Sleep and Biological Rhythms (Ch.14) Flashcards
1
Q
Types of “Circa Rhythms”
A
- Circatidal (12 hrs)
- Circadian (24 hrs)
- Circalunar (30days)
- Circannual (one year)
2
Q
Period:
A
The time interval separating one peak or trough from the next in a repeating cycle
3
Q
Zeitgeber:
A
Time giver
4
Q
- Circadian Rhythms (reoccurring naturally on a 24 hour clock) slightly are the result of an
A
Endogenous clock (a clock from within)
5
Q
Daily Rhythms persist in..
A
constant conditions
6
Q
Rythms develop normally in the absence of…
A
external cycles (innate)
7
Q
Tau:
A
- Tau varies across and within species in the same environment
- Tau can be selected by breeding altered by gene mutations and eliminated by gene knockouts
8
Q
Jean deMairan 1729 identified the first circadian rhythm in the Mimosa Plant using …
A
temporal isolation
9
Q
- Adaptive Significance of Circadian clocks: External coordination and anticipation to:
A
- Geographic Stimuli (light, temp)
- Biological stimuli (food resources, predators, mates)
10
Q
Do circadian clocks contribute to fitness in Natural Habitats?
A
-SCN ablated animals were in burrows at night however they were active which increase their predation
11
Q
Entrainment phase
A
Animals display different endogenous(originating from within) periods that don’t exactly match the environmental light dark cycle
12
Q
Entrainment Hypothesis
A
Entrainment is achieved by daily adjustment of rhythm phase, to offset the difference between τ and T.
- Squirles see light for only a few seconds every 3 to 4 days
13
Q
Retinohypothalmic Tract:
A
- Intrinsically photosensitive retinal ganglion cells
- Axons that make up the RHT do not originate from rods and cones
14
Q
Entrainment Pathway
A
- Light enters the eyes through the rods and cones and Speacialized ganglion cells (containing melanopsin)
- Then go through the Retinohypothalaamic tract to thalamus to form the vision
(END OF ENTRAINMENT)
15
Q
Evidence that the SCN are an endogenous circadian clock
A
- Lesions of the SCN eliminate rhythmicity
- Electrical or chemical stimulation of the SCN induces phase shifts
- SCN neurons oscillate (move back and forth at a normal speed)
- SCN transplants can restore rhythms after SCN lessons (with the period of the donor)
16
Q
What other Stimuli contribute to entrainment besides light?
A
- Arousal
- Exercise
- Drugs
- > these stimuli exert their influences on the SCN via another neural pathway
17
Q
Chronotype: Night owls and early birds
A
-Between ages 10 and 40 men tend to be later risers than females
18
Q
Why Study Circadian Rhythms?: Human Performanc and Societal cost
A
Physical and cognitive capacities vary throughout the day (shift work, travel, education, sports)
- Need of job, demand for services (firefighter)
- Problemed areas: performance and productivity, safety, health
19
Q
Why Study Circadian Rhythms?: Medicine
A
Rhythms are important for both diagnosis and treatment
20
Q
Why Study Circadian Rhythms?: Psychopathology
A
Disruption of circadian timing implicated in sleep and affective disorders
21
Q
Shift work and Productivity
A
- The greater you work the greater your output, BUT for many jobs productivity per hour of work is lower on 10-12 compared to 8
- Leads to increased risk of accident
22
Q
Health Problems of Shift Workers
A
- Sleep and Vigilance
- Cardiovascular System (50% increase in risk - increases with years of exposure to shift work)
- Gastrointestinal System - Significant increase for GI disease (e.g. ulcers)
- Hormonal and reproductive system
- Anxiety, depression, substance use
23
Q
Circadian windows of vulnerability
A
- Heart attacks and strokes more likely in the morning
- Asthma attacks and strokes more likely in the evening
24
Q
Circadian disruption underlying disease processes
A
- Do circadian disorders cause other disorders (concerns about circadian disruption and cancer vulnerability)
25
Circadian Rhythms in treatment efficacy
An effective dose at one time of day may be ineffective at another time
26
Circadian Rhythms in baseline function
You need to know circadian variation to know what is normal for a given time of day (eg. temp and fever)
27
3 Methods used for Examining Sleep States
- Electrical brain potentials can be used to classify levels of arousal and states of sleep
1. Electroencephalography (EEG)
2. Elector-oculography (EOG)
3. Electromyography (EMG)
28
1. Electroencephalography (EEG)
-Records electrical activity in the brain
29
2. Electro-oculography (EOG)
- Records eye movements
30
Electromyography (EMG)
- Records muscle activity
31
2 Distinct Classes of Sleep:
1. Non-rapid eye movement sleep (NREM)
| 2. Rapid eye movement sleep (REM)
32
1. NREM
- Can be divided into 4 stages, 3 and 4 of NREM sleep are characterized by slow wave EEG activity
- Parasympathetic autonomic profile
- Metabolism and neural activity reduced
- Respiration slow, regular
33
2. REM
- Characterized by small amplitude, fast EEG waves, no postural tension, and rapid eye movements
- Sympathetic autonomic profile
- Metabolism and neural activity increased; phasic PGO waves
- Respiration irregular, cardiovascular tone increased
- Dreaming
34
How Many stages are there of Slow Wave Sleep?
4
35
1st stage of Slow Wave Sleep
- Show events of irregular frequency and similar amplitude as well as Vertex Spikes or sharp waves
- Heart rate slows, muscle tension reduces, eyes move about
- Lats several minutes
36
2nd stage of Slow Wave Sleep
- Defined by waves of 12 to 14 Hz that occur in bursts, called sleep spindles
- K complexes appear - sharp negative EEG potentials
37
3rd stage of Slow Wave Sleep
- Defined by the appearance of large amplitude, very slow waves called delta waves (slow wave sleep)
- Delta waves occur about once per second
38
4th stage of Slow Wave Sleep
- Delta waves are at least half of the time
| - REM sleep follows
39
In a typical night of a young adult sleep:
- Sleep time 7-8 hr
- 45 to 50% is stage 2 NREM sleep
- 20% is REM sleep
- Cycles last 90-100 min
- Cycles early in the night have more stage 3 and stage 4 SWS, and later cycles have more REM sleep
40
Sleep Changes Across the lifespan
REM gets a lot shorter
41
Sleep in Marine Animals
- Some marine animals show different sleep stages on land
- e.g: Seal - Unihemispheric NREM sleep in water
- Bilateral NREM and REM sleep on land
42
Consequences of sleep deprivation in humans:
- Slow reaction time (16h SD equivalent to legal alcohol intoxication)
- Irritability
Lapse in concentration
- hallucinations (multiple days)
- fatal familial insomnia
43
Consequences of sleep deprivation in animals:
- Longterm: characterized by a metabolic syndrome that leads to death
44
Energy Conservation (Biological Functions of Sleep)
- Decrease in required metabolic (chemical process that occurs and maintains life) energy
- > Metabolic activity in the brain is decreased
45
Avoid Predation (Biological Functions of Sleep)
Temporal niches of predator and prey
46
Body Restoration (Biological Functions of Sleep)
Recovery from illness
- Evidence: Sleep inhibits immune function
- More sensitive to pain
- More likely to develop diabetes
- More likely to develop cancer
47
Memory Consolidation (Biological Functions of Sleep)
Performance on learning task is better if training and testing is separated by a sleep bout
- Sleep aids memory consolidation: some parts more than other
48
Sleep enforces niche adaptation:
- Each species physiology is specifically adapted to a particular time of day
- Humans are diurnal (example: eyes adapted for daylight conditions
- Bats: are nocturnal. (example: echolocation)
- Sleep is for aligning wake and sleep to the appropriate time of day to avoid falling prey
49
What generates slow wave sleep?
the forebrain
50
Bremer:
Isolated brain (encephala isle) vs isolated forebrain (cerveau isle)
51
The basal forebrain receives ______ signals from the ___________ nucleus of the hypothalamus
- GABAergic
- tuberomammilarary
THEREFOR the basal forebrain promotes NREM sleep due to GABA release from the TMN
- Left alone this system would leave the brain engages in NREM indefinitely
52
The _____ formation wakes up the forebrain
reticular
- The reticular formation is a diffuse network of cells extending from the medulla to the thalamus
- Stimulation in the reticule activating system in sleeping animals wakes them up
- Lesision of the reticular activating system induces indefinite sleep (coma)
53
The ____ trigger REM sleep
Pons
- LEsision just lateral to the locus coeruleus abolish REM
- Simulation sot the same region can induce prolonged REM
54
During REM sleep...
- Motorneurons are inhibited - loss of muscle tone (which requires the LC as lesions result in a lack of inhibition)
55
A hypothalamic sleep center
The lateral hypothalamus contains neurons that synthesize hypocretin (orexin)
- These hypocretin neurons project to:
1. The basal forebrain
2. the reticular formation
3. the locus coerules
4. Tuberomammilary nucleus
56
Narcolepsy
Sudden Day time sleep
- Patients suffer from rapid REM onset and excessive daytime sleepiness
- Patients have suffered from about 90% of heir hypocretin neurons
- hypocretin Inhibits sleep and prevents the transition from wake to REM
