Week 12 - Consciousness Flashcards
What is consciousness?
‘Our subjective experience of the world, our bodies, and our mental perspectives’ (Lilienfeld et al., 2015)
What’re the two main functions of consciousness?
To monitor: monitor self and environment -> monitor perception, thoughts, emotions, goals, problem solving plans
To control: to regulate thought and behaviour -> initiate or terminate behaviour to attain goals
Neurobiology of Arousal – Reticular Activating System (RAS)
To be conscious, there needs to be a certain level of arousal
RAS – includes midline nuclei in the upper brainstem (pons, medulla, midbrain and posterior hypothalamus).
Controls arousal – projects to thalamus and frontal regions
Alternate sleep and waking and control general level of brain and behavioural arousal
The Nature and Function of Sleep
- We spend ~1/3 of our lives asleep, but scientists are still unclear about the exact function of sleep
- The amount of sleep people (anddifferentspecies) need varies dramatically
- People find their peak in alertness and arousal at different times (e.g. “night owls” vs. “early birds”)
What is the rate of sleep needed across the lifespan?
We begin needing a lot of sleep, it then decreases throughout our lifetime
Sleep as a circadian rhythm
- Sleep-wake cycle is governed by circadian rhythms
- Circadian rhythms are biological clocks that evolved around the daily cycles of light and dark
- Other circadian rhythms include body temperature, and hormones
Wakefulness
Normal waking is associated with an irregular pattern of EEG characterised by:
– Beta waves (13-22 Hz): higher mental activity
– Alpha waves (8-12 Hz): calm wakefulness
Sleep - stage 1
Stage 1 sleep is brief (5-10 minutes) with slower theta waves (4-7 cycles per second).
- Hypnagogic imagery: confused dreamlike images
- Hypnic myoclonia: sense of falling/uncontrolled muscle contractions
Sleep - stage 2
Stage 2 sleep (10-30 mins)
EEG pattern of slightly slower waves, interrupted by bursts of:
- Sleep spindles: bursts of low- amplitude activity (12-14 Hz)
- K complexes: occasional slow, high amplitude waves
- Muscles relax, heart rate slows, body temperature decreased, eye movements cease
Sleep - stage 3 and 4
- Stage 3 sleep marked by 20- 50% slow delta waves (1-2Hz).
- Stage 4 sleep characterised by >50% delta waves.
- Stages 3 and 4 together are “delta sleep” or deep sleep (15-30 mins)
Sleep – Rapid Eye Movement (REM) Sleep
- In REM sleep (10-20 mins), EEG resembles the faster, waking brain pattern.
- Eyes move rapidly back & forth
- Autonomic activity increases
- Muscles are “turned off”
Sleep- wake cycle
- Complete cycle of REM/non-REM is 90 mins
- Sleep-wake cycle occurs 4-5 times a night
- As the night progresses, we spend less time in delta sleep and more in REM (25% of sleep in REM)
Dreaming
Everyone dreams several times a night
Dreaming is more common in REM sleep
What are NREM dreams?
- shorter
- more throughout life
- repetitive
- concerned with daily tasks
What are REM dreams?
- more dreams
- emotional/ illogical
- prone to plot shifts
Dream Content
- Often simulation of everyday life
- Negative themes more common than positive
- Some cultural differences in content
What’re the most frequent dreams?
- Being chased or perused
- Being lost, late or trapped
- Falling
- Flying
- Losing valuable possessions
- Sexual dreams
- Experiencing great natural beauty
- Being naked or dressed oddly
- Injury or illness
Lucid dreaming
• Awareness of dreaming
• Often when something bizarre or
unlikely happens
- Features of waking and REM
- Can we control our dreams to change our reality?
What is Freuds psychodynamic theory of why we dream?
Psychodynamic theory of dreaming (Freud)
•Repressed wishes or unconscious desires of the‘ ego’
•Interpretation based on working out the latent from
the manifest content
• BUT
– Why don’t we have more positive dreams? – Why don’t we have more sexual dreams? – Why are many dreams everyday activities? – Nightmares aren’t wish fulfilment?
Activation/synthesis theory of why we dream:
• Forebrain tries to interpret signals received from other brain areas during REM
– Acetyl choline activates Pons
– Signals sent thalamus and then
language/visual areas of forebrain
– Amygdala activation adds emotional content
Forebrain hypothesis in why we dream:
– Damage to forebrain can stop dreaming, suggesting
interaction between forebrain areas is important
Neurocognitive perspective on why we dream
– Processing or solving problems, integration of previously learned and new information, memory consolidation (including emotional)
– Complexity of dreaming mirrors cognitive development