Spectro-Temporal Receptive Fields of the Primary Auditory Cortex in the Rat

Studying central perceptual representations remains a challenge due to the multidimensional and non-linear nature of auditory perception. The spectro-temporal receptive field (STRF) serves as a linear model representing the optimal stimulus for an auditory neuron. Despite the rat (Rattus norvegicus) being a key biomedical model, STRF properties in its primary auditory cortex (A1) remain not fully described. This study characterized A1 spectro-temporal properties in the rat, extracting functional parameters to describe neuronal response dynamics: characteristic frequency, latency, bandwidth, sparseness index, and signal-to-noise ratio. Acute extracellular neurophysiological recordings were performed in anesthetized adult male rats using A1 microelectrodes. Responses were evoked with TORC (Temporally Orthogonal Ripple Combinations) stimuli, and STRFs were estimated via reverse correlation. Analysis revealed tuned neuronal units with short latencies and a preference for high and low frequencies. Furthermore, the spatial response distribution across A1 functionally corroborated its characteristic tonotopic gradient. In conclusion, estimating STRFs under anesthesia establishes a methodological and functional baseline for rat cortical responses. Strategically, this provides comparative support for future studies contrasting this basal activity with awake animal recordings, enabling the evaluation of cognitive and behavioral influences on auditory processing.