Discrimination of motion direction in perimetrically blind fields.

Area of Science:

• Neuroscience
• Visual Perception
• Cortical Plasticity

Background:

• The striate cortex is crucial for visual processing.
• Understanding residual visual capacities after brain lesions is important for rehabilitation.

Purpose of the Study:

• To investigate motion direction discrimination in patients with striate cortex lesions.
• To determine the neural substrates responsible for residual visual function.

Main Methods:

• Testing motion direction discrimination in a forced-choice task.
• Assessing patients with bilateral and unilateral striate cortex lesions.
• Comparing patient performance with controls (implied).

Main Results:

• Patients with striate cortex lesions showed high success in discriminating motion direction.
• No optokinetic nystagmus was observed in cortical blindness cases.
• Hemispherectomized patients performed at chance level, indicating lesion specificity.

Conclusions:

• Residual motion discrimination depends on cortical structures beyond the primary visual cortex.
• The homologue of the monkey's area MT is a likely neural substrate for this residual capacity.