The clock that times us:Electromagnetic signatures of time estimation

As time is a fundamental dimension of our existence, perceiving the flow of time is an ubiquitous experience of our everyday life. This so-called sense of time is utilized in our everyday activities, for example, when we expect some events to happen, but it also prevents us from taking a morning shower for too long. This ability to perceive time intervals of several seconds has been commonly explained by a pacemaker-accumulator theory positing that some brain areas create the sense of time by accumulating some sort of neural quantity produced by other brain regions that play a role of pacemaker. We investigated this theory by recording electro-magnetic signals of the human brain to answer if indeed brain tells time using accumulation of its own activity. Several neuroimaging studies presented in my thesis suggest that the process of accumulation cannot be seen as the brain’s clock. I found that accumulation-like traces observed in the brain activity reflect excitation of neuronal populations needed to prepare for an upcoming event, whereas timing ability is preserved even beyond the time when accumulation ends. As accumulation is not responsible for subjective experience of time, this thesis proposes that temporal information has to be provided by another brain process possibly, involving the cortico-striatal mechanisms relying on detection of oscillatory patterns in the cortex or on the dynamics of neural population codes in cortical and subcortical areas. Therefore, although water flows while we are taking a morning shower, tracking time is more like observing the changing pattern of the nightly sky than just measuring the flow of water