What 7 components make up the CANS?
1) cochlear nuclei (CN): VCN and DCN
2) superior olivary complex (SOC)
3) lateral lemniscus
4) inferior colliculus
5) medial geniculate body
6) auditory cortex
7) corpus callosum
What is the function of the CANS?
- CANS plays a crucial role in receiving and processing sound information, enabling humans and animals to perceive and interact with their acoustic environment
The CANS incorporates several brain regions from the ____ to the ____
cochlear nuclei, cerebral cortex
Our understanding of the human central auditory system is derived from what 4 things?
1) post-mortem anatomical studies
2) psychophysical and electrophysiological experiments
3) structural and functional imaging
4) comparative studies with laboratory animals
What did neuroanatomy of the auditory system help build a foundation for?
speech and language acquisition and diagnosing and treating hearing, speech, and language disorders
What are the 4 crossings of the CANS?
The blue areas have to cross information from one side to another
- 1st cross: DCN
- 2nd cross: TB (trapezoid body)
- 3rd cross: LL
- 4th cross: AC through the corpus callosum
Information to one ear is crossing to the other side of the brain
What are the 2 components of the cochlear nucleus (CN)?
- ventral cochlear nucleus (VCN)
- dorsal cochlear nucleus (DCN)
The primary afferents of the AN are divided into ____ and ____ branches in the CN
ascending, descending
The ascending branch travels to the ____.
rostral pole of the VCN
The descending branch travels to the ____
DCN
The CN is the ____ stage of transforming acoustic information
initial
Where does the CN receive efferent fibers from?
auditory thalamocortical pathways (top down processing)
Explain the CNs characteristic frequency (CF)
the frequency to which it is most sensitive, corresponds to a specific location on the BM of the cochlea.
Explain the CNs tonotopic organization
mimics the BMs cochleotopic organization
CN - The human VCN contains what 5 cells?
- spherical bushy cells
- globular bushy cells
- stellate cells
- octopus cells
- small cap cells
CN VCN - what do the spherical/globular bushy cells and stellate cells do?
- maintain spectral sensitivity and signal patterns
CN VCN - what tests of AP target spherical/globular bushy cells and stellate cells?
- frequency pattern test or pitch pattern test or changes in timing/intensity
- these tests will target these cells directly to show place of involvement
CN VCN - What is a job that only stellate cells do?
stellate cells have different firing patterns and provide excitatory and inhibitory input to other neurons in the cochlear nucleus
CN VCN - What do octopus cells do?
- handle precise timing for detecting sound structures
CN VCN - What tests of AP target octopus cells?
- gap detection
- problem with this task could mean problem with the octopus cells in the VCN
CN VCN - what do small cap cells do?
their function is still unknown
CN DCN - What does the DCN do?
receives input from auditory and non-auditory sources and undergoes complex processing
CN DCN - explain the 3 layers of the DCN
The DCN is organized into 3 layers, containing different types of neurons and interneurons:
1) the molecular layer: dendrites of fusiform cells
2) granule cells: input to layer 1
3) fusiform cells, giant cells, interneurons that link to DCN and VCN
neural fibers connect the layers (and also connect to other parts of the brain)
CN DCN - what do fusiform and giant cells do?
- fusiform cells exhibit a “pauser” firing pattern, while giant cells show a “buildup” pattern.
- fusiform and giant cells are sensitive to monaural acoustic cues, providing information about sound sources in the vertical plane
