Functional neuroanatomy of executive functions has been delineated in a large number of neuroimaging studies using conflict-inducing tasks. The neural basis of alcohol’s effects on cognitive control is poorly understood despite the evidence of impaired ability to evaluate competing demands and to inhibit maladaptive responses. In order to investigate effects of moderate intoxication, healthy social drinkers participated in both alcohol (0.60 g/kg ethanol for men, 0.55 g/kg for women) and placebo conditions while being scanned using blood oxygen level dependent (BOLD) fMRI. A modified 4-color Stroop task combined reading and color naming and used manual responses. Twenty subjects (10 women) were instructed to press a button corresponding to the font color except when a word was written in gray in which case they had to respond to the meaning of the word. Alcohol increased reaction times and a tendency to make more errors on incongruent trials. Behavioral indices of alcohol-induced premature responding correlated with the current drinking levels and impulsivity traits, suggesting an interaction between alcohol effects and personality predispositions. A distributed fronto-parietal cortical network was activated by incongruity. However, moderate alcohol inebriation selectively attenuated anterior cingulate cortex (ACC) activation during both high-conflict trials and erroneous responses, indicating vulnerability of the regulative function subserved by the ACC. By disrupting top-down, strategic processing, alcohol may interfere with goal-directed behavior, resulting in poor self control. The present results support models proposing that alcohol-induced prefrontal impairments diminish inhibitory control and are modulated by dispositional risk factors and levels of alcohol consumption.

Prior neuroimaging evidence indicates that decision conflict activates medial and lateral prefrontal and parietal cortices. Theoretical accounts of cognitive control highlight anterior cingulate cortex (ACC) as a central node in this network. However, a better understanding of the relative primacy and functional contributions of these areas to decision conflict requires insight into the neural dynamics of successive processing stages including conflict detection, response selection and execution. Moderate alcohol intoxication impairs cognitive control as it interferes with the ability to inhibit dominant, prepotent responses when they are no longer correct. To examine the effects of moderate intoxication on successive processing stages during cognitive control, spatio-temporal changes in total event-related theta power were measured during Stroop-induced conflict. Healthy social drinkers served as their own controls by participating in both alcohol (0.6 g/kg ethanol for men, 0.55 g/kg women) and placebo conditions in a counterbalanced design. Anatomically-constrained magnetoencephalography (aMEG) approach was applied to complex power spectra for theta (4–7 Hz) frequencies. The principal generator of event-related theta power to conflict was estimated to ACC, with contributions from fronto-parietal areas. The ACC was uniquely sensitive to conflict during both early conflict detection, and later response selection and execution stages. Alcohol attenuated theta power to conflict across successive processing stages, suggesting that alcohol-induced deficits in cognitive control may result from theta suppression in the executive network. Slower RTs were associated with attenuated theta power estimated to ACC, indicating that alcohol impairs motor preparation and execution subserved by the ACC. In addition to their relevance for the currently prevailing accounts of cognitive control, our results suggest that alcohol-induced impairment of top-down strategic processing underlies poor self-control and inability to refrain from drinking.

Rationale Flexible behavior optimization relies on cognitive control which includes the ability to suppress automatic responses interfering with relevant goals. Extensive evidence suggests that the anterior cingulate cortex (ACC) is the central node in a predominantly frontal cortical network subserving executive tasks. Neuroimaging studies indicate that the ACC is sensitive to acute intoxication during conflict, but such evidence is limited to tasks using manual responses with arbitrary response contingencies. Objectives The present study was designed to examine whether alcohol's effects on top–down cognitive control would generalize to the oculomotor system during inhibition of hardwired saccadic responses. Methods Healthy social drinkers (N=22) underwent functional magnetic resonance imaging (fMRI) scanning and eye movement tracking during alcohol (0.6 g/kg ethanol for men, 0.55 g/kg for women) and placebo conditions in a counterbalanced design. They performed visually guided prosaccades (PS) towards a target and volitional antisaccades (AS) away from it. To mitigate possible vasoactive effects of alcohol on the BOLD (blood oxygenation level-dependent) signal, resting perfusion was quantified with arterial spin labeling (ASL) and used as a covariate in the BOLD analysis. Results Saccadic conflict was subserved by a distributed frontoparietal network. However, alcohol intoxication selectively attenuated activity only in the ACC to volitional AS and erroneous responses. Conclusions This study provides converging evidence for the selective ACC vulnerability to alcohol intoxication during conflict across different response modalities and executive tasks, confirming its supramodal, high-level role in cognitive control. Alcohol intoxication may impair top–down regulative functions by attenuating the ACC activity, resulting in behavioral disinhibition and decreased self-control.

Despite the subjective experience of being in full and deliberate control of our actions, our daily routines rely on a continuous and interactive engagement of sensory evaluation and response preparation streams. They unfold automatically and unconsciously and are seamlessly integrated with cognitive control which is mobilized by stimuli that evoke ambiguity or response conflict. Methods with high spatio-temporal sensitivity are needed to provide insight into the interplay between automatic and controlled processing. This study used anatomically-constrained MEG to examine the underlying neural dynamics in a flanker task that manipulated S-R incongruity at the stimulus (SI) and response levels (RI). Though irrelevant, flankers evoked automatic preparation of motor plans which had to be suppressed and reversed following the target presentation on RI trials. Event-related source power estimates in beta (15–25 Hz) frequency band in the sensorimotor cortex tracked motor preparation and response in real time and revealed switching from the incorrectly-primed to the correctly-responding hemisphere. In contrast, theta oscillations (4–7 Hz) were sensitive to the levels of incongruity as the medial and ventrolateral frontal cortices were especially activated by response conflict. These two areas are key to cognitive control and their integrated contributions to response inhibition and switching were revealed by phase-locked co-oscillations. These processes were pharmacologically manipulated with a moderate alcohol beverage or a placebo administered to healthy social drinkers. Alcohol selectively decreased accuracy to response conflict. It strongly attenuated theta oscillations during decision making and partly re-sculpted relative contributions of the frontal network without affecting the motor switching process subserved by beta band. Our results indicate that motor preparation is initiated automatically even when counterproductive but that it is monitored and regulated by the prefrontal cognitive control processes under conflict. They further confirm that the regulative top-down functions are particularly vulnerable to alcohol intoxication.