The Consciousness Problem Flashcards
problem of other minds
impossible to know how another being’s/person’s experience is like
qualia
is-likeness of conscious experience (e.g., of the redness of red) , raw feeling, subjective first-person view
explanatory gap
how to link subjective experience with the workings of the brain? -> hard problem of consciousness
philosophical zombies
exactly like us in a physical respects and behaving just like us - but lacking conscious experience
- if philosophical zombies were possible, consciousness would be non-physical-> dualism vs. materialism
dualism
consciousness is nonphysical, separate from the brain, and thus beyond the scope of the (physical) sciences
materialism
consciousness is physical and can be understood by understanding the physical workings of the brain and body
blindsight
blind man can “see” and avoid obstacles
contrastive approach to consciousness (… - … = …)
conscious processing - unconscious processing = consciousness markers
-> holy grail of consciousness science
states of consciousness
arousal (vigilance/wakefulness) are enabling conditions for conscious experience
conscious processing
awake, eyes closed
seeing a face
unconscious processing
dreamless sleep
failing to see a face
consciousness markers
markers of states of consciousness
markers of contents of consciousness
subcortical structures (6)
Cerebrum, cerebellum, thalamus, basal ganglia, spinal cord, brainstem (pons, medulla oblongata)
cerebellum
does not contribute to consciousness
- complete absence of cerebellum has little effect on consciousness
basal ganglia
damage can cause akinetic mutism
damage can lead to cognitive problems, but no full loss of consciousness
akinetic mutism
impairments in decision making, emotion, self-initiated actions
brainstem
brainstem activating systemy provide background conditions for consciousness (states)
- lesions cause coma or death
- ascending reticular activating system (ARAS) and related neuromodulatory systems
- brainstem is insufficient for contents of consciousness, but provides background conditions (states)
coma
absence or arousal or consciousness
intact brainstem and damaged cortex
vegetative state (presence of arousal, absence of consciousness)
- some patients with intact brainstemand damaged cortex may be misdiagnosed as being in vegetative state although they may be “minimally conscious”
thalamus
may play an important role in consciousness
- lesions to the intralaminar nuclei (ILN) of the thalamus (targets of ARAS) can cause coma
- ILN and neighbouring nuclei receive little sensory input, but engage in cortico-thalamo-cortical-loops
deep brain stimulation in anesthetised monkeys
can restore consciousness, restore thalamocortical connectivity, activate cortical areas, and restore cortical responses to oddball tones
What EEG changes occur during the transition from wakefulness to sleep?
Back: High-amplitude slow waves appear, reflecting loss of consciousness as neurons alternate between depolarization and hyperpolarization.
what causes slow waves during sleep or anaesthesia
Decreased ARAS activity
Thalamic inhibition
Cortical deafferentation (input disconnection)
What typically happens to dreams during deep sleep?
Dreams are usually not reported after deep sleep.
What are the key EEG changes in wakefulness, sleep, and altered consciousness?
Wakefulness: Activated EEG with fast, low-amplitude waves.
Sleep/Anesthesia: Slow waves increase, reflecting loss of consciousness.
Vegetative to Conscious State: Activated EEG increases.
How can neural correlates of consciousness be studied?
Present a stimulus: Sometimes perceived (conscious), sometimes not (unconscious).
Use minimal contrast: Ensure input differences between conscious and unconscious states are minimal.
Example methods:
Bistable stimuli
Motion-induced blindness
Binocular rivalry
Continuous flash suppression
Masking
Contrastive approach: Compare neural activity for conscious vs. unconscious content.
binocular rivalry
Dissimilar images shown to each eye cause alternating conscious perceptions.
Physical stimulation remains constant, but perception changes.
Neural activity reflects conscious perception, not the external world.
Helps isolate neural mechanisms for the contents of consciousness.
fusiform face area (FFA)
face-specific
parahippocampal place area (PPA)
house-specific
role of primary visual cortex
may have n indirect role like the retina or may be crucial for consciousness
- (classic monkey binocular rivalry studies)
-> train monkeys to report their conscious percepts during binocular rivalry via lever press
–> V1 better reflects stimulus than percept
–> higher-level visual areas reflect percept
masking and word processing
- Presenting masks before and/or after a
briefly presented stimulus (e.g., a word or
picture) can render a stimulus invisible - By inserting blanks, the same stimulus can
be visible - Masking is widely used to study
unconscious processes and contents of
consciousness
-> unseen masked words activate high-level visual areas
-> visual words activate these areas more strongly, plus frontal and parietal areas
global (neuronal) workspace theory
unconscious: feed forwarding processing
conscious: recurrent processing and frontoparietal “ignition”
