Role of Visual and Vestibular Feedback in Motor Control

Question 1

Central visual pathway

Answer 1

Optic nerve -> chiasm -> tract -> LGN -> visual cortex

or

Optic nerve -> chiasm -> tract -> superior colliculus -> eye movement

Question 2

visual field

Answer 2

visual area seen by each eye when head is fixed

Question 3

Left hemifield projects

Answer 3

Nasal half of the left eye and temporal half of the right eye

Question 4

How do you get monocular vision

Answer 4

Cut optic nerve

Question 5

How do you lose temporal portions of both halves of visual field

Answer 5

Cut optic chiasm

Question 6

Pituitary tumors result in

Answer 6

loss of temporal portions of both halves of visual field because optic chiasm compromised

Question 7

Lesion at right optic nerve

Answer 7

WW BB

Question 8

Lesion at optic chiasm

Answer 8

BW WB

Question 9

Lesion at right optic radiations/tract/LGN

Answer 9

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Question 10

Lesion at right occipital visual cortex

Answer 10

BW BW

Question 11

Does visual cortex have distinct cell layers?

Answer 11

Yes

Question 12

What kind of organization of neurons does visual cortex have?

Answer 12

Columnar

Question 13

What are some specific visual stimuli that visual cortex neurons can respond to?

Answer 13

orientation, edge, movement of object across visual field

Question 14

What responds to an aspect of the visual object

Answer 14

orientation columns

Question 15

What are each slice of orientation columns for

Answer 15

Each slice of the block of tissue is presumed to specialize in the analysis of straight lines in a particular orientation

Question 16

When are columns of cells (orientation columns) activated

Answer 16

They are activated only when the visual stimulus has a particular orientation

Question 17

Blobs

Answer 17

Regularly spaced columns of cells which respond to color

Question 18

What has “zebra appearance” from top down viewpoint

Answer 18

Ocular dominance columns, irregular in size

Question 19

Receptive fields

Answer 19

Something that cells in the visual cortex have. These cells react when a stimulus is presented to a certain area on the retina.

Question 20

Two main projections from visual cortex

Answer 20

Parietal lobe

Temporal lobe

Question 21

Visuomotor transformations

Answer 21

Parietal lobe, dorsal stream

Question 22

Visual perception, visual memory

Answer 22

Temporal lobe, ventral stream

Question 23

Dorsal stream

Answer 23

Behavioral control path, where system

projects to frontal lobes

Question 24

Dorsal stream disease

Answer 24

optic ataxia

hemispatial neglect

Question 25

optic ataxia

Answer 25

patient has difficulty using visual input to guide hand or arm movements

Question 26

hemispatial neglect

Answer 26

patient is unaware of half of visual field on opposite side from cortical lesion

Question 27

ventral stream

Answer 27

what system, conscious perception path | recognition of shapes, faces, route finding

Question 28

visual agnosia

Answer 28

patients can describe the visual features of an object, but cannot name the object

Question 29

ventral stream disease

Answer 29

visual agnosia

Question 30

diabetic retinopathy

Answer 30

excess glucose weakens blood vessels in the eye | bulge (aneurysm) and bleed damage retina

Question 31

vestibular function

Answer 31

control of balance, head position | organs of balance - inner ear (membraneous labyrinth)

Question 32

What detects angular rotation of head in 3 directions

Answer 32

Semicircular ducts (canals)

Question 33

What detects linear head acceleration (head tilt) relative to direction of gravity

Answer 33

otolith organs

Question 34

where is info from semicircular ducts and otolith organs sent to, what's it for

Answer 34

cerebellum, brainstem | for control of balance, head position

Question 35

sensory receptor in vestibular system

Answer 35

hair cells

Question 36

components of hair cells

Answer 36

stereocilia (short), kinocilium (long)

Question 37

how does hair cells sense

Answer 37

firing of hair cells depends on direction of hair cell bending tonic release of transmitter -> + or - AP

Question 38

What depolarizes hair cells

Answer 38

bend hair cells towards kinocilium (long)

Question 39

What is the afferent fiber for hair cells

Answer 39

VIII

Question 40

endolymph

Answer 40

fluid inside canals (SC ducts)

Question 41

how is angular head rotation detected

Answer 41

hair cells located in ampullae of SC stimulated by force exerted by inertia of endolymph when head moves Work in pairs to determine direction of head rotation

Question 42

How do hair cells work in pairs

Answer 42

depolarization of cells in one canal and hyperpolarization on the other side

Question 43

how does head sense linear acceleration

Answer 43

hair cells in utricle have CACO3 (otolith stones) in gelatinous material, which cause deformation of gelatinous mass when tilt - bend hair cells

Question 44

Balance problems

Answer 44

Vertigo, symptom of Meniere's Disease

Question 45

vertigo

Answer 45

illusion of spinning - unequal inputs from the two vestibular nerves - interpreted by the brain as movement - role of vision, tactile input - symptom of Meniere's disease