Functional Connectivity Between the Auditory Cortex and Hippocampus During Auditory Object Recognition in Ferrets

Abstract

Perceptual invariance is crucial in auditory scene analysis and behaviour regulation. It allows individuals to recognize consistent objects regardless of variations in sensory input. Despite its importance, the neural mechanisms and involved brain structures still need to be better understood. This study explores the roles of the auditory cortex (AC), the hippocampus (HPC), and their functional connectivity in perceptual invariance, using chronic electrode recordings in female ferrets. Ferrets were trained to identify the word ‘instruments’ from distractor words in a Go/No-Go task, for water rewards. To test perceptual invariance the pitch of the trained words was varied with a half octave shift being applied to either the whole speech stream on the trial (‘inter-trial roving’) or randomly to each word within the stream (‘intra-trial roving’). Our primary investigation was whether these ferrets could reliably perform the task despite such variances. Observations on their hit rates, false alarm rates, and overall correctness, compared against a theoretical 33% chance performance (given a 2-second response window and target occurrences between 0.5-6.5 seconds), indicated that ferrets consistently performed well above chance. Furthermore, a more nuanced analysis inquired if the ferrets' recognition ability was invariant to changes like the gender of the talker. Results from Granger causality tests revealed functional connectivity between the HPC, and the AC. Ferrets demonstrated a significant capacity for perceptual invariance in this auditory task, and our preliminary data suggest that a strong neural interplay between the AC and HPC exists and may potentially play a role in facilitating this phenomenon.