Accumulation of neural activity in the posterior insula encodes the passage of time

Department of Psychiatry, University of California San Diego, 8939 Villa La Jolla Dr, Suite 200, La Jolla, CA 92037-0985, USA.
Neuropsychologia (Impact Factor: 3.3). 08/2010; 48(10):3110-20. DOI: 10.1016/j.neuropsychologia.2010.06.023
Source: PubMed


A number of studies have examined the perception of time with durations ranging from milliseconds to a few seconds, however the neural basis of these processes are still poorly understood and the neural substrates underlying the perception of multiple-second intervals are unknown. Here we present evidence of neural systems activity in circumscribed areas of the human brain involved in the encoding of intervals with durations of 9 and 18s in a temporal reproduction task using event-related functional magnetic resonance imaging (fMRI). During the encoding there was greater activation in more posterior parts of the medial frontal and insular cortex whereas the reproduction phase involved more anterior parts of these brain structures. Intriguingly, activation curves over time show an accumulating pattern of neural activity, which peaks at the end of the interval within bilateral posterior insula and superior temporal cortex when individuals are presented with 9- and 18-s tone intervals. This is consistent with an accumulator-type activity, which encodes duration in the multiple seconds range. Given the close connection between the dorsal posterior insula and ascending internal body signals, we suggest that the accumulation of physiological changes in body states constitutes our experience of time. This is the first time that an accumulation function in the posterior insula is detected that might be correlated with the encoding of time intervals.

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    • "Recordings in functional magnetic resonance imaging (fMRI) indicated that activity within the insular cortex increased continuously during the perception of duration (Wittmann et al., 2010, 2011). Moreover, the experience of temporal delay between external acoustic stimulation and the heart beat is related to anterior insula activation (Critchley et al., 2004). "
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    • "Here, we show a correlation between activation responses in the anterior insula and RT during the TOP task (Fig. 5). This finding is also consistent with the accumulation function of the anterior insula, which postulates that our sense of time reflects the accumulation of physiological changes in body states (Wittmann et al. 2010; Bueti and Macaluso 2011). The anterior insula is also involved in TD learning (Sutton and Barto 1981; Sutton 1988) during Pavlovian conditioning. "
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