Interaural Time Difference Tuning in the Rat Inferior Colliculus is Predictive of Behavioral Sensitivity

Recent studies have shown that rats are a useful model for binaural cochlear implant (CI) research, with behavioral sensitivity to interaural time differences (ITDs) of CI stimuli which are better than those of human patients. Here, we characterize ITD tuning in the rat inferior colliculus (IC) and explore whether quality of tuning can predict behavioral performance. We recorded IC responses to stimuli of varying pulse rates and envelope types and quantified both mutual information (MI) and neural d' as measures of ITD sensitivity. Neural d' values paralleled behavioral ones, declining with increasing click rates or when envelopes changed from rectangular to Hanning windows. While MI values increased with experience, neural d' did not. However, neural d' values correlated much better with behavioral performance than MI. Thus, neural d' appears to be a particularly well suited to predicting how stimulus parameters will impact behavioral performance.