Functional Localization of a ‘‘Time Keeper’’ Function Separate Separate

i t c k w t s c i t m The functional neuroanatomy of time estimation has ot been well-documented. This research investigated he fMRI measured brain response to an explicit, rospective time interval production (TIP) task. The tudy tested for the presence of brain activity reflectng a primary time keeper function, distinct from the rain systems involved either in conscious strategies o monitor time or attentional resource and other ognitive processes to accomplish the task. In the TIP ask participants were given a time interval and asked o indicate when it elapsed. Two control tasks (countng forwards, backwards) were administered, in addiion to a dual task format of the TIP task. Whole brain mages were collected at 1.5 Tesla. Analyses (n 5 6) ielded a statistical parametric map (SPM 5z6) reflectng time keeping and not strategy (counting, number anipulation) or attention resource utilization. Addiional SPM 5z6s involving activation associated with the ccuracy and magnitude the of time estimation reponse are presented. Results revealed lateral cerebelar and inferior temporal lobe activation were associted with primary time keeping. Behavioral data rovided evidence that the procedures for the explicit ime judgements did not occur automatically and utiized controlled processes. Activation sites associated ith accuracy, magnitude, and the dual task provided ndications of the other structures involved in time stimation that implemented task components related o controlled processing. The data are consistent with rior proposals that the cerebellum is a repository of odes for time processing, but also implicate temporal obe structures for this type of time estimation ask. r 2000 Academic Press