PSY280H5 Lecture Notes - Lecture 1: Psychophysics, Receptive Field, Absolute Threshold
Document Summary
Horizontal cells are critical for responses (surround antagonism and lateral inhibition) Upon receiving light: cones and rods shut down. Inside rhodopsin, chromophore (protein molecule of different shape) determines function. events: Chromophore stick out of the membrane, activate transducin. Decrease of binding of cgmp to na/ca channel -> channel close -> hyperpolarization the amplification in event: 1 photon -> 100 transducin -> 70 pde activated -> hydrolyse 10,000 cgmp aka: 1 photon -> hydrolyse 70,000,000 cgmp. ~ ganglion cell has baseline activity at rest, it allows detection of change in environment by reducing/increasing activity some dude studied monkeys by measuring the neuro-input, he found: Off centre: light to center result in decreased activity. Human and most animals have equal distribution of on and off. Ganglion cells are sensitive to contrast of the difference of adjacent regions. Why do we see more grey spot from the peripheral? there"s no overlap therefore theres no contrast.
