An auditory fMRI correlate of impulsivity.

Impulsivity and serotonergic neurotransmission have previously been shown to be linked to the intensity dependence of auditory evoked potentials. The present study investigates whether impulsivity in normal healthy subjects has a similar influence on the neuronal correlates of the coding of sound intensity using functional magnetic resonance imaging (fMRI). Forty-four participants completed Cloninger's Tridimensional Personality Questionnaire (TPQ). The dependence of fMRI activation on sound intensity was examined using continuous pink noise with varying intensity as acoustic stimuli. Imaging data were analyzed for the volume of activation sensitive to sound intensity. Impulsivity has a significant effect on the volume of activation sensitive to sound intensity. Persons with high impulsivity scores on the TPQ scale show approximately twice the volume of activation when compared with persons with low impulsivity scores. The neuronal correlate of impulsivity as revealed by fMRI gives strong evidence of a link between impulsive behavior and neural activity evoked by auditory stimulation. This link may prove useful for measuring central serotonergic neurotransmission in a clinical setting.