Special Senses: Vision

Question 1

what nerve is the tactile sensory ending around the eye?

Answer 1

trigeminal, CN5

Question 2

what nerve is the motor unit around they eye - orbicularis oculi?

Answer 2

CN7, facial

Question 3

what cranial nerve does the majority of eye movement?

Answer 3

CN3

Question 4

where is light focused?

Answer 4

fovea centralis

Question 5

which species has a better fovea - diurnal or nocturnal?

Answer 5

diurnal

Question 6

what neurons are in the retina?

Answer 6

bipolar cells
horizontal cells
amacrine cells
ganglion cell

Question 7

which is rods and which is cones?

Answer 7

Question 8

which is rods and which is cones?

Answer 8

Question 9

which is rods and which is cones?

Answer 9

Question 10

which is rods and which is cones?

Answer 10

Question 11

which is rods and which is cones?

Answer 11

Question 12

which is rods and which is cones?

Answer 12

Question 13

the more light the ____ the response and the _____ transmitter is released

Answer 13

the more light the greater the response and the less transmitter is released

Question 14

is light energy converting to chemical energy a graded potential?

Answer 14

yes

Question 15

what does one bipolar neuron recieve convergent input from?

Answer 15

many rods

Question 16

are rods or cones more sensitive to structural detail?

Answer 16

cones

Question 17

what allows for cones to have high visual acuity?

Answer 17

one-to-one wiring

Question 18

what is the trade off for cones being able to see high spatial discrimination?

Answer 18

requires ample light

Question 19

which species is tetrachromatic? what does this mean?

Answer 19

avians - opsins absorb red, green, blue, and UV

Question 20

where does the signal from the rods and cones go to?

Answer 20

bipolar and ganglion cells

Question 21

what do horizontal and amacrine cells provide?

Answer 21

lateral transmission

Question 22

what happens when light does not hit a certain part of the retina?

Answer 22

affected by adjacent portion that it did hit - increase contrast, directional sensitivity, color discrimination

Question 23

which arrow is the direction of light vs the direction of visual processing?

Answer 23

red - direction of light
blue - direction of visual processing

Question 24

what does lateral inhibition do?

Answer 24

increase contract and sharpness of visual response

Question 25

when are excited ganglion cells inhibited?

Answer 25

if neighboring photoreceptors are also excited

Question 26

what do horizontal cells do when ganglion cells are stimulated in a well-defined illuminated field?

Answer 26

send inhibitory signals to neighboring ganglion cells

Question 27

map out the optic nerve to the occipital cortex

Answer 27

optic nerve -> optic chiasm ->nasal fiber to opposite side , temporal fiber to same side -> fibers go to thalamus -> synapse on lateral geniculate nucleus -> occipital cortex

Question 28

In mammals ganglion cells project to the _______ and _______ visual cortex

Answer 28

In mammals ganglion cells project to the ipsilateral and contralateral visual cortex

Question 29

An injury to the left hemisphere will affect perception in what visual field?

Answer 29

right

Question 30

what are the 3 kinds of eye movement?

Answer 30

eye position
accommodation
regulation of pupil size

Question 31

what is eye position

Answer 31

convergence of the two eyes to focus objects on the fovea
follow objects, fixate visual field

Question 32

what is accommodation

Answer 32

adapt focal length to increase optic power by altering shape of lens

Question 33

what is regulation of pupil size

Answer 33

constriction of pupil to reduce spherical aberration

Question 34

what is this an example of?

Answer 34

convergence

Question 35

what is this an example of?

Answer 35

divergence

Question 36

what reflex tests eye following an object, fixate the visual field?

Answer 36

vestibulo-ocular reflex

Question 37

what is stabismus

Answer 37

misalignment of eyes

Question 38

when might double vision occur?

Answer 38

strabismus
object projected on different part of retina

Question 39

A patients with left lateral displacement (Exotropia) could have a lesion where?

Answer 39

left oculomotor nucleus, CN3

Question 40

what is esotropia

Answer 40

eye turned inward

Question 41

what is the neural control of accomodation?

Answer 41

RGS pathway
retina -> optic nerve -> lateral geniculate nucleus -> visual cortex -> superior colliculus -> oculomotor nucleus -> parasympathetic motor efferent to ciliary muscle, CN3

Question 42

what does ciliary muscle contraction do the lens?

Answer 42

relax tension, more curved, focus on nearby target

Question 43

what is the diameter of the pupil regulated by?

Answer 43

ANS

Question 44

what controls the iris sphincter muscle?

Answer 44

parasympathetics

Question 45

what controls the iris dilator muscle?

Answer 45

sympathetics

Question 46

what does the retino-geniculo-striate pathway do?

Answer 46

conscious visual perception

Question 47

what is the retino-tectal pathway

Answer 47

provides pupillary reflexes and reflex orientation of eyes to visual targets

Question 48

map out the retino-tectal pathway

Answer 48

ganglion cells -> pretectal nuclei -> edinger westphal nucleus -> oculomotor (CN3)

Question 49

what is the retino-hypothalamic pathway?

Answer 49

provides for light to set up physiological rhythms in suprachiasmatic nucleus (SCN)

ex. short and long day breeders

Question 50

map out the eye blink reflex - touch the cornea/eyelid

Answer 50

free nerve endings in cornea stimulate CN5 -> CN5 terminates in spinal trigeminal nucleus-> reticular formation interneurons send bilateral axons to facial nucleus -> CN7 send axons down the facial nerve to orbicularis oculi -> lower eyelids

Question 51

map out the menace response - don’t touch cornea/eyelid

Answer 51

visual stimulus relayed on CN2 -> CN2 goes to occipital cortex via thalamus -> threat perceived -> motor neurons stimulate ipsilateral facial nerves in CN7 -> CN7 motor neurons excite orbicularis oculi -> lower eyelides

Question 52

what can cerebral lesion result in with the menace reflex?

Answer 52

loss of menace reflex

Question 53

what is a good test to asses damage to cortex?

Answer 53

menace response

Question 54

what pathway does the pupillary light reflex go on?

Answer 54

retino-tectal pathway

Question 55

map out the pupillary light reflex pathway

Answer 55

ganglion cells of retina project bilaterally to pretectal nucleus via CN2 -> pretectal nuclei project crossed and uncrossed fibers to edinger-westphal nucleus -> rise of preganglionic parasympathetic fibers -> exit brain via CN3 -> synapse with postganglionic parasympathetic neurons of ciliary ganglion -> sphincter muscle of iris excited

Question 56

what is a direct response to the pupillary light reflex?

Answer 56

ipsilateral side respond to stimulus

Question 57

what is consensual response to the pupillary light reflex?

Answer 57

contralateral side responds after ipsilateral stimulus

Question 58

what is the deficit?

Answer 58

left CN2 deficit

Question 59

what is the deficit?

Answer 59

left CN3 deficit

Question 60

what caused the animal to be blind?

Answer 60

possible right cerebral hemisphere lesion

Question 61

what is seen in horner’s syndrome?

Answer 61

-nicotating membrane ventromedial in conjunctival sac
-prolapsed nicotating membrane

Question 62

what space is the nicotating membrane in?

Answer 62

enophthalmic state

Question 63

what is horners syndrome?

Answer 63

damage to sympathetic NS to eye

Question 64

what can damage sections 1,2,3 - horner’s syndrome

Answer 64

1 & 2 - infection, inflammation, injury, spinal compression
3 - middle or inner ear diease

Question 65

what are the symptoms of horner’s syndrome?

Answer 65

miosis (small pupils)
ptosis (drooping of upper eyelid)
enopthalmus (sunken eyes)
prolapsed nicitating membrane