The Auditory Nervous System ILO 1 Afferent and Efferent Neurons Flashcards
ILO 1 Afferent and Efferent Neurons (28 cards)
Where do Type I afferent neurons synapse to?
IHC’s (95%)
Where do Type II afferents synapse to?
OHC’s (5%)
Which nerve carries the signal from the primary afferent neurons in the IHC’s to the brain?
VIIIth Nerve
The neurotransmitter of the primary afferents is likely to be what?
Glutamate (glu)
Which afferent neurons are in contact with a lot of surface area at the base of the cell?
Type I - at base of IHC’s
What does LOC Efferent stand for?
Lateral olivochochlear efferent neurons
Where do LOC Efferents synapse with?
Synapse to the Type I afferents
What does MOC Efferent stand for?
Medial olivocochlear efferent neurons
Where do MOC efferents synapse to?
Directly to the cell wall of the OHC’s
Are LOCS connected to the brain:
a) ipsilaterally and contralaterally
b) ipsilaterally
c) contralaterally
b) ipsilaterally
Are MOCS connected to the brain:
a) ipsilaterally and contralaterally
b) ipsilaterally
c) contralaterally
a) ipsilaterally and contralaterally
The primary afferent neurons pass through the Habenula perforata to form what?
Connect at the spiral ganglion to form the trunk of the modiolus.
What does IAM stand for
Internal Auditory Meatus
(nerves forming the trunk of the modiolus and proceeeds through to the bony IAM)
Why are Type II afferents less frequency specific?
Because they connect to multipe hair cells across the range of the cochlea meaning theyre spread across a greater range of frequencies.
How many Type I afferents synapse with one IHC?
5 (makes them very frequency specific)
Do medial efferents synaps with multips OHC bodies?
Yes
Which afferent projects radially (straight line)
Type I afferents ususally to a single IHC
Which afferent projects radially and basally?
Type II afferents. To connect with a number of OHC’s
Which Type of afferent is myelinated?
Type I (thick 2-5 micrometres)
What type of afferent has the slowest conduction time?
Type II. 10 x slower than Type I
Which afferent is thin and unmyelinated?
Type II
Type I afferents can be further categorised according to what?
Spontaneous Rate (SR)
How rapidly they’re firing in the absense of sound.
Name the three SR categories
Low SR neurons <0.5 spikes/sec
Medium SR neurons 0.5 - 17.5 spikes/sec
High SR neurons >17.5 spikes/sec
Which SR neurons have the lowest threshold?
High SR neurons because they’re already firing so they fire in response to sound first.
