Emergence of abstract sound representations in the ascending auditory system. (July 2021)

• Record Type: Journal Article
• Authors: Harpaz, Mor; Jankowski, Maciej M.; Khouri, Leila; Nelken, Israel
• Is Part Of: Progress in neurobiology. Volume 202(2021)
• Publication Date: 2021-07
• Subjects: Auditory cortex -- Inferior colliculus -- Auditory thalamus -- Rats -- Neuropixels probes -- Complex sounds -- Stimulus-specific adaptation; Neurobiology -- Periodicals; Neurology -- Periodicals; Neurology -- Periodicals; Neurobiologie -- Périodiques; 612.8
• DOI: 10.1016/j.pneurobio.2021.102049
• Languages: English
• ISSNs: 0301-0082

Abstract

Highlights: Stimulus-specific adaptation (SSA) is found as early as in the inferior colliculus. We studied SSA using spectrally-balanced broadband stimuli (tone clouds). Tone clouds neutralize frequency-specific mechanisms of SSA. SSA to tone clouds is large and early in auditory cortex, weak and late subcortically. Auditory cortex represents sound identity rather than frequency content. Abstract: Auditory processing begins by decomposing sounds into their frequency components, raising the question of where the representation of sounds as wholes emerges in the auditory system. To address this question, we used stimulus-specific adaptation (SSA), the reduction in the responses of a neuron to a common sound (standard) which does not generalize to another, rare sound (deviant). SSA to tone frequency has been demonstrated in multiple stations of the auditory pathway, including the inferior colliculus (IC), medial geniculate body (MGB) and auditory cortex. We designed wideband stimuli (tone clouds) that have identical frequency components but are nevertheless distinct. Tone clouds evoked early and substantial SSA in primary auditory cortex (A1) but only late and minor SSA in IC and MGB. These results imply that while in IC and MGB sounds are largely represented in terms of their frequency components, in A1 they are represented as abstract entities.