How the Brain Keeps Time
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We’ve talked about time intervals in past blogs. It’s an important part of Learn 2 Focus’ brain-training programs, and enables our kids to pay attention, play the piano, play sports or hold a conversation. Take inTime for example, which uses beat and rhythm-based music to stimulate awareness of time intervals - or Interactive Metronome which uses auditory and visual rhythmic cues to create neural pathways which improve skills associated with executive function.
Neuroscientists at MIT and Columbia University have now figured out how neurons in one part of the brain measure time intervals and accurately reproduce them. Check out my five key takeaways from this article:
http://news.mit.edu/2015/neuron-firing-patterns-underlie-time-measurement-brain-1008
1. The lateral intraparietal cortex (LIP) plays a role in sensorimotor function, and represents elapsed time, as animals measure and then reproduce a time interval. Firing patterns of population of neurons in the LIP could coordinate sensory and motor aspects of timing.
2. Jazayeri, who joined the MIT faculty in 2013, began studying timing in the brain by testing humans’ ability to measure and reproduce time using a task called “ready, set, go.” In this experiment, the subject measures the time between two flashes (“ready” and “set”) and then presses a button (“go”) at the appropriate time — that is, after the same amount of time that separated the “ready” and “set.”
3. From these studies, he discovered that people do not simply measure an interval and then reproduce it. Rather, after measuring an interval they combine that measurement, which is imprecise, with their prior knowledge of what the interval could have been. This prior knowledge, which builds up as they repeat the task many times, allows people to reproduce the interval more accurately.
4. To find out what happens in the brain during this process, Jazayeri recorded neuronal activity in the LIP of monkeys trained to perform the same task. When the interval is short, the slope during the second phase is steep. This allows the activity to increase quickly so that the animal can produce a short interval. When the interval is longer, the slope is gentler and it takes longer to reach the time of response.
5. While LIP represents time during interval reproduction, Jazayeri believes that tracking time occurs throughout brain circuits that connect subcortical structures such as the thalamus, basal ganglia, and cerebellum to the cortex.
