PSY280 - 3. MIDDLE VISION Flashcards

Question

Lateral inhibition

Answer 1

inhibition that is transmitted across the retina and can cause perceptual effects inhibition that get transmitted across retina to illustrate contrast

Answer 2

sheet of branching axons that transmit lateral inhibition | like horizontal cells

Answer 3

when you shine light at other photoreceptors, the activity of A goes down produces antagonistic effect on A increasing intensity of light at B, decreases the firing inhibition is proportional to excitation

Answer 4

perception of brightness affected by presence of an adjacent/surrounding area Dark area surrounding square on the right causes receptors under area to fire less rapidly though they send less Inhibition to the neurons under the right Square Because cells under the left square receive more inhibition, their response is to decrease

Answer 5

just at 4, firing rate increases, betw 3-5 increases more, when you expand to inhibitory surround it results in less firing

Answer 6

perceptual system translates it as to something diff Illusory light + dark bands near a light dark border Lateness high as we begin moving to the right across a later start but then near the border right be the lightness becomes even higher

Answer 7

6 receptors in circuit send signals to bipolar cells + each bipolar cells sends lateral + addition to its neighbors on both sides Receptors ANB are on the light side of the border so receive intense illumination, receptors C and D are on the darker side and received a illumination Receptors X, a and B generate responses of 100 whereas C, D and Y generate responses of 20 Increase in lightness on the light side of the border at sea and a decrease in lightness on the Darkside at D

Answer 8

not a step function change in stimulus intensity is a step function. perception of nonuniformity uneven inhibitory signal

Answer 9

signal is slightly higher response in activity even more inhibition for dark side due to higher intensity light slightly higher activation on 1 side translates into greater contrast

Answer 10

A is excitatory centre C,D,E,B is all receiving same intensity so they give a LI of 10 units D receives lateral inhibition signals from F, G, H, A, F + H only send over 2 units of inhibition so A is receiving more inhibition

Answer 11

affected by surrounded area physically exactly the same intensity lateral inhibition white surround send over more inhibition than dark surround light surround lessens centre stimulation

Answer 12

large RF - more coverage of peripheral retina ‣~10% of RGCs ‣stimulation: transient receptive field reflected in dendretic field increase in response occurs on changes, then goes back to normal

Answer 13

small RF - especially concentrated in the fovea ~90% of RGCs stimulation: sustained need a lot to cover whole retina fires at same rate for as long as you leave the light on

Answer 14

collection of nuclei that’s primary role is to relay sensory info from periphery to the cortex. sensory gateway on top of the brain stem - subcortical, last stop to cortex

Answer 15

involved in reflexive orienting to visually salient events reflexive orients to something unexpected to inspect the event/object more

Answer 16

About 10% of RGCs travel directly to superior colliculus via tectopulvinar pathway, mostly of the parasol type 90% go through geniculate to thalamus mostly of parasol in periphery, highly sensitive, but not accurate, so superior colliculus orients you to there

Answer 17

Half of the projections from each eye cross over to the opposite hemisphere through the optic chiasm right side of each eyeball translates to right hemisphere = left visual field left side of each eyeball translates to left hemisphere = right visual field

Answer 18

part of the retina closest to the temple receives information from the contralateral side of space. contralateral organization is by visual field, not by eye contralateral = opposite by the time it reaches the V1, theres a contralateral representation

Answer 19

2 major purposes: regulation of information & organization of information. tiny part of the thalamus 2 thalami + LGN

Answer 20

for every 10 impulses, it sends only 4 to the cortex receives more info from cortex than it sends out cortex tells LGN what it wants top-down processing

Answer 21

input from parasol cells - color-blind ‣large RFs ‣large,fast-moving objects ‣sensitive to light contrast

Answer 22

geniculate = bent knee 6 layers inner 2 - magnocellular layers from parasol RGCs, from rods - colour blind like transient - respond to large contrast changes to movement

Answer 23

input from midget cells - mostly foveal information small RFs - details of stationary objects sensitive to color contrast

Answer 24

outer 4 layers mostly from midget midget ganglion cells mostly from cones which have high degree of precision prefer sustained activation which is needed to discover detail

Answer 25

layers alternate between contralateral & ipsilateral inputs (by eye) left LGN + right LGN from magnocellular - parvocellular: C I , I C I C

Answer 26

retinotopically organized: areas on retina adjacent to each other are represented in adjacent regions of LGN same organization on LGN as retina centre of LGN, get a column of cell that analyze same part of the retina perpendicular electrode track

Answer 27

primary receiving area for vision signals from retina first reach cortex after LGN retinal ganglion cells + LGN cells have same centre surround organization

Answer 28

neurons in V1 like bars of light adjacent arrangement determined by measuring responses of simple cortical cell to bars with different orientations

Answer 29

Cell response with 25 nerve impulses per second to a vertically oriented bar and cells response decreases as the bar is tilted away from the vertical and begin stimulating inhibitory areas of the neurons receptive field measured output of neuron depending on orientation as you move bar of light in orientation - it increases firing as it aligns more with orientation of its receptive field most firing at a perfectly align bar of light

Answer 30

Circular RFs in LGN are transformed into elongated RFs in striate cortex via convergence. V1 can see the lines other cortexes can see more and more temporal cortex can see the picture

Answer 31

respond best to bars of light of particular orientation cells with side-by-side receptive fields Cells in striate cortex have excitatory + inhibitory areas any bar that also stimulates inhibitory surround inhibits activation

Answer 32

respond best to bars of light of particular orientation that are moving Many complex cells respond best to particular direction of movement

Answer 33

respond best to moving bars of light of a particular length, or to moving corners or angles Neurons respond selectively to oriented lines + stimuli with specific length firing increases as length increases until preferred length corners or angles - specific angle + specific movement surround inhibitory field that slows firing rate

Answer 34

simple, complex and end-stop sells fire in response to specific features of the stimulus

Answer 35

very specific Firing causes neurons to eventually become fatigued/adapt Neurons firing rate decreases + neuron fires less when that stimulus is immediately presented again Only neurons that were responding to verticals are near vertical adapt + neurons that we’re not firing do not adapt

Answer 36

Method: psychophysical measurement of the effect of selective adaptation to orientation Contact threshold: minimum intensity difference between two adjacent bars that can just be detected And adapt the person to one orientation by having the person view a high contrast adapting stimulus for a minute or two

Answer 37

Remeasure the contrast threshold for all to stimuli One vertical feature detectors are adapted it is necessary to increase the difference between the black and white vertical bars in order to see them Adaptation selectively affects only some orientations Orientation detectors play a role in perception

Answer 38

Damage to the fusiform face area Inferotemporel cortex in the Temporel lobe was right for study Prosopagnosia: people with Temporel damage unable to recognize faces Fusiform face area: area on the underside of the Temporel lobe of the human cortex

Answer 39

proposes that a particular object is represented by the firing of a particular neuron. Specificity coating propose that a particular object is represented by the firing of a neuron that responds only to that object and not the other objects

Answer 40

There are neurons that are specifically to eat object in the environment Grandmother cell: neuron that responds only to a specific stimulus

Answer 41

proposes that a particular object is represented by the pattern of firing across a large number of neurons. Representation of a particular object by the pattern of a firing of a large number of neurons Large number of stimuli can be represented because groups of neurons can create a huge number of different patterns

Answer 42

occurs when a particular object is represented by a pattern of firing of only a small group of neurons Particular object is represented by a pattern of firing of only a small group of neurons with majority of neurons remaining silent Features are objects are represented by the pattern of firing of groups of neurons Sometimes the groups are small sometimes large

Answer 43

there are elements of grandma cells that are being described in literature patient getting surgery for epilepsy neuron is firing preferentially for steve carrell there are probably gonna find another preference of another cell