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No blindsight following hemidecortication in human subjects?
P Stoerig1, J Faubert, M Ptito
1Institute of Medical psychology, Ludwig-Maximilians-University, Munich, Germany.
Neuroreport
|August 12, 1996
Summary
Cerebral hemidecortication patients retain residual vision in their blind fields. This vision, though reduced, allows conscious perception of light and color, likely due to intraocular light diffusion.
Area of Science:
- Neuroscience
- Ophthalmology
- Visual Perception
Background:
- Cerebral hemidecortication results in a functionally blind hemifield.
- Understanding residual visual function is crucial for patients with neurological damage.
Purpose of the Study:
- To quantify visual sensitivity in the blind hemifield of hemidecorticated patients.
- To investigate the characteristics of residual vision in the affected visual field.
Main Methods:
- A guessing paradigm was employed to measure visual sensitivity.
- Visual sensitivity was assessed in both blind and normal hemifields of four patients.
- Control experiments examined the influence of background luminance, local platform luminance, and spatial summation.
Main Results:
- Visual sensitivity was reduced by approximately 3 log units in the blind hemifield.
- Stimuli detected in the blind field also elicited conscious sensations of light and color.
- Residual vision showed normal dependence on background luminance but was independent of local platform luminance and lacked spatial summation.
Conclusions:
- Residual vision in the blind hemifield of hemidecorticated patients is measurable and associated with conscious perception.
- The characteristics of this residual vision suggest it originates from intraocular light diffusion and reflection, not cortical processing.