Sleep Flashcards
Polysomnogram
Multiple features/dimensions to records of sleep in studying sleep behaviour
Electro-Encephalogram (EEG)
- Records electrical activity in the brain
- Many surface electrodes
- Signals are a summation of the activity of the population of neurons close to the electrode
- Synchronised acticity: large deflections. Unsynch: averages out
Electro-Oculogram (EOG)
- Measuring the movement of the eyes
Electro-Myogram (EMG)
Observes muscle tension
Electro-Cardiogram (EKG)
Record the electrical signals in the heart
Hertz
1 cycle/second
- how we measure the frequency of cycle for an occurrence
- you don’t necessarily measure them, you classify them in the groups following
Delta-waves
< 4Hz
Theta-waves
3.5-7.5 Hz
Alpha-waves
8-113 Hz
Beta-waves
13-30 Hz
Sleep Spindles
Bursts of neural oscillatory activity
K-Complexes
- Single big deflection seen in EEG recording
- indicator of Stage 2 sleep
Slow Wave Sleep
- Stage 3 and Stage 4 sleep
- Delta waves; St3 is < 50% and St4 is > 50%
REM Sleep (Rapid Eye Movements)
- Brain is very active (theta and beta activity)
- Rapid Eye Movements
- Loss of muscle tone: paralysis
- Usually after 45 mins of SWS
- Penile erection/vaginal secretion
- Clear, narrative dreams
Pontine-Geniculate-Occipital (PGO) waves; confirmed in animals - aka Paradoxical Sleep
Paradoxical sleep
- Theta and beta waves apparent during REM sleep which is usually indicators of wakefulness
Sleep deprivation
- Compensate by more sleep later (mostly SWS and REM sleep)
- No effect on ability to exercise
- Clear effect on concentration and cognitive abilities
- Clear effect on emotional control
Contralateral Primary Somatosensory
Cortex
Early cerebral hemisphere of the primary somatosensory cortex only contains a tactile representation of the opposite (contralateral) side of the body
Memory Consolidation
- The brain needs to perform two mutually-exclusive functions:
1. Be aware of its environment at all times
2. Store memories for the longer term - The theoretical reason is that for proper long-term memory consolidation, you really ideally need the brain circuits to repeat the memory
- Needs this repetition by the brain to reinforce the connections associated with it
- One hypothesis on why we need to sleep is to turn off external inputs to allow the brain to process the memories
- REM Sleep: Consolidation of procedural memories and/or emotional memories
- SWS: Consolidation of explicit memories (hippocampus-dependent)
- The dichotomy is NOT absolute
REM Sleep Rebound Phenomenon
Activation-Synthesis Hypothesis
- External stimuli
- Internal stimuli (recent experiences, memories)
- Brain synthesises a “story”
- Dreaming as a side effect of how the brain needs to process information during REM sleep
- Mechanistic, not functional explanation
Inferior Frontal Cortex
Brain Stem: Medulla
Brain Stem: Pons
Brain Stem: Midbrain
Forebrain: Cerebral Hemispheres
Forebrain: Thalamus
Forebrain: Hypothalamus
Telencephalon
Diencephalon
Mesencephalon
Metencephalon
Myelencephalon
Primary Visual Cortex
Inferior Frontal Cortex