the occipital lobe

Question 1

list the occipital areas and their features\functions

Answer 1

-V1 (small receptive field): Delineation/orientation.Most visual input via lateral geniculate body (LGB) through V1 on to V2 and subsequently to specialized secondary areas.
-V2:form\texture.A portion of visual input ‘skips’ V1 and goes directly to V2

both V1 and V2: are heterogeneous with areas specialized for color, form and motion
-Color: Blobs and thin stripes
-Form: Interblobs and thick stripes
-Motion: Interblobs and pale stripes

-V3:form\texture,Shape of objects in motion
-V4:form\texture,color
-V5:motion

V3,V4,V5: more dinstinc functions:

-V8:color
-area LO:object recognition
-V3a:motion
-MT:motion

Question 2

what are the 3 streams in the occipital lobe and their functions?(where their info goes)

Answer 2

-Dorsal stream – Vision for Action

Parietal cortex:
Egocentric orientation in space: determining spatial location of objects relative to self
Visual guidance of movement (grasping, catching, avoiding objects)

-STS stream – Vision for location

superior temporal sulcus
Allocentric location: determining spatial location of objects relative to each other
Spatial localization of objects
Spatial memory (“visual space”)
Perceiving specific types of movements (e.g., body language)
Polysensory neurons combining information from dorsal and ventral stream for categorization (Ch15)

-Ventral stream – Vision for recognition

Inferior temporal cortex: “vision for recognition“
Visual recognition of objects like tools, hands, faces
Specific responses of cells to complex objects (e.g., faces) (Ch 15)

Question 3

what types of disorders r linked to the visual stream?

Answer 3

-Disorders of visual pathways (from eye to cortex)
Hemianopia
Scotomas

-Lesions of the cortex:
Cortical blindness, Blindsight, Agnosia
Selective loss of motion, color, object recognition

Question 4

where are the info from both eyes conbined? why is it important to know?

Answer 4

-optic chiasm
Lesions before optic chiasm involve one eye
Lesions after chiasm involve both eyes and one visual field

Question 5

what happens when the optic nerve is severed?

Answer 5

• the optic nerve, is located before the chiasm, thus you lose eyesight in one eye

Question 6

what happens when the optic chiasms severed?

Answer 6

you lose sight in ur temporal field
-the outer side of the visual field of each eye

Question 7

what happens when the optic tract is severed?

Answer 7

• you lose sight in one of the visual fields, becasue the lesion is after the chiasm

Question 8

what are agonsias?

Answer 8

inability to combine individual visual impressions into complete patterns
Inability to recognize
Inability to draw or copy

. can have different kind of agnosias
object agnosia
prosopagnosia
etc…