Synesthesia and Lateral Inhibition: A Case Study
Bibliographic record
Abstract
Introduction: Synesthesia is a perceptual phenomenon when a stimulus in one sensory modality elicits an additional percept in the same or in another modality (e.g., when black letters and numbers are perceived as color graphemes or when sounds inducing color percepts). Although the underlying mechanisms of synesthesia are not known, it is largely thought that the synesthetic brain is characterized by a hyperconnectivity between different regions including the visual areas. Lateral inhibition (LI), which involves inhibitory local interactions between neighboring neurons in the visual brain, might be a new approach to explore the nature of the putative abnormal connectivity in synesthesia. Objective: The purpose of this study was to assess brain responses associated with lateral inhibition in synesthesia using scalp-recorded EEG. Methods: Steady-state visual evoked potentials (ssVEPs) were recorded from Oz in a color-grapheme synesthete female (27 years old) and in 12 control non-synesthetes using the windmill/dartboard paradigm (Zemon and Ratliff, PNAS, 1982). Stimuli consisted in four radial contiguous patterns, two static and two dynamic that were presented at a reversal-contrast frequency of 4.28 Hz and 30% contrast. Fast Fourier Transform (FFT) analysis was conducted to extract the fundamental and the second harmonic of ssVEPs in order to calculate the suppression and facilitation LI indices. Then, z-scores were computed for the synesthete subject in relation with the non-synesthete subjects. Results: No significant difference in the suppression or facilitation index was found. Conclusion: Lateral inhibition processing in the visual cortex is not abnormal in synesthesia. This case-study finding challenges the nature of the hyperconnectivity hypothesis in synesthesia. Meeting abstract presented at VSS 2014
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.003 | 0.003 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.004 | 0.003 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".