Spike-timing precision underlies the coding efficiency of auditory receptor neurons
Ariel Rokem, Sebastian Watzl, Tim Gollisch, Martin Stemmler, Andreas V. M. Herz & Inés Samengo
Journal of Neurophysiology 95: 2541-2552 (2006)
Abstract
Sensory systems must translate incoming signals quickly and
reliably so that an animal can act successfully in its
environment. Even at the level of receptor neurons, however,
functional aspects of the sensory encoding process are not yet
fully understood. Specifically, this concerns the question how
stimulus features and neural response characteristics lead to an
efficient transmission of sensory information. To address this
issue, we have recorded and analyzed spike trains from grasshopper
auditory receptors, while systematically varying the stimulus
statistics. The stimulus variations profoundly influenced the
efficiency of neural encoding. This influence was largely
attributable to the presence of specific stimulus features that
triggered remarkably precise spikes whose trial-to-trial timing
variability was as low as 0.15 ms - one order of magnitude shorter
than typical stimulus time scales. Precise spikes decreased the
noise entropy of the spike trains, thereby increasing the rate of
information transmission. In contrast, the total spike train
entropy, which quantifies the variety of different spike train
patterns, hardly changed when stimulus conditions were altered, as
long as the neural firing rate remained the same. This finding
shows that stimulus distributions that were transmitted with high
information rates did not invoke additional response patterns, but
instead displayed exceptional temporal precision in their neural
representation. The acoustic stimuli that led to the highest
information rates and smallest spike-time jitter feature
pronounced sound-pressure deflections lasting for 2-3 ms. These
upstrokes are reminiscent of salient structures found in natural
grasshopper communication signals, suggesting that precise spikes
selectively encode particularly important aspects of the natural
stimulus environment.
Last modified: Fri Nov 28 11:23:27 CET 2008