Wednesday, September 18, 2013

Competing models of time perception

Anyone that knows me will know my fascination with time. Not how we go about measuring time but time it self. Here there are 2 equally important paths of endeavor. One is that of a global scale and involves the very nature of the universe; Space-Time continuum and General Relativity.  The second is equally baffling – how does the brain code time.

There are multiple competing models of time perception with no real consensus. For example we know that the Suprachiasmatic nucleus uses environmental cues, most importantly light, to determine the time of day and year thus coordinating circadian rhythms. This however is more about tracking time and less about perception of time. Also, this may not be the structure that links events to time – i.e. history.

According to a recent MIT study groups of neurons in the primate brain code time with extreme precision. Institute Professor Ann Graybiel says “All you do is time stamp everything, and then recalling events is easy: you go back and look through your time stamps until you see which ones are correlated with the event,"

Neuroscientist Paul King of the Redwood Center for Theoretical Neuroscience at UC Berkeley explains fast time interval estimation (sub-second) to be important for timing complex behavior and playing musical instruments. Slow time interval estimation may be important for planning the day, although daylight and hunger can provide cues. Intervals greater than a day may rely on observing the repetition of day-night cycles and seasonal changes.

The above diagram shows the accuracy of time interval estimation for humans and other animals, along with proposed neural mechanisms for each time scale. Slow time scales (hours) are at the top and fast scales (milliseconds) are at the bottom. It’s a fascinating model.

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