vision 2 Flashcards
what retinal information is in the optic nerve
-the retinal nerve contains information from the ipsilateral temporal retina and the ipsilateral nasal retina
what visual field information is in the optic nerve
visual field information about the contralateral nasal visual field and the ipsilateral temporal visual field is in the optic nerve
what happens if you cut an optic nerve
you lose vision in the contralateral nasal visual field and ipsilateral temporal visual field
-the other eye should be able to restore the nasal visual field because that region is binocular
what nerves intersect at the chiasm
the right and left nasal retinas which convey information about their ipsilateral temporal visual fields
what is the benefit of center surround antagonism
it provides enhancement and edge detection
how do horizontal cells influence photoreceptor cells
horizontal cells hyperpolarize photoreceptor cells
what is the mechanism for depolarization of ON center bipolar cells
-metabotropic channels are activated by glutamate on ON center bipolar cells. This is accomplished by a G protein channel and secondary messengers (unknown exactly)
-TRP1 channels remain closed
what are the characteristics of magnocellular cells
10% total RGC cells, large receptive field, expansive dendritic field, respond to large moving objects, rapid conduction,
what are the characteristics of parvocellular cells
80% retinal ganglion cells, smaller receptive field, small dendritic field, concentrated in fovea, slower conduction
what are the characteristics of koniocellular cells
1% of RGCs, large dendritic field
where do blue On/yellow Off cells project to
the parvocellular and koniocellular pathways
parvocellular pathway
parvocellular cells (P cells) project from the retina to the ventral geniculate nuclei (layers 3-6) to the striate cortex (layer 4c beta) to the interblob and blob regions to other cortical areas
magnocellular pathway
magnocellular cells (M cells) project from the retina to the ventral geniculate nuclei (layers 1 and 2) to the striate cortex (layer 4c alpha) to layer 4b and to the blob (collateral), then to extrastriate cortical regions
koniocellular pathway
nonM/nonP ganglion cells to the extra laminal area in the VGN to the blob to the extrastriate areas
what kinds of cells are in the interblob
complex and simple cells; binocular, orientation selective, direction selective
what kinds of cells are in the blob
monocular, wavelength sensitive, circular receptive field
what is the difference between simple and complex cells
idk watch lecture again if u get this and dont know still
-simple cells will either fire if activated or not fire if not while complex cells will fire for different conditions??
are visual signals between the eyes segregated up in the striate cortex
yes
fun fact: most v1 neurons outside of layer 4c are orientation selective
did you know that?
where does mixing of the pathways for both eyes first occur
in v1 of the striate cortex
location of intracortical pyramidal cells which make horizontal connections
layer 3
are most intracortical connections horizontal or radial
radial
where do stellate neurons project to
4b alpha and 3 beta. 2 and 3 receive binocular input
what is the difference between stellate and pyramidal cells
LOOK AT LECTURE if u dont know this yet
which pyrimidal cells project to cortical areas outside of the striate cortex
layers 2, 3, and 4b
which pyrimidal cells project to the superior colliculus and pons
layer 5
which pyrimidal cells project back to the LGN
layer 6
what retinal and visual information does meyer’s loop represent
inferior retinal quadrant/superior visual field
what happens if you cut right meyer’s loop
you lose the right eye’s nasal visual field and the left eye’s ipsilateral temporal visual field
the left eye can still see the right eye’s visual field, so you end with 150 degree vision only missing the left eye’s temporal visual field
what are ipRGCs and what is their significance
these are inner plexiform retinal ganglion cells which control circaidian photoentrainment and control the pupillary light reflex
what is the significance of the macula
the macula is an area behind the retina and the fovea sits inside, very important for vision
where is the striate cortex located
the occipital lobe
what is the pupillary light reflex pathway
axons from the retina/optic nerve synapse with edinger westphal nucleus interneuron then the pretectum then the ciliary ganglion then innervate the pupilliary constrictor muscle
what is the difference between stellate and pyrimidal cells and their projections
ocular dominance columns
Regions of neurons in the striate cortex that synapse with axons carrying transduced
signals from either the left or right eye
describe the receptor field of simple cells
binocular, orientation selective, elongated on-off region,
describe the receptor field of complex cells
binocular, orientation selective, do not fire for certain orientations, no antagonistic flanks/distinct on off regions
