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PS3822 - Consciousness > Wk12 - Neural Correlates of Consciousness > Flashcards

Wk12 - Neural Correlates of Consciousness Flashcards

1
Q

Define neural correlates of consciousness

A

The minimal neural mechanisms jointly sufficient for any one specific conscious percept

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2
Q

Are neural correlates necessary or sufficient for consciousness?

A

Both necessary and sufficient

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3
Q

What part of the brain is important for recognising faces?

A

Bilateral occipito-temporal face processing pathway

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4
Q

What is it called when someone cannot recognise faces even though they can see them?

A

Prosopagnosia

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5
Q

Are there distinct relationships between areas of the brain and conscious qualia?

A

Yes

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6
Q

How can we look for neural correlates of consciousness?

A

We can compare brain activity during conscious and unconscious perception

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7
Q

What sensory modality is useful to examine when looking for consciousness?

A

Vision

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8
Q

Why is vision a useful modality to help us understand consciousness?

A

It is easy to manipulate visual stimuli

It is easy to manipulate consciousness of the visual perception

We have advanced knowledge of visual systems and pathways compared to higher cognitive processes

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9
Q

Is the primary visual cortex necessary for all forms of visual perception?

A

No - V1 is less active during REM sleep even though there is visual consciousness

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10
Q

What happens if V1 is damaged?

A

Patients can still dream with no loss of visual content - there is still conscious perception of visual material

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11
Q

Is cortical or sub-cortical processing associated with conscious visual awareness?

A

Cortical

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12
Q

What evidence from emotion studies shows us that sub-cortical areas are involved in vision?

A

Sub-cortical areas are involved in perception of threatening stimuli, even before you have the conscious experience

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13
Q

What is the idea of binocular rivalry?

A

2 images are presented to each eye at the same time. People are unable to be conscious of both stimuli at exactly the same time - they will have a conscious experience of the face for a while followed by a conscious experience of the pattern

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14
Q

What changes in binocular rivalry?

A

The participant’s consciousness of the two stimuli.

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15
Q

Do the stimuli stay the same in binocular rivalry?

A

Yes

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16
Q

Why is it important that the physical stimuli stay the same in brain imaging studies of consciousness?

A

Because physical differences in stimuli causes changes in brain activity. E.g., a brighter stimulus is likely to increase visual cortex activity

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17
Q

How can an experiment be designed so that we can look at differences in the brain as a result of conscious experience, not difference in stimuli?

A

Keep the physical stimuli the same. Present 2 stimuli at the same time.

Ask the participant which stimulus they are concentrating on. The brain activity will differ when the conscious perception is different.

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18
Q

Who carried out a monkey study on binocular rivalry (vision) and consciousness?

A

Logothesis

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19
Q

Describe Logothesis’ monkey study of vision and consciousness

A

Implanted neurons inside the brain

Monkey performed a binocular rivalry task

Monkey had to press levers in order to report which stimulus they were perceiving

Stimuli = monkey face or pattern

20
Q

What did Logothesis find in his monkey experiment about neurons in high-level cortical areas?

A

Neurons in the inferior temporal cortex only responded to the perceptually dominant stimulus (the monkey face that the monkey consciously perceived)

21
Q

What did Logothesis find in his monkey experiment about neurons in area V1?

A

Neurons in area V1 fired the same regardless of what stimulus the monkey was conscious of at the time

22
Q

When was the firing rate of neurons in inferior temporal cortex low?

A

When the monkey perceived the starburst

23
Q

When was the firing rate of neurons in inferior temporal cortex high?

A

When monkey pulled the lever to show that he was consciously seeing the monkey face

24
Q

What can we conclude from Logothesis monkey experiment?

A

Neuron cells respond to the conscious visual perception that the monkey is having.

Neurons don’t respond to stimulus changes.

25
Q

What can we conclude about the relationship between the inferior temporal cortex and consciousness?

A

The neurons in the inferior temporal cortex is the correlate to the conscious experience of a monkey face

26
Q

What can we clearly see from the Logothesis monkey experiment?

A

We can see how the neuron firing rate from individual neurons changes with conscious perception

27
Q

Who carried out a concept cell study?

A

Quiroga et al. (2005)

28
Q

Describe Quiroga’s (2005) concept cell study

A

8 human patients with epilepsy

Implanted depth electrodes

Showed different pictures of individuals, animals, objects, and geographical landmarks

Recorded responses from parts of the temporal cortex

29
Q

How many units did Quiroga (2005) record from?

A

993 units of the medial temporal gyrus

30
Q

What did Quiroga find about a single unit in the left posterior hippocampus?

A

A single unit in the left posterior hippocampus fired in response to all pictures of Jennifer Aniston (just visual images)

31
Q

What did Quiroga find about a single unit in the right anterior hippocampus?

A

A single unit in the right anterior hippocampus selectively responded to the concept of Halle Berry (images, voice recordings, writing of the name)

32
Q

What studies give evidence for conscious recognition?

A

Quiroga - Jennifer Aniston concept cell

Logothesis - Monkey binocular rivalry

33
Q

In Quiroga’s study, what can we tell from looking at the medial temporal lobe neuron spiking graph?

A

We can tell which stimulus is being shown to a participant, at a level way above chance, by looking at the firing of a single neuron in the medial temporal lobe

34
Q

When does firing of recognition in medial temporal lobe neurons occur?

A

Only occurs with conscious recognition

35
Q

What is the hierarchy along which specificity increases?

A

Sensory input –> Parahippocampal / Perihinal cortices –> Entorhinal cortex –> Hippocampus

36
Q

Where is neuron firing in the medial temporal lobe most specific?

A

In the hippocampus

37
Q

What does specificity of neuron firing depend on, in terms of concepts?

A

Specificity of neuron firing depends on conscious subjective opinion.

38
Q

What is an example of specificity of neuron firing depending on conscious subjective opinion?

A

If people were shown a picture of both the Sydney Opera House and the Bahai Temple but they thought that both pictures were of the Sydney Opera House, their SOH neuron would fire in response to both images.

Even though the stimuli were different, the conscious subjective opinion was the same so the neurons fired in response to both images.

39
Q

Can participants modify the firing of individual medial temporal lobe neurons to project their thoughts onto an external display?

A

Yes. Participants were presented with semi-transparent images of Josh Brolin and Marilyn Monroe. If participants thought about MM, MM would appear on the computer screen, connected via electrodes.

40
Q

What can active MTL neurons control?

A

Can control the opacity/transparency of images when the participant decided which image to focus on. Could see this activity in real-time.

41
Q

What is the problem with the concept cell study of MM?

A

The participant has to have a conscious decision to think of MM first before thinking about MM and increase the firing. The participant is aware of MM before the neuron fires.

It is not clear how the relationship between neurons and conscious concepts works in a cause-and-effect way.

42
Q

What is a homunculus?

A

A small person in our head that decides what we are going to think about

43
Q

What theory can be seen in line with the homunculus problem?

A

Dualism - there must be a strong relationship between neurons and conscious concepts but it is not entirely clear how this works in a cause-and-effect way

44
Q

What is the homunculus problem?

A

We know that the patient’s mind/brain is involved in deciding to think about MM, but the nerve cells in the MTL are also the participant’s mind. It is not clear how these are connected/work in a cause-and-effect way

45
Q

What are the neural correlates of conscious vision?

A

Neurons in the inferior temporal cortex (monkey experiment)

46
Q

What is the neural correlate which is important for the conscious experience of concepts?

A

Hippocampus (Quiroga - JA)

PS3822 - Consciousness (4 decks)

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