Olfactory and Visual Systems Flashcards
Bradykinesia (slow movement) would be associated with what disease ?
Parkinsons disease
hemiballismus, a dramatic movement disorder would be the result of damage to where in the brain?
subthalamic nucleus
Chorea, which causes rapid involuntary movements, is a disorder most commonly associated with what disease ?
Huntingtons disease
gait ataxia is most commonly the result of injury to the ______ of the cerebellum
vermis
fearless, and placid behavior, known as Kluber-Bucy Syndrome, is the result to injury where ?
amygdala
the inability or failure to form new memories would be the result of injury to where in the brain ?
hippocampus
hemiparesis and spasticity on one side of the body would occur with an injury to the _______ of the internal capsule
posterior limb
dismetria, or the inability to coordinate movements (touch finger to nose tip), would be the result of injury to _____ of the cerebellum
lateral hemisphere
what are the 2 main functions of olfaction
taste and smell
the origin of the olfactory system that sits in the roof of the nasal cavity is called what ?
olfactory epithelium
what does the olofactory epithelium contain
3 million receptor cells
sensory endings for CN V (irritant smells)
what is structure of an olfactory receptor and why are the unusual amongst other human nuerons
structure : vesicle w/10-30 cilia emerging out
-unique bc its replaced throughout life as its lifespan is only 1-2 months
what are olfactory fila and where do they go ?
- bundles of olfactory axons
- pass through holes in cribiform plate ending in olfactory bulb
- * olfactory fila make up CN I**
olfactory bulb develops as an outgrowth of ?
telencephalon
what are mitral cells
main projection neuron of olfactory bulb which form olfactory tract
what forms the glomerulus in the olfactory bulb
dendrites
each olfactory receptor is specific to _______ mitral cell glomerulus
one
fibers in the olfactory tract have projections to where ? What 2 are where they generally end ?
- anterior olfactory nucleus
- olfactory tubericle
- Primary Olfactory Cortex (Main end)
- Amygdala (Main end)
what two eye structures focus the image on the retina
cornea and lens
focusing and image requires what ? which eye structures allow this to happen
refraction
- cornea (70 %)
- lens (30%)
what does the iris do ?
affects brightness and quality of image focused on retina
the retina has how many nuclear layers ? and how many synapses occur w/in these layers
3 nuclear layers w/ 2 synapse layers
what are the 2 photoreceptors in the retina and what is unique to each
Rods - rhodopsin, low acuity and dim light
Cones - high acuity, color, lots of lights
what happens to old rod and cone photoreceptor cells as they age
phagocytized by pigment epithelium
where is the blind spot in the retina and, how does the brain accomodate for this area
at the optic disk where there are no photoreceptors
-brain automatically fills this space in
what is the macula ?
specialization of the retina designed for vision of highest acuity
-contains fovea in center
what is the fovea
center of macula
- area of lots of cones and no rods
- area of highest visual acuity
what is the thalamic relay nucleus for the optic pathway
lateral geniculate nucleus (LGN)
after optic tract fibers end in the LGN, where do they project to
visual cortex in occipital lobe
Fibers that represent inferior visual fields are the most _______ radiations, whereas fibers representing superior visual fields are _______________
superior, inferior in radiations
what part of the internal capsule is involved with the superior visual field
retrolenticular part
what part of the internal capsule has optic radiations pertaining to the inferior visual field
sublenticular part
Explain the visual fields, which cross and which remain uncrossed
- fibers of nasal half of retina cross at optic chiasm
- fibers of temporal half remain uncrossed
what part of the optic pathway is responsible for depth perception
optic chiasm, allows for comparison of areas via each retina
The structure of the LGN is made of _____ layers
6
what layers of the LGN are responsible for contralateral eye, which layers are responsible for the ipsilateral eye
1,4,6 contralateral
2,3,5 ipsilateral
what is the parvocellular layer
layers 3-6 of the LGN responsible for color and form
what is the magnocellular layer
layers 1-2 of LGN responsible for movement and contrast
who was the first to describe the retinotopic organization of the eye using bullet wound injuries
Dr. Tatsuji Inouye
in relation to the occipital lobe, the inferior visual field lies above the _______ whereas the superior visual field lies below this
calcarine sulcus
where is the macula represented in reference to position on the occipital lobe
most posteriorly, peripheral fields anteriorly
what is the line of gennari
striate cortex, or the thin myelin line in primary visual cortex
Visual field deficits are named according to what ?
the part of the visual field that is lost
define these terms,
- anopia
- hemianopia
- quadrantanopia
- homonymous
- heteronymous
- anopia - loss of one or more quadrants
- hemianopia - loss of half visual field
- quadrantanopia - loss of quarter of visual field
- homonymous - same visual field lost in each eye
- heteronymous - 2 eyes having non-overalpping field loss
damage anterior to the optic chiasm would result in visual field loss for ?
ipsilateral eye
damage at the chiasm causes what type of visual field deficits
heteronymous deficit
damage to optic tract results in what type of visual field loss
homonymous deficit
a lesion in the temporal lobe that interupts Meyers loop would affect what visual field
affect superior visual field cuz meyers loop plays a role in infereior retinal quadrant
what is unique about a PCA infarction that results in an eye deficit
the macula is spared in deficit
what would happen in the pupillary light reflex if there was a lesion in the occulomotor nerve
- both constrict if shined in unnaffected eye optic nerve
- neither constrict if shine in affected eye optic nerve
how would the pupillary light reflex act if ther there was a lesion in the optic radiations
No affect
how would a lesion in the visual cortex affect the pupillary light reflex
No effect
Besides the LGN to the visual cortex, what are the additional destinations for visual information
- superior colliculus
- hypothalamus
- superchiasmatic nucleus
what is the role of the occipital lobe primary visual cortex in vision
Breaks down visual information and distributes to extrastriate cortex
the striate and visual cortex in the occipital lobe have a _______ organization
collumnar
each cortical module or collumn controls _____ aspect of the visual field
one
what layers of the LGN make up the ventral stream of visual information
Parvocellular layers 3-6 responsible for color and form
what layers of the LGN are responsible for the dorsal stream of visual information
Magnocellular layers 1-2 responsible for movement and context
