Challenging Populations Flashcards
Why would there be a cortical response when the ABR is absent?
- Don’t need neural synchrony at the level of the corex, but it is required for the ABR
- ABR reflects highly synchronous discharges with precision on the order of fraction of ms
- Synchrony is necessary for speech perception in noise
- Cortical potentials require synchrony that is several ms
- Cortex is able to make use of varied and limited input
How can patients with cochlear implants be used to study central auditory pathways?
- Maturation
- Relationships with speech perception
- Relationships with speech production
- Sensitive time periods/cortical reorganization
What is the relationship between development of central auditory pathways and development of early communicative behavior?
Studies examined the link between babbling and auditory pathway development following implantation
2-7 months: precanonical
- Babbling is not related to the primary language
7-10 months
- Babbling is specific to the primary language
The earlier the intervention, the better the babbling
What is the neural basis of reduced plasticity in late implanted children?
Cross-modal reorganization
Congenitally deaf cats (relative to hearing cats)
- Superior localization in the peripheral visual field
- Lower (better) visual movement detection thresholds
Why would a clinician to incorporate evoked potentials in a hearing aid fitting?
Use them if you can’t get any audiometric data
- Can be used as an objective hearing aid evaluation for young infants and difficult-to-test people
- Complete the cortical measurement while the child wears their hearing aids
What are desirable characteristics of cortical responses?
- No reliance on a template
- Able to use information from contributing portions of the waveform
- Able to discount non-contributing portions of waveform
What can evoked potentials tell you about neural speech processing?
Older adults often have difficulty understanding speech in noise
FFR: amplification increases detection of speech components in older adults with hearing loss
- Larger responses recorded with amplification
- Demonstrates how hearing aids can make speech signals available to the listener
Effects of amplification on the FFR:
- Phase locking was better for aided condition than unaided
Does hearing aid use enhance neural encoding over time?
After 6 months of hearing aid use:
- Reduces age-related delays in latencies
- Improves working memory
- Cortical amplitude increases with hearing aid use
Describe the auditory profile of patients with ANSD.
Sometimes can obtain audiograms, but not ABRs
- Can measure some cortical potentials in some patients with ANSD
Speech understanding
- May be okay in quiet, but poor in noise
How can the use of cortical potentials be used in management of infants with ANSD?
Hearing levels range from normal to profound and hearing loss can fluctuate
May not get cortical potential measurements in patients with very severe hearing loss
What are the results of cortical responses to speech?
Cortical potentials in quiet are normal, but with noise the amplitudes are diminished and the latencies are delayed
The harder the condition, the lower the amplitude, the more delayed the latency
What ABR results are obtained for patients with ANSD?
No waveforms present with harder SNRs
Only see waveforms when the SNR is 0 and above
What latency relates to speech-in-noise perception?
N1
- The better the speech perception, the earlier the latency or the larger the amplitude
- Indicated good correlation between percent correct and latency
