TB10 P&C Lecture 3; Gain control and normalisation 0.0 / 5 ? PsychologyTB10 P&CUniversityNone Created by: mint75Created on: 24-05-16 12:31 What is gain control? Lets neurons control their sensitivity e.g luminance, contrast, blur 1 of 22 Why is gain control needed? Because neurons have a limited range, and range in the word can vary enormously 2 of 22 What is a canonical computation? A simple circuit that can explain every brain on the planet 3 of 22 What is the correct process? Retina -> LGN -> cortex 4 of 22 What is contrast? The luminance variation in the visual field. Expressed as a decimal or percentage 5 of 22 What is the currency of the early visual system? Contrast 6 of 22 Cells in LGN are tuned for...? Eye of origin 7 of 22 What was found by Bonds (1989) using masks? Neurons maintain ability to code differences by shifting sensitivity to the average 8 of 22 Who proposed 'THE' model? Heeger 9 of 22 What is the function of the gain pool? Feeds back a divisive signal to each neuron receiving an input. inputs divided by SUM of the local average response 10 of 22 What indicates a PERFECT function in gain control? The curve shifting to the right 11 of 22 The gain pool for early contrast normalisation...? Does not care about spatial frequency or orientation 12 of 22 According to gain control...? Neural activity is moderated by the local activity of the group across time and space 13 of 22 What is a transducer function (Nachmias and Sansbury, 1974)? How a neuron converts input to output 14 of 22 What is the 'dipper' function? Not everything obeys Webers Law. The dip = visual system MOST sensitive to contrast and steepest part of response curve 15 of 22 In the dipper function...? Sensitivity is proportional to the slope of the curve and adding a mask shifts the dipper to the right 16 of 22 Which disorder(s) is sensitive to HZ flicker? SZ and epilepsy 17 of 22 Photosensitive epilepsy can be triggered by...? High contrast visual flicker 18 of 22 In typical people...? You get worse at detecting motion as the disk gets bigger bc of long range gain control 19 of 22 Are older people better or worse at the disc motion task than younger? Better 20 of 22 Which gene, if taken from a human and induced in a fruit fly causes Parkinsons? LRRK2-G2019S 21 of 22 What % of patients in Tunis carry the 'Parkinson' gene? 40% 22 of 22
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