ABSTRACT
Our perceptual experience of sound depends on the integration of multiple sensory and cognitive domains, but the networks sub-serving this integration are unclear. There are connections linking different cortical domains, however we do not know if there are also connections between multiple cortical domains and subcortical structures. Retrograde tracing in rats revealed that the inferior colliculus – the auditory midbrain - receives dense descending projections from not only the auditory cortex, but also the visual, somatosensory, motor, and prefrontal cortices. While all these descending connections are bilateral, those from sensory areas show a more pronounced ipsilateral dominance than those from motor and prefrontal cortices. Anterograde tracing from cortical areas identified by retrograde tracing, showed cortical fibres terminating in all three subdivisions of the inferior colliculus, targeting both inhibitory and excitatory neurons. These findings demonstrate that auditory perception is served by a network that includes extensive descending connections from sensory, behavioural, and executive cortices.
Footnotes
The abstract has been updated and some typographical errors have been corrected.
LIST OF ABBREVIATIONS
- AC
- auditory cortex
- AI
- agranular insular cortex
- Au1
- primary auditory cortex
- AuD
- secondary auditory cortex dorsal zone
- AuV
- secondary auditory cortex, ventral zone
- Cg1
- cingulate cortex area 1
- Cg2
- cingulate cortex area 2
- Den
- dorsal endopiriform nucleus
- DI
- dysgranular insular cortex
- DP
- dorsal peduncular cortex
- DZ
- primary somatosensory cortex dorsal zone
- Ect
- ectorhinal cortex
- GI
- granular insular cortex
- IC
- inferior colliculus
- ICC
- central nucleus of inferior colliculus
- ICD
- dorsal cortex of inferior colliculus
- ICL
- lateral cortex of inferior colliculus
- IL
- infralimbic cortex
- LO
- lateral orbital cortex
- M1
- primary motor cortex
- M2
- secondary motor cortex
- MO
- medial orbital cortex
- PFC
- prefrontal cortex
- Prh
- perirhinal cortex
- PrL
- prelimbic cortex
- RSA
- retrosplenial agranular cortex
- RSG
- retrosplenial granular cortex
- RSGb
- retrosplenial granular b cortex
- S1
- primary somatosensory cortex
- S1BF
- primary somatosensory barrel cortex
- S1Tr
- primary somatosensory cortex trunk region
- S2
- secondary somatosensory cortex
- TeA
- temporal association cortex
- V1B
- primary visual cortex, binocular area
- V1M
- primary visual cortex, monocular area
- V2L
- secondary visual cortex, lateral area
- V2M
- secondary visual cortex, mediolateral area
- VC
- visual cortex
- VO
- ventral orbital cortex
