A spectrotemporal analysis of DCN single unit responses to wideband noise in guinea pig

Abstract

Spectrotemporal receptive fields (STRFs) were estimated for chopper and pauser units recorded in guinea pig dorsal cochlear nucleus (DCN). Sixteen wideband, periodic noise stimuli, represented as time-frequency surfaces of energy density, were crosscorre-lated in time with the unit's corresponding period histograms to determine if specific energy patterns tended to precede spike occurrence. The STRFs obtained were unique to the DCN, as compared to the ventral cochlear nucleus (VCN) [Clopton and Backoff. 1991, Hear. Res. 52, 329–344] in their degree of temporal and spectral complexity. Certain unit response types, classified from their peristimulus-time histograms (PSTHs) to tonebursts, were associated with distinctive patterns in the STRFs. All STRFs had at least one region of elevated energy density (peak region) closely preceding spike occurrence, which may reflect a short-pathway, primary excitatory input (or inputs) to the neuron. In addition, some units displayed low-energy regions (troughs) with greater temporal precedences on their STRFs, particularly when higher stimulus intensities were used. This analysis approach appears to have potential for investigating functional neural connectivity and predicting responses to novel complex stimuli, although specific implementations of the technique impose limitations on the interpretation of results.