W6 - Reality Flashcards

1
Q

Does detecting modulations in colour rely in output of local/distributed neurons

A

Not due to single neural characteristic. Distribution representation rather than relying on output of local/individual neurons

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2
Q

What are the 2 evidences to suggest that detecting colour modulation is part of a distributed representation

A
  1. ) Psychophysical sensitivity to chromatic stimuli far better than that of any individual neuron
  2. ) Different neural expansions in Magnocellular and Parvocellular pathways from retina to V1
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3
Q

Evidence that colour modulation is part of a distributed network: psychophysical sensitivity chromatic stimuli > neuronal senstivity

A

More sensitive= lower threshold level needed to identify stimulus.

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4
Q

M and P Pathways to Retina Cortex

A

M Pathways involved in luminance
P Pathways involved in colour
- Both are anatomically distinct

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5
Q

M pathway in Retical Cortical Expansion

A

Retina: Larger receptive field than P
LGN: 1-to-1 relationship between retina and LGN
V1: Principle point of expansion

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6
Q

P pathway in Retical Cortical Expansion

A

Retina: Lesser receptive field than P
LGN: Principle point of expansion
V1: Little (not 1-to-1) relationship between LGN and V1

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7
Q

Is there more feedback between: V1 to LGN, or LGN to V1

A

More feedback between V1 to LGN

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8
Q

Study about M and P pathways

A

Studies in motion in purely chromatic stimuli (no luminance) reveal strange behaviour consistent with spatiotemporal interaction prior to motion extraction.

  • More slowly
  • Reliance on luminance for motion detection.
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9
Q

fMRI study about M and P Pathways

A

Cardinal tuning in V1

> Represents some kind of feedback, unlike the single cones of retina, whole V1 has cardinal representation.

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10
Q

Why is there more feedback from V1 to LGN?

A

Mediating factor on Parvocellular activity, and then feed back into V1

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11
Q

V4 vs V1

A

V4: Sense of Colour (taking into account cortex)
V1: Threshold & Hue

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12
Q

Why is there difference between representation of colour and that of cardinal space

A

May be due to feedback from cortex and strong connections between LG and cortex
> Basic sense of colour is not well predicted by basic properties represented by cones.

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13
Q

Colour discrimination: between vs within categories

A

Discrimination between categories is easier than discrimination within categories.

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14
Q

Is colour vision categorical/continous? Cropper (2013) study

A

Discrimination vs Categorization Task (Without colour names):

Discrimination: Highly accurate performance (i.e., responding ‘same’ only when the test colour was very similar to the reference colour)

Categorization: Everyone their own categorical structure and much as the broader
> No categorical boundary effect

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15
Q

What does the discrimination v categorisation task by cropper (2013) suggest

A

We still lack a predictive and quantitative model of how we see simple visual stimuli.

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16
Q

What is syneaesthesia

A

Involuntary conjoint perception across two modalities

17
Q

Is synaesthesia objective?

A

No. It is a subjective experience/unique and consistent

18
Q

What is the most common syneaesthesia

A

Colours (70%)

19
Q

How do hallucinogens work

A

Mimicking active group on neurotransmitter serotonin (5H-T), which is associated with mood, sleep, appetite, psychosis.

Increasing 5H-T = Increase cortical activity = reduce inhibition

20
Q

What happens when inhibition is reduced and cortical activity is increased in system

A

Visual and auditory hallucination

21
Q

How do hallucinogens affect simple visual tasks?

A

Affects motion detection

- Disruptions in integrating simple isolated vectors to a
coherent representation (Biological motion, flow fields, structure from motion)
22
Q

Study: Carter et al. (2004) Motion Perception and Psilocyblin. What were the 2 tasks & results

A
  1. Right motion contrast sensitivity
    - 2 alternative choice
    - Rigid
    - Can do with basic motion detector
  2. Motion Integration sensitivity
    - 2 alternative choice
    - Non Rigid
    - Basic motion detector must be integrated into global precept

> Only affected in Task 2. Therefore, Psilocyblin affected integration and failure to inhibit.

23
Q

What is relationship between hallucinogenics and schizophrenia

A

Same psychosis - In SZ patents, simple visual task requiring less integration led to better performance (due to context)

24
Q

Study: Dakin et al. (2005) Contrast of central disk and SZ patients. Results

A

Controls: Stronger contextual suppression > More vulnerable to ‘contrast’ illusion > Less accurate at judging contrast where contrasts disrupts judgement

SZ: Weaker contextual suppression > Less vulnerable to ‘contrast’ illusion > More accurate at judging contrast since contrasts does not disrupt judgement

25
Q

Schizotypy (at high levels, mirrors SZ) and hallcinations

A

High positive schizotypy (wild day dreams, etc) linked to having hallucination-like visual experienes

26
Q

Study: Partos, Cropper, & Rawlings (2016): Schizotypy and image meaning. Study and findings

A

Present random array of white dots and instructed dots show something meaningful

> Individuals on higher psychoticism, neuroticism, and hallucination-proneness perceived more meaningful images of complex nature of dots
High positive schizotypy score = Increased tendency to perceive complex meaning in random visual noise.