Is there a common dopaminergic basis of time perception and reaction time?

The effects of 3 mg haloperidol and 125 mg Madopar on duration discrimination (DD) as well as reaction times were tested in a placebo-controlled, double-blind crossover study with 24 healthy male volunteers. Performance in DD was significantly impaired under haloperidol compared to placebo as well as to Madopar. No changes could be demonstrated for Madopar compared to placebo. Similar results were obtained for measures of reaction time. Significant negative correlations between individual changes in DD and measures of reaction time under each drug condition revealed that subjects with drug-induced impairment in DD also show an increase in reaction times. The nearly identical patterns of drug-induced changes in DD and measures of reaction time may be interpreted in terms of a common neural basis.