LECTURE 15: visual , auditory and vestibular systems Flashcards
for the pupullary light reflex which CN had afferents and efferents
aff- CN 2
eff- CN 3
the lateral geniculate body is in which structure ?
thalamus
how mnay layers of tissues does the eye have? what are they ?
3
-sclera and cornea (front part)
- chorodi with blood vessel and ciliary body (front part)
- retina (innermost layer) with visual neurons
what part of the eye controls the amount of light that enters
pupil
what part of the eye accommodated for near objects
lens
the fovea of the eye has the highest visual ___ and smallest visual ___
acuity
field
the fovea can only see __ receptors
cone
what is the optic disc
blind spot
what is the jelly like fluid in the eye
vitreous humor
which layer of the retinal contains melanin to decrease background scatterning of light
outer pigmented layer
the inner neuronal layer of the retinal has ___ neurons chain responsible for ____
3
phototransduction
the inner neruonal layer of the retinal has photoreceptors that have graded membrane potentials… what are the 2
cone receptors (color)
rod receptors (B &W)
the inner neuronal layer of the retinal has ___ cells that transfer into to the ___ cells
bipolar
ganglion
what cells in the inner neuronal layer of the retinal generate action potentials as 1st order neruons
ganglion
what are the 2 inerneurons of the inner neuronal layer of the retinal
horizontal cells and amacrine cells
what cells are apart of the horizontal cells
photoreceptors and bipolar cells
what cells are apart of the amacrine cells?
bipolar and ganglion cells
what is it called when there is a relsease of NT by the photoreceptors that results in the generation of action potentials in the ganglion cells
phototransduction
which receptors have low light sensitivity , small receptive field and color vision (day)
cone
which receptors have hgih light sensitivity , large receptive field and black and white vision (night)
rod
what does the ganglion cells synapse with to transmit visual perception
optic nerve
in the central pathway of visual perception where is the 2nd order neuron cell body
in the lateral geniculate body inside of the thalamus
in the central pathway of visual perception the 2nd order neuron cell body going thru what
optic radiation and primary visual cortex
where is the primary visual cortex
in occipital lobe along calcarine fissure
the cuneus / upper bank is responsible for what
lower quadrant of B eyes
the lingula / lower bank is responsible for what
upper quadrant of B eyes
the retinotopically organized has _ fovea region and _ peripheral refions of ipsi and contra visual hemifields
1 and 3
what kind of fibers does the optic nerve have
ipsi nasal and temporal nerve fibers
in the optic chiasm the ___ fibers cross to ___ side
nasal
contralateral
in the optic tract what = 1 hemi visual field
ipsilateral temporal nerve fibers and contralateral nasal nerve fibers
the L optic tract carries info from the ___ hemi visual field which consists of fibers from _ temporal hemi retina and _ nasal hemi retina
R
L
R
the R optic tract carries info from the ___ hemi visual field which consists of fibers from _ temporal hemi retina and _ nasal hemi retina
L
R
L
which tract has optic radiation
geniculocalcarine
what is the visual association cortex
higher order visual processing
in the visual association cortex the dorsal stream is in what cortex
parieto occipital
in the visual association cortex the ventral stream is in what cortex
occipito temporal cortex
in the visual association cortex the dorsal stream has to do w what
motion , high temporal resolution
in the visual association cortex the ventral stream has to do w what
perception of form , high spatial resolution and visulal acuity
what are the 3 things in the visual association cortex
dorsal stream
ventral stream
parallel channels
what are the neural pathways of the visual system
vision and reflex
what is the recognition and location of objects
vision
what are the 2 sensory processing
peripheral visual processing and central visual processing
what controls the size of pupil and curvature of lens
reflex
central visual processing is ___ visual image
contra
the entire visual field is the entire view seen by ___ ___ without moving the ___
both eyes
head
how is the visual image when projected onto the retina
inverted and reversed (L/R and up/down)
image from monocular zone projects only to ___ nasal hemi rentia, from ____ zone to portions of ___ hemi retinas
ipsilateral
binocular
bilateral
what are the 2 functional categories for eye movement motor control
stabilize gaze and directing gaze
which gaze is keeping eye position stable during head movements to keep environment from visually bouncing
stabilize gaze
what is the vestibulo- ocular reflex
action of vestibular info on eye position during fast head movements
what is optokinetic reflex
use of visual info to stabilize images during slow head movements
saccades and smooth pursuit are examples of what gaze
direct
movements of the eyes are either ___ or ___
conjugate or vergence
what movement is when both eyes move in same direction
conjugate
what are the 2 different type of vergence
convergence and divergence
what is convergence
b eyes move toward midline when target moves from far to near
what is divergence
both eyes move away from midline to shift gaze to distant object
what are ballistic, rapid eye movements
saccades
saccades allows us to ___ our visual field , ___ to focus attention on parts of scene that convey the most significant info
scan
pausing
saccades eye movements align ___ with particular part of the scene
fovea
saccades can have a velocity up to ___ degrees/sec
700
what is slower tracking movement of eyes
smooth pursuit
during smooth pursuit you keep moving object on ___
fovea
which eye movement has velocity up to 100 degrees/sec
smooth pursuit
which reflex is elicited by moving head
vestibulo-ocular reflex
optokinetic reflex is elicited by moving ____ ____
visual stimuli
during vestibulo -ocular reflex you are fixating on an object and moving head ___ to ___
side to side
during vestibulo -ocular reflex your eyes automatically move in ___ distance /speed but in ___ direction of head movement
same
opposite
which reflex keeps image of object at same place on retina
vestibulo ocular reflex
during the optokinetic reflex it allows the eyes to do what
follow large objects in visual field
which reflex adjusts eyes position during slow movements ( < 1 hz)
optokinetic reflex
how many gaze centers are in the reticular formation of the brain stem
2
what is considered the horizontal gaze center in the brain stem
paramedian pontine reticular formation
the rostral interstitial nucleus in midbrain reticular formation is considered to be what
vertical gaze center
what does the medial longitudinal fasciculus of the brainstem do for eye control
coordinates activations of both neural circuits
which CN are associated with eye movements
3 (III)
4 (IV)
6 (VI)
which N is for the vestibulo - ocular reflex and optokinetic reflex
vestibular
what is the function of the forebrain for controlling the eye movements
initiating and accurately shifting eyes toward targets
the frontal eye field of the forebrain does what
contalateral saccades and smooth pursuit
the frontal eye field of the forebrain is connected with the ____ _____ directly and indirectly via the ___ ___
contralateral paramedian pontine recitular formation
- superior colliculus
the parieto- occipital - temporal cortex of the forebrain does what to control eye movement
ispilateral smooth pursuit
what are the 3 things that the parieto- occipital - temporal cortex is connected with
vestibular nucleu
cerebellum
paramedian pontine reticular formation
lesions here can causes increase latency and reduces accuracy, frequency and velocity of saccades
superior colliculus (optic tectum)
what does the basal ganglia do in the forebrain to control eye movements
proper initiation of eye movements
what are the 2 loops in the basal ganglia for control of eye movements in the forebrain
oculomotor loop
prefrontal loop
what in the forebrain does the correct execution of eye movements
cerebellum
what tracts are in the cerebellum that control eye movements
vestibulocerebellum and spinocerebellum (vermis)
what does homonymous mean
same part of visual field of B eyes
what does anopsia/anopia mean
defect in visual field
if you had a lesion to the R optic N what would the clinical implication be ?
loss of vision in the R eyey
if you had a lesion to the optic chiasm what would the clinical implication be ?
bitemporal hemianopsia
(L temporal , R temporal)
if you had a lesion to the R optic tract what would the clinical implication be ?
L homonymous hemianopsia
( L eye temporal and R eye nasal)
if you had a lesion to the R meyer’s loop what would the clinical implication be ?
L superior homonymous quadrantanopsia
( L upper temporal , R upper nasal)
if you had a lesion to the R V1 what would the clinical implication be ?
L homonymous hemianopsia with macular sparing
the ear converts acoustic energy to __ __
action potentials
which part of the ear transmits sound waves that vibrate the tympanic membrane
external ear
what are the 3 ossicles and 2 muscles that are found in the middle ear
O: malleus , inus and stapes
M: tensor tympani (V3 - CN 5 third branch) and stapedius (CN VIII)
the internal ear (bony labyrinth) contatins what 2 apparatus
auditory and vestibular
what is included in the auditory apparatus of the internal ear
cochlea
what is included in the vestibular apparatus of the internal ear
semicircular canals, utricle and saccule
in the auditory apparatus the ___ is hallow , coiled structure filled with ____ - membranous labyrinth
cochlea
fluid
in the auditory apparatus the ___ membrane vibrates in response to sound
basilar
in the auditory apparatus the organ of ___ includes hair cells that get bent initiating ____ ____
Corti
mechaneoelectrical trasnfuction
the auditory apparatus activates the ____ nerve of CN ___-
cochlear
VIII
inthe mechanoelectrical trasnductiion of the eye …. the sound waves hit the ___ membrane causing ossicles to move which then causes the membrane at opening to ___ to move/vibrate , causing the fluid in the cochlear to move , causing the basilar membrane and embedded ___ cells to vibrate , causing hair cells to bend against the attached and immobile ____ membrane causing the hair cells to depolarize and activated the ____ nerve endings
tympanic
cochlea
fluid
hair
tectorial
cochlear
what orients head and eyes towards sounds
auditory inputs
auditory inputs raises over all activity of the ___
CNS
what does the auditory inputs give a person
conscious awareness and understanding of sounds
describe the bilateral ascending pathwyas of the major auditory pathways ?
where does ti start ?
medullar?
pons?
midbrain?
thalamus?
cortex?
starts in the cochlear and goes to the auditory N (CN VIII) and then going to the cochlear nuclei in the medulla and then to the superior olive in the pons then thru the nucleus of lateral lemniscus in the pons and reticular formation and then it goes thru the infeiror colliculi in the midbrain to the medial geniculate body of the thalamus and finally to the primary auditory cortex inthe temporal lobe
what info goes thru the superior colliculi
visual , auditory and somatosenosry
in the major auditory pathways the sound localization is due to ____ arrangement
parallel
the interaural time goes thru the ___ ___ ___ in the pons
medial superior olive
the intersural intensity difference goes thru the ___ ___ ___ in the pons
lateral superior olive
what carries out input integrative functions such as processing of sound frequencies and integration of cues for localizing sound in space
inferior colliculus
____ from cochlea travel via auditory n to cohlear nucleus
afferents
what is responsible for organized tonotopically , supporting basic auditory functions
primary auditory cortex
what does the secondary auditory cortex do
compares sound with memories of sound to categorize them
what does wernickes area do
imput in comprehending speech
where is the wernickes area located
posterior ot the primary auditory cortex (left side of brain)
the vestibular apparatus includes ___ semicircular canals , ___ otolithic organs and _____ labyrinth
3
2
membranous
in the vestibular apparatus the 3 semicircular canals are arranged ___ to each other , each having a swelling called ___
perpendicularly
ampulla
what are the 3 semicircular canals called in the vestibualr apparatus
anterior
posterior
horizontal
what are the 2 otolothic organs of the vestibular apparatus called
utricle
saccule
the membranous labyrinth of the vestibular apparatus is seperated from bony labyrinth by ___ ___
perilympth fluid
the membranous labyrinth of the vestibular apparatus hollow and filled with ___ ___
endolymph fluid
the membranous labyrinth of the vestibular apparatus have ___ receptor cells that blend with fluid movement
hair
the semicircular canals each open at both end into the ___
utricle
each semicircular canal has an ___ that contains a __ with supporting cells and sensory hair cells
ampulla
crista
what is it called when the hair cells are embedded in gelatinous structure
cupula
in the semicircular canals when the head is still what is happening to the hair cells
baseline rate of firing
in the semicircular canals when the head starts or stops turning , the ___ and ___ cells bend causing increase/decrease in firing depending on the ___ of bending
cupula
hair
direction
in the semicircular canals when the head is moving at a steady rate the hair cells in the ___ catch up to the head movement and return to ____ firing
endolymph
baseline
the cupula of the semicircular canals is only active when
during acceleration/deceleration of rotational head movements
in the semicircular canals the R and L work ___ and ____
reciprocally and simultaneously
horizontal SCCs have same ____ of rotation and work as a ___ pair
axis
functional
if signals coming from the semicircular canals are not reciprocal then what happens
impaired postural control , eye movments and /or nausea can occur
___ and ___ are membranous sacs that respond to linear acceleration/deceleration and head position relative to gravity
utricle and saccule
each urticle and saccule sac have a ___ which contains supporting cells and hair cells embedded in gelatinous mass with microscopic calcium carbonate crystals on top
macula
___ movement of the head displaces the otoconia that then move ____ substance and ___ cells to stimulate or inhibit firing of neurons , depending of direction of movement
linear
gelatinous
hair
____ apparatus contains sensory hair receptors that respond to head position relative to gravity and movements
vestibular
the central vestibular system is made up of what
4 vestibular nuclei in B junction of pons and medulla
the vestibulocerebellum receives vestibular input and impacts ___ ___ and ___ ___
postural control and eye movement
the vestibulocerebellum has connections with what 4 things
vestibular aparatus , vestibular nuclei , inferior olive and spinal cord
in the vestibulocerebellum the amount of muscular reflex responses is dependent on what
its processing of vestibular and visual input
when there are vestibular disorders what is essential for adaptations in postural/balance systems
vestibulocerebellum
the vestibulo-cervical reflex is a ___ pathway that deals with ___ adjustments of the ___ in response to activation of ____
descending
postural
head
semicircular cancal
the vestibulo-cervical reflex goes to which tract and then which nucleus
medial vestibuluspinal tract to medial vestibular nucleus
which reflex is a descending pathway that deals with postural and tone adjustments of the body
vestibulo-spinal reflex
what tracts are apart of the vestibulo -spinal reflex
lateral and medial vestibulospinal tracts and reticulospinal tract
what is the bilateral connections to extraocular eye muscles and superior colliculus
medial longitudinal fasciculus
the vestibulocolic pathway goes to the CN ___ nucleus to affect the cervical muscles of postural control
XI (spinal assessory)
if the descending pathway of the vestibular system is disrupted what will that result in
balance deficits with impacts movements abilities/control (mostly in low light and/or uneven surgace conditions
the cerebello thalamocortical pathways is a ___ pathways in the ___ and ___ vestibular nuclei
ascending
lateral and superior
what is the pathway of the cerebello thalamocortical pathway
to the lateral and superior vestibular nuclei (in the pons) to the thalamus and then near S1 facial area and posteroir parietal cortex
the S1 face area and posterior parietal cortex is involved in ____ of body orientation in ____ space
perception
extapersonal
if someone has a lesions in the R posterior parietal cortex what does that cause
altered perceptions of of personal and extrapersonal space
where is the first order neuron cell in the vestibular pathways
vestibular ganglion (also called scarpas ganglion)
where is the second order neuron found n the vestibular pathways
vestibular nuclei in the pons/medulla
the second order neuron in the vestibular pathways also receives input from ____ cerebellum
ipsilateral
____ is formed by descending axons of the 2nd order neurons in the vestibular pathway
VST (medial and lateral vestibulospinal tracts)
what is the function of the ipsilateral lateral vestibulospinal tract
tonic excitatory effects on extensors
what is the function of the B medial VST
influences neck muscles and head movement
when the visual cortex is more active then the vestibular cortex is ___
inhibited (vise versa)
if you have angular accelerations of the head which receptors are on
semicircular canals
when there is linear acceleration of the head or head position relative to gravity whcih receptors are on
saccule and utricle
in the vestibular , auditory , or visual systems the disorders may affects what 5 things
receptors , CNs, brainstem nuclei , tracts within the CNS or associated cortical areas
the central vestibular system can have ___ and/or __ disorders
peripheral
central
vestibular and visual systesm are tightly linked for ____ ____ and ___ ___
postural control and eye movements
vestibular and auditory systems are tightly lined due to what
geography and sharing the same CN
