Principles of Neuroscience Lecture 7, Vision, Further pathways Flashcards
What are the two types of ganglion cells and describe their features
Mango cellular type : large, involved in motion detection, Parasol shape
Parvo cellular : small, involved with colour and visual acuity
Describe the path of information from the retina
Retina - photoreceptor cells - optic nerve - Lateral Geniculate nucleus in Thalamus - Primary Visual cortex
Describe the structural arrangement in the Lateral Geniculate Nucleus
LGN is located in the thalamus
There are six layers in the LGN that have input from either of the different types of ganglion cell.
Layers 1 & 2 : Magnocellular
Layers 3,4,5 & 6 : Parvocellular
Describe the functional divisions in the occipital lobe
V1 : primary visual cortex. Receives information from the thalamus (LGN) by the calcarine fissures
V2,3 : areas to which information travels next.
What is V1?
Primary Visual Cortex
Describe the functional layers in V1.
Into which layer does the LGN input information?
There are 6 layers of neurons. 1 2 & 3 4A 4B 4C 5 6
The LGN inputs information into 4C (within 4C are more divisions)
What is important about the organisation of information in V1?
Retinotopic organisation : the same mapping from the retina is maintained in V1
Contralateral representation of visual fields
At what point does information from each eye get combined?
M - type information : at 4B
P - type information : at 3
What are the pathways that information takes after the Primary Visual Cortex?
Dorsal : where is the thing I’m seeing –> motion. Naturally, this comes from M-cells.
Information goes from V1 - V2 - V3 - MT(middle temporal lobe)
Ventral: What is the thing I’m seeing? –> colour and shape.
This is derived from P-type information.
Information feeds from V1 - V2 - V3 - V4 - IT (inferior temporal lobe)
Into which layer does LGN input information in the V1?
Specifically, into which layers is P type and M type information fed?
4C.
P - type : 4C beta
M - type : 4C alpha
Which cell is also called midget?
Parvocellular ganglion cell
Describe orientational selectivity.
Which neurons exhibit this?
Neurons respond most strongly to bars moving at certain rotations
Only the neurons in the visual cortex
Which type of cell is described as parasol
Magnocllular ganglion cell
What does orientation all selectivity mean for vision?
This means we can see edges of objects clearly
Input from LGN into the V1 is isolated to …
Ocular dominance columns