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Complete summary consciousness 2020
- Instelling
- Maastricht University (UM)
this is a complete English summary for the second year course consciousness. it includes all literature and lectures.
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Voorbeeld 4 van de 72 pagina's
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Door: paulzautsen • 2 jaar geleden
Voorbeeld van de inhoud
EXAM SUMMARYCONSCIOUSNESS 2020
Problem 1: the inverted spectrum
Consciousness is at it simplest the sentience or awareness of internal or external existence. This is very
vague and consciousness remains a puzzling phenomenon for many researchers and scientist. There is no
actual definition of consciousness as it is hard to define, we’ll see that later.
The science of consciousness is about relating 3rd-person data to 1st -person data; relating brain processes
(objective) to conscious experience (subjective). 3rd-person data is the objective, observable (often)
processes, the data we get from an fMRI machine are 3rd-person. 1st-person data is the subjective
experience of a certain phenomenon, it is what the person who experiences it, experiences and how they
experience it. 1st-person data cannot be wholly expressed in terms of 3rd-peron data, which makes the
process of studying and defining consciousness even harder.
Scientists have tried to find a bridge between 3rd- and 1st-person data by constructing a fundamental
theory, but for that to happen they needed good methodologies for collecting data. Methods for
collecting 3rd-person data have been well developed and are essentially abundant→ imaging methods,
psychophysical methods, etc… The only method of access we currently have to 1st-person data is
introspective verbal report, but there are limitations to its usefulness→ introspective verbal reports only
capture the gross and simple features. Expressing this data is done by using formalisms, but these rely on
simple language, which is imprecise.
− The development of more sophisticated methodologies for investigating 1st-person data and that
of formalisms for expressing them is the biggest challenge facing a science of consciousness.
Some people (among them the behaviourists) have objected using 1st-person data at all or have heavily
criticized it;
− There’s a lack of incorrigible access to our experiences
− There’s the idea that introspection on an experience changes it
− It is impossible to access al our experiences
− Some have argued that formalisms cannot capture fully the content of our experiences→
experiences are ineffable
Scientists can maybe capture the structure of an experience (seeing occurs because the light-receptors in
the eyes are activated, etc…) but the intrinsic, non-structural aspect remains somewhat of a mystery.
Others have argued there is an underlying structure to subjective experience→ proto-qualia or building
blocks. `
,Still there remain questions about reliability; the current way of gathering 1st-person data is untutored
introspection of gross features + the formalisms (emotions) seem very inexpressible.
Consciousness in a medical sense
The 2 main components of consciousness are awareness (command following) and arousal (eyes
opening). In a medical sense consciousness is when a person shows evidence of purposeful behaviour in
response to the environment, this can be as little as visual pursuit, and the person is awake.
These 2 components can be used to describe a mental state:
− Consciousness content (qualitative aspect/ awareness)
o Nothing noticed- normal perception- hallucinations
o Impaired
▪ Clouded=alcohol
▪ Narrowing= phobia
▪ Awareness shift= psychosis
− Consciousness level (quantitative aspect/ arousal)
o Awake-unarousable-dead
o Impaired
▪ Drowsiness
▪ Somnolence; abnormal sleepiness, acoustically arousable
▪ Sopor; no spontaneous movement, reaction to pain stimuli
▪ Coma; no reaction, not even to pain stimuli
One can become unconscious due to a concussion: the force causes the brain to hit the front of the skull
and then the back of the skull this leads to head trauma, destroyed tissue and swelling. This swelling can
cause reduced space in the head which leads to high pressure, dysfunctional arousal systems and
impairment of consciousness. Other causes for loss of consciousness are high intracranial pressure,
psychogenic, neurological, medical intervention, physiological.
Medically assessing consciousness often happens following certain procedures and guidelines:
− Awake?
− Oriented in place and time?
− Reacting purposefully?
− Fixating eyes?
− Emotional reactions?
− Mental status
− Brainstem reflexes, cranial nerve status
− Vital parameters
− Sensorimotor examination
− Vegetative response?
, The search for neural correlates of consciousness
Neuroscience has come to play a major role in the search for the neural correlate of consciousness (NCC);
the neural systems primarily associated w/ conscious experience.
Many proposals have been put forward but the bigger question is how can one search for it, as the NCC is
not directly or straightforwardly observable. Chalmers suggests we use principles of interpretation, pre-
experimental bridging principles= principles based on a combination of conceptual judgments about what
counts as a conscious process and information gleaned from out 1st-person perspective on our own
consciousness.
− Presence of these principles has strong and interesting consequences in the search for the NCC.
The principle of verbal report: when information is verbally reported, it is conscious. This can be
extended into; when information is directly available for verbal report it is conscious. This is limiting to
those that possess language→ we do not say children are unconscious just because they cannot produce
a verbal report. It seems better to say; if the information is available for an arbitrary response, it is
conscious
The underlying general principle= when information is directly available for global control in a cognitive
system, then it is conscious.
Blindsight= when one has some availability got control, but no conscious experience. Best handled by
invoking the directness criterion: insofar as the info here is available for report and other control
processes at all, the availability is indirect by comparison to the direct and automatic availability in
standard cases.
− Availability for voluntary control is relevant
A rational reconstruction of the search for the NCC might not work exactly as described but the rational
underpinnings of the procedure have something like this form:
1. Consciousness ↔ global availability (= bridging principle)
2. Global availability ↔ neural process X (empirical work)
3. Consciousness ↔ neural process X
1 and 2 are highly intertwined and from this follow 6 consequences:
1. If NCC is arrived at via this methodology→ consciousness is a mechanism of global availability, it
sub serves GA
2. A full story about the neural process associated w/ consciousness will do 2 things
a. We will know how information is made directly available
b. It will isolate the processes underlying consciousness itself
c. The methodology assumes a relationship between availability and consciousness, it does
nothing to explain it but nevertheless the basis is isolated.
3. It’s likely there will be many NCC’s→ there are many mechanisms of GA
4. This way of thinking allows one to make sense of the idea of a consciousness module, which
would require some sort of functionally localizable, internally integrated area
, 5. According to Crick and Koch the NCC of visual consciousness cannot be found in V1. The V1
doesn’t contain neurons that project to the PFC, which is known to be associated to control
processes
6. Sometimes the NCC is conceived of as the Holy grail for a theory of consciousness→ given the
methodology there’s no way of definitively establishing a given NCC as an independent test for
consciousness
The correlations between the NCC and consciousness are only relevant because they satisfy the criterion.
If we realize the central role of pre-experimental assumptions in the search for the NCC, we will also have
to realize what we can and cannot expect the search to tell us.
Brain structures crucial for consciousness
The following brain structures and areas have been implicated in conscious experience and some are
necessary for someone to be perceived as conscious. However, these are not equivalent to the NCC.
− Reticular activating system RAS
− Thalamus (relay station)
− Cerebral cortex (thalamo-cortical system)
o Fontal and parietal lobes
o Fusiform face area
o Corpus callosum
− Ascending and descending information flow
− Pathways:
o Arousal: cholinergic and noradrenergic
o Awareness: dopaminergic and serotonergic
Different states of consciousness
Until the 50’s most comatose patients died or recovered w/ severe deficits, in the 50’s the heart-lung
machine and intensive care unit were devised. Around the same time people started making a distinction
between patients who were locked-In (not a disorder of consciousness, but hereafter still mentioned w/
them because interesting I guess?) and vegetative state patients. The most recent discovery is of patients
who are now called minimally conscious.
Coma: absence of arousal and awareness, state of unresponsiveness to external stimulation,
persists for more than 1h.
Brain death: final breakdown of all brain functions, no clinical evidence of brain function as
evaluated by 2 different neurologists at multiple times. There is no blood passing through the
brain tissue anymore which results in an ‘empty skull’ look and a flat EEG
Locked-in syndrome: almost complete motor de-efferentiation, preservation of cognitive, sensory
and emotional functions. The person is fully conscious and awake
o Incomplete; still some motor performance left like a thumb or finger→ Stephen Hawking
o Classical: whole body except eye
o Complete; no movement possible whatsoever
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