1
Q
Polysomnogram
A
Multiple features/dimensions to records of sleep in studying sleep behaviour
2
Q
Electro-Encephalogram (EEG)
A
- 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
3
Q
Electro-Oculogram (EOG)
A
- Measuring the movement of the eyes
4
Q
Electro-Myogram (EMG)
A
Observes muscle tension
5
Q
Electro-Cardiogram (EKG)
A
Record the electrical signals in the heart
6
Q
Hertz
A
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
7
Q
Delta-waves
A
< 4Hz
8
Q
Theta-waves
A
3.5-7.5 Hz
9
Q
Alpha-waves
A
8-113 Hz
10
Q
Beta-waves
A
13-30 Hz
11
Q
Sleep Spindles
A
Bursts of neural oscillatory activity
12
Q
K-Complexes
A
- Single big deflection seen in EEG recording
- indicator of Stage 2 sleep
13
Q
Slow Wave Sleep
A
- Stage 3 and Stage 4 sleep
- Delta waves; St3 is < 50% and St4 is > 50%
14
Q
REM Sleep (Rapid Eye Movements)
A
- 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
15
Q
Paradoxical sleep
A
- Theta and beta waves apparent during REM sleep which is usually indicators of wakefulness
16
Q
Sleep deprivation
A
- 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
17
Q
Contralateral Primary Somatosensory
Cortex
A
Early cerebral hemisphere of the primary somatosensory cortex only contains a tactile representation of the opposite (contralateral) side of the body
18
Q
Memory Consolidation
A
- 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
19
Q
REM Sleep Rebound Phenomenon
A
20
Q
Activation-Synthesis Hypothesis
A
- 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
21
Q
Inferior Frontal Cortex
A
22
Q
Brain Stem: Medulla
A
23
Q
Brain Stem: Pons
A
24
Q
Brain Stem: Midbrain
A
25
Forebrain: Cerebral Hemispheres
26
Forebrain: Thalamus
27
Forebrain: Hypothalamus
28
Telencephalon
29
Diencephalon
30
Mesencephalon
31
Metencephalon
32
Myelencephalon
33
Primary Visual Cortex
34
Inferior Frontal Cortex
35
Arousal
- Mechanisms of arousal involve Reticular Activating System
36
Brainstem Reticular Formation
A group of dozens of nuclei running through medulla, pons and tegmentum
37
Reticular Activating System (RAS)
- The system involved in keeping us alert and awake
- Neurotransmitters: Acetylcholine, Noradrenaline, Serotonin, Histamine, Hypocretin
38
Acetylcholine
- Two groups of acetylcholine neurons:
1. One group in the Reticular Activating System in the Pons (Metencephalon)
- One group in the Basal Forebrain (Telencephalon)
39
Serotonin
- Mechanisms of arousal
- From Raphe Nuclei (RAS in Pons and Medulla)
- Influenced locomotion and cortical arousal, but not sensitive to external sitmuli
40
Noradrenaline
- Mechanisms of arousal
- From Loecus Coeruleus (in RAS in Pons)
- Related to vigilance,induced by external sitmuli
41
Histamine
- Mechanisms of arousal
- In the Tuberomammilary Nucleus (in the Hypothalamus)
- High during waking, low during sleep
- Anti-histamines put you to sleep
42
Basal Forebrain (in the Telencephalon)
43
Locus Coeruleus (in the Pons)
- literally means blue place
- related to vigilance, induced by external stimuli
- small structure in the brain but it has lots and lots of axons that cover most of the rest of the brain and releases noradrenaline
44
Vigilance
Alertness influenced by external stimuli
45
Raphe Nuclei
- RAS in Pons and Medulla
- Serotonin
- Influences locomotion and cortical arousal, but not sensitive to external stimuli
- Internally driven in alertness
46
Tuberomammillary Nucleus
47
Hypocretin (= Orexin)
- In the lateral hypothalamus
- Has excitatory (hypocretinergic) connections to various different brain areas
- Active during active waking and exploration
48
Lateral Hypothalamus
49
Flip-flop System
Influenced by:
- Homeostatic control (maintaining your working system; brain recovery)
- Allostatic control (override in case of danger)
- Circadian control (controls sleep relative to the day-night cycle)
50
Ventrolateral Preoptic Area (vIPOA)
- Mechanisms of Sleep Induction
- in hypothalamus
- controls the switch from wakefulness to sleep
- connects through GAGA-ergic (inhibitory) synapses to all the areas involved in alertness
- receives inhibitory input from most of these same brain areas
- if this is active, we are asleep
51
GABA-ergic (inhibitory) neurons
52
Homeostatic control
- Adenosine
- Increased levels of adenosine cause more delta-activity during Slow Wave Sleep
- Adenosine has inhibitory effects on neurons
53
Astrocytes (type of glia)
54
Glycogen
55
Adenosine
- Neurotransmitters
- Made by astrocytes which use up their glycogen stores
- Inhibitory effects on neurons (a hyperpolarised membrane to make it less likely to fire action potentials)
56
Adenosine deaminase
- Breaks down adenosine
- This enzym exists in at least 2 versions (based on different alleles for the gene)
- The G/A genotype works more slowly than G/G genotype
- G/A people need about 30 min more SWS
57
Allostatic control
- Over-ride in case of danger
- Being hungry or stressed keeps us awake
58
Ghrelin
A hormone signalling an empty stomach; Stimulates hypocretinergic neurons
59
Leptin
A hormone signalling full fat reserves and glucose; Inhibits hypocretinergic neurons; Suppresses appetite
60
Circadian control
- Controls sleep relative to the day-night cycle
- SCN excites the Ventral Subparaventricular zone (vSPZ) through synapses and chemical signals
vPSZ excites the Dorsomedial nucleus of the Hypothalamus (DMH)
- DMH: inhibits VLPOA and excite the lateral hyp. (hypocretinergic)
Circadian control of sleep/wake cycles
61
Suprachiasmatic nucleus (SCN)
Endogenous Clock; in the hypothalamus; Sets the Circadian rhythm clock
62
Encapsulated Transplants
63
Period genes
64
Cryptochromes
65
Clock gene
66
Bmal1 (Brain and Muscle ARNT-like 1)
67
Heterodimer
68
Transcription Factor
69
Positive feedback
70
Negative feedback
71
Ventral Subparaventricular Zone (vSPZ)
72
Sublaterodorsal Nucleus
- Involved in the second flip-flop system to initiate REM sleep
- in dorsal pons (REM ON)
- Mutual inhibition between this and Ventrolateral Peri-aqueductal Gray Matter (vIPAG)
73
Ventrolateral Peri-aqueductal grey matter
- Involved in the second flip-flop system to initiate REM sleep
- in midbrain (REM OFF)
- Mutual inhibition between this and Sublaterodorsal Nucleus (SLD)
74
Pontine-Geniculate-Occipital Waves (PGO
waves)
75
Lateral Geniculate Nucleus (in Thalamus)
- what leads to the PGO waves
76
Tectum (mesencephalon)
77
Sub-coerulear Nucleus (in the Pons)
78
Magnocellular Nucleus (in medial Medulla)
Muscle Paralysis
79
Insomnia
80
Sleep Apnea
81
Narcolepsy
82
Cataplexy
83
Hypnagogic Hallucinations
84
REM Sleep Behaviour Disorder
85
Dreams
- Everybody dreams during REM sleep (but also some during non-REM stage)
- Dreams are easily forgotten
- Eye movements may be related to scanning visual scenes in dreams
- SWS is sometimes accompanied by night terrors, but not narrative dreams
