Neural and Behavioral Correlates of Pure Tone and Narrowband Noise Processing in Rats: A Tradeoff between Discrimination and Sensitivity.

Accurate characterization of auditory pathway responses is critical for understanding neural disorders that affect hearing, including both peripheral and central deficits, as well as broader neurodevelopmental conditions. Animal models provide a way to investigate auditory circuit activation with high spatial and temporal resolution. Here, we first assessed behavioral detection of pure tones (PT) and narrowband noise (NBN) stimuli in male rats, revealing that NBN targets were detected at lower amplitudes than PT targets, consistent with human auditory detection patterns. We then compared these behavioral results with neural responses recorded in female rats' medial geniculate body (MGB), a thalamic relay to the auditory cortex. Using high-density multichannel recordings, we found that NBN stimuli elicited greater neural sensitivity at low amplitudes, whereas PT stimuli evoked faster responses and higher peak firing rates. MGB units achieved maximal frequency discrimination at amplitudes close to detection threshold, with a sharp decline at both lower and higher intensities, suggesting that neurons with lower sensitivities primarily contribute to processing at moderate to high sound levels. Decoding analyses demonstrated accurate frequency classification from MGB population activity, with PT yielding higher accuracy than NBN, highlighting the potential of multichannel recordings for precise auditory information assessment. Our results indicate that NBN and PT stimuli differentially probe auditory thalamic processing, with NBN advantageous for detecting subtle sensitivity changes and PT optimal for timing analyses. These findings advance the translational relevance of rodent models for preclinical evaluation of therapies targeting central auditory deficits.