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Changes in peri-calcarine cortical thickness in blindsight.
Loraine Georgy1, John D Lewis1, Gleb Bezgin2
1Montreal Neurological Institute, McGill University, Montreal, Canada.
Neuropsychologia
|April 11, 2020
Summary
Blindsight, the ability to process visual information without conscious awareness, shows increased cortical thickness in the intact visual cortex. This brain reorganization supports non-conscious vision despite primary visual cortex (V1) damage or hemispherectomy.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Neuroimaging
Background:
- Blindsight describes visual processing without conscious awareness in individuals with primary visual cortex (V1) damage.
- This phenomenon can occur in patients with localized V1 lesions or following hemispherectomy for epilepsy.
- Existing research suggests the intact visual cortex plays a compensatory role in blindsight, supporting non-conscious visual processing.
Purpose of the Study:
- To investigate anatomical differences in the visual cortex of the intact hemisphere in individuals with blindsight.
- To explore the relationship between cortical thickness and blindsight, considering varying degrees of brain damage.
Main Methods:
- Cortical thickness analysis using T1-weighted MRI data.
- Comparison of three blindsight subjects (two with hemispherectomy, one with V1 lesion) against healthy controls from the NKI dataset.
Main Results:
- Significant increases in cortical thickness were observed in the visual cortex of all blindsight subjects compared to controls.
- These findings were consistent across subjects regardless of age of onset, cause, or extent of brain damage.
Conclusions:
- The study provides anatomical evidence of cortical reorganization in the intact hemisphere of blindsight patients.
- Increased cortical thickness suggests a compensatory mechanism supporting non-conscious visual processing after V1 damage or hemispherectomy.
- Findings align with previous research highlighting brain plasticity and reorganization in response to visual cortex injury.
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