What's the science?
Everyday we need to speak and move at different speeds depending on the situation, but the way we control the timing of our speech and movements is not well understood. This week in Nature Neuroscience, Wang and colleagues report a new mechanism in the brain for controlling how we time things in a flexible way.
How did they do it?
They performed an experiment where monkeys were trained to flexibly make movements after both short and long time intervals. They recorded the rate of neuron firing during this time using electrodes in two brain regions known to be involved in brain timing: the medial frontal cortex and the caudate.
What did they find?
They demonstrate that in both of these regions, the longer the time interval before the monkey's movement, the slower the neuron firing rate. This means that the speed of neuron firing is scaled according to the time interval. In other words, the brain has a mechanism for adjusting its firing rate so that movements can stay flexible. This scaling of neuron firing explained both the timing and flexibility of the monkey's movements.
What's the impact?
This is the first study to clarify the mechanism through which the brain controls timing of movements. Previous models of timing didn't quite fit with the data recorded from the brain. Now we have a better understanding of how we can play music, speak at different speeds and move when we want to.
Read the original journal article here.
J. Wang, D. Narain, E. A. Hosseini, M. Jazayeri, Flexible timing by temporal scaling of cortical responses. Nat. Neurosci. 21, 102–110 (2017).