پتانسیل برانگیخته اواسط تأخیر در پرخاشگری تکانشی خودگزارش شده

The present study was conducted to examine psychophysiological differences in arousability among individuals who display impulsive aggressive outbursts. Amplitude and latency for the mid-latency evoked potentials (P1, N1 and P2) were obtained at scalp electrode sites. The evoking stimuli were three intensities (low, medium, high) of photic stimulation. Compared to non-aggressive controls, impulsive aggressive subjects showed significantly reduced P1 amplitude, which is indicative of an inefficient sensory gating mechanism. In addition, these subjects exhibited significantly larger N1 amplitude implying an enhanced orienting of attention to stimuli. Impulsive aggressive subjects also exhibited shorter P1, N1 and P2 peak latency. These results suggest that impulsive aggressive individuals may display quicker orienting and processing of stimuli in an attempt to compensate for low resting arousal levels. Finally, impulsive aggressive subjects augmented the P1–N1 component more frequently than controls, which is consistent with previous studies examining impulsivity and sensation seeking. Together, these findings extend previous work concerning the underlying physiology of impulsive aggression. It has been suggested that impulsive aggressive individuals may attempt to compensate for low resting arousal levels by engaging in stimulus seeking behaviors. Accordingly, the present findings imply similar physiological compensatory responses as demonstrated by heightened orienting of attention, processing and arousability. In addition, a compromised sensory gating system in impulsive aggressors may exacerbate such circumstances, and lead to later cognitive processing deficits.

Violence is a widespread problem in today's society, and individuals who commit such acts often display impulsive aggressive behavior out of proportion or inappropriate to the eliciting situation or stimuli. According to Barratt et al. (1997) impulsive aggression is defined as ‘a hair trigger response to a stimulus that results in an agitated state and culminates in an aggressive act; during the agitated state, interpersonal communication is non-adaptive and information processing appears to be inefficient.’ In order to develop treatments and interventions for this type of problem behavior, psychophysiological research has been conducted with violent and impulsive persons (Barratt et al., 1997, Gerstle et al., 1998 and Mathias and Stanford, 1999). The primary focus of these studies has been to identify differences in the neural function of those individuals who display impulsive aggressive behaviors. Accordingly, physiological measures in these individuals have indicated a low level of arousal during resting conditions (Fishbein et al., 1989, Convit et al., 1991, Barratt et al., 1997 and Mathias and Stanford, 1999). However, it has also been suggested that impulsive aggressors display a greater magnitude of change in arousal in reaction to a stimulus, when compared to controls (Mathias and Stanford, 1997). In conjunction with low arousal levels, there is some question as to the efficiency of attentional processes in aggressive individuals as well (Raine, 1997).