Lecture 8 - The Visual System Part 2 Early Visual Processing Flashcards
What are the synaptic pitstops of the primary central visual pathway?
-the LGN or the lateral geniculate nucleus of the thalamus which receives projections from the RGCs in the retina via the optic nerve
-the Primary Visual cortex or V1 which is in the occipital lobe and is the striate cortex
What is the overview of the central visual pathway?
retina—> optic nerve —–> optic chiasma—->LGN—–> V1
What are the cells present in the LGN of the thalamus?
-on-center off-surround
-off-center on surround
What layers of the LGN receive info from the contralateral eye?
layers 1,4,6
What layers of the LGN receive info from the ipsilateral eye?
layers 2,3,5
What layers of the LGN are involved in the magnocellular pathway?
layers 1,2
What layers of the LGN are involved in the parvocellular pathway?
layers 3-6
What layer of the primary visual cortex or V1 do the LGN cells converge onto?
layer 4
What type of cells do LGN cells converge onto in the layer 4 of the primary visual cortex or V1?
simple cells
What do simple cells in V1 show a preference for?
-orientation and direction of the light stimulus
-from which eye it originates like ocular dominance
-color of the stimulus
What do simple cells in layer 4 of V1 converge onto?
complex cells
What layers of V1 detect color stimulus and what is this population of cells called?
layers 2-3
color blobs
What did Hubel and Wiesel do?
-real time electrode activity to record the activity of simple cell in V1
-the targeted electrode was placed in V1 in a cat and the electrical activity was recorded and they found that certain cells had a preference for the orientation and direction of each light in a columnar organization of V1
What type of organization is seen in V1?
hypercolumn organization
What do the simple and complex cells of a particular column in V1 show preference for?
-orientation of stimulus
-direction and position
-ocular dominance
-color via color blobs in layers 2,3
