Hierarchical differences in the encoding of sound and choice in the subcortical auditory system

Mackey, Chase A.; Dylla, Margit E.; Bohlen, Peter A.; Grigsby, Jason D.; Hrnicek, Andrew; Mayfield, Jackson M; Ramachandran, Ramnarayan

doi:10.1152/jn.00439.2022

Cited by 3 publications

(1 citation statement)

References 90 publications

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“…While we demonstrate that ICC and MGV neurons exhibit context-dependent and learning-related plasticity, the neural mechanisms underlying these changes remain uncertain. Context-dependent changes in activity have been noted as early as the auditory nerve (Delano et al, 2007; Gehmacher et al, 2022) and cochlear nuclei (Oatman, 1971; Ryan et al, 1984), and population-level activity from cochlear nucleus neurons can predict behavioral detection thresholds (Mackey et al, 2023). Plasticity in these early regions is likely mediated by descending inputs from the superior olivary complex; indeed, medial olivocochlear bundle activity increases during perceptual training on a phoneme-in-noise discrimination task (Boer & Thornton, 2008).…”

Section: Discussionmentioning

confidence: 99%

Neural correlates of flexible sound perception in the auditory midbrain and thalamus

Ying,

Stolzberg,

Caras

2024

Preprint

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Hearing is an active process in which listeners must detect and identify sounds, segregate and discriminate stimulus features, and extract their behavioral relevance. Adaptive changes in sound detection can emerge rapidly, during sudden shifts in acoustic or environmental context, or more slowly as a result of practice. Although we know that context- and learning-dependent changes in the spectral and temporal sensitivity of auditory cortical neurons support many aspects of flexible listening, the contribution of subcortical auditory regions to this process is less understood. Here, we recorded single- and multi-unit activity from the central nucleus of the inferior colliculus (ICC) and the ventral subdivision of the medial geniculate nucleus (MGV) of Mongolian gerbils under two different behavioral contexts: as animals performed an amplitude modulation (AM) detection task and as they were passively exposed to AM sounds. Using a signal detection framework to estimate neurometric sensitivity, we found that neural thresholds in both regions improved during task performance, and this improvement was driven by changes in firing rate rather than phase locking. We also found that ICC and MGV neurometric thresholds improved and correlated with behavioral performance as animals learn to detect small AM depths during a multi-day perceptual training paradigm. Finally, we reveal that in the MGV, but not the ICC, context-dependent enhancements in AM sensitivity grow stronger during perceptual training, mirroring prior observations in the auditory cortex. Together, our results suggest that the auditory midbrain and thalamus contribute to flexible sound processing and perception over rapid and slow timescales.

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Section: Discussionmentioning

confidence: 99%

Neural correlates of flexible sound perception in the auditory midbrain and thalamus

Ying,

Stolzberg,

Caras

2024

Preprint

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Receptive-field nonlinearities in primary auditory cortex: a comparative perspective

Homma,

See,

Atencio

et al. 2024

Cerebral Cortex

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Cortical processing of auditory information can be affected by interspecies differences as well as brain states. Here we compare multifeature spectro-temporal receptive fields (STRFs) and associated input/output functions or nonlinearities (NLs) of neurons in primary auditory cortex (AC) of four mammalian species. Single-unit recordings were performed in awake animals (female squirrel monkeys, female, and male mice) and anesthetized animals (female squirrel monkeys, rats, and cats). Neuronal responses were modeled as consisting of two STRFs and their associated NLs. The NLs for the STRF with the highest information content show a broad distribution between linear and quadratic forms. In awake animals, we find a higher percentage of quadratic-like NLs as opposed to more linear NLs in anesthetized animals. Moderate sex differences of the shape of NLs were observed between male and female unanesthetized mice. This indicates that the core AC possesses a rich variety of potential computations, particularly in awake animals, suggesting that multiple computational algorithms are at play to enable the auditory system’s robust recognition of auditory events.

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Hierarchical differences in the encoding of amplitude modulation in the subcortical auditory system of awake nonhuman primates

Mackey,

Hauser,

Schoenhaut

et al. 2024

Journal of Neurophysiology

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Sinusoidal amplitude modulation (SAM) is a key feature of complex sounds. While psychophysical studies have characterized SAM perception, and neurophysiological studies in anesthetized animals report a transformation from the cochlear nucleus' (CN; brainstem) temporal code to the inferior colliculus' (IC; midbrain's) rate code, none have used awake animals or nonhuman primates to compare CN and IC's coding strategies to modulation-frequency perception. To address this, we recorded single-unit responses and compared derived neurometric measures in the CN and IC to psychometric measures of modulation frequency (MF) discrimination in macaques. IC and CN neurons often exhibited tuned responses to SAM in rate and spike-timing measures of modulation coding. Neurometric thresholds spanned a large range (2-200 Hz DMF). The lowest 40% of IC thresholds were less than or equal to psychometric thresholds, regardless of which code was used, while CN thresholds were greater than psychometric thresholds. Discrimination at 10-20 Hz could be explained by indiscriminately pooling 30 units in either structure, while discrimination at higher MFs was best explained by more selective pooling. This suggests that pooled CN activity was sufficient for AM discrimination. Psychometric and neurometric thresholds decreased as stimulus duration increased, but IC and CN thresholds were higher and more variable than behavior at short durations. This slower subcortical temporal integration compared to behavior was consistent with a drift diffusion model which reproduced individual differences in performance and can constrain future neurophysiological studies of temporal integration. These measures provide an account of AM perception at the neurophysiological, computational, and behavioral levels.

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Hierarchical differences in the encoding of sound and choice in the subcortical auditory system

Cited by 3 publications

References 90 publications

Neural correlates of flexible sound perception in the auditory midbrain and thalamus

Neural correlates of flexible sound perception in the auditory midbrain and thalamus

Receptive-field nonlinearities in primary auditory cortex: a comparative perspective

Hierarchical differences in the encoding of amplitude modulation in the subcortical auditory system of awake nonhuman primates

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