Podcast
Questions and Answers
What is the total percentage of REM sleep typically experienced by adults during a night's sleep?
What is the total percentage of REM sleep typically experienced by adults during a night's sleep?
Which of the following is NOT a function of electroencephalogram (EEG) measurements?
Which of the following is NOT a function of electroencephalogram (EEG) measurements?
During REM sleep, which measurement method would best assess eye movement activity?
During REM sleep, which measurement method would best assess eye movement activity?
Which stage of sleep shows a significant reduction in muscle activity, indicating deeper sleep?
Which stage of sleep shows a significant reduction in muscle activity, indicating deeper sleep?
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In the context of biological rhythms, which of the following is classified as an ultradian rhythm?
In the context of biological rhythms, which of the following is classified as an ultradian rhythm?
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What is the primary feature of a vegetative state?
What is the primary feature of a vegetative state?
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Which statement accurately depicts brain death?
Which statement accurately depicts brain death?
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In the context of acute coma, what describes behavioral responsivity?
In the context of acute coma, what describes behavioral responsivity?
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What does the term 'neurological responsiveness' refer to?
What does the term 'neurological responsiveness' refer to?
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What is primarily retained in individuals with a vegetative state?
What is primarily retained in individuals with a vegetative state?
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Which characteristic is NOT associated with brain death?
Which characteristic is NOT associated with brain death?
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What is a key feature distinguishing acute coma from vegetative state?
What is a key feature distinguishing acute coma from vegetative state?
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How is brain death clinically and legally defined?
How is brain death clinically and legally defined?
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Which of the following accurately defines consciousness?
Which of the following accurately defines consciousness?
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What characterizes the state of coma?
What characterizes the state of coma?
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In which state can an individual show no spontaneous movements or responses to pain?
In which state can an individual show no spontaneous movements or responses to pain?
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Which of the following best describes a vegetative state?
Which of the following best describes a vegetative state?
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What is brain death characterized by?
What is brain death characterized by?
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Which state is associated with an absence of voluntary actions?
Which state is associated with an absence of voluntary actions?
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Which term describes a temporary or prolonged state where responsiveness to external stimuli is lacking?
Which term describes a temporary or prolonged state where responsiveness to external stimuli is lacking?
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What feature distinguishes unconsciousness from consciousness?
What feature distinguishes unconsciousness from consciousness?
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What GCS score range is classified as severe traumatic brain injury?
What GCS score range is classified as severe traumatic brain injury?
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What mechanism often causes coma in relation to the brain?
What mechanism often causes coma in relation to the brain?
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Which of the following is a common cause of coma?
Which of the following is a common cause of coma?
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Which state describes the level of consciousness where a patient may show minimal signs of awareness?
Which state describes the level of consciousness where a patient may show minimal signs of awareness?
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In what duration is coma generally expected to last?
In what duration is coma generally expected to last?
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What characterizes a persistent vegetative state in terms of awareness?
What characterizes a persistent vegetative state in terms of awareness?
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Which type of coma is characterized by normal or near-normal brain activity, disrupted motor pathways, and limited behavioral response?
Which type of coma is characterized by normal or near-normal brain activity, disrupted motor pathways, and limited behavioral response?
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What is the GCS score indicative of moderate brain injury?
What is the GCS score indicative of moderate brain injury?
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What reflects a critical ability when assessing the spectrum of consciousness?
What reflects a critical ability when assessing the spectrum of consciousness?
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What is a characteristic of delirium in the spectrum of consciousness?
What is a characteristic of delirium in the spectrum of consciousness?
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What is the primary function of intrinsically photosensitive retinal ganglion cells (ipRGCs)?
What is the primary function of intrinsically photosensitive retinal ganglion cells (ipRGCs)?
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Which neurotransmitter accumulates in the brain to create sleep pressure?
Which neurotransmitter accumulates in the brain to create sleep pressure?
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How does the suprachiasmatic nucleus (SCN) influence melatonin secretion?
How does the suprachiasmatic nucleus (SCN) influence melatonin secretion?
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What role does melatonin play in the body?
What role does melatonin play in the body?
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What effect does the SCN have on peripheral clocks in the body?
What effect does the SCN have on peripheral clocks in the body?
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What does the production of melatonin typically do during the evening?
What does the production of melatonin typically do during the evening?
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Which external factor primarily influences the activity of the SCN?
Which external factor primarily influences the activity of the SCN?
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What occurs to adenosine levels in the brain during prolonged periods of wakefulness?
What occurs to adenosine levels in the brain during prolonged periods of wakefulness?
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What role does adenosine play in the regulation of sleep?
What role does adenosine play in the regulation of sleep?
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Which condition is characterized by persistent difficulty in falling or staying asleep?
Which condition is characterized by persistent difficulty in falling or staying asleep?
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What is the primary mechanism associated with excessive daytime sleepiness?
What is the primary mechanism associated with excessive daytime sleepiness?
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What effect does caffeine have on adenosine receptors?
What effect does caffeine have on adenosine receptors?
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Which of the following conditions involves interruptions in breathing during sleep?
Which of the following conditions involves interruptions in breathing during sleep?
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What is a common symptom associated with insomnia?
What is a common symptom associated with insomnia?
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Acute and chronic classifications are related to which sleep disorder?
Acute and chronic classifications are related to which sleep disorder?
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Which of the following is NOT a potential cause for excessive daytime sleepiness?
Which of the following is NOT a potential cause for excessive daytime sleepiness?
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Study Notes
Course Information
- Class: Year 2, Semester 1
- Course: CNS
- Code: CNS
- Title: Consciousness, Unconsciousness, Sleep & EEG
- Lecturer: Dr. Melanie Föcking (RCSI-IE), Dr. Colin Greengrass (RCSI-BH)
- Date: 08.11.2023
Learning Objectives
- ALO167: Define consciousness and unconsciousness and describe coma, vegetative state and brain death
- ALO168: Characterise circadian rhythms, ultradian rhythms and sleep stages
- ALO169: List neurophysiological measurements to characterise sleep stages
- ALO170: Recall benefits of sleep
- ALO171: Describe the regulation of sleep-wakefulness cycle
- ALO172: List sleep disorders
Defining Consciousness, Unconsciousness, Coma, Vegetative State, and Brain Death
- ALO 167: Define consciousness and unconsciousness and describe coma, vegetative state and brain death
O-PET fMRI
- Cerebral metabolism in conscious healthy individuals, patients in vegetative state, patients in locked-in syndrome and patients in a minimally conscious state
- Colour scale represents mg glucose metabolised per 100 g of brain tissue per minute
Consciousness
- Definition: A state of self-awareness, perception, ability to respond to stimuli, ability to act with judgement
- Features: Awareness of surroundings, thoughts, feelings, and memories. Awareness of one's internal sensations, thoughts and experiences. Encompasses ability to perceive, communicate and exhibit purposeful behaviour
Sleep
- Sleep is a state of changed consciousness from which a person can be aroused by stimulation.
- Alternating in a 24-hour cycle (circadian rhythm) with wakefulness
- A physiological state
Unconsciousness
- Definition: A temporary or prolonged state in which there's a lack of responsiveness to external stimuli and an absence of voluntary actions.
- Features: Absence or disruption of consciousness where an individual cannot respond to external stimuli
Coma
- Definition: A state of profound unconsciousness characterised by inability to sense and respond to external stimuli and loss of sleep-wake-cycle
- Features: A profound state of unresponsiveness caused by injury, disease, or toxins where an individual shows no spontaneous movements, does not respond to painful stimuli, and cannot be awakened.
- Mechanism: Often involves injury to both cerebral hemispheres or the reticular activating system in the brainstem
- Causes: Intoxication, acute neurological injuries, metabolic disorders, CNS infection, stroke, hypoxia
- Duration: Generally, few days to few weeks (2-5 weeks). Some patients progress to a vegetative state or die.
Glasgow Coma Scale (GCS)
- Traumatic brain injury is graded as mild, moderate, or severe based on the level of consciousness or Glasgow coma scale
- Severe: GCS 3-8
- Moderate: GCS 9-12
- Mild: GCS 13-15
Spectrum of Consciousness
- Describes the range of consciousness levels from fully alert to persistent vegetative state and death
- Includes: Fully Alert and Attentive, Delirium, Locked-in Syndrome, Minimally Conscious State, Persistent Vegetative State, Acute Coma, Prolonged Coma and Brain Death
- Behavioural and Neurological Responsiveness are crucial measurements differentiating between the states
Circadian Rhythms, Ultradian Rhythms, and Sleep Stages
- ALO168: Characterise circadian rhythms, ultradian rhythms and sleep stages
- Circadian rhythm is a cycle that lasts approximately a day/24 hours
- Ultradian rhythm occurs many times within the span of a day
- Infradian rhythms are naturally occurring cycles in the human body that last longer than 24 hours but shorter than 1 year
Circadian Rhythms
- Definition: Biological processes that display an endogenous oscillation of about 24 hours.
- Mechanism: Regulated primarily by the suprachiasmatic nucleus (SCN) of the hypothalamus.
- Features: Roughly 24-hour cycles regulating physiological processes, influenced by the natural environment (e.g., light-dark cycles).
Ultradian Rhythms
- Definition: Biological processes that display an endogenous oscillation several times within 24 hours.
- Mechanism: Several hormonal feedback loops, NREM/REM sleep cycle, Hunger Cycles
- Features: Occurring several times with a 24-hour period
Sleep Stages
- Definition: The distinct patterns of brain wave activity during sleep.
- Includes: NREM (Non-Rapid Eye Movement) and REM (Rapid Eye Movement) sleep.
- NREM sleep has 4 stages, each deeper than the last
- REM sleep has a low amplitude, high-frequency activity pattern
Neurophysiological Measurements for Sleep Stages
- Neurophysiological measurements are used to characterise sleep stages
- These measurements include EEG, EOG, and EMG. EEG measures brain wave activity
Electroencephalogram (EEG)
- Main clinical applications: Epilepsy diagnosis, sleep disorder diagnosis, coma/altered state assessment, brain death confirmation
- Different wave patterns like Beta and Alpha distinguish stages of wakefulness and different states of sleep
Electrooculogram (EOG)
- Monitors eye movements, especially during REM phases
Electromyogram (EMG)
- Assesses skeletal muscle activity, decreasing as sleep deepens. Reduced activity indicates deep NREM sleep, no activity indicates REM sleep
Benefits of Sleep
- ALO 170: Recall benefits of sleep
- Cognitive Benefits: Memory consolidation, glymphatic clearance, neurogenesis
- Physiological Benefits: Cellular regeneration, immune modulation, endocrine homeostasis, muscle recovery, energy rebalance, glycaemic control and cardiovascular equilibrium
Effects of Sleep Deprivation
- Cognitive impairment, mood disturbances, physical health risks, immune system suppression, and impaired metabolism
Importance of REM Sleep
- Memory consolidation, emotional regulation, dreaming, and motor skill learning
Regulation of Sleep-Wakefulness Cycle
- ALO 171: Describe the regulation of sleep-wakefulness cycle
- Reticular Activating System (RAS) located in the brain stem, is network of neurons playing a crucial role in controlling arousal and wakefulness. The RAS projects to various brain regions influencing transitions between consciousness levels
- Neurotransmitters like acetylcholine, noradrenaline, serotonin, and histamine play a role in promoting wakefulness and alertness.
Regulation of the Sleep-Wake Cycle
- Suprachiasmatic Nucleus (SCN) located in the hypothalamus acts as central regulator of circadian rhythm and sleep/wake cycle
- SCN receives input from light sensitive cells in the retina. Melatonin controls sleep/wake regulation, produced by the pineal gland and rises in evening to promote sleepiness
- Adenosine builds up during wakefulness and increases the "sleep pressure" to promote sleep further
Sleep Disorders
- ALO 172: List sleep disorders. Includes: Insomnia, Excessive daytime sleepiness (EDS), Sleep Apnea, Narcolepsy, Parasomnias (such as Night terrors, Sleep walking and Sleep Talking), and Restless Leg syndrome
Developmental Aspects
- Sleep patterns change with age. Neonates have a lot more REM sleep compared to adults who sleep less in REM sleep.
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Description
Test your knowledge on sleep patterns, particularly focusing on REM sleep, EEG functions, and biological rhythms. This quiz will challenge your understanding of different sleep stages and their characteristics. Perfect for students of psychology and biology alike!
