Functional localization of a "time keeper" function separate from attentional resources and task strategy

The functional neuroanatomy of time estimation has not been well-documented . This research investigated the fMRI measured brain response to an explici t, prospective time interval production (TIP) task. The study tested for th e presence of brain activity reflecting a primary time keeper function, dis tinct from the brain systems involved either in conscious strategies to mon itor time or attentional resource and other cognitive processes to accompli sh the task. In the TIP task participants were given a time interval and as ked to indicate when it elapsed. Two control tasks (counting forwards, back wards) were administered, in addition to a dual task format of the TIP task . Whole brain images were collected at 1.5 Tesla. Analyses (n = 6) yielded a statistical parametric map (SPM {z}) reflecting time keeping and not stra tegy (counting, number manipulation) or attention resource utilization. Add itional SPM {z}s involving activation associated with the accuracy and magn itude the of time estimation response are presented. Results revealed later al cerebellar and inferior temporal lobe activation were associated with pr imary time keeping. Behavioral data provided evidence that the procedures f or the explicit time judgements did not occur automatically and utilized co ntrolled processes. Activation sites associated with accuracy, magnitude, a nd the dual task provided indications of the other structures involved in t ime estimation that implemented task components related to controlled proce ssing. The data are consistent with prior proposals that the cerebellum is a repository of codes for time processing, but also implicate temporal lobe structures for this type of time estimation task, (C) 2000 Academic Press.