Model of the effect of extracellular fields on spike time coherence

Accurate spike timing is emerging as an important concept in the encoding of sensory stimuli. Accurately timed spiking has been recorded in-vivo in the visual and auditory cortex, many layers removed from the primary sensory neurons. This temporal accuracy may be maintained despite noisy synaptic transmission by the simultaneous firing of multiple neurons. Here we show in simulations that a coherent polarization of a population of neurons through extracellular fields can further increase the coherence of the population's firing times. We discuss the potential relevance of such a common input as an external "clock" signal in a spatio-temporal code.