Chapter 4

Question 1

4 signatures of consciousness (GNWS)
(What is measured, not the mechanism itself)

Answer 1

1. A sudden ignition of parietal and prefrontal circuits
2. A late slow wave called the P3 wave (P3b)
3. A late and sudden burst of high-frequency oscillations
4. A synchronization of information exchanges across distant brain regions.

Question 2

Global neuronal network communication (GNWS)

Answer 2

• Brain regions can communicate in different frequency bands
• Different cognitive processes are related to different frequency dynamics
• Some frequency bands are more strongly coupled to certain cognitive/perceptual processes

Question 3

Global ignition (GNWS)

Answer 3

It is an all or none process which drives conscious access. If stimuli strength is held at threshold then sometimes it becomes conscious and sometimes it doesn’t.
Stimulus strength decides whether or not it crosses the threshold of consciousness. Also internal fluctuations and attention play a role.

Question 4

AMPA and NMDA role in processing

Answer 4

AMPA is responsible for feedforward processing and NDMA for feedback processing

Question 5

Role of thalamus and attention in consciousness (GNWS)

Answer 5

Thalamus involved in awakening the network.
When vigilance (wakefulness) is low, spontaneous activity is reduced and the ignition property disappears. Strong sensory input quickly decays without triggering global ignition.
The network behaves like an anesthetized brain. It only responds in peripheral sensory areas and activation fails to climb to workspace areas.

Question 6

GNWS anatomy

Answer 6

Large pyramidal neurons present for the global broadcasting of conscious information, especially in the prefrontal cortex and other hubs. These neurons have long axons and dendrites that connect to many other cells further away. .

Question 7

Regions part of the Global Workspace

Answer 7

Strong functional and structural connections between prefrontal, parietal, temporal, and posterior cingulate cortex. These are part of the global workspace.

Question 8

4 stages of information processing (GNWS)

Answer 8

1. Subliminal (unattended): weak bottom up stimulus and absent top down attention. Very little activation.
2. Subliminal (attended): weak stimulus and present attention. Strong feedforward activation. Activation decreases with depth. No frontoparietal activation and no reportabillity.
3. Preconscious: strong stimulus but absent attention. Intense feedback activation yet confined to sensorimotor areas. Priming at multiple levels. No reportability.
4. Conscious: strong stimulus and attention. Intense activation of frontoparietal network and long distance loops. Conscious reportability.

Question 9

Necessity of higher order neural activity for consciousness (GNWS)

Answer 9

Experiments show that higher order activation is not sufficient for consciousness but it is necessary..