Cortical Area V1 Flashcards
Where do ganglion cells terminate
LGN of thalamus- primary visual pathway
Superior colliculous- saccades
Pretectum- Pupillary responses
Hypothalamus- circadian control
What is central homonymous defect and where is the lesion at
VF defect in central vision OU. Damage to the lesion at tip of occipital lobe
Most of the LGNs input is from
Most from V1
RGC 80% parvocellular, 20% magnocellular.
Activation of V1 neurons depends completely on LGN input, but v1 receives many other cortical and subcortical inputs.
6 layers of the LGN
1- contra lateral. Magnocelllular. On and off.
2- ipsilateral. Magnocellular. On and off.
3- ipsilateral. Parvo. Off.
4- Contralateral. Parvo. Off
5- ipsilateral. Parvo. On.
6- contra lateral. Parvo. On.
Retinotopic Mapping. What portion of the VF does each correspond to?
Posterior LGN
Anterior LGN
Lateral/inf LGN
Medial/Superior LGN
Central visual field
peripheral visual field
superior VF
Inferior VF
Ratio of Relay to interneurons
Relay: Interneurons 4:1
Relay cells receive input from where?
-what NT does it use
Interneurons do what?
-What NT does it use?
Relay: receive input from sources outside the LGN. Including magnocellular, parvocellular, and koniocellular. Uses glutamate. Excitatory.
Interneurons help with input/output within the LGN.
GABA. Inhibitory.
Central sulcus separates what portions of the brain
Frontal and parietal
Sylvian/lateral fissure separates what portions of the brain
temporal from frontal and parietal
Transverse fissure separates what portions of the brain
Cerebellum from occipital lobe
Why is V1 called the striate cortex?
Has a stripe of myelin down the center called the line of gennari. Projects into layer 4B from 4C alpha
First site along primary visual pathway that has binocular neurons- they can respond to either eye or both
V1
Cortical mag
mm of cortex/deg of VF
Inverse cortical mag
deg of VF/mm of cortex.
Layers of V1
Layer 1: Supergranular. Synapses are sending info to each other.
Layer 2,3,4A,4B: Supragranular. Send excitatory output to other cortical areas. Koniocellular cells send axons to blob cells in layer 3.
Layer 4C: Granular layer. LGN sends input here from M and P cells. Within this layer, signals from the R and L eye are separated. Monocular.
(parvo–> 4C beta. Magno–> 4C alpha)
Layer 5, 6: Infragranular. Send output to cortical and subcortical areas.