Functional anatomy of timing differs for production versus prediction of time intervals

Abstract

Timing is required both for estimating the duration of a currently unfolding event, or predicting when a future event is likely to occur. Yet previous studies have shown these processes to be neuroanatomically distinct with duration estimation generally activating a distributed, predominantly right-sided, fronto-striatal network and temporal prediction activating left-lateralised inferior parietal cortex. So far, these processes have been examined independently and using widely differing paradigms. We used fMRI to identify and compare the neural correlates of duration estimation, indexed by temporal reproduction, to those of temporal prediction, indexed by temporal orienting, within the same experimental paradigm. Behavioural data confirmed that accurate representations of the cued interval were evident for both temporal reproduction and temporal orienting tasks. Direct comparison of temporal tasks revealed activation of a right-lateralised fronto-striatal network when timing was measured explicitly by a temporal reproduction task but left inferior parietal cortex, left premotor cortex and cerebellum when timing was measured implicitly by a temporal orienting task. Therefore, although both production and prediction of temporal intervals required the same representation of time for their successful execution, their distinct neural signatures likely reflect the different ways in which this temporal representation was ultimately used: either to produce an overt estimate of an internally generated time interval (temporal reproduction) or to enable efficient responding by predicting the offset of an externally specified time interval (temporal orienting). This cortical lateralization may reflect right-hemispheric specificity for overtly timing a currently elapsing duration and left-hemispheric specificity for predicting future stimulus onset in order to optimize information processing.