Consciousness Flashcards
What are the 2 theories of consciousness?
- integrated information theory of consciousness
- global workspace theory of consciousness
What is the integrated information theory of consciousness?
- consciousness can be described as different
- “levels”
What is the global workspace theory of consciousness?
- changes in consciousness involve vigilance and wakefulness
What is the default mode network (DMN)?
- brain is active even when not actively doing anything
- main parts of the DMN: Prefrontal cortex, posterior cingulate, angular gyrus
What is sleep?
- sleep is a behavior, not the absence of behavior
- Bremer showed that it is a coordinated activity from the brainstem, not the absence of activity
What are the functions of sleep?
- memory consolidation (REM)
- Song birds: playing their song during sleep leads to activity that matches them practicing their song
- activity in the hippocampus during REM
- amount of REM sleep increases after periods of training/learning
What is another function of sleep?
- energy conservation (deep sleep)
- we sleep to conserve energy: species that sleep more tend to have higher metabolic rates
~ as we age, metabolism goes down-as does the amount of sleep
What are the other proposed functions?
- Brain development in children/teens
- sleep may be a safe place to discharge emotions and relief from stresses
- possibly needed for physical health
- deep sleep = human growth
What are the stages of sleep?
- slow wave sleep - stages 1-4
- REM sleep
What are slow wave sleep stages 1-2?
- mostly alpha, beta, and theta waves
- K complexes in stage 2: response to environmental stimuli
What are the slow wave sleep stages 3-4?
- mostly delta waves
What waves are in REM sleep?
- beta and theta waves
How do we progress through the stages at night?
- the first 4 hours contain more slow wave sleep
- the second 4 hours contain more REM
- REM episodes occur approximately every 90-120 minutes
What brain structures involved in sleep?
- 2 main circuits involved in arousal
- 1) one is focused on sleep
- 2) one is focused on wakefulness: Suprachiasmatic Nucleus (SCN) appears to mediate between the two
What are the 2 sleep structure?
Raphe Nuclei (pons) and gigantocellular tegmental field
What does the Raphe Nuclei do?
- serotonergic network
- activity seems to be linked to slow wave sleep
- slow wave
What does the Gigantocellular tegmental field?
- acetylcholine based
- activity linked to REM sleep
- originates PGO waves (ponto-geniculo-occipital) that occur with eye movements
What does the high level structures do in sleep?
- preoptic area (hypothalamus)
- receives serotonin from raphe nuclei
- releases GABA to inhibit wakefulness structures
- initiate sleep
What are the low level structures in wakefulness?
- locus coeruleus (pons): linked to norepinephrine network, activity linked to wakefulness
What are the high level structures in wakefulness?
- postier hypothalamus: this is the area that is inhibited by the preoptic area that leads to sleep
- basal forebrain and thalamus likely also play a role in excitation of the cortical structures
what processes that regulate when we sleep?
- circadian rhythms
What does our circadian rhythm do?
- SCN is the likely center of circadian rhythms~retinohypothalamic tract sends info to it- allows for light to play a role
- transplants of SCN establish donor rhythms in recipient animals
~ bred hamsters with 20 hour rhythms; transferred into normal hamsters; shorter cycles ensued
What is the SCN activity and light/dark cycles?
- the SCN is active during the day in both diurnal and nocturnal animals
- SCN seems to tell animals whether it is day or night, but not cause specific behaviors
- linked to the pineal gland~ secretes melatonin
What are the geetic links to SCN?
- light triggers the fluctuation of some proteins
increasing and decreasing various proteins lead to sleep/wake cycles
What are the processes that regulate when we sleep?
- homeostasis debt: sleep pressure builds while you’re awake until you need to sleep, sleep pressure decreases while asleep
~ glycogen - ATP reserves/energy source
~ as the brain uses energy, ATP turns into adenosine
~ increased adenosine levels lead to slow wave sleep- adenosine inhibits wakefulness structures-glycogen levels build up during slow wave sleep
What is insomnia?
- a sleep disorder
- usually treated with GABA agonists (Benzodiazepines) or melatonin agonists
What is sleep apnea?
- a sleep disorder
- has obstructive vs central
~ obstructive = physical obstruction
~ central = brain signal issue
What is narcolepsy?
- a sleep disorder
- excessive daytime sleepiness, cataplexy, paralysis, and hallucinations
-enters REM at inappropriate times: both throughout the day and nighttime cycles
What are the causes of narcolepsy?
- low hypocretin levels: possibly due to autoimmune issues
- genetic link to possible
- brain injuries to REM and wakefulness areas
What are circadian rhythm’s disorders?
- they are issues when your SCN and the light/dark cycle in the environment don’t align
- advanced sleep-wake phase disorder: falls asleep too early and wakes up too early
- delayed sleep wake phase disorder: falls asleep and wakes up too late
