Population Clocks: Motor Timing with Neural Dynamics

Abstract

This chapter focuses on motor problems that explicitly require timing, as opposed to the production of any sequence of movements, such as touching different points on a computer screen. One area known to be important for motor coordination, the cerebellum, was one of the first structures hypothesized to contribute to timing and it has been proved that the cerebellum is critical to some forms of motor timing. Different neocortical areas have also been implicated in motor timing. Biologically plausible implementations of such spectral, or delay line, models have been proposed, including the time constants of neurotransmitter receptors, the time constant of slow membrane conductances, and the decay time of inhibitory postsynaptic potentials. The cerebellar circuitry is unique for its absence of recurrent excitatory activity. Consequently, the cerebellum cannot sustain a self-maintaining and dynamic pattern of activity in the absence of an external input. Population clock models propose that motor timing arises from the time-varying activity of a population of neurons.