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BSMS202 > Consciousness > Flashcards

Consciousness Flashcards

consciousness

1
Q

What is the definition of consciousness?

A
  • The state of being aware of and responsive to one’s surroundings - Awareness or perception of an inward psychological or spiritual fact
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2
Q

Objective definitions of consciousness

A

Ability to respond to stimuli: sensation (pain, touch proprioception), auditory (verbal, non-verbal), visual, olfactory and taste The ability to speak, the ability to orientate in time and place

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3
Q

Subjective definitions of consciousness

A

The experience of sensory stimuli

the experience of emotion, memory, thought, self and non-self, experience of free will

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4
Q

Key aspects & requirements of human consciousness

A

Arousal Input: - sense organs - proprioception -interoception -emotion

Output and control:

Motor: speech, locomotion, dexterity

Cognitive: differentiation of awareness (naming, defining, recognising unique features) integration of awareness (categorising, semantics), perception and conception, memory, reasoning/logic/rationality, representation of space and time, representation of self & non-self, language, agency

Emotional system: drive/instinct - to percieve, think act

Sensory - subjective experience of emotion motor - e.g. expression of anger, laughter, pain

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5
Q

Physiological & pathological states and consciousness

A

Sleep, coma, death PVS, MCS, locked in syndrome

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6
Q

Describe sleep

A

-Decreased arousal (and hence awareness & therefore consciousness) -physiological -active process -reversible and cyclical

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7
Q

Describe slow wave sleep

A

Stage 3 sleep, full of delta waves waves less than 4Hz Deep, slow brain waves known as delta waves begin to emerge during stage 3 sleep. This stage is also sometimes referred to as delta sleep. During this stage, people become less responsive and noises and activity in the environment may fail to generate a response. It also acts as a transitional period between light sleep and a very deep sleep.

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8
Q

Describe Stage 2 sleep

A

Stage 2 is the second stage of sleep and lasts for approximately 20 minutes. The brain begins to produce bursts of rapid, rhythmic brain wave activity known as sleep spindles. Body temperature starts to decrease and heart rate begins to slow.

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9
Q

REM sleep

A

The brain becomes more active

Body becomes relaxed and immobilized

Dreams occur

Eyes move rapidly

Most dreaming occurs during the fourth stage of sleep, known as rapid eye movement (REM) sleep.

REM sleep is characterized by eye movement, increased respiration rate, and increased brain activity.

REM sleep is also referred to as paradoxical sleep because while the brain and other body systems become more active, muscles become more relaxed.

Dreaming occurs due to increased brain activity, but voluntary muscles become immobilized.

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10
Q

Coma

A
  • characterised by a complete loss of wakefulness and reactivity
  • a state of unresponsiveness to external stimuli with eyes closed
  • pathological but usally reversible -prolonged unconsciousness
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11
Q

Causes of coma

A

sedation/anaethesia

epilepsy

electrolyte/metabolic

disturbance of thermoregulation

structural damage to brainstem/thalamus/cortex e.g. stroke, trauma, tumour

inflammation, infection

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12
Q

metabolic coma

A

triphasic theta hepatic, uraemia, diabetic, pancreatic, adrenocorticoid failure

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13
Q

Name this stage of sleep?

A

slow stage of sleep

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14
Q

Name this stage of sleep

A

Stage 2 sleep

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15
Q

Name this stage of sleep

A

REM sleep

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16
Q

Name this EEG pattern

A

Triphasic theta - in metabolic coma

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17
Q

Outcomes of metabolic coma

A

Reversal and recovery

survival into vegetative state or minimally conscious state

irreversible cessation of function of brainstem (brainstem death), cerebral cortex (neocortical death), body

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18
Q

Glasgow coma scale

A

Max 15, min 3

coma of 8 (e.g. E2, M5, V1 - just conscious)

Eye opening (E) - spontaneous (4), to speech (3), to pain (2), no response (1)

Eye opening is an index of arousal

Absent eye opening distinguishes coma/brainstem death from PVS and MCS

Best motor response to verbal command (M) - obeys commands (6), localises to pain (5), flexion-withdrawal to pain (4), flexion-abnormal to pain (3), extension to pain (2), no response (1)

Best verbal response (V), oriented and converses (5), disoriented and converses (4), inappropriate words (3), incomprehensible sounds (2), no response (1)

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19
Q

Vegetative state

A

Awake but unaware

Absent awareness (& hence consciousness)

Preserved arousal (preserved sleep/wake cycle)

No voluntary response to environment

Variably preserved reflex responses to environment

Cause: widespread damage to cerebral cortex (esp anoxia, head injury) – Neocotical Brain death

Persistent Vegetative State >4 weeks

ØPermanent Vegetative State

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20
Q

Categories of vegetative state

A

Continuing vegetative state (4 weeks)

Permanent vegetative state

  • after a non-traumatic brain injury 6 months in the UK
  • after traumatic brain injury 1 year

Unresponsive wakefulness syndrome (UWS)

  • proposed by the European Task Force on Disorders and Consciousness, yet to be fully defined
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21
Q

RCP guidelines for coma

A

A state of unrousable unresponsiveness, lasting more than 6 hours in which a person:

  • cannot be awakened
  • fails to respond normally to painful stimuli, light or sound
  • lacks a normal sleep-wake cycle and
  • does not initiate voluntary actions
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22
Q

RCP guidelines for vegetative state

A

a state of wakefulness without awareness in which tehre is preserved capacity for spontaneous or stimulus-induced arousal, evidenced by sleep-wake cycles and a range of reflexive and spontaneous behaviours

VS is characterised by complete absence of behavioural evidence for self- or environmental awareness

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23
Q

Minimally conscious state (MCS)

A

A state of severely altered consciousness in which minimal but clearly discernible behavioural evidence of self- or environmental awareness is demonstrated.

MCS is characterised by inconsistent, but reproducible, responses above the level of spontaneous or reflexive behaviour, which indicate some degree of interaction with their surroundings

24
Q

Continuing VS

A

A state of VS lasting for more than 4 weeks

May be classified as permanent VS if it has persisted for:

>6 months following anoxic or other metabolic brain injury

>1 year following traumatic brain injury

in cases of genuine clinical uncertainty, a further period of targeted monitoring (6-12 months) may be required to make a diagnosis of permanent VS

Recovery from permanent VS may be regarded as highly improbable

25
Q

Minimally Conscious state

A

Like vegetative state but with at least 1 of 11 items:

  1. consistent movement to command
  2. reproducible movement to command
  3. object recognition
  4. object localization
  5. reaching
  6. visual pursuit
  7. fixation
  8. automatic motor response
  9. object manipulation
  10. localization to noxious stimulation
  11. intelligible but non-functional verbalization

Emergence from MCS signaled by at least one of two items:

functional communication

object use

26
Q

Locked in syndrome

A

conscious (Aroused and aware)

unable to respond (de-efferented)

most cases are partially locked in:

  • preserved vertical eye movements
  • reserved eye opening

Causes:

  • ventral pontine damage
  • severe Guillian Barre syndrome
27
Q

Brain stem reflexes

A

Corneal blink reflex -trigeminal (opthalmic branch) afferent, pons, facial efferent

Pupillary light reflex

Reflex conjugate eye movement to the side when turning patient’s head (vestibulo-occular reflex)

28
Q

Brain stem death

A

Irreversible cessation of brainstem function

Such that consciousness could never be regained

  • Absent Reflexes
    • Pupils
    • Ice Calorics
    • Corneals
    • Pain
    • Gag
    • Cough
  • Apnoea - 5 min test after pre-oxygenation and allowing CO2 to reach 6Kpa
  • No arousal
29
Q

Legal requirements

A

Presence of an irreversible cause e.g. anoxia, structural damage

Absence of reversible cause e.g. drugs, hypothermia, alcohol, posions, metabolic (pupils react) or electrolyte disturbances

Irreversible cessation of function of:

  1. Brainstem (brainstem death) – confirmed by 2 doctors
  2. Cerebral cortex (neocortical death)
  3. Body

Must be repeated after 24 hours

Ongoing life support?

Organ donation

30
Q

Macroscopic structures which correlate anatomically with consciousness

A

Cerebral Cortex

Reticular activating system

Thalamus

  • Motor & sensory nuclei (cortical relay)
  • Thalamic reticular nucleus (gabaergic, indirect: inhibitory on thalamus)
  • Intralaminar nucleus esp centro-median nucleus
  • Claustrum

Default Mode Network (subjective consciousness)

Anterior Cingulate Cortex

Prefrontal Cortex

Inferior Temporal Cortex

31
Q

Microscopic structures which correlate anatomically with consciousness

A

Von Economo neurones

Crown of Thorns neurons

32
Q

What are Von Economo neurons and where are they found?

A

Large spindle-shaped soma (or body), gradually tapering into a single apical axon, with only a single dendrite facing opposite.

Found in 2 very restricted regions in the brains of hominids (humans and other great apes)

  • Anterior cingulate cortex (ACC)
  • Fronto-insular cortex (FI)

Also in the dorsolateral prefrontal cortex of humans.

Also found in the brains of the humpback whales, fin whales, killer whales, sperm whales, bottlenose dolphin, Risso’s dolphin, beluga whales, African and Asian elephants, to a lesser extent in macaque monkeys and raccoons

3 times higher concentrations of VENs in cetaceans in comparison to humans

?represents convergent evolution due to adaptation to larger brains

allows rapid communication across relatively large brains

33
Q

Which is the von economo neuron and the normal pyramidal neuron?

A
34
Q

Cerebral cortex

A

Creation of maps of the self and environment

Processing to integrate the maps and to respond appropriately

35
Q

Intralaminar thalamic nuclei (including centro-median nucleus)

A

General anaesthetics suppress activity in ILN

Bilateral lesions of C-M nucleus

  • Coma or severe delirium
  • Death
  • Persistent vegetative state
  • Mutism

Unilateral lesions of C-M nucleus

  • Unilateral neglect
36
Q

Ascending reticular activating system

A

Serotonergic nuclei: dorsal raphe & median raphe

Dopaminergic nuclei: ventral tegmental area & substantia nigra pars compacta

Noradrenergic nuclei: locus coeruleus & related brainstem nuclei

Histaminergic nuclei: tubero-mamillary nucleus

Cholinergic nuclei

  • Basal Nucleus of Meynert (attention)
  • Pontine tegmentum: laterodorsal tegmental nucleus & pedunculopontine nucleus
37
Q

What are some individual arousal systems?

A

Midbrain

  • Dorsal raphe nucleus – 5HT
  • Parabrachial nucleus glutamate, CRGP, dynorphin
  • Pretectal area
  • Periaqueductal grey
  • Ventral Tegmental area - Dopamine

Pons

  • Locus coeruleus – Noradrenaline
  • Latero-dorsal tegmental nucleus – Acetyl Choline
  • Pedunculopontine nucleus – Acetyl Choline
  • Pontine raphe nuclei – 5HT
  • Intralaminar centro-median nucleus - glutamate

Hypothalamus

  • Tuberomammillary nucleus - Histamine
  • Lateral hypothalamus – Hypocretin, glutamate

Basal Forebrain

  • Substantia Innominata - Acetyl Choline
38
Q

Functional imaging in disorders of consciousness

A

Coordinate-based meta-analysis

SPECT, PET & fMRI

Decreased activity (compared with healthy controls)

39
Q

Default mode network (DMN)

A

Medial prefrontal cortex (mPFC)

Ventral medial prefrontal cortex (vMPFC)

Medial temporal lobes (mTL)

Posterior cingulate cortex (PCC)

Precuneus and posterior inferior parietal lobule (pIPL)

40
Q

When is the default mode network activated?

A

DMN Components activated in:

Self-Reference:

  • Autobiographical information (episodic memory) Detailed memory related to specific events in time
  • Self-reference: traits and descriptions
  • Reflecting about one’s own emotional state
  • Remembering the past and envisioning the future (?free will)

Reference to other conscious entities:

  • Theory of Mind
  • Moral reasoning
  • Social evaluations & social categorization / status
  • Story comprehension
41
Q

What is the role of the anterior cingulate cortex?

A

Role in consciousness?

Error detection and conflict monitoring

Sense of volition

Registration of pain

Social evaluation

Reward-based learning

42
Q

Claustrum

A

Electrode between the left claustrum & anterior-dorsal insula.

Stimulation reproducibly resulted in:

  • complete arrest of volitional behaviour
  • unresponsiveness
  • Amnesia

No negative motor symptoms or mere aphasia.

Disruption of consciousness did not outlast the stimulation

No epileptiform discharges.

43
Q

Crown of thorns

A

Giant neurons encircling the brain

Three neurons stretched across both brain hemispheres, and one of the three wrapped around the organ’s circumference like a ‘crown of thorns’, Koch says

44
Q

Phyisiolohical correlates of consciousness

A

Surface EEG

  • High frequency, de-synchronized waking rhythm
  • Alpha rhythm
  • Gamma synchronization around 40Hz esp visual cortex
  • High band gamma synchrony (85-150hz) – fronto-parietal

Event-Related Potentials

  • Sensory
    • P300 (P3a & P3b) - attention
    • N400 – response to meaningfulness of stimuli
    • Late positive complex (LPC) – explicit recognition memory
  • Motor
    • Bereitschafts-Potential – conscious preparation for voluntary movement (“free will”?)
45
Q

Functional and theoretical correlates of consciousness

A

fMRI activation patterns during stimulation (especially in response to spoken questions)

Perturbational Complexity Index (PCI – Transcranial Magnetic Stimulation- evoked potentials

MEG Indices

  • Lempel-Ziv Complexity (LZc) - quantifies the number of distinct patterns present in data
  • Amplitude Coalition Entropy (ACE) - reflects the entropy over time of the set of most active channels
  • Synchrony Coalition Entropy (SCE) - reflects the entropy over time of the constitution of the sets of synchronous channels

Phi (Integrated information theory) - ? how measured

The observations of Glasgow Coma Score testing might be described as the physical or somatic correlates of consciousness

46
Q

Neuro-scientific theories of consciousness

A

Seek to explain consciousness purely in terms of neural events occurring within the brain (physicalism)

  • Gerald Edelman (re-entrant circuits)
  • Daniel Dennett
  • Francis Crick & Christof Koch (The Claustrum)
  • Dehaene & Changeaux (2001) Global Workspace
  • Integrated information theory Tononi et al. (2008/2014)
  • Antonio Damasio (“Self comes to Mind” 2010)

Quantum Theories of Consciousness

  • Eg Penrose & Hameroff (1998)
47
Q

Inattentional blindness

A

inattentional blindness, also known as perceptual blindness, is a psychological lack of attention that is not associated with any vision defects or deficits. It may be further defined as the event in which an individual fails to perceive an unexpected stimulus that is in plain sight.

48
Q

Conscious perceptions

A

are constructions

e.g. neon spreading illusion

virtual reality can induce artificial out of body experiences

49
Q

Subjective qualities of human consciousness

A

What is it like to be me or you?

Ability to experience sensory stimuli

Ability to experience emotion

Ability to experience memories

Ability to experience self

Ability to exert Free Will

  • to direct the flow of thought
  • to make decisions to act or think
50
Q

The hard problem of consciousness

A

Nobody has the slightest idea how anything material could be conscious. Nobody even knows what it would be like to have the slightest idea how anything material could be conscious - Jerry Fodor

Trying to explain what it is like to be me or you

arises from brain structure and electrochemical activity

Leibniz’s mill

51
Q

Leibniz’s mill

A

One is obliged to admit that perception and what depends upon it is inexplicable on mechanical principles, that is, by figures and motions.

Imagining that there is a machine whose construction would enable it to think, to sense, and to have perception, one could conceive it enlarged while retaining the same proportions, so that one could enter into it, just like into a windmill.

Supposing this, one should, when visiting within it, find only parts pushing one another, and never anything by which to explain a perception.

Thus it is in the simple substance, and not in the composite or in the machine, that one must look for perception

52
Q

Philosophy of mind - dualism and monism

A

Dualism

  • Socrates, Plato & Aristotle
  • Decartes
  • Res Extensa & Res Cogitans

Monism

  • Pre-Socratic
  • Heraclitus, Parmenides
  • Post-Socratic
  • Stoics & Plotinus - one substance, identified as God
  • Spinoza
  • Leibniz
  • Hegel

Modern Materialism– The Theory of everything

53
Q

Consciousness as an illusion

A

the self as a construction

  • buddhism
  • Metzinger - the transparent avatar
54
Q

Difficult problems of consciousness

A

The hard problem - why is it like something to be a conscious organism

binding - integrating all the aspects into a single unified perception - senses (especially vision), memory, emotions, sense of self, sense of free will to direct thought and action

location of consciousness

splitting of consciousness

unconscious awareness

other minds

dreams

55
Q
A

BSMS202 (8 decks)

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