Lecture 7- Vision II: Central processing Flashcards
What are the characteristics of the M ganglion cells?
-magnocellular=large cells -large receptive fields -make up about 10% of ganglion cells -motion detection, flicker and analysis of gross features -can tell if sth is moving or not, not good at fine detail
What are the characteristics of the P ganglion cells?
-parvocellular= small cells -more numerous (about 80% of ganglion cells) -provide fine detail (visual acuity) and colour vision
What is this picture showing?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/305/111/377/q_image_thumb.png?1395126250)
-this pic shows the AP of a P ganglion cels as reacting to different frequencies of light -one ganglion cell, it responds best to one wavaelength= black it is important for carrying info for colour
What is the output region of the ganglion cells?
-many brain regions -mainly the lateral geniculate nucleus (LGN) in the thalamus
What is the visual pathway?
- Retina
- Optic nerve
- LGN
- Optical radiations
- Visual cortex
- starts in the retina= the axons of optic nerve then synapse with the thalamus (LGN), then the LGN neurons have optic radiations (white matter) goes all the way back to the visual cortex V1
![](https://s3.amazonaws.com/brainscape-prod/system/cm/305/111/379/a_image_thumb.png?1395126300)
Where is the optic chiasm and what happens there?
- lies at the base of the brain, anterior to the pituitary
- the fibres from right and left optic nerves combine to form the optic chasm
![](https://s3.amazonaws.com/brainscape-prod/system/cm/305/111/380/a_image_thumb.png?1395126334)
What fibres cross at the optic chiasm?
-nasal
What hemisphere is the right visual field “viewed” by?
-left
What hemisphere is the left visual field “viewed” by?
-right
Explain:
![](https://s3.amazonaws.com/brainscape-prod/system/cm/305/111/384/q_image_thumb.png?1395126380)
-the nasal fibres cross over -get information from both eyes in each hemisphere -partial crossing of the visual field
How many layers are there in the LGN?
-6 -contain 2 typesof cells
What layers do the magnocellular cells and the parvocellular cells occupy in the LGN?
-6 layers -Magno=1 and 2 (one layer for info from each eye) -Parvo =3,4,5,6= two of these for info from each eye
What cells in the LGN do the the P and M ganglion cells target?
P ganglion= parvocellular cells M ganglion= magnocellular cells
What is the function of the thalamus?
-functional relay station for sensory information -except for taste!
Is the visual information separated or mixed in the LGN?
-separated, keep M and P streams of information separate, and information from each of the eyes is also kept separate
What are the optic radiations?
- the axons of the magnocellular and parvocellular LGN neurons carrying information to the visual cortex
- white matter, big, enclose the ventricles
![](https://s3.amazonaws.com/brainscape-prod/system/cm/305/111/390/a_image_thumb.png?1395126417)
Where do the LGN neurons project to?
-the primary visual cortex