Latencies of eighth nerve fibre responses with respect to their relative contribution to the compound action potential in the guinea pig

We present a study of the latencies of click-evoked post-stimulus time histograms (PSTHs) in the guinea pig in the context of the auditory nerve fibre's contribution to the compound action potential (CAP) recorded at the round window. The latencies of the dominant PSTH peak were studied as a function of relevant physiological fibre properties, in particular the characteristic frequency (CF) and the spontaneous discharge rate (SR). We found that high-SR fibres have shorter latencies than low-SR fibres. These findings are discussed in the context of correlation between synaptic morphology and SR as described in the literature. The PSTH latency as a function of CF is described separately for low- and high-CF fibres for each of the two SR subgroups. Finally, we discuss to what extent the various subgroups of fibres contribute to the N1 peak of the CAP, the most commonly studied component.