Foveal orientation, opto-kinetic reflex and blindsight
15. What is the neurobiological explanation of blindsight?
A dissociation between awareness and saccade targeting - individuals not conscious of what they see
A dissociation between perception and saccade targeting - individuals not conscious of what they see
A failure to orient to objects on one side of visual space, as a result of inability to make saccades
A failure to orient to objects on both sides of visual space, as a result of inability to make saccades
16. What is active vision?
The inability to perceive stimuli on the opposite hemisphere to brain damage
The simultaneous movement of both eyes in the opposite direction to maintain binocular vision
Vision that is shaped by how eye movements process information, which are the first and last step in seeing. Only relevant information is processed in a bottom-up fashion.
Vision is the recipient of information, and has top-down control.
17. What did Rolfs (2015) find?
Patients with damage to area v1 can still display blindsight
Eye movements actively serve perceptual and cognitive goals - saccades affect content of visual memory.
There is a dissociation between visual perception and eye movements
Lesion to the posterior parietal cortex (dorsal pathway) causes perception deficits.
18. What does damage to the Colliculus cause?
Difficulty reaching
Difficulty controlling saccadic impulses
Failure to orient toward objects in the same hemisphere as the damage
Smooth pursuit deficits
19. What is the role of the Dorsal pathway in vision?
(Slow) Visuo-motor behaviours for adaptation and reaction
(Fast) Visuo-motor behaviours for adaptation and reaction, including information on the size and location of objects
(Slow) Conscious perception and interpretation, via comparison with memory and allocation of meaning.
(Fast) Conscious perception and interpretation, via comparison with memory and allocation of meaning
20. What did Takemura et al., (2016) find?
Parvocellular deficits cause dyslexia
There is a major grey matter pathway called the Vertical Occipital Fasciculus (VOF) which allows the dorsal and ventral pathways to interact and combine information about object and spatial properties
There is a major white matter pathway called the Vertical Occipital Fasciculus (VOF) which allows the dorsal and ventral pathways to interact and combine information about object and spatial properties
Dorsal and ventral pathways ignore subortical structures