Disorders Of Visual And Spatial Perception Flashcards
How can you see with only one eye?
Information from both the left and the right visual fields enter both eyes
Where is visual information from one Field of vision processed?
By the contralateral visual cortex
Where does crossing of information occur in the brain?
At the Optic chiasm so lesions posterior of the optic chiasm result in contralateral visual fields processing defect
Where is the lower half of the visual field processed?
By gyri above the calcarine fissure and vice versa
Where is visual information originally processed?
The occipital lobe
Which pathway is the dorsal stream and what does it process?
The occipital parietal pathway, processes special features location and movement
Where
Which pathway is the ventral stream and what does its process?
The occipital temporal pathway, identifies objects including faces
What
What are the two subtypes of visual object agnosia?
Apperceptive and associative
How is apperceptive agnosia formed?
Early on, usually bilateral lesions to the dorsal occipital lobe or parietal region. Usually after a cardiac arrest or carbon monoxide poisoning causing a lack of oxygen to the brain
What are the symptoms of apperceptive agnosia?
Occurs before a complete visual percept is formed so the patient is unable to identify objects has knowledge of the objects but can’t recognise it.
How is associative agnosia formed?
Later, bilateral lesions to the inferior temporal occipital junctions
What are the symptoms of associative agnosia?
Visual percept is fully formed but patient can’t connect this to semantic meaning but can copy it. Can be category specific
What is prosopagnosia?
A deficit in identifying familiar faces. Usually goes with a more general visual agnosia.
What causes prosopagnosia?
Damage to fusiform face area but usually more extensive than this. Part of the ventral stream.
What is simultanagnosia?
And impairment in the ability to see more than one object in a scene at any time or appreciate the multiple aspects of a single object.
What causes simultanagnosia?
Typically caused by a bilateral superior parietal occipital type lesion.
What is cortical blindness what is this associated with?
Loss of vision not caused by damage to eye or optic nerve, break down very early and visual processing pathway.
What is cortical blindness caused by?
Big bilateral occipital lesions, just as information enters the primary visual cortex
What is neglect?
Failure to report, respond, orient to stimuli on one side typically the left.
How is neglect formed?
Damage to the paraquito and occipital lobe together opposite to the side of the brain lesion
What are common causes of Visio spatial abilities?
Stroke, anoxia,Alzheimer’s disease, Lewy body dementia,Posterior cortical atrophy
How do you treat neglect?
Visual scanning training or blocking the good side of vision
