Main Articles Flashcards
What kind of neuroimaging did Owen use?
fMRI
Describe the main outline of Owen’s 2006 study
- A patient in vegetative state was (verbally) asked to perform two imagery tasks:
1) Imagine playing tennis
2) Imagine visiting the rooms in your home - Neural activation was found to be highly similar to that of a healthy, conscious person
Describe the neural activity that was produced in the subject of Owen’s study.
Spatial mental imagery task (visiting rooms): Parahippocampal gyrus, posterior parietal cortex, lateral premotor cortex
Motor imagery task (playing tennis): supplementary motor areas
What conclusion did Owen draw from his study?
That patients in the vegetative state have consciousness and an active mental life.
What was the basic intention behind the study by Monti (2010)?
Investigating the ability of vegetative or minimally conscious subjects to communicate using their brain activation
What was asked of the participants in Monti’s study?
Similar to Owen: Imagery tasks:
1) Motor Imagery - Imagine standing on a tennis court and swinging an arm to hit a ball back and forth
2) Spatial Imagery - Imagine navigating the streets of a familiar city or walking from room to room in your house.
Additionally:
3) Communication Task - The participants were asked to attempt to answer yes-or-no questions by using either motor or spatial imagery to modulate their brain activity.
What were the results of Monti’s study?
Only 5 out of 54 participants were able to willfully manipulate their brain activity. Out of these 5, only one could use this to answer the questions
What is an interesting characteristic of the 5 people in Monti’s study, that could willfully modulate their brain activity?
They all had traumatic brain injury
What does Monti’s study add to the clinical diagnostics of patients whose consciousness is impaired?
- fMRI complements existing diagnostics by providing a method for detecting covert signals of residual cognitive function and awareness
- Clinical categorisation in this field can be risky and difficult
Burton criticizes Owen’s conclusions from his study. Explain his photograph-analogy.
He says that fMRI is like a photo from the outside of a house - One can see whether lights are on and even calculate how much electricity is used. But whether someone is at home to consciously experience this light is still unclear.
What gives rise to the neural processes found by Owen, according to Burton?
The pieces of the neural circuity that are able to make unconscious choices might still be physically intact and thus produce the fMRI output we see.
What ethical comments does Burton make about the study by Owen?
He says that Owen gives families of LIS patients false hope and that consciousness in these patients would be torture for them.
What does Burton say, Owen’s study actually shows?
How much neural activity is at a subconscious level
In his article, Kim et al. show multiple techniques for manipulating visual awareness. What criteria are these evaluated on?
- Generalizability
- Visual Field Dependency
- Duration
- Robustness
- Invariant Stimulation
What psychophysical techniques are described by Kim et al.?
- Degraded Visual Stimulation
- Masking & Crowding
- Bistable Perception (Figures; Binocular Rivalry)
- Motion induced Blindness
- Flash Suppression
- Inattentional Blindness
- Change Blindness
- Attentional Blink
What is the theory behind visual masking / Degraded visual stimulation (according to Kim et al.)?
That the exposure is too brief for re-entrant signals to occur, which are required for conscious percept.
What do Kim et al. mention as a limitation of degraded visual stimulation?
It is a very exact procedure that is not very generalizable.
What are limitations of visual crowding according to Kim et al.?
- It can only validly be done in the periphery
- Participants might still be aware of the presence of the target but not consciously identify it. This might blur the line between aware and unaware.
- Doesn’t fulfill the criterion of invariant stimulation
What do Kim et al. mention as something one can do in visual crowding but not in masking?
Showing the stimulus for extended periods
How do Kim et al. define bistable perception?
When an observer experiences fluctuations in the content of their awareness despite unchanging visual stimulation
What are advantages of bistable perception mentioned by Kim et al.?
- Extended viewing periods
- No change in physical stimulation
- Figures can be large and don’t require fixation on some point
What is a disadvantage of bistable perception according to Kim et al.?
The inability to control the timing
What is something that binocular rivalry adds to the advantages of bistable figures? (Kim et al.)
Any two dissimilar cues can be used and not just ambiguous figures.
What do we have to do according to Kim et al., in order to find the NCVA?
produce the physiological effect of seeing something without being aware of it
How does DeGraaf (2016) define attention and why it happens?
Attention is the prioritized processing of some inputs from a larger set of selectable items. There is an advantage in not having to consciously perceive everything.
What two types of Attention does DeGraaf (2016) differentiate?
Top-Down/Endogenous and Bottom-Up/Exogenous
How do the Posner tasks used in DeGraaf (2016) differ between their endogenous and exogenous versions?
In the endogenous posner task, arrows near the fovea indicate where the target might appear while in the exogenous posner task, cues appeared in the location where the targets would appear. This forces the attention of the participant to this location rather than letting him/her autonomously adjust their attention.
Why was the time between showing the arrows (endogenous posner task) and showing the target larger than that between showing the endogenous cues and the target? (DeGraaf, 2016)
Because the arrows can act as exogenous cues as well, grabbing attention in the middle. The added time gives the opportunity to recover from this.
Which other theories did DeGraaf discuss?
Feature Integration Theory, Resource Theory, Broadbent’s Filter Theory, Egly’s Object Attention
Describe the 2x2 design by Koch et al. (2012).
Factor 1: Visibility of the target grating (Manipulated by flash suppression using a grey “ring”)
Factor 2: Locus of attention (Participants asked to either do a letter detection task or focus on the presence of the grating.)
What was the main finding of Koch et al. (2012)?
BOLD activation was determined by whether the participant focused on the grating or the letter detection task. When focusing on the grating, there was more activity in relevant areas, independently of whether the target was actually visible.
