Lecture 3: Neural correlates of consciousness Flashcards
What does it mean to ask what the neural correlates of consciousness are?
What cortical areas, pathways, neurons or mechanisms mediate conscious experiences?
The minimal set of neuronal events necessary and sufficient for conscious experience
How are NCC’s typically tested in the lab?
Stimuli is shown which often reflects some simplified version or aspect of the outside world and then brain activity is recorded at multiple levels (neuronal spiking, within a brain region, between brain regions etc). We then see how that maps on to conscious perception
What three important concepts are discussed in the book in regards to consciousness?
Vigilance—the state of wakefulness, which varies when we fall asleep, wake up, faint, enter a coma or anesthesia
Attention—the focusing of our mental resources onto a specific piece of information
Conscious access—the fact that some of the attended information eventually enters our awareness and becomes reportable to others (in any way)
What is the relationship between these three concepts according to Dehaene?
Vigilance and attention are just enabling conditions for conscious access necessary but not always sufficient to make us aware of a specific piece of information.
How does the lecturer describe a vegetative state?
A situation where a person is ‘awake’ but does not have conscious experience
Describe a state with low vigilance but a high content (or vividness) of consciousness
REM sleep or even more so lucid dreaming
What is meant by binocular rivalry?
when two distinct images are presented to your two eyes, the brain will spontaneously oscillate and let you see one picture, then the other, but never both at the same time.
What is meant by masking?
We can flash a word so briefly that study participants will fail to notice it (also: subliminal images).
What is meant by crowding?
We can create a carefully cluttered visual scene, in which one item remains wholly invisible to a participant because the other items always win out in the inner competition for conscious perception.
What is meant by perceptual rivalry?
When there is an image that can be perceived in two ways (ie old and young woman) and your perception can move between the two, its very difficult to see both
What does perceptual and binocular rivalry demonstrate about perception?
It is serial: You have one interpretation at the time
Describe a version of the binocular rivalry paradigm used to study subliminal information and how this can be achieved
Continuous flash suppression is when one eye is shown an erratic static-like moving image in one eye and a lower contrast image in the other eye. The second image can take a long time to be perceived and when it is, it is often sudden and called a breakthrough. There is also a breakthrough version where the contrast of the flashing version is slowly decreased while the contrast of the image of the face slowly increases.
The advantage for this is that subliminal information can be presented for a long time! Differences in breakthrough time for different types of stimulus can be calculated
What is the general idea of pattern and metacontrast masking?
A stimulus appears before and after the target stimulus (which is only presented for a short time) to prevent conscious perception of the target stimulus
Name and describe another form of manipulation so that participants do not register a particular stimuli
Attentional manipulations - We can also distract your attention: as any magician knows, even an obvious gesture can become utterly invisible if the watcher’s mind is drawn to another train of thought.
Give an example of how these methods could be used to study consciousness
In one condition the stimulus could be heavily masked so that the subjects are never consciously aware of the stimulus, while in another it could be lightly masked so that subjects always see the stimulus. fMRI recordings could then be compared.
