Top-Down Inference in the Auditory System: Potential Roles for Corticofugal Projections

Alexander Asilador, Daniel A. Llano

Research output: Contribution to journalReview articlepeer-review


It has become widely accepted that humans use contextual information to infer the meaning of ambiguous acoustic signals. In speech, for example, high-level semantic, syntactic, or lexical information shape our understanding of a phoneme buried in noise. Most current theories to explain this phenomenon rely on hierarchical predictive coding models involving a set of Bayesian priors emanating from high-level brain regions (e.g., prefrontal cortex) that are used to influence processing at lower-levels of the cortical sensory hierarchy (e.g., auditory cortex). As such, virtually all proposed models to explain top-down facilitation are focused on intracortical connections, and consequently, subcortical nuclei have scarcely been discussed in this context. However, subcortical auditory nuclei receive massive, heterogeneous, and cascading descending projections at every level of the sensory hierarchy, and activation of these systems has been shown to improve speech recognition. It is not yet clear whether or how top-down modulation to resolve ambiguous sounds calls upon these corticofugal projections. Here, we review the literature on top-down modulation in the auditory system, primarily focused on humans and cortical imaging/recording methods, and attempt to relate these findings to a growing animal literature, which has primarily been focused on corticofugal projections. We argue that corticofugal pathways contain the requisite circuitry to implement predictive coding mechanisms to facilitate perception of complex sounds and that top-down modulation at early (i.e., subcortical) stages of processing complement modulation at later (i.e., cortical) stages of processing. Finally, we suggest experimental approaches for future studies on this topic.

Original languageEnglish (US)
Article number615259
JournalFrontiers in Neural Circuits
StatePublished - Jan 22 2021


  • auditory
  • colliculus
  • cortex
  • descending
  • medial geniculate body
  • speech perception
  • thalamus
  • top-down

ASJC Scopus subject areas

  • Sensory Systems
  • Cellular and Molecular Neuroscience
  • Cognitive Neuroscience
  • Neuroscience (miscellaneous)


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