Is there a 'retinotopic' representation of echo locations in the calcarine cortex of the blind brain?
Bibliographic record
Abstract
We have shown previously that activity in calcarine cortex of an early blind echolocation expert is greater for mouth-click echoes reflected from objects located in contralateral space. Here, we used fMRI to investigate in more detail whether or not the mapping of echoes in the calcarine cortex of an early blind echolocation expert resembles retinotopic mapping in the sighted brain. We also investigated the mapping of sound sources. An early blind expert echolocator listened to binaural recordings of echolocation and source sounds in the fMRI scanner. The recordings were made earlier as the echolocator made clicks in the presence of a sound reflecting surface (or simply listened to a sound emitting loudspeaker) located at azimuth angles from -60°, -20°, 0°, +20°, to +60°. In addition, at -20° and +20° azimuth, recordings were made separately at 0°, -20° and +20° elevation. For each location in echo and source conditions, the participant had pressed a response key with a separate finger. For echolocation, we were able to map -20° azimuth in medial right calcarine, +20° azimuth in medial left calcarine, and 0° azimuth towards the apex of the occipital pole. For source hearing, we were able to map only -60° azimuth in medial right calcarine, anterior to the -20° azimuth echo representation. We were unable to map elevation for either echoes or sources. We were able to confirm the validity of our analysis by mapping the motor representation of the fingers used to press the response keys. In their entirety, the data are consistent with the idea that there is a representation of azimuth of echo locations in calcarine cortex that resembles the representation of azimuth of visual locations in retinotopic coordinates. The data suggest that this mapping is more pronounced for echolocation than source hearing. Meeting abstract presented at VSS 2013
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".