars denote within-subject error.

Figure 3. Medial Frontal/Cingulate (8,16, 38)

Percent signal change and activation of medial frontal/anterior cingulate (8, 16, 38). Sagittal and coronal views (t=3.8, p<.001, uncorrected, voxels >10) showed significant activation during NoGo trials among heavy drinkers relative to light drinkers. Graph provides the plots of % signal change for the medial frontal/cingulate cortex.

Figure 4. Right Anterior Insula (32, 18, 10)

Percent signal change and activation of insula (32, 18, 10). Sagittal and coronal views (t=3.66, p<.001, uncorrected, voxels >10) showed significant activation during NoGo trials among heavy drinkers relative to light drinkers. Graph provides the plots of % signal change for the anterior insula.