Increased blood flow in the basal ganglia when using cues to direct attention

We used positron emission tomography (PET) in ten subjects to study the bra in regions involved in voluntary shifts of attention. For six scans, subjec ts per formed a visual target detection task in which the location of the t arget was indicated in advance on some proportion of trials by the appearan ce of an arrow cue at fixation. The informative cues were successful in spe eding reaction time to the target. Blood flow in the left putamen was corre lated with the proportion of informative cues provided within a scan. We di scuss this finding in terms of three possible interpretations: attentional shifts, response inhibition, and motor preparation related to the use of th e right hand to respond. Blood flow in: cortical regions commonly associate d with attention was not related to cue ratio, a finding that may reflect a utomatization of the processes involved in interpreting and using the cues.