Neuro- olfactory and visual Flashcards
the cell bodies of what type of neurons are found in the surface epithelium of the olfactory system
primary afferent neurons (SSA)
what is special about the primary afferent neurons of the olfactory system
they are replaced monthly
the centrally directed processes of the ______ ______ _____ neuron is the olfactory nerve
bipolar primary afferent
the olfactory nerve passes through what?
the cribiform plate
what type of olfactory neuron projects directly to the cerebral cortex
mitral cell, second order neuron
Olfactory dysfunction can be an early sign of what?
Alzheimer disease
what causes the severing of olfactory nerve fibers? where does this occur?
head trauma
-occurs at the cribiform plate
Lateral fibers from primary olfactory nerves terminate where?
Piriform lobe/cortex
what are the 3 parts the piriform cortex?
1) Uncus
2) Periamygdaloid cortex
3) Anterior entorhinal cortex
nerve fibers from the piriform lobe can reach the Posterior orbitofrontal cortex via what?
Mediodorsal nucleus (MD) section of the thalamus
what is special about the Posterior orbitofrontal cortex?
it is where we consciously appreciate smells
olfactory tract neurons arise from where? where do they terminate?
origin- olfactory bulb
termination- piriform cortex
cortical reorganization follows what?
olfactory loss
an image passing through the pupil is _____
inverted
what is a visual field? A retinal field?
Visual- what the patient sees
Retinal- region of the retina onto which the image is projected
where is the fovea centralis found?
within the macula lutea (directly behind cornea)
where are a high concentration of cones found?
fovea centralis
the peripheral retina has a high concentration of ____
rods
what is the peripheral retina sensitive to?
Light levels & movement
where is the “Blind spot” of the eye?
Optic disk
where do optic nerve fibers exit the eye?
the optic disk
the retina is the visual __________
neuroepithelium
name the layers of neurons of the retina
(From superficial to deep)
A) ganglion cells (either parvo or magnocellular)
B) Bipolar cells
C) Rods/Cones
which neuron provides high resolution images and registers color?
cones
ganglion midget/parvocellular cells serve the ______
macula
Ganglion midget cells are the origin of which visual system?
(AKA- ganglion Parvocellular cells)
- the “what” visual system
Ganglion parasol/magnocellular cells serve what?
the peripheral retina
they are large cells
ganglion parasol cells are the origin of what?
Magnocellular visual system
_____ cells help identify the object we are looking at
ganglion midget cells
_____ cells are found in the periphery. they help locate where an object is
parasol
the optic nerve gives a ______ projection
retinotopic
the optic nerve is covered by what?
meninges
- dura mater
- arachnoid mater
- pia mater
increased ____ _____ can affect the optic disk
CSF pressure
what structure sets our circadian rhythm?
Hypothalamus
-the suprachiasmatic nucleus
during the pupillary light reflex, afferent fibers from the optic nerve synapse on the _____
Pretectum
where do the efferent fibers from the Pretectum go during the pupillary light reflex?
to the edingter-westphal nucleus
then out in the oculomotor nerve
the pupillary light reflex is both ____ and ____
direct and consensual
T/F: the retina must always send signals to the amygdala thru the superior colliculus
false- the retina can also send info directly to amygdala
what types of images are involved with the amygdala?
emotionally significant
what are the projections from the Lateral geniculate body?
Geniculocalcarine projections
-become “optic radiations” and eventually reach the primary visual cortex
what is the name of the important fissure found in the occipital lobe?
Calcarine fissure
fibers from the lateral geniculate body travel to the _________
primary visual cortex
what are the areas of the occipital lobe important for vision?
- primary visual (straite) cortex
- secondary & tertiary (extrastriate) cortex
blindness due to a loss of the primary visual cortex can still do what?
determine object location by vision
a loss of what structure causes a person to “deny blindness”
primary visual cortex
known as “Anton syndrome”
Visual Agnosia is the loss of what?
secondary and/or tertiary visual cortex
what can sufferers of Visual Agnosia not do?
- Recognize (name) objects based on vision
- Know what object is used for
Charles Bonnet Syndrome causes what?
Visual hallucinations
what is Charles Bonnet syndrome associated with?
age and reduced vision:
A) cataracts
B) Glaucoma
C) Macular degeneration
T/F: the visual hallucinations can be emotionally disturbing to sufferers of Charles Bonnet syndrome
False- they are amusing or disturbing but not emtional
the visual processing occurring in the secondary & tertiary visual areas:
A) color and stereopsis
B) movement/direction/velocity
C) perceived motion of stationary targets as person moves
what region is responsible for processing visual info about movement/direction/velocity?
-V5/MT areas
secondary & tert visual areas
the MST (medial supr temporal area) is responsible for what?
- part of the dorsal stream
- visual processing- perceived motion of a stationary target when observer is moving
the “what”/ventral visual system: summary
A) midget parvocellular retinal ganglion cells
B) identification of visual image
C) processed as part of a ventral stream
The “where”/dorsal visual system: summary
A) parasol magnocellular retinal ganglion cells
B) location, movement of visual image
C) processed as part of a dorsal stream
What is the fusiform face area (FFA)?
- inferior aspect of occipitotemporal cortex
- identifies faces
what is Prosopagnosia? what causes it?
Loss of ability to name faces
- caused by lesion of FFA
T/F: the fusiform face area (FFA) is larger on the dominant hemisphere of the brain
false- larger on the non-dominant side
Which retinal neuron gives rise to the fibers of the optic nerve?
Ganglion cell (axons)
Name three structures in which primary visual fibers terminate
1) Amygdala
2) lateral geniculate body
3) Visual cortex (in the optic lobe)
a lesion of the Optic Nerve will lead to what?
monocular blindness
one eye blind
a lesion to the Optic Chiasm will causes what?
loss of lateral vision
Optic Tract lesion:
Loss in contralateral half of each eye
ex- lesion of the right optic tract- vision from the left side of BOTH eyes
Geniculocalcarine tract lesion:
Quadrantanopia
- loss of one quadrant from each eye
- example: loss of the upper right quadrant from BOTH eyes
injury to the Primary Visual Cortex:
Anton Syndrome (denial of blindness)
