Hearing and CNS Flashcards
Central auditory processing disorder
CNS can not process sound information, leads to scrambling of words, brain can not keep up
Types of nerve fibres in cochlea (spiral ganglion)
Type 1 : afferents from IHC’s, make up 90%
Type 2: innervate OHC’s. less of these
What can be said about the tonotopic organisation in the auditory system?
It remains throughout, from the cochlea through to the auditory cortex
What are the two principles involved in the frequency coding of nerves?
Place principle: the tonotopical organisation of the cochlea means frequency is detected by the spatial orientation from base to apex
Volley: low frequencies are detected by temporal firing of nerves int time to the frequency (won’t work at high frequencies)
How is auditory intensity coded?
- Rate of firing of individual nerve fibres
- number of fibres increases as energy is spread along the organ of corti
What is a summary of the auditory pathway?
Cochlea; cochlear nucleus; superior olivary complex; inferior colliculus; MGB; auditory complex
Cochlear nucleus
medulla
Where auditory nerve fibres terminate; extracts some features of sound
Superior olivary complex
pons
Binaural centre; Important for determining interaural timing and intensity thus sound localisation
Inferior colliculus
Midbrain
Processing centre, integrates with visual system.
Helps with localisation
PAC
Links with Wernickes and Broca’s to do with understanding of speech
Anatomy of cochlear nucleus
Dorsal, sends info to the IC in midbrain
Ventral (two parts) ends info to SOC
What is important about binauaral hearing? (all levels above the cochlear nucleus)
Extracting speech in noise; localising sound in space, processing speech
