  A fundamental problem in neuroscience is to understand how sequences of
action potentials ("spikes") encode information about sensory signals and motor
outputs. Although traditional theories of neural coding assume that information
is conveyed by the total number of spikes fired (spike rate), recent studies of
sensory and motor activity have shown that far more information is carried by
the millisecond-scale timing patterns of action potentials (spike timing).
However, it is unknown whether or how subtle differences in spike timing drive
differences in perception or behavior, leaving it unclear whether the
information carried by spike timing actually plays a causal role in brain
function. Here we demonstrate how a precise spike timing code is read out
downstream by the muscles to control behavior. We provide both correlative and
causal evidence to show that the nervous system uses millisecond-scale
variations in the timing of spikes within multi-spike patterns to regulate a
relatively simple behavior - respiration in the Bengalese finch, a songbird.
These findings suggest that a fundamental assumption of current theories of
motor coding requires revision, and that significant improvements in
applications, such as neural prosthetic devices, can be achieved by using
precise spike timing information.
