Sleep Flashcards
How does DNA become protein?
DNA –> transcribes to –> RNA –> translates to –> protein
An action potential typically runs from…
The cell body along an axon to the synapse.
What does a polysomnogram include?
- EEG (Electro-encephalogram)
- EOG (Electro-oculogram)
- EMG (Electro-myogram)
- EKG/ECG (Electro-cardiogram)
- Airflow
- Oximeter
How does an EEG work?
Measured by putting electrodes on the scalp (outside of the head). Picks up the sum of all the voltage changes in the brain, that happens due to the individual neutrons firing. Big signals when all neurons are doing the same thing in the same area of the brain.
Types of sleep on EEG
Aroused - Each neuron is doing it’s own job, so only small deflections in EEG.
Relaxed - Bigger deflections (alpha waves) with a bit more synchronisation.
Deep sleep - Delta waves appear as all neurons are doing the same job.
EEG Wave classification
Beta - 13-30 Hz
Alpha - 8-13 Hz
Theta - 3.5-7.5 Hz (in humans)
Delta - Less than 4 Hz
Stages of sleep in more detail
Awake - A lot of alpha and beta activity as there are quick and small neuron changes in the brain.
Stage 1 - Begins theta activity (a little slower). People don’t realise they’re asleep.
Stage 2 - Sleep spindles happen (little bursts of 12-15 Hz). Also K Complexes once a minute that is one big deflection.
Stage 3 and 4 - Delta activity begins. People know they’re asleep now.
REM Sleep
Brain is very active with theta and beta activity. Eyes move rapidly (REM) Loss of muscle tone: paralysis. Penile erection/vaginal secretion. Clear, narrative dreams. Also called Paradoxical Sleep.
Circadian cycles sleep
Most animals sleep on a circadian cycle. Some species (river dolphins) sleep in very short bouts (but still 7h a day total) Other species (ducks, dolphins) sleep with one hemisphere at a time.
Sleep deprivation
The body tends to compensate sleep once deprived by adding more REM and slow wave sleep.
Exercise doesn’t effect sleep deprivation.
It does have a clear effect on concentration and cognitive abilities, as well as emotional control.
Evolutionary Theory
Sleep conserves energy during the least productive times of a species’ day.
This does not account for hemispheric sleep or short sleep bouts in other species.
And only explains why we sleep when we do.
Brain Recovery Theory
Slow wave sleep recovers the state of your brain, as slow wave sleep isn’t effected by physical exercise but is by increases in brain temperature and mental exercise. Slow wave sleep also allows metabolic breakdown products to clear from the brain.
Memory Consolidation Theory
The brain needs to perform two separate functions:
- Be aware of the environment at all times
- Store memories for the longer term
Sleep replays the memories in order to make the memories more outlasting.
Parts of sleep in Memory Consolidation Theory
REM sleep: Consolidation of procedural and/or emotional memories.
Slow wave sleep: consolidation of explicit memories that are hippocampus dependent.
Memory Consolidation Theory: REM Sleep
More during early development (infancy) as they learn new skills. In rats, if they learnt a maze they will have more REM sleep after. REM sleep deprivation causes worse memory retention.
Memory Consolidation Theory: Slow Wave Sleep
Memory traces stored in the hippocampal circuitry are replayed during slow wave sleep.
Experiments with humans also confirm the importance of slow wave sleep for explicit memory consolidation.
Rasch et al (2007)
Participants had to study a group of paired cards and had to remember them the next day.
Learning happened while they smelled a rose odour. While in slow wave sleep rose odour would be wafted towards participants. Get tested without rose odour.
Odour helped triggered the memory of the cards in slow wave sleep and consolidates it.