The General control of Vision Flashcards
What does the optic nerve tract contain?
nerve fibers from both retinae
Where is the optic tract have visual pathways?
in each cerebral hemisphere so it can receive signals from both eyes.
Nerve fibers from both retinae are project where?
structures in both right and left visual pathways.
How does the visual pathways receive signals?
from only one half of the visual field of each eye.
The visual pathway of the left cerebral hemisphere receive signals from where?
the right nasal visual field and vice versa.
What forms an optic nerve?
the axons of retinal ganglion cells.
What does decussate mean?
cross over
The optic nerve fibers from each nasal halves of each retina do what?
cross over at the optic chiasm.
The optic nerve fibers from the temporal halves do what?
remain on the same side or ipsilateral.
What is ipsilateral?
on the same side.
The nerve fibers from nasal halves combine with fibers from opposite temporal halves of the retinae to form what?
the two optic tracts.
What forms the two optic tracts?
The nerve fibers from nasal halves combine with fibers from opposite temporal halves of the retinae.
Thalamus will transport the signal to where?
the visual cortex
What part of the brain does melanopsin perceive light?
mid brain
What occurs in the occipital lobe?
Where our vision is processed
What is the main role of the superior colliculus?
To react moves eyes without moving head when sounds occur.
What is known as the optic tectum?
The superior colliculus.
Where is the superior colliculus located?
In the dorsal aspect of the midbrain (mesencephalon).
Where is the midbrain located?
in the central to the two thalami.
Where is the inferior colliculus located?
located posterior to the superior colliculus.
What forms the corpora quadrigemina or tectum?
The inferior an posterior colliculi
What does quadrigemina or tectum form?
The dorsal roof of the midbrain.
What causes movements of the eye towards a specific direction?
Unconscious signals transmitted from the retina directly to the superior colliculus.
The superior colliculus neurons innervate the extra ocular muscles of the eye balls that are:
oculomotor, trochlear, and abducent nerves.
What does the inferior colliculus acts as?
a relay site for neurons in the auditory pathway.
what serves as the relay nuclei?
the lateral geniculate nuclei.
The lateral geniculate nuclei relay signals in the optic tract to where?
to primary visual cortex (V1) via the optic radiation.
What does the lateral geniculate nuclei control?
the amount of signal transmitted to the visual cortex according to the feedback.
The signal transmitted from the lateral geniculate nuclei causes what?
feedback information from the visual cortex.
feedback information processed by the visual cortex is carried by what?
corticofugal fibers.
What do corticofugal fibers do?
regulate (inhibit) the actions of lateral geniculate nuclei.
Signals from the reticular formation of the midbrain inhibit what?
the actions of lateral geniculate nuclei.
What causes the visual system to focus on important signals?
The feedback information from the visual cortex and reticular formation.
The auditory system transmits signals through the lateral geniculate nuclei to do what?
directly focus visual system on source of sound.
Magnocellular M cells of the lateral geniculate nucleus do what?
receive and transmit signals from Y or M retinal ganglion cells.
Magnocellular M cells respond to what?
Rapid changes in visual image.
Magnocellular M cells transmit information about what?
black and white vision only.
Parvocellular P cells of lateral geniculate nucleus are what?
receive and transmit signals from X or P retinal ganglion cells.
The P cells transmits what?
color vision.
P cells transmit fine details of what?
visual image…. accuracy of image.
What are Koniocellular K cells of lateral geniculate nucleus?
are neurochemically distinct from M and P cells.
The K cells in the two most dorsal of koniocellular layer transmit what?
low visual acuity signals to primary visual cortex.
The K cells in the middle pair layer transmit what?
signals from blue cones to color blobs in primary visual cortex.
The K cells in the ventral layers do what?
Participate in superior colliculus function.
The Y or M retinal ganglion cells precept exclusively to what structure?
to magnocellular layers of lateral geniculate nucleus.
The X or P retinal cells precept exclusively to what structure?
to the parvocellular layers of the LGN
The K retinal ganglion cells project exclusively where?
to koniocellular layers.
Do not confuse M,P,or K retinal ganglion cells with what?
M,P, or K neurons of the lateral geniculate nucleus.
