Week 5 Flashcards
What is the lateral geniculate nuclei
90% if fibres terminate here in primates
Pathway responsible for conscious visual attention
Retinal input to LGN accounts for 10% of synapses
Visual cortical feedback accounts for 30% of synapses
How many layers does the LGN have
6
what are the 6 layers seperated into
Parvo + Magno
Konio
What are the Magno layers
1+ 2 layers = larger cells
What are the Parvo layers
3 + 4+ 5 + 6 = smaller cells
What are the Konio cell layer
interlayers
even smaller cells
koniocells
Which are the contralateral eye fibres
1, 4, 6 layers
What are ipsilateral eye fibres
2, 3, 5 layers
what is the purpose for the LGN
-Important regulatory function
-Regulates strength of signals sent to cortex and pre-sorts info into significant streams
-Amplify differences in illumination ie. Edge and contrast
-Emphasise sudden changes in simulation
-Integrate across large retinal areas
What is the superior colliulus
multisensory midbrain structure
controls:
Integration of visual and auditory signals
Direction of visual attention
What are Parvo cells
and what they do
-Colour opponent – differentially sensitive to colour - red/green pathway
-Retinal fields are 2-3x smaller than magno cells
-Important for analysing spatial detail
What are Magno cells
and what they do
-Cells not differentially affected by colour
-Response depends on relative intensity of centre and surround
-Respond vigorously to fast abrupt fluctuations in light intensity within their RFs
What are Konio cells
and what they do
Colour opponent – differentially sensitive to colour – blue/yellow pathway
Some respond to sound and touch as well as visual stimulation
What is the Vision cortex (V1)
Primary visual cortex
Anatomically split into 6 layers
What is layer 4 of the visual cortex
4a + 4b + 4c
