Several studies have documented QEEG changes induced by first generation antipsychotics. Few studies investigated QEEG modifications induced by second generation antipsychotics and reported inconsistent results. The present study is aimed to investigate, by means of high temporal resolution imaging techniques, changes in QEEG cortical current source density induced by haloperidol, risperidone and placebo in young healthy male subjects.

Each subject underwent three sessions, separated by at least a one-week interval. In each session, subjects received a single oral dose of placebo, or haloperidol (3 mg) or risperidone (1 mg). EEGs were recorded during a resting condition, before and 6 hours after drug administration.

With respect to placebo, a significant increase of delta and theta power was observed for both drugs; alpha1 increase was significant only for risperidone; in addition, beta1 power was increased by haloperidol and alpha2 power was decreased by risperidone. LORETA analysis revealed significant differences in cortical generators activity between placebo and haloperidol, involving frontal, cingulate and temporal regions for all EEG bands, except beta3. For risperidone, as compared with placebo, LORETA showed a significant increase of cortical current source density in frontal regions for delta, theta and alpha1.

The widespread increase of current source density for most EEG bands observed after haloperidol may suggest that this drug has a lower regional specificity of action on EEG cortical generators than risperidone.