Neurophysiology of time perception
Several lines of evidence suggest neurophysiological markers in the EEG and dopaminergic and GABAergic neurotransmitter activity to be related to our ability to track time. In our lab, we use a variety of neurophysiological and behavioural methods to investigate these neural signatures and their role in inter- and intra- individual timing variability.
Our research suggests a link between temporal underestimation of visual stimuli and basal concentrations of the neurochemical GABA in primary visual cortex, as measured with magnetic resonance spectroscopy. This finding implies a local neurophysiological factor in visual cortex that contributes to inter-individual variability in the perceived duration of visual stimuli. We also study the sources of intra-individual variability in timing, such as fluctuations in dopamine. For instance, we previously demonstrated that perceived time dilates with increased dopamine in a behavioural study that used spontaneous eye blinks as a proxy of striatal dopamine receptor availability. Other ongoing work in our lab investigates time perception in relation to EEG oscillations and in response to non-invasive brain stimulation.
Terhune, D. B., Sullivan, J. G., & Simola, J. M. (2016). Time dilates after spontaneous blinking. Current Biology, 26, R459-460.
Matthews, W. J., Terhune, D. B., van Rijn, H., Eagleman, D. M., Sommer, M. A., & Meck, W. H. (2014). Subjective duration as a signature of coding efficiency: Emerging links among stimulus repetition, predictive coding, and cortical GABA levels. Timing and Time Perception Reviews, 1, e3.
Terhune, D. B., Russo, S., Near, J., Stagg, C. J., & Cohen Kadosh, R. (2014). GABA predicts time perception. Journal of Neuroscience, 34, 4364-4370.
Timing and cognition
Another major interest of lab members is how perceived time relates to cognitive functions. Perceived time is not isomorphic to physical time, as shown by temporal distortions in altered states of consciousness, under the inﬂuence of hallucinogens, and in many psychiatric and neurological conditions. Our research is aimed at elucidating these phenomena by studying timing abilities in different states of consciousness.
We previously studied how moment-to-moment interval timing varies with fluctuations in attentional states in mind-wandering. This study suggests that subjective time contracts and the timing precision deteriorates when our minds wanders. By contrast, mind wandering did not seem to impact the metacognitive assessment of one’s performance (i.e., how aware we are of our timing performance). In another publication from our lab, we review the role of claustrum in consciousness, positing that it supports the temporal integration of cortical oscillations in response to sensory input. Our other ongoing research investigates the effects of pharmacological interventions on timing, and the relation between time perception and the experience of pain.