Tinnitus
- perception of ringing sound in the ears
Objective tinnitus
An actual sound is produced in the ears.
This may be due to middle ear muscle spasms, spontaneous ** otoacoustic emissions ** (produced by inner ear), or vascular problems.
Subjective tinnitus
Experienced by the individual, usually in association with another disorder.
Most common with noise-induced hearing loss.
Associated with both conductive and sensineural hearing loss.
Cochlear Implants
How are they inserted?
Electrodes are inserted into the cochlea to electrically stimulate auditory nerve fibers along the basilar membrane’s tonotopic map.
What does the cochlear implant device include?
A microphone, sound processor, transmitter (outside), andreceiver (surgically implanted)
What does the cochlear impact do and what’s it effective for?
Overcomes damage to the hair cells, but not damage to the cochlear auditory nerves.
Very effective for speech perception if done early (by 12-18 months)
If someone ruptures their tympanic membrane, they will experience:
A. Conductive hearing loss
B. Sensineural hearing loss
C. Objective Tinnitus
D. Subjective tinnitus
A
Auditory nerve fibers synapse in a series of sub cortical structures:
- cochlear nucleus
- superior Oliver’s nucleus
- inferior colliculus
- medial geniculate nucleus
- auditory receiving area
The first cortical region to receive auditory information is in the ______
Temporal lobe
Primary Auditory Cortex (PAC or A1)
It is believed to have broadly ** tonotopic** organization, matching the structure established in the consoles. There are thought to be multiple tonotopic maps in auditory cortex [not neatly organized]
Is the medial geniculate nucleus tonotopic ally organized?
A. Yes, abs
B. Prob
C. No
Yes
In A1, different patches of cortex responds to different _____
Characteristic frequencies (CF)
Natural sounds include
Speech, laughter, animal sounds, musical instruments, and tools.
Tonotopic maps can be found in
A1 (core area)
Neurons respond better to low frequencies are on the ____ and those that respond best to high frequencies are on the ___.
Left; right
The auditory cortex appears
Hierarchically organized
- neural signals travel through the core (including A1), then belt, followed by the parables area.
Simple sounds
Pure tones
Cause activation in the core area
Belt and parabelt areas
Are preferentially activated in response to more complex stimuli (tones, voices) made up of many frequencies. B
Bender and Wang recorded from a cell just outside A1 and found that it responded to______ with the scene fundamental frequency.
Complex Tones
Such cells were called pitch neurons
Norman used fMRI to measure responses to complex tones perceived as pitch (100 Hz) and frequency, match noise.
- The noise stimulus contains all the frequencies, but wasn’t perceived as having a specific pitch.
- Areas in interior auditory cortex were more responsive to pitch.
Effect of training (experience dependent plasticity) on tonotopic maps:
- Monkeys were trained to discriminate between two frequencies near 2500 Hz.
- Trained monkeys showed tonotopic maps (in A1) within large areas with neurons that responded to 2500 Hz compared to untrained monkeys. Importantly, rthe monkeys were better at the task after training
Where or Dorsal Stream
Start in the posterior core and belt, and extends to the parietal and prefrontal corticosteroids.
- Responsible for locating sound.
What or ventral stream
Starts in the anterior portion of the core belt, and extends to the prefrontal cortex.
- Responsible for identifying sounds
Patient with temporal lobe damage has trouble ____ but can ____.
Recognizing sounds; localize.
