Wk11-27-CI Challenges w/ Diff Pop'ns Flashcards
Where in the body does the auditory input from both ears first come together?
Isilateral and contralateral superior olivary complex
- most of the signal crosses to the contralateral side
Auditory activity in the cortex is dominated by the (ipsi/contra)-lateral pathway
Contra
What type of recordings can we use to measure auditory activity at each level of the pathway?
EEG recordings (electroencephalography)
Hemispheric specialization for _____ and ______ information develops with maturation
Temporal and spectral
True/False: One study found more temporal information is seen on the left side and more spectral information on the right side
True
Match the following numbers and levels:
a) ABR
b) Late latency response
c) Middle latency response
I. Brainstem
II. Thalamus
II. Cortex
ABR - Brainstem
Middle latency response - Thalamus
Late Latency response - Cortex
What can we deduce from deviations from normal of the peak amplitude or latency?
Based on when the deviations occur (e.g. ABR vs Middle latency vs late latency responses), we can infer where in the auditory pathway the problem is
- can also help us determine if children have a delay in auditory development
ABR can be used to help identify ______ in the cochlea
Lesions
- also, acoustic tumours in the AN or brainstem
At what age do we begin to see the adult-like P1N1P2 complex?
Over 12 years of age
What is the primary difference between the auditory cortical response of children older and younger than 7 years of age?
Younger than 7 years old = P1/P2 complex (No N1) with an amplitude ~6microVolts
7-12 years old = P1/P2 of ~ 3 microVolts, with shallow N1
What happens to the auditory activity and development of the auditory system in individuals who are deaf?
Early auditory deprivation causes reorganization in the auditory system
- visual input becomes processed in the auditory cortex
- Lee et al found that by 20.3 years of age, the auditory system is completely taken over
True/False: Children who are implanted with CI’s during the sensitive period perform better than their peers that are implanted later, after longer periods of deafness
True
How do we measure early auditory development? What do we find post-implantation?
eABRs
Auditory brainstem function becomes faster and more efficient over the first year after implantation
Examining unilateral cochlear implant use, researchers have found that auditory brainstem development improves mostly during the first ____ (1, 5, 10) year(s) of use
1 year; largely no change in wave eV absolute latency from 1 year to 10 years
How did researchers show that unilateral CI use promotes maturation of auditory midbrain function?
By comparing middle latency responses of CI users with responses of normal hearing peers
- shape is very similar, and no significant differences were found between latencies and amplitudes of the 2 groups
Based on middle latency response, does early CI implantation allow for normal-like auditory development?
Yes; normal-like cortical responses are seen over the long-term, but differences from normal remain in LATER LATENCIES
(CI users’ P2 shows a higher amplitude than normal hearing listeners)
How was increased perceptual processing was found to influence P2?
Increased amplitude
- found during an experiment which involved auditory training; the P2 wave was higher post training
One study found that CI users rely more on _____ cues compared to normal hearing listeners, to identify emotion
Visual; CI users also take more time to decide which reaction it was, compared to normal hearing listeners.
What is one concern of sequential CI implantation compared to simultaneous?
It may create a mismatch between the development of the left and right auditory pathways
Mismatched ABRs persist in children with more than __ years of unilateral hearing, despite time after bilateral implantation
2 years
- children who receive both implants during the time of brainstem development (simultaneously or within 6-12 months) do not show this mismatch after 2 years.
Does unilateral implant use lead to mismatched auditory CORTICAL responses at bilateral implantation also?
Yes
_______ imaging is used to localize areas of the brain that respond to sound (measures activity and localizes the activity under each peak in different hemispheres)
Beamformer
- the measurements are referred to as dipole moments
Gordon et al found that cortical activity is abnormally (small/large) in the contralateral cortex after more than 1.5 years of unilateral implant use
Large
- this reflects an abnormal strengthening of pathways from that ear
- we protect the brain from these changes by providing children with bilateral implants simultaneously
