Lecture 11 Flashcards
What is the cortex made up of and what is the subcortex(what happens if damage occurs here)?
The brain cortex (farthest out layer) is organised into several lobes, the frontal lobe, parietal lobe, temporal lobe, occipital lobe and has three major sulci, the central sulcus (frontal lobe and parietal lobe), the lateral sulcus (temporal lobe and frontal lobe) and the parieto occipital sulcus (parietal lobe and occipital lobe).
The Subcortex is beneath the cortex and damage to this area is catastrophic because it contains the critical processes of the brain.
Where does the signal from the eyes travel to?
The signal from the eyes travels firstly to the lateral geniculate nucleus in the subcortex, half of the fibers (right side of eye vision) travels to the left side of the brain, the other half travels to the right side, this means that some fibers cross over and some don’t. The signal then travels to V1(primary visual cortex, also known as striate cortex).From here a ventral stream goes up to parietal and does pattern perception, A Dorsal stream goes down for spatial location (temporal).
What did Mishkin and Ungerleider do in relation to vision?
Roughly half of the brain is devoted to vision, but damage in different areas can lead to different problems, e.g object discrimination problems as opposed to landmark discrimination. This was tested by Mishkin and Ungerleider on monkeys by training them for these two types of tasks, they then formed surgical lesions on the monkeys, half lost their inferior temporal cortex (object discrimination impaired, could be relearned, landmark discrimination ok), half lost their parietal lobe (landmark discrimination impaired, object discrimination ok). This is called double dissociation as damage in one area leads to impairment of a particular problem. They could relearn the tasks because of backup areas in the brain and the task not being to complicated.
What are the two ways neurons can relay information?
Cells fire at a baseline rate, these can slow down or speed up in relation to stimuli, both of which provide information.
What are some of the specific jobs of cells involved with vision?
Rods and cones diffuse light (rods change speed lots for dark, cones for light), retinal ganglion cells detect spots of light. Lateral geniculate nucleus cells like spots of light, but also do many other tasks. V1 cells like lines of different orientations, V2 has cells which like lines of particular sizes, beyond V1 they start to like complex shapes and as we get further we can find cells which like 90 degree profiles of monkey faces.
What is the grandmother cell hypothesis?
The Grandmother cell hypothesis is that if you look hard enough for a cell you could find a cell which particularly responds to your specific grandmother, any cell which is this specific is a grandmother cell. These are memory cells.
