Chap 13 Flashcards
What are the interactive functions of areas V1 to V5 ?
V1: Line orientation
V2: Form
V3: Dynamic form
V4: Color
V5: Motion
What are the 3 principles of the Wiring Diagram of the visual cortex?
- V1 is the first processing level, projects to all other occipital regions
- V2 is the second level, that can also project to other regions
- After V2, 3 pathways emerge to the parietal cortex and inferior temporal cortex
Where do the 3 streams from the occipital lobe project to ?
- Dorsal to the parietal cortex
- Ventral to the temporal cortex
- STS stream to the temporal cortex
What are some distinct functions of the 2 main pathways ?
Parietal
- object/facial/body analysis
- analysis of landmarks and biological motion
Temporal
- voluntary eye movement
- directed grasping and reaching
- visuomotor guidance
What are the 5 main Visual functions ?
- Vision for action
- Action for vision
- Visual recognition
- Visual space
- Visual Attention
Describe vision for action and action for vision
Vision for action
- visual processing to perform directed movements (ex reaching for a cup)
Action for vision
- distinguishing between stimuli for selective processing
Describe visual recognition, space and attention
Recognition
- identifying objects, foods, people
Space
- knowledge of objects relative to ourself and to other objects
Attention
- neurons response selectively to different stimuli at a given place and time to make specific movement
What are the 3 arguments suggesting the dorsal stream has visual control of actions ?
- neurons in the posterior parietal region are only active when the brain acts on visual information
- Must act as a connection between visual world and action taken on it
- lesions to the parietal cortex cause deficit to visual motor spatial control
What do imaging studies suggest about facial and spatial recognition ?
- the temporal lobe lights up when asked to identify faces
- the parietal lobe lights up when asked to locate a dot that was placed somewhere on a face
What is apperceptive agnosia ?
Failure to recognize objects
- caused by damage to the lateral parts of the occipital lobes
What is associative agnosia ?
Failure to recognize objects despite its apparent perception
- cant match shapes, but can draw them from memory
- caused by damage to the anterior temporal lobe
What is prosopagnosia ?
Failure to recognize faces including one’s own
- caused by damage right below the calcarine fissure
If blindness occurs in both visual fields, where is damage most likely ?
The eye, the retina or the optic nerve
What is monocular blindness ?
- damage to the eye, retina or nerve produces blindness in the specific eye
What is bitemporal hemianopia ?
- blindness in both temporal (outside) fields
- caused by disturbance to the chiasm
What is nasal hemianopia?
- blindess in one nasal field (half of one visual field)
- caused my lateral chiasm lesions
What is homonymous hemianopia ?
- blindness in one entire visual field (half of each visual field/each eye)
- caused by damage to the optic tract, geniculate body or V1
What are scotomas ?
lesions that cause blindspots
What is cortical Blindness ?
When a person has no conscious ability to see due to damage, but can report on the shape of the an object presented to them in the “blind” field
What is the outcome of V4 damage ? Referring to the JI case study
lost the ability to see color, and after time also lost the ability to remember, think or dream in color
- there is a link between imagery and memory that is dependent on certain cortical structures
What is the outcome of V5 damage ? referring to the case study ?
Patient could not see liquid filling a cup or people entering and leaving rooms, they simply appeared
What is optic ataxia ?
deficit in visually guided hand movements like reaching and grasping
What is the outcome of damage to the right and left occipitotemporal region ?
- damage to the right= deficit in face identification
- damage to the left= deficit in reading
