Timing of spike discharges in cat auditory cortex neurons: implications for encoding of stimulus periodicity.

Neurons at more central stations in the central auditory pathway show progressively poorer responses to high-frequency stimulus periodicities. This has been attributed to the relatively poorer spike timing in forebrain auditory neurons. This study directly examined the timing of spikes evoked by brief tone pulses which were varied in peak level and repetition rate. The experiments revealed that at tone repetition rates which produced progressively poorer entrainment, the timing of spike discharges remained sufficiently precise to support entrained responses. The fact that responses were poor indicates that imprecision in spike timing may not be the only factor limiting the encoding of temporal frequency. The data are discussed in relation to evidence on the temporal tuning of central neurons seen in studies using continuous amplitude modulations.