Article 4: Neural signature of conscious processing of auditory regularities

Question 1

2 distinct neural events of detection of novel auditory stimulus

Answer 1

• Mismatch negativity response
• Followed by a later neural response labeled P300 (P3a and P3b) complex

MMN reflects a preattentive nonconscious response, whereas the late component of the P300 complex (P3b) has been theorized as an index of working memory updating and is empirically associated with conscious access.

Question 2

Local-Global paradigm (article 4)

Answer 2

5 tones are presented to a subject. They can be standard or deviant.
To detect a global deviant one has to integrate information across longer periods of time. This requires recurrent interactions and thus consciousness.

The local effect (within trial): Contrast between local deviant and local standards (xxxxY vs xxxxx sequences)

The global effect: contrasts between rare trials and frequent trials during the testing phase.

Question 3

EEG results article 4 (local vs global deviant) Healthy participants

Answer 3

• Frontal activation for local effect, MMN unchanged whether subjects had to mind-wander or pay attention.
• Parietal activation for global effect, P3b disappears when distracted. MMN does not. Not attending audio implies no global ignition. P3b is wave for conscious access.

Question 4

fMRI and intracranial results article 4

Answer 4

Local effect: only auditory cortex activation.
Local and early effect: short temporal integration
Global effect: frontoparietal network activation
Global and late effect: long temporal integration

Question 5

EEG results in DOC patients (article 4)

Answer 5

• Local effect (MMN) is a sign for unconscious state.
• Global effect (P3b) is a sign for consciousness and reflects presence of consciousness in DOC patients.
• The presence of a global effect in VS/MCS predicts recovery to conscious state later.