Electrical resonances in central auditory neurons

In the auditory pathway, signal processing depends on the filter functions of neurons. We used frequency analysis to investigate the contributions of intrinsic membrane properties to the input-output relationships in neurons. The whole-cell tight-seal recording technique in brain slices of chicks was used to study neurons at four levels of the auditory pathway. Neurons displayed resonant peaks in their voltage responses to injected sinusoidal currents that swept through a specified frequency range. Higher resonant frequencies tended to predominate at relatively lower stations in the auditory pathway (approximately 100 Hz in the nucleus magnocellularis, 24 Hz in the nucleus laminaris, 6 Hz in the nucleus ovoidalis). Field L neurons (cortex homologue) displayed low pass filter characteristics without resonance. We propose that the subthreshold membrane resonances amplify synaptic inputs at specific frequencies and contribute to the chick's ability to decode temporal sound parameters.