Academic journal article Cognitive, Affective and Behavioral Neuroscience

Drink Alcohol and Dim the Lights: The Impact of Cognitive Deficits on Medial Frontal Cortex Function

Academic journal article Cognitive, Affective and Behavioral Neuroscience

Drink Alcohol and Dim the Lights: The Impact of Cognitive Deficits on Medial Frontal Cortex Function

Article excerpt

Scalp electroencephalogram (EEG) recordings indicate that regions in the medial frontal cortex (MFC) are active following errors. Alcohol consumption reduces this error-related activity, perhaps suggesting that alcohol disrupts the operation of an error-monitoring system in the MFC. However, it could also be that alcohol consumption affects the MFC only indirectly, by impairing stimulus processing and thus making errors harder to detect. This interpretation leads to the prediction that stimulus degradation should likewise reduce error-related activity in the MFC. To test this hypothesis, behavioral and EEG data were collected as participants performed a speeded response task with either bright or very dim stimuli. The results using dim stimuli replicated the observed effects of alcohol consumption-with slowed responses accompanied by reduced error-related MFC activity. The sensitivity of the MFC to disrupted processing elsewhere in the brain suggests complications in interpreting evidence of disturbed MFC function.

Normal cognitive functioning depends critically on our ability to monitor our thoughts and actions so that we can identify situations in which we need to try harder or try something different (i.e., when increased cognitive control is required). Neuroimaging studies have consistently implicated regions in the medial frontal cortex (MFC), particularly the dorsal anterior cingulate cortex and the presupplementary motor area, in this monitoring process. Thus, MFC activity is observed when participants make errors (Falkenstein, Hohnsbein, Moorman, & Blanke, 1990; Gehring, Goss, Coles, Meyer, & Donchin, 1993) and when conditions of response uncertainty, or conflict, make errors likely (Botvinick, Nystrom, Fissell, Carter, & Cohen, 1999; Carter et al., 1998). Findings such as these have led to the suggestion that the MFC is involved in monitoring ongoing performance in order to signal the need for increased cognitive control.

Scalp electroencephalogram (EEG) recordings have identified event-related brain potential correlates of the proposed MFC monitoring functions. MFC activity following errors is evident in EEG recordings as the errorrelated negativity (ERN), a frontocentral component that peaks within 100msec of an incorrect response (Falkenstein et al., 1990; Gehring et al., 1993). Meanwhile, conflict-related activity in the MFC is reflected in a second EEG component, labeled the N2, that shares the frontocentral scalp distribution of the ERN (Kopp, Rist, & Mattler, 1996; Nieuwenhuis, Yeung, van den Wildenberg, & Ridderinkhof, 2003; van Veen & Carter, 2002; Yeung, Botvinick, & Cohen, 2004). Together, the ERN and N2 provide a window on MFC function, and a good deal of research has focused on identifying the cognitive and neural basis of these components.

One fruitful line of research has been the use of the ERN and N2 to investigate how MFC function is affected by various neurological disturbances. To this end, the two components have been studied in various clinical populations, including individuals with schizophrenia (Alain, McNeely, He, Christensen, & West, 2002; Kopp & Rist, 1999; McNeely, West, Christensen, & Alain, 2003), borderline personality disorder (Ruchsow et al., 2006), depression (Hajcak, McDonald, & Simons, 2004; Luu, Collins, & Tucker, 2000), anxiety disorder (Hajcak, McDonald, & Simons, 2003), and obsessive-compulsive disorder (Gehring, Himle, & Nisenson, 2000; Nieuwenhuis, Nielen, MoI, Hajcak, & Veltman, 2005). The ERN and N2 have also been used to investigate the cognitive impact of alcohol (Curtin & Fairchild, 2003; Ridderinkhof et al., 2002), caffeine (Tieges, Ridderinkhof, Snel, & Kok, 2004), and other psychoactive drugs (de Bruijn, Hulstijn, Verkes, Ruigt, & Sabbe, 2004; Riba, Rodriguez-Fomells, Morte, Munte, & Barbanoj, 2005; Zirnheld et al., 2004). Taken together, the available evidence paints a clear picture of an MFC monitoring system that is sensitive to a wide range of neurological disturbances. …

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