NEURONAL CORRELATES OF PERCEPTUAL AMPLITUDE-MODULATION DETECTION

The goal of the present paper is to relate the coding of amplitude mod ulation (AM) in the auditory pathway to the behavioral detection perfo rmance. To address this issue, the detectability of AM was estimated b y modelling a single neuron located in the central nucleus of the infe rior colliculus (IC). The computational model is based on cochlear nuc leus responses and a coincidence detection mechanism. The model replic ated the main feature of the neuronal AM transfer function, namely a b andpass function. The IC-unit model was initially tuned to a 200-Hz mo dulation frequency. A single neurometric function for AM detection at this modulation frequency was generated using a 2-interval, 2-alternat ive forced-choice paradigm. On each trial of the experiments, AM was t aken to be correctly detected by the model if the number of spikes in response to the modulated signal exceeded the number of spikes in an o therwise identical interval that contained an unmodulated signal. Psyc hometric functions for 4 human subjects were also measured under the s ame stimulus conditions. Comparison of the simulated neurometric and p sychometric functions suggested that there was sufficient information in the rate response of an IC neuron well-tuned in the modulation-freq uency domain to support behavioral detection performance.