Lecture 2 - visual system Flashcards
What does the spinning dancer illusion demonstrate and how does it work.
It demonstrates the opponent process theory as the mechanisms for moving one direction are competing with moving the other direction. The perception changes when one mechanism starts to out compete the other and takes over due to cell fatigue or habituation.
Cell formation/order in retina (back to front)
photo receptors, bipolar cells and then retinal ganglion cells
Photosensitive retinal ganglion cells
A small number of cells that utilise the photopigment melanopsin which is maximally sensitive to blue morning light. They have a connection to the suprachiasmatic nucleus and are critical for entering circadian rhythms.
Synaptic transmission and vessicles
The action potential comes down the axons and causes the release of a neurotransmitter from synaptic vesicles in which it is stored. These vesicles move out to membrane at the synaptic cleft, release there neurotransmitter molecules that interact with receptors that cause ion channels to open or close. This causes ion flow into a dendrite in the postsynaptic cell.
Hyperpolarisation - inhibitory postsynaptic potential (IPSP)
A change in a cells membrane potential that makes it more negative. It is the the opposite of depolarisation. It inhibits action potentials by increasing the stimulus required to move the membrane potential to the action potential threshold. This is called IPSP, inhibitory because it is inhibiting the synapse/neuron from further firing and post synaptic because it happens after the cell fires.
dichromatic
only blue and green (no red)
Most common form of colour blindness
Deuteranomaly, weak in green
2nd most common colour blindness
protanopia, weak in red
opponent process theory in colour
colour perception is controlled by the activity of 2 opponent systems; a blue-yellow mechanism and a red-green mechanism. A result of this is that there are colour combinations that we cannot see, such as reddish green or yelloish blue.
