auditory nerve

what are type 1 neurons

afferent, connects to IHC directly, responsible for all auditory info but pain, thick and myelinated

what are type 2 neurons

afferent, connects to OHC directly, conveys pain info, thin and unmyelinated

lateral olivocochlear neurons

indirectly connects to IHC, efferent, thin and unmyelinated, may affect balance of left and right ear

medial olivocochlear neurons

connects to OHC, efferent, thick and myelinated, controls amount of gain in cochlear amplification

describe the tonotopic organization of the auditory nerve

the auditory nerve consists of lower frequencies towards the center of the nerve bundle and higher frequencies towards the outer edges

post synaptic potential

creates a more positive charged environment within the postsynaptic cell/ caused by flow of positively charged ions into the postsynaptic cell

action potential

firing response done by auditory nerve due to postsynaptic potential

rising phase

depolarization, positive ions rush in

falling phase

repolarization, positive ions rush out

spontaneous rate

in silence, neuron is at rest and fires spontaneously due to tip links on the IHC being partially open

peristimulus time histogram

representations of the response of the auditory nerve over time/ shows activity of one neuron just before, during, and after stimulation by a signal

tuning curve

a representation of one neuron and how it responds to different frequencies/ frequency on x axis and threshold (dB) on y axis

characteristic frequency

specific frequency where the neuron responds to best

rate level functions

input-output functions/ measures firing rate of a single auditory neuron as a function of input level

saturation as it relates to rate level functions

no further increase in firing rate

phase locking

for sinusoids up to 2000 Hz, AN firing occurs only during one phase of the stimulus (for low frequency sounds, spikes occur only at a certain phrase of the waveform/ for high frequency sounds, spikes occur randomly within cycle)

place coding

the mapping of stimulus frequencies to a place on the basilar membrane

place theory

the theory explaining the process of hearing based on place coding

rate place frequency coding

section of BM is displaced, causing IHC there to release neurotransmitters/ fires certain afferent fibers/ brain recognizes this to be at certain frequency

periodicity theory

states that frequency is coded based on the period of the waveform/ rate or frequency of neural impulses is the mechanism for coding frequency

volley principle

individual neurons cant fire more than 1000 times per second, but group of neurons can work together to follow phase of the wave

temporal code frequency coding

pitch determined by period of neuron firing patterns/ brain calculates signal over time to determine frequency

coding of intensity

as intensity increases, firing rate of neuron increases up to saturation point/ point between threshold and saturation point is dynamic ranges

strategies of coding intensity

area of basilar membrane that’s affected and number/ types of neurons that fire

non linear responses

suppression, distortion products, sharp tuning near the CF

suppression

the response to a tone at CF will decrease when a second tone at another frequency is added/ amount of suppression depends on frequency and intensity of suppressor

distortion products

when two primary tones are played at the same time, there are combination tones that occur (due to OHC)

sharp tuning at CF

auditory neurons are frequency selective (tuning curves carried through from cochlea, become more asymmetric from low to high frequencies)