The role of the human anterior insular cortex in time processing.

The anterior portion of the human insula is implicated in a wide range of tasks that involve judgements of short periods of time (a few seconds or less). However, it is only one of several brain regions that share this property. We review the evidence for its involvement and discuss the nature of the contribution it might make to time judgements. The anterior insula is frequently identified in functional MRI studies that require participants to generate a time interval to match an internal or external template, or to discriminate between the durations of two stimuli. It is involved in many different timing tasks and is active irrespective of the stimulus modality used to present the stimuli. However, the role of the anterior insula in timing remains uncertain. Indeed, rather few studies have attempted to distinguish different possible contributions. The fact that it is active in a variety of tasks suggests that it may be involved in some indirect or general way. For example, during time discrimination, the anterior insula may be concerned more with discrimination than with time, as it is sometimes also active during other discrimination tasks. Other structures may be more strongly associated with core timing functions.