Chapter 4 Flashcards
(35 cards)
What is a retinotopic map?
Map of the retina on the cortex
More space is the cortex is allocated to locations near the fovea then to locations in peripheral
What is it called when the brain gives images in the fovea more space in the brain?
Cortical magnification factor
What is the cortex organized in?
Columns
Explain how the striate cortex is organized into location columns
A column in the visual cortex that contains neurons with the same receptive field locations on the retina.
Basically, each receptive field overlaps, but goes to separate parts in the brain
It was concluded that the cortex is also divided into orientation columns, what are these?
Each column in the brain contain cells that respond best to a particular orientation. (Ex, vertical tree, sideways road)
How long is each column?
1mm
What is a hyper column?
Unit that combines: location, orientation, and ocular dominance
They serve a specific area on the retina
What is tiling?
The adjacent (and often overlapping) location columns working together to cover the entire visual field (similar to covering a floor with tiles)
What is the extrasriate cortex?
Collective term for visual areas in the occipital lobe and beyond (V2, V3, V4, and V 5)
What is Ablation /lesioning ?
Removal of an area of the brain. This is usually done in experiments on animals to determine the function of a particular area.
What happened in the object discrimination problem ?
Shown an object that had nothing in it. Then presented with two objects, they should select the new one immediately to get the treat.
What is the landmark discrimination problem?
Choosing the object closest to the location
What happens to the object discrimination problem when part of temporal lobe is abaltioned ?
This damages the ability to determine an objects identity. Called the what pathway.
Also ventral pathway
What happens to the landmark discrimination problem when part of the parietal lobe is removed?
This causes difficulty in determining the objects location. Called the where pathway
Also called the dorsal pathway
There is another theory on what the dorsal stream (where) also does, what is it?
It also provides information about how to direct action with regard to a stimulus.
Ex. When a monkey looks at and object
AND when it reaches to the objects
What is double dissociations?
Have brain dmg in two people
One: can see object a but not b
Two: can see object b but not a
Patient DF and orientation
Damage to ventral pathway and could not determine orientation of letters to fit them in slots.
This prompted the idea that where pathway could also be called how or action pathway.
What is the info-temporal (IT) cortex?
Area of the brain outside V1 (striate cortex) that does object perception and facial recognition
Also continues through the what stream
What is the hippocampus?
Place for forming and storing memories
What is contextual modulation?
Change in response to a stimulus presented within a neurons receptive field caused by stimulation outside of the receptive field.
What is the optic chiasm?
And x shaped bundle of fibres on the underside of the brain, where nerve fibres are activiated by stimulation of one side of the visual field cross over to opposite side of the brain
What’s the lateral geniculate nucleus (LGN)?
Where 90 percent of signals from retina go.
It’s the nucleus in the thalamus that receives inputs from the optic nerve and, in turn, communicates with the cortical receiving area for vision.
What is the superior colliculus?
The area in the brain that is involved in controlling eye movements and other visual behaviours. This area receives about 10 percent of the ganglion cell fibres that leave the eye in the optic nerve.
Where does the LGN receive signals from?
More signals from cortex then from the retina.
Takes signals from cortex and retina, puts them together and sends to cortex for more processing
