Temporal orienting deficit after prefrontal damage.

The aim of this study was to explore, for the first time in patients, the neural bases of temporal orienting of attention as well as the interrelations with two other effects of temporal preparation: the foreperiod effect and sequential effects. We administered an experimental task to a group of 14 patients with prefrontal lesion, a group of 15 control subjects and a group of 7 patients with a basal ganglia lesion. In the task, a cue was presented (a short versus long line) to inform participants about the time of appearance (early versus late) of a target stimulus, and the duration of the cue-target time intervals (400 versus 1400 ms) was manipulated. In contrast to the control group, patients with right prefrontal lesion showed a clear deficit in the temporal orienting effect. The foreperiod effect was also affected in the group of patients with prefrontal lesion (without lateralization of the deficit), whereas sequential effects were preserved. The group of basal ganglia patients did not show deficits in any of the effects. These findings support the voluntary and strategic nature of the temporal orienting and foreperiod effects, which depend on the prefrontal cortex, as well as the more automatic nature of sequential effects, which do not depend on either prefrontal cortex or frontobasal circuits.