Lecture 14 - Consciousness

What are the two key aspects of consciousness?

(1) Awareness of environment and self, and (2) Content of consciousness (the specific experiences or thoughts being held)

Define "levels of consciousness."

The state of wakefulness/awareness ranging from full wakefulness → drowsiness → sleep → coma → anesthesia

Define "content of consciousness."

The specific perceptions, thoughts, or experiences that fill conscious awareness at a given time

Which brain structures are central to maintaining consciousness?

The cortex (information processing) and the thalamus (relay and integration)

What is lucid dreaming, and which brain regions are active?

Awareness during REM sleep; linked to increased activity in the anterior prefrontal cortex, parietal cortex, and temporal cortex

What is general anesthesia/coma, and which areas are disrupted?

State of unconsciousness caused by cortical and thalamic disruption, leading to breakdown in connectivity

What happens in locked-in syndrome?

Person is fully conscious but unable to move due to damage to the ventral pons

What is the minimally conscious state, and which brain area is affected?

Patient can fixate/respond to simple commands; linked to reduced cortical activity

What is unresponsive wakefulness syndrome, and what brain areas are damaged?

Eyes may open but only reflexive behavior occurs; damage to cortex and/or thalamus

What is the Mirror Self-Recognition (MSR) test used for?

To test self-awareness by placing a visible mark on the subject and observing if they touch themselves rather than the mirror

What was Mitchell’s (1993) critique of the MSR test?

Argued success may result from kinaesthetic-visual matching (linking movements to mirror reflection), not true self-awareness

What are explicit (declarative) memories?

Conscious memories, including episodic (events) and semantic (facts)

What did rhesus monkey memory studies show?

Monkeys opted out of tests when memory was poor (after delays), showing awareness of their own memory strength (metacognition)

What is the Neural Correlate of Consciousness (NCC)?

The specific neuronal processes that correlate with conscious experience

What is the materialist position on consciousness?

The view that consciousness arises from physical brain processes, not separate from biology

What are bistable percepts, and why are they important in NCC research?

Stimuli like the Necker cube where perception alternates despite a constant stimulus—used to study conscious perception independent of sensory input

What is binocular rivalry?

Different images shown to each eye lead to alternating conscious percepts despite stable sensory input

Which brain regions are implicated in visual NCC?

Fronto-parietal networks (introspection/action), and extrastriate occipital & parietal regions (perceptual changes)

What happens to connectivity during propofol anesthesia or non-REM sleep?

Long- and short-range connectivity breaks down, impairing information integration and causing loss of consciousness

How does Transcranial Magnetic Stimulation (TMS) reveal differences in conscious states?

In wakefulness, stimulation spreads across cortex; in sleep/anesthesia, activity dies out quickly → shows reduced long-range communication

How does lucid dreaming differ from non-lucid REM sleep in brain activity?

Lucid dreaming shows increased BOLD activity and connectivity in anterior prefrontal, parietal, and temporal cortices, allowing self-reflection

What is the key insight about functional connectivity and consciousness?

Consciousness depends not just on brain activity, but on the integration and coordination of distributed networks