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Phys Psyc I > Ch 12: identifying stimuli and stimulus objects > Flashcards

Ch 12: identifying stimuli and stimulus objects Flashcards

1
Q

Grandmother cell coding scheme vs population coding scheme

A
  1. Grandmother cell coding scheme:
    - there is one neuron dedicated to identifying each possible stimulus object.
  2. Population coding scheme:
    - seeing an object activates a specific COMBINATION of neurons that collectively represent the object.
    - some of these neurons might also be active when you see a different stimulus.
    - the code does not reside in the activity of the individual neurons but in their combination.
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2
Q

____ ___ is the pathway that uses spatial information to guide eye, head, and hand movements.
____ ___ is the pathway concerned primarily with object identification

A

DORSAL STREAM is the pathway that uses spatial information to guide eye, head, and hand movements.
VENTRAL STREAM is the pathway concerned primarily with object identification

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3
Q

dorsal and ventral streams both originate from ___

A

V1

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4
Q

The dorsal stream originates in the ___ of the ___ lobe and then passes through the ___ ___ ___ to the ___ and __ cortices

A

The dorsal stream originates in the V1 of the OCCIPITAL lobe and then passes through the POSTERIOR PARIETAL CORTEX to the PREMOTOR and MOTOR cortices

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5
Q

The ventral stream proceeds from __ to the inferior portion of the ___ ___

A

The ventral stream proceeds from V1 to the inferior portion of the TEMPORAL LOBE

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6
Q

how do on-center retinal ganglion cells respond to bright spots presented at the center of their spatial receptive field?

A

by increasing in firing rate

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7
Q

How do on-center retinal ganglion cells respond when they are stimulated with a ring of light surrounding the center of their receptive field?

A

they lower their firing rates

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8
Q

stimulating on-center retinal ganglion cells with uniform light yields what response?

A

no response (no change in firing rate)

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9
Q

off-center retinal ganglion cells respond with increased firing rates to:

A

dark spots in the receptive field’s center

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10
Q

on- and off-center ganglion cells receive input from:

A

ON and OFF bipolar cells

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11
Q

surround cone inhibitory influence is due primarily to retinal ____ cells

A

surround cone inhibitory influence is due primarily to retinal HORIZONTAL cells

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12
Q

the input from photoreceptors onto horizontal cells is _____, whereas the output of horizontal cells back onto photoreceptors is ______

A

the input from photoreceptors onto horizontal cells is EXCITATORY, whereas the output of horizontal cells back onto photoreceptors is INHIBITORY

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13
Q

What generates the center-surround organization and what is its purpose?

A 
LATERAL INHIBITION (surround inhibition) through HORIZONTAL CELLS generates the center-surround organization.
It SHARPENS LOCAL STIMULUS CONTRAST
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14
Q

Our visual system is more sensitive to ___ luminance contrast than to ___ luminance

A

Our visual system is more sensitive to LOCAL luminance contrast than to ABSOLUTE luminance

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15
Q

Significance of Mach bands

A

-at the boundary between luminance intensites, the lighter coloured square seems to be even brighter and the darker square seems to be darker in colour.
-this is because lateral inhibition enhances the contrast when there are zones of different intensities
(light edge on dark square, dark edge on light square)

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16
Q

which brain region provides the major visual input to V1?

A

Lateral geniculate nucleus (LGN)

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17
Q

The LGN has ___ distinct layers

A

6

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18
Q

Do V1 neurons respond better to lines and edges or to circular spots?

A

lines and edges

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19
Q

V1 simple cells respond best to lines presented at a ___ ____ and in a ____ ____

A

V1 simple cells respond best to lines presented at a SPECFIC LOCATION and in a PARTICULAR ORIENTATION

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20
Q

What did Hubel and Wiesel hypothesize what the reason V1 cells become sensitive to lines rather than spots?

A

They hypothesized that each simple cell receives CONVERGING INPUT from multiple geniculate neurons whose receptive field centers are ALL THE SAME TYPE and ARRANGED IN A LINE

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21
Q

If the receptive fields of the geniculate neurons converging on a V1 neuron are all of the ON-CENTER type, then…

A

the V1 simple cell should respond to a BRIGHT line that falls across those on-centers

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22
Q

If the receptive fields of the geniculate neurons converging on a V1 neuron are all of the OFF-CENTER type, then…

A

the V1 simple cell should respond best to a DARK line tht covers those off-centers

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23
Q

direction sensitivity is generated mainly in the __ __

A

visual cortex

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24
Q

V1 Simple vs complex cells

A
  • both respond preferentially to bright or dark lines and edges in a particular orientation
  • complex cells receive converging input from multiple V1 simple cells
  • complex cells respond to activity in any of their converging input lines, whereas simple cells fire only when a particular combination of geniculate neurons is excited
25
Q

Sine-wave grating

A

a series of parallel bands varying continuously in brightness according to a sine-wave function, along a line perpendicular to their lengths

26
Q

Spatial frequency

A

the relative width of the bands in a sine-wave grating, measured in cycles per degree of visual angle

27
Q

the visual angle between adjacent sine waves is ___ when the waves are closer together

A

smaller

28
Q

Although Hubel and Wiesel’s studies suggested that neurons in V1 detected lines and edges, subsequent research found that they actually responded best to ________

A

sine-wave gratings

29
Q

what is the spatial frequency of a sine-wave grating?

A

its variation in brightness measured in cycles per degree of visual angle

30
Q

small objects, details within large objects, and large objects with sharp edges provide a signal rich in ___ ______

A

high frequencies

31
Q

large areas of light and dark are represented by __ ___

A

low frequencies

32
Q

most important visual information is that contained in ___ spatial frequencies

A

low

33
Q

how does ISOI work?

A

Intrinsic signal optical imaging (ISOI) measures changes in tissue oxygenation.
Oxygenated and deoxygenated blood absorb light differently.
Orange light directed at animal’s exposed cortex.
ISOI measures dip in blood oxygenation due to neural activity.
images are taken

34
Q

aperture problem

A
  • seen in neurons with a SMALL receptive field
  • When looking at a moving straight line through an aperture, the edge always seems to move at right angles to its long axis, regardless of the underlying object’s true direction of motion
35
Q

How can the aperture problem be solved?

A

by combining info from multiple neurons

ie. multiple edges in multiple apertures

36
Q

Results from the monkey experiment where their MT cells were stimulated

A

-monkeys failed to identify the movement direction correctly when the preferred direction of the stimulated neurons differed from that of the dots that were presented.
THE ELECTRICAL STIMUATION BIASES THE MONKEY’S PERCEPTION OF MOVEMENT DIRECTION IN FAVOR OF THE DIRECTION TO WHICH THE STIMULATED NEURONS ARE TUNED AND AGAINST THE OPPOSITE DIRECTION

37
Q

MT in “MT neurons” stands for

A

middle temporal

38
Q

Red-green opponent cells compare the activation levels of __ and ___ cones

A

L- and M-cones

39
Q

blue-yellow opponent cells compare the activity if the __ cones to the combined activity of the __ and __ cones

A

blue-yellow opponent cells compare the activity if the S-cones to the combined activity of the L- and M-cones

40
Q

bottom-up vs top-down spatial attention

A

bottom-up: something captures your attention

top-down: looking towards an area to see if something is happening

41
Q

double opponent cells

A

give opposite responses to opposite wavelengths in center vs. surround

42
Q

the phenomenon that perception of colour barely changes as it gets darker is called

A

color constancy

43
Q

colour-sensitive patches in the anterior occipital and posterior temporal lobes are called ___

A

globs

44
Q

what do Face-selective neurons respond to

A

respond strongly to faces and poorly to scrambles faces or other stimuli. They respond more poorly to faces without eyes than with eyes.

45
Q

What happens when you electrically stimulate face-selective cells?

A

perception becomes biased in favour of faces

46
Q

What is the name of the largest face-selective patch in the inferior portion of the temporal lobe?

A

fusiform face area

47
Q

higher neural response for (basic/superordinate) words

A

basic

48
Q

Category-sensitive neurons can be found in the:

A

inferior temporal cortex

49
Q

what is agnosia?

A

deficit in object identification

50
Q

porisipagnosia

A

inability to identify faces

-problems in conducting in INFERIOR LONGITUDINAL FASCICULUS

51
Q

cell assembly in the olfactory cortex

A

repeated exposure to a specific olfactory stimulus forges the olfactory cortex neurons activated by that stimulus into a coherent entity (cell assembly)

52
Q

different olfactory cortex nerves converge onto a single ___ ___, which diverges onto ___ ___

A

different olfactory cortex nerves converge onto a single OLFACTORY GLOMERULUS, which diverges onto OLFACTORY EPITHELIUM

53
Q

the auditory cortex ascends to the neocortex though a series of ___, ____ and ___ nuclei

A

the auditory cortex ascends to the neocortex though a series of MEDULLARY, MIDBRAIN and THALAMIC nuclei

54
Q

Whee is gthe auditory cortex?

A

it lies along the superior edge of the temporal lobe

55
Q

auditory cortex is divisible into 3 regions:

A

core, belt, and parabelt regions

56
Q

What region of the audtory cortex is the primary auditory cortex (A1) part of?

A

core

57
Q

when the belt area is damaged, what can it produce?

A

an auditory agnosia

58
Q

damage to the left belt results in __ __ and damage in the right belt results in ___

A

damage to the left belt results in RECEPTIVE APHASIA (ie. Wernicke’s aphasia) and damage in the right belt results in AMUSIA

Phys Psyc I (8 decks)

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