Mapping Long-term Cortical Maturation of the Auditory System in Adolescents who are Deaf and have used a Unilateral Cochlear Implant to Hear
Bibliographic record
Abstract
In the present Thesis, we used novel imaging tools to study maturation of the auditory brain in adolescents who are deaf and have use a unilateral cochlear implant (CI) to hear for most of their lives. A CI is a surgically implanted auditory prosthesis that establishes hearing in children who are deaf. The aims of implantation are to halt any effects of deafness on the brain and promote normal auditory development. Unfortunately, CIs do not restore normal hearing as they provide only a crude representation of sounds and eliminate important cochlear processing. It has recently been shown that unilaterally stimulating the auditory system with a CI and leaving the opposite pathways deprived of input for longer than 1.5 years compromises bilateral auditory development. We are now exploring the cortical consequences of missing this sensitive period and driving maturation of the auditory cortex with unilateral implant stimulation. We measured electrically-evoked cortical responses in adolescents who had over a decade of unilateral CI experience before receiving a second implant in the opposite deprived ear. This provided an unparalleled opportunity to assess the effects of long-term unilateral stimulation/deprivation on the auditory pathways in the adolescent brain. We tracked the development of cortical responses with CI experience and localized underlying areas of cortical activity in the brain using our beamformer imaging methods. Neural synchrony of these responses was calculated to assess the co-ordination of activity across brain regions in response to sound. Our results indicate that long-term unilateral implant stimulation promotes normal-like maturation of the auditory cortex with good speech perception outcomes, providing a general impression that some degree of auditory development proceeds normally. However, abnormally strengthened activity from the hearing ear to the contralateral cortex and increased synchrony in networks known to be involved in cognitive processing suggests that cortical abnormalities persist into maturation. In the opposite deprived ear, cortical responses were atypical, had abnormally large dipoles and abnormal neural synchrony, perhaps reflecting cortical un-coupling/dis-connectivity in response to sound. We suggest that unilateral maturation of the auditory cortex drives lasting auditory asymmetries and leaves the deprived pathways unprotected from deafness-induced abnormalities.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".