Neural and Behavioral Correlates of Pure Tone and Narrow-Band 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 narrow-band 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 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.<b>Significance statement</b> While pure tones and narrow-band noise are both used in humans and animals to study auditory function, the sensitivity at neural circuit and behavioral level for these two parametric stimulus sets has not been systematically characterized. Here we examine behavioral and thalamic neural responses in the medial geniculate body of the rat to these stimulus sets, revealing overall similarity but also divergences in terms of latency, sensitivity, responsivity and classification performance. We conclude that stimulus choice critically shapes neural and perceptual sensitivity, showing that specific stimuli are better suited to quantify distinct aspects of auditory function. Our findings support the development of robust preclinical protocols for evaluating auditory dysfunction and enhancing the translational relevance of animal models.