TASK 6 Flashcards
_circadian rhythms
– animal and human’s daily routine (24h)
_zeitgeber
– A stimulus (usually the light/dark) that resets the biological clock that is responsible for circadian rhythms
_The control of seasonal rhythms and circadian rhythms involves another part of the brain (WHICH?)
the pineal gland. This structure sits on top of the midbrain, just in front of the cerebellum. The pineal gland secretes a hormone called melatonin
_melatonin
– A hormone secreted during the night by the pineal body; plays a role in circadian and seasonal rhythms
_diurnal
– being active during the daylight
_nocturnal
– being active during the night
Most animals attend diurnal/nocturnal rhythms because of their biological clock, humans have clocks but otherwise they would follow it as well, even if ….
It is regulated (usually) by endogenous factors (light/dark)
_free running
– animal that maintains its own cycle, not caring about the daily routine
_entrainment
– synchronizing a biological rhythm to an environmental stimulus
_suprachiasmatic nucleus (SCN)
– region of the hypothalamus above the optic chiasm where the circadian oscillator is located, it produces circadian rhythms
_melanopsin
– A photo pigment present in ganglion cells in the retina whose axons transmit information to the SCN and the thalamus – photo pigment found within particular retinal ganglion cells that project to the suprachiasmatic nucleus
_retinal ganglion cells send their axons along the _______________________??
retinohypothalamic pathway (RHT)
_infradian
– referring to a rhythmic biological event whose period is longer than that of a circadian rhythm – that is, longer than a day
_circannual
– occurring on a roughly annual basis
_ultradian
– referring to a rhythmic biological event whose period is shorter than that of a circadian rhythm , usually from several minutes to several hours long
_retinohypothalamic tract (RHT)
– it is a photic neural input pathway involved in the circadian rhythms of mammals. The origin of the retinohypothalamic tract is the intrinsically photosensitive retinal ganglion cells (ipRGC), which contain the photo pigment melanopsin. It splits off at the optic chiasm to synapse directly within the SCN. These retinal ganglion cells contain melanopsin
We have an endogenous circadian clock (dark-light) proved with an experiment with people in a cave with no light for few weeks who showed ??different or not different?? circadian rhythms
differeny
_electroencephalography (EEG)
– provides a way to define and describe stages of sleep and arousal. Supplemented with _electromyography (EMG) _electro-oculography (EOG)
_electromyography (EMG)
– measures muscle tension
_electro-oculography (EOG)
– records eye movement
SLEEP PERIODS
Adults usually show repeated cycles (4-5 periods per night) of about 90-110 minutes each. The REM periods are longer in the last periods (40 min) and shorter in the first periods. Teenager should wake up after, they have different circadian rhythms compared to adults Each period has STAGES. REM occurs in stage 1 from the second period on, usually preceded by stage 2 . So stage 1, 2, 3 then back to the 2 and then 1 (which is REM)
_Waking
– awake human’s EEG is desynchronized. It is a mix of high frequencies with low amplitude. Also called beta activity
_alpha activity
– Smooth electrical activity of 8–12 Hz recorded from the brain; generally associated with a state of relaxation
_betha activity
– Irregular electrical activity of 13–30 Hz recorded from the brain; generally associated with a state of arousal
_tetha activity
– EEG activity of 3.5–7.5 Hz that occurs intermittently during early stages of slow-wave sleep and REM sleep
_delta activity
– Regular, synchronous electrical activity of less than 4 Hz recorded from the brain; occurs during the deepest stages of slow-wave sleep
_stage 1
NREM – alpha rhythms appear during relaxation, meaning reduction of muscle tension and slow heart rate. Also eyes may roll slowly. Vertex spikes (sharp waves) start this stage
_stage 2
NREM – defined by sleep spindles (waves of 12-14 Hz) and K complexes. If awakened during these first two stage of sleep, many participants deny that they were asleep, even though they failed to respond to signals while in those stages
_stage 3 and 4
NREM – defined by large-amplitude, very slow waves also defined as SWS – slow waves sleep, widespread synchronization of cortical activity . People in this stage would recognize one person speaking, but if more people are talking then they would hear just a buzz. Neurons tend to do synchronized activity, instead of doing different jobs (as when you are awake) _down state _up state
_down state
– A period of inhibition during a slow oscillation during slow-wave sleep; neurons in the neocortex are silent and resting
_up state
– A period of excitation during a slow oscillation during slow-wave sleep; neurons in the neocortex briefly fire at a high rate
_night terror
– sudden arousal in NREM sleep is marked by intense fear and autonomic activation
REM stages
– rapid eye movement stages – usually accounts for the 20% of the total sleep. In this stage we do the most vivid dreams, which means that this stage is characterized by vivid images meanwhile usually the other stages are characterized by “thinking” dreams.
_nightmares
– happen when someone is awaked from REM stage. Many medications make nightmares more frequent
_Deprivation effects
_heart disease _depression _obesity _stroke _hypertension _dyslipidemia _anxiety _increases in irritability _difficulty in concentrating _episodes of disorientation Why? _Could be interruption of circadian rhythms or sleep dept _Long sleep deprivation leads mammals to death
_nonsleepers
– people who sleep really little (few exceptions), like an hour a day as Ray Meddis , and still their health and functions are perfectly fine
_microsleeps
– are brief, unintended episodes of loss of attention associated with events such as a blank stare, head snapping, and prolonged eye closure which may occur when a person is fatigued but trying to stay awake to perform a monotonous task like driving a car or watching a computer screen
_REM rebound
- is the lengthening and increasing frequency and depth of rapid eye movement (REM) sleep which occurs after periods of sleep deprivation. When people have been prevented from experiencing REM, they take less time than usual to attain the REM state
_Oversleep effects (as adults)
_depression _psychotic disorders _drowsiness during day _low mood and lack of motivation
_ecological niche
– unique assortment of environmental opportunities and challenges to which each organism is adapted (nocturnal or diurnal species adapt to night/day activity)
SLEEP FUNCTIONS
_sleep REBUILD and RESTORES materials used during waking, such as proteins _sleep allows to GET RID of waste products, such as Amyloid beta _dreams do not stay in our long term memory, unless we write them down or talk about them (which is good because thus we do not waste important long-memory storage) _we do not learn during sleep, but if we learn something (verbal or non-verbal) right before sleep then sleep CONSOLIDATES memory _IMPROVES (simple) sequence motor learning in several tasks
_forebrain system,
can display SWS _generate slow wave sleep
_brainstem system,
activates forebrain into wakefulness _reticular formation activates forebrain into wakefulness
_pontine system,
triggers REM sleep _pons triggers REM sleep _subcoeruleus – region of the pons, ventral to the locus coeruleus where some neurons are active only during REM sleep. The main function is to inhibit motor neurons to keep them from fire. Prevents neurons from reaching threshold and producing an action potential
_hypothalamic system,
affects the brain regions above to determine whether the brain will be awake or asleep _hypocretins (orexin) – neuropeptides produced in the hypothalamus that are involved in switching between sleep states, in narcolepsy, and in the control of appetite. They tell the other neurons to stay asleep during sleeping
FLIP FLOP property
A flip-flop can assume one of two states _the sleep neurons are active and inhibit the wakefulness neurons _the wakefulness neurons are active and inhibit the sleep neurons These regions are mutually inhibitory; it is impossible for neurons in both sets of regions to be active at the same time. In fact, sleep neurons in the vlPOA are silent until an animal shows a transition from waking to sleep. ADVANTAGES _When it switches from one state to another, it does so quickly DISADVANTAGES _people with narcolepsy and animals with damage to the orexinergic system of neurons exhibit just this characteristic. They have great difficulty remaining awake when nothing interesting is happening, and they have trouble remaining asleep for an extended amount of time
_ventrolateral preoptic area (vlPOA)
– A group of GABAergic neurons in the preoptic area whose activity suppresses alertness and behavioural arousal and promotes sleep
_sublaterodorsal nucleus (SLD)
– A region of the dorsal pons, just ventral to the locus coeruleus, that contains REM-ON neurons; part of the REM flip-flop
_ventrolateral periaqueductal gray matter (vlPAG)
– A region of the dorsal midbrain, that contains REM-OFF neurons; part of the REM flip-flop
_adenosine
– A neuromodulator that is released by neurons engaging in high levels of metabolic activity; may play a primary role in the initiation of sleep
_acetylcholine
– One of the most important neurotransmitters involved in arousal—especially of the cerebral cortex _first group – one in the pons _second group – one located in the basal forebrain, produce activation and cortical desynchrony when they are stimulated _third group – located in the medial septum, controls the activity of the hippocampus
_norepinephrine
– Neurons of the locus coeruleus give rise to axons that branch widely, releasing norepinephrine (from axonal varicosities) throughout the neocortex, hippocampus, thalamus, cerebellar cortex, pons, and medulla; thus, they potentially affect widespread and important regions of the brain
_serotonin
– Almost all of the brain’s serotonergic neurons are found in the raphe nuclei, which are located in the medullary and pontine regions of the reticular formation. The axons of these neurons project to many parts of the brain, including the thalamus, hypothalamus, basal ganglia, hippocampus, and neocortex. Stimulation of the raphe nuclei causes locomotion and cortical arousal (as measured by the EEG)
_histamine
– A neurotransmitter synthesized from the amino acid histidine; plays an important role in maintenance of wakefulness and arousal.
_hypocretins (orexin)
–neuropeptides produced in the hypothalamus that are involved in switching between sleep states, in narcolepsy, and in the control of appetite. They tell the other neurons to stay asleep during sleeping
_narcolepsy
– disorder that involves frequent, intense episodes of sleep, which last from 5 to 30 minutes and can occur anytime during the usual waking hours. These episodes usually occur every 90 minutes. Narcoleptic people have way less hypocretins than normal people _hypocretins (orexin) – neuropeptides produced in the hypothalamus that are involved in switching between sleep states, in narcolepsy, and in the control of appetite. They tell the other neurons to stay asleep during sleeping SYMPTOMS _sleep attack _cataplexy _hypnagogic hallucination
_sleep attack
– A symptom of narcolepsy; an irresistible urge to sleep during the day, after which the person awakens feeling refreshed
_cataplexy
– sudden loss of muscle tone, leading to collapse of the body WITHOUT loss of consciousness
_hypnagogic hallucination
– A symptom of narcolepsy; vivid dreams that occur just before a person falls asleep; accompanied by sleep paralysis
_sleep paralysis
– temporary inability to move or talk either just before dropping off to sleep or, more often, just after waking. In this state people may experience sudden sensory hallucinations. It doesn’t last more than few minutes
_sleep enuresis (bed-wetting)
– associated with SWS. Pharmacological approaches can be used to reduce stage 3 sleep and increase stage 2.
_somnambulism (sleep-walking)
– episodes that last from few seconds to minutes and the person usually doesn’t remember these experiences. These episodes occur during SWS and are more common during the first half of the night
_sleep-related eating disorder
– A disorder in which the person leaves his or her bed and seeks out and eats food while sleepwalking, usually without a memory for the episode the next day
_REM behaviour disorder (RBD)
– characterized by organized behaviour – such as fighting an imaginary person, eating a meal, acting like a wild animal – sometimes the person remembers the dream. This disorder usually begins after the age of 50 and is more common in men than women
_sleep state misconception
– a person’s perception that he has not been asleep when in fact he/she has. Typically occurs at the start of a sleep episode. They are still more conscious that a normal person who sleeps during NREM
_sleep-onset insomnia
– difficulty in falling asleep (overall due to environmental conditions, shift work, time zone changes)
_sleep- maintenance insomnia
– difficulty in staying asleep (overall due to respiratory problems)
_sleep apnea
– a sleep disorder in which respiration slows or stops periodically waking the person. Excessive daytime sleepiness results from the frequent nocturnal awakening
_hypersomnia
– refers to either excessive daytime sleepiness or excessive time spent sleeping, is a condition in which a person has trouble staying awake during the day. People who have hypersomnia can fall asleep at any time - for instance, at work or while they are driving
HOW TO IMPROVE IF YOU HAVE SLEEP PROBLEMS?
JUST IF you have problems _do not snooze the alarm _do not use caffeine _in bed you should sleep only. Do not stay awake and stay in bed otherwise you would associate staying awake with the bed _de-stress during the day (like doing 5 deep breaths during the day) _try to prepare for sleep (classical conditioning) – like reading a book, take a shower/bath _change the sedentary lifestyle, stop sitting down (less than 5 hours a day!) _sleep problems can be a sign of physiological issues
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