Introduction Flashcards
Why do we dream?
Dreaming is epiphenomena- no meaning, something that happens whilst brain recovering (dominant theory)
Evolutionary theory- dreams have been preserved through evolution for a reason
Why do we sleep?
Restoration- brain builds up by-products in day, shuts down at night so by-products can be removed, resources also used up during day, needs to restore other functions
Circadian rhythms- night time cold, lots of energy to keep warm so evolutionary advantage to sleep at night
How to study sleep
- wake person up & ask them or see what they can do
- look at responsiveness during sleep
- do something before sleep & watch sleep
- look at those who don’t sleep/dream
- look at changes in sleep with age
- look at sleep of other species
How to study stages of sleep
muscle tone- collapses when asleep, in REM completely goes
Eye movement- REM
brain activity- observes changes throughout night
Body movement
Respiration- increase before REM
Body temperature- drops during night, rises before wake up
EEG- waves varying in amplitude & frequency
Stages of sleep
Alert wakefulness- awake
Drowsiness
Stage 1- initial
Stage 2
Stage 3
Stage 4- deep sleep
Stage 1- emergent (REM)
Difficult to differentiate 3 & 4, recycle through stages through night
Sleep cycles
15/30 mins to fall asleep
5/6 cycles a night
Don’t always go through all stages
Deep sleep at start of night, lighter towards end
Individual variability in sleep cycles but very similar
REM sleep
70% of time in REM sleep person will be dreaming, highly correlated but not the same
lack of core muscle tone so you don’t act out dreams
REM & low muscle tone not perfectly aligned
Lack of muscle tone but no REM= sleep paralysis
REM episodes tend to lengthen throughout night
REM 90 mins after sleep onset, 45 mins after stage 4
Pulse goes wild, depending on dream
Easier to wake from REM than deep sleep
Intervals between periods of REM are constant
Basic brain anatomy points
Pons
Medulla
Spinal cord
Cortex
Thalamus
Cerebellum
Corpus callosum
Pituitary gland
Important anatomical structures in sleep & dreaming
Hypothalamus- controls stages of sleep, under thalamus
Brain stem nuclei & pons & medulla
Basal forebrain
Amygdala
Thalamus (reticular nucleus)
Cortex
Neuroanatomical structure
Cluster of cell bodies- distinct because they differ from neighbouring clusters by relative mixtures of cell bodies e.g. shape
Separated from other clusters of cell bodies by axonal connections
So, structures can be large or small- structures can seem to have a clear shape or very rough shape, when there is no obvious shape other terms emerge e.g. networks/webs
Implications of structures for functions
Cells look different because they are composed of different densities & different proportions of various types of neurons & glial cells
Implicit assumption that if 2 areas look different then they are doing something different i.e. performing a different function
Implicit assumption that 2 areas that surround each other are doing related functions
Direction
Front- anterior
Back- posterior
Outer edge- lateral
Middle- medial
High up- superior
Low down- inferior
