Neural patterns of conscious visual awareness in the Riddoch syndrome

Area of Science:

• Neuroscience
• Visual Perception
• Clinical Neurology

Background:

• Riddoch syndrome is characterized by the ability to perceive visual motion in the absence of primary visual cortex function.
• This phenomenon is associated with activity in the motion-sensitive area V5.
• Understanding the neural basis of this syndrome offers insights into conscious visual experience.

Purpose of the Study:

• To investigate the neural correlates of conscious visual motion perception in a patient with Riddoch syndrome.
• To characterize the role of motion area V5 and other brain regions in this condition.
• To explore the determinants of perceptual experience in visual field defects.

Main Methods:

• Multimodal magnetic resonance imaging (MRI) was used to assess patient ST.
• Analysis focused on V5 activity, subcortical input, and neural patterns during motion perception.
• Investigated activation in medial visual areas and the inferior frontal gyrus.

Main Results:

• Patient ST's V5 area was intact, received direct subcortical input, and showed decodable neural patterns during conscious motion perception.
• Moving stimuli activated medial visual areas but were unperceived without concurrent V5 activity.
• High confidence in motion discrimination correlated with inferior frontal gyrus activity.

Conclusions:

• Riddoch syndrome involves intact V5 function and specific subcortical inputs for conscious motion perception.
• Conscious visual experience in this syndrome is critically dependent on V5 activity.
• Hallucinatory motion perception in Riddoch syndrome is associated with hippocampal activity, offering new insights into conscious visual processing.