Connectional heterogeneity in the mouse auditory corticocollicular system

Yudintsev, Georgiy

doi:10.1101/571711

Cited by 5 publications

(8 citation statements)

References 38 publications

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“…We note that layer 6 projections to the thalamus are more numerous than layer 5 projections but tend to have smaller and more distal terminals (Lee and Sherman, 2010), and relay inhibition through the thalamic reticular nucleus (Lam and Sherman, 2010). Layer 6 corticocollicular projections also emanate from smaller neurons than layer 5 and have thinner neuronal projections and end in smaller terminals (Yudintsev et al, 2019). These data suggest that the layer 6 system may operate on a slower time scale, and is more likely to engage inhibitory interneurons, and thus may have a different set of functions than the layer 5 system that has yet to be identified.…”

Section: Circuit-level Mechanisms Of Corticofugal Top-down Controlmentioning

confidence: 79%

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

Asilador

Llano

2021

Front. Neural Circuits

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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.

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Section: Circuit-level Mechanisms Of Corticofugal Top-down Controlmentioning

confidence: 79%

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

Asilador

Llano

2021

Front. Neural Circuits

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“…We note that layer 6 projections to the thalamus are actually more numerous than layer 5 projections, but tend to have smaller and more distal terminals (Lee and Sherman, 2010), and relay inhibition through the thalamic reticular nucleus (Lam and Sherman, 2010). Layer 6 corticocollicular projections also emanate from smaller neurons than layer 5 and have thinner neuronal projections and end in smaller terminals (Yudintsev et al, 2019). These data suggest that the layer 6 system may operate on a slower time scale, and is more likely to engage inhibitory interneurons, and thus may have a different set of functions than the layer 5 system that have yet to be identified.…”

Section: Circuit-level Mechanisms Of Corticofugal Top-down Controlmentioning

confidence: 79%

Top-down inference in the auditory system: Potential roles for corticofugal projections

Asilador¹,

Llano²

2020

Preprint

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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 sensory hierarchy (e.g., auditory cortex). As such, virtually all proposed models to explain top-down facilitation are focused on the cerebral cortex, 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 stages of processing complements modulation at later (i.e., cortical) stages of processing. Finally, we suggest experimental approaches for future studies on this topic.

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“…Therefore, it is not surprising to find a bilateral projection system to the inferior colliculi, which also project to motor structures to mediate escape responses (Kawamura, 1975;Aitkin and Boyd, 1978;Edwards et al, 1979;Cadusseau and Roger, 1985;Appell and Behan, 1990;Huffman and Henson, 1990;Lesicko and Llano, 2020). The presence of a bilateral layer 6 system, which we have previously speculated to serve a modulatory role (Yudintsev et al, 2019;Asilador and Llano, 2020), was less expected, but may suggest that the dual functions of layer 5 and layer 6 are necessary for the potential escape function of the layer 5 corticofugal projections. The absence, then, of a bilateral projection to the LC may suggest that this region is less likely to be involved in rapid motor escape behaviors than DC.…”

Section: Discussionmentioning

confidence: 93%

Patterns of Unilateral and Bilateral Projections From Layers 5 and 6 of the Auditory Cortex to the Inferior Colliculus in Mouse

Sekaran

Deshpande

Ibrahim

et al. 2021

Front. Syst. Neurosci.

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The auditory cortex sends massive projections to the inferior colliculus, but the organization of this pathway is not yet well understood. Previous work has shown that the corticocollicular projection emanates from both layers 5 and 6 of the auditory cortex and that neurons in these layers have different morphological and physiological properties. It is not yet known in the mouse if both layer 5 and layer 6 project bilaterally, nor is it known if the projection patterns differ based on projection location. Using targeted injections of Fluorogold into either the lateral cortex or dorsal cortex of the inferior colliculus, we quantified retrogradely labeled neurons in both the left and right lemniscal regions of the auditory cortex, as delineated using parvalbumin immunostaining. After dorsal cortex injections, we observed that approximately 18–20% of labeled cells were in layer 6 and that this proportion was similar bilaterally. After lateral cortex injections, only ipsilateral cells were observed in the auditory cortex, and they were found in both layer 5 and layer 6. The ratio of layer 5:layer 6 cells after lateral cortex injection was similar to that seen after dorsal cortex injection. Finally, injections of different tracers were made into the two inferior colliculi, and an average of 15–17% of cells in the auditory cortex were double-labeled, and these proportions were similar in layers 5 and 6. These data suggest that (1) only the dorsal cortex of the inferior colliculus receives bilateral projections from the auditory cortex, (2) both the dorsal and lateral cortex of the inferior colliculus receive similar layer 5 and layer 6 auditory cortical input, and (3) a subpopulation of individual neurons in both layers 5 and 6 branch to innervate both dorsal cortices of the inferior colliculus.

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Connectional heterogeneity in the mouse auditory corticocollicular system

Cited by 5 publications

References 38 publications

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

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

Top-down inference in the auditory system: Potential roles for corticofugal projections

Patterns of Unilateral and Bilateral Projections From Layers 5 and 6 of the Auditory Cortex to the Inferior Colliculus in Mouse

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