Sleep and Biological Rhythms 03 18 2014 Pt 1 Sleep during sleep What techniques are used to understand brain and muscle activity EEG electroencephalogram EMG electromyogram an electrical potential recorded from an electrode placed on or in a muscle chin EOG electro oculogram an electrical potential from the eyes recorded by means of electrodes placed on the skin around them detects eye movements We also measure heart rate respiration etc Know the order in which we move thru the stages of sleep and generally that brain activity slows and becomes more synchronized from low amplitude high frequency activity to high amplitude low frequency as we get into deep sleep and how REM sleep is different Know when we would see alpha activity vs beta activity vs delta activity and what sleep spindles and k complexes are associated with Awake alpha activity relaxation beta activity arousal Stage 1 theta activity o transition between wakefulness and sleep neurons in cortex becoming more synchronized Stage 2 sleep spindle k complex Stage 3 Delta activity Stage 4 Delta activity o Synchronous activity during the deepest stages of slow wave sleep Down state neurons are resting hyperpolarized Up state neurons excited firing depolarized REM Theta activity Beta activity Compare and contrast REM sleep and non REM sleep in terms of functions of each we spent a bit of time on this EEG activity muscle tone and ability to rouse SWS slow wave stages 3 4 synchronized EEG activity hard to rouse groggy no dreaming but possible thoughts of emotions o Functions function is to rest the brain not body REM Desynchronized EEG activity rapid eye movements muscle paralysis dreaming easy to rouse would appear alert o Functions brain development and learning What brain regions are active and inactive during REM sleep think of this in terms of dreaming BTW can dreams occur in non REM sleep What is more common cognitively than dreaming in non REM sleep REM low activity in prefrontal cortex poor organization and lack of logic in dreams low activity in v1 no visual input high activity in visual association cortex hallucinations dreams rapid eye movements Dreams CAN occur in non REM sleep but more common in REM What is evidence that REM and non REM sleep might be involved in consolidating different types of memories REM facilitates consolidation of implicit non declarative memory o Learn a non declarative task in morning nap tested in evening No nap test performance worse than at end of No REM nap test performance about the same as end REM nap test performance improved over end of training of training training SWS facilitates consolidation of declarative memory o Learning is even better if thinking about that info during o Learn list of paired words declarative vs mirror drawing SWS non SWS nap improved performance of declarative but not What are symptoms of sleep deprivation non declarative task Affects cognitive more than physical abilities can tolerate a lot Symptoms confusion weight loss inability to regulate body but can also be fatal temperature What is the role of adenosine in sleep Glycogen is stored energy for neurons can be converted to glucose for neurons to use More brain activity glycogen level fall from being used o Decreased glycogen is associated with increased adenosine breakdown of ATP o Adenosine is inhibitory o Adenosine is sleep promoting Intracerebroventricular infusion increase sleep Adenosine receptor antagonist caffeine decrease sleep Especially important for SWS o Less adenosine less time in SWS o Slower breakdown of adenosine more SWS What neurotransmitters are wakefulness promoting NT Acetycholine Noepinephrine Serotonin Histamine Orexin Hypocretin sleep except Ach o High during wakefulness low during SWS low during REM We discussed 3 general factors controlling sleep homeostatic allostatic and circadian Understand these and what chemical signals are important for each Homeostatic go without sleep sleep longer to make up your sleep debt o Adenosine is important override homeostatic control Allostatic Ractions to stressful factors in the environment that o Stress hormones very important as well as neuropeptides involved in hunger and thirst o Might stay awake when tired if being threatened or if really Circadian Restrict sleep to certain portions of the day o Suprachiasmic nucleus SCN and melatonin from pineal gland hungry or thirsty very important Understand the sleep wake flip flop and the role of orexin in this system In what major brain region in the sleep promoting region How does adenosine affect the sleep wake flip flop How do other things like circadian signals and hunger or satiety signals affect it Sleep wake flip flop Saper 2001 this system is good bc flip flop happens quickly best thing is to be asleep or awake not somewhere in between o Sleep promoting region vlPOA Other factors system o Bad because it is unstable but Orexin provides stability to o Excitatory circadian signals and hunger signals o Inhibitory satiety signals and adenosine What brainstem regions are important in REM sleep and what do they do Excitatory projections from pons REM ON 1 o Activate cholinergic cells in midbrain directly or indirectly depolarize thalamic neurons MRF also activates cells for control of eye movement Inhibitory reticulospinal neurons o Decrease muscle tone Generally speaking what is insomnia What are some causes of insomnia Insomnia trouble going to sleep or staying asleep o Causes psychiatric distress depression chronic medical disorders pain elderly drug dependency insomnia caused by side effects of ever increasing doses of sleeping medications What is sleep apnea Cessation of breathing while sleeping During an episode level of CO2 stimulates chemoreceptors which wakes person up gasping for air O2 returns to normal cycle repeats Causes o Airway obstructed during sleep obesity o Brain mechanisms for breathing cease to function properly elderly What is narcolepsy Understand the various components that can occur along w narcolepsy Narcolepsy A sleep disorder genetic and environmentally influenced characterized by periods of irresistible sleep attacks of cataplexy sleep paralysis and hypnagogic hallucinations o Sleep attack an irresistible urge to sleep during the day after which the person awakens feeling refreshed 2 5 mins Happens when bored o Cataplexy complete paralysis that occurs during waking Same mechanism that causes paralysis during REM sleep happends when excited o Sleep paralysis