Decreased Cortical Activity in Impulsivity

Impulsivity is supposed to be related to several different clinical problems and disorders, such as attention-deficit hyperactivity disorder, conduct disorder, substance abuse, pathological gambling, and certain personality disorders. Several different theories have attempted to reveal the psychophysiology of impulsivity. For example, Gray suggested that a behavioural activation system is the neuroanatomical basis of impulsivity. The personality dimension of impulsivity as proposed by Gray is closely related to extraversion. In a preceding theory Eysenck suggested that extraversion is inversely related to cortical activity and the activity of the ascending reticular activating system. The present study aimed to investigate the relation of trait cortical activity and impulsivity. Fifty-nine participants (29 males and 30 females) defined the sample of the present study, who were assessed at three occasions of measurement each separated by five weeks. At the beginning of each session, the subjects were administered a series of questionnaires, including the Eysenck Impulsivity Questionnaire at one occasion. The EEG was recorded on each occasion during eight 1-min resting baseline periods and 61 electrodes were used to calculate a current source density derivation. General linear models of alpha activity as the dependent variable revealed a main effect of impulsivity on alpha activity across all occasions and electrodes, F(1,57)=7.92, p=0.007. The respective correlation between mean alpha activity and impulsivity was r=0.35. Thus high impulsive subjects showed an increased alpha activity or decreased cortical activity under rest. The findings may be in line with the suggestion of Eysenck that reduced general cortical activity is related to extraverted personality, in particular impulsivity.