Sleep Biorhythms PDF

EXAM 3 Chapter 11 Sleep Biorhythms Biological clocks Circadian rhythm→ repeating cycle of about 24 hrs ○ Sleep and walking cycles ○ Zeitgeber→ a stimulus that helps to establish and maintain biorhythms Light (the most powerful zeitgeber...

EXAM 3 Chapter 11 Sleep Biorhythms Biological clocks Circadian rhythm→ repeating cycle of about 24 hrs ○ Sleep and walking cycles ○ Zeitgeber→ a stimulus that helps to establish and maintain biorhythms Light (the most powerful zeitgeber) Regardless of the amount of sleep, if it is at night then people are more likely to have an accident. Going from no exposure to sunlight to exposure helps the cycle reset. Physical activity, eating, temperature, sleep-related hormones When it is hot you feel sleepy Any stimulus out there that helps your brain get queued to something Ultradian cycles→ wakefulness cycles that occur throughout the day, also present at night ○ Every 90-120 minutes When you feel tired in the afternoon that is going down in an ultradian cycle People can have different types of circadian rhythms, this is called chronotypes. ○ Morning person (lark) ○ Night person (owl) ○ In-between Shift maladaptation syndrome→ problems in health, personality, mood, and interpersonal problems resulting from sleep disruption due to shift work. Managing Circadian Rhythms Suprachiasmatic nucleus (SCN) → are of the hypothalamus responsible for maintaining circadian rhythms (on top of optic chiasm) ○ Active during daytime Distinguishing day and night  ○ Retinohypothalamic pathway (retina to SCN) Intrinsically photosensitive retinal ganglion cells (ipRGCs) Cells that are only sensitive to light, leave the brain and go to the SCN This tells your brain that you should be up Hormones that help you sleep comes from the hypothalamus Hypothalamus controls the endocrine system The suprachiasmatic nucleus is the part in the hypothalamus that controls those hormones for sleep ○ On top of the optic chiasm (because it senses the most powerful zeitgeber of all, light) ○ The activity in the SCN produces activity in the sympathetic nervous system, which goes to the pineal gland and the neurons stop the melatonin production. When there is not much light, the SCN stops having that big of an impact on the sympathetic neurons and that allows the pineal gland to release more melatonin. SCN tells time ○ Protein production and degradation ○ At night proteins are stopped being produced and in the day the proteins start being produced ○ Until you have adequate levels are up then you are not tired ○ The brain is a clock and will wake you up in a 10 min range naturally SCN stimulates the sympathetic nervous system ○ Low light levels Released from Pineal gland Melatonin→ participates in the regulation of circadian rhythms ○ 4:00AM ○ Makes you unconscious…do not put you to sleep ○ Artificial light ○ SCN cycles are independent of what they are being given. Seen that people with autism have low levels of melatonin and might need the supplement to regulate sleep Melatonin has been shown to help neurodegenerative disorders like altzheimers. SCN rhythms are influenced by light information. ○ Astrocyles (cell structure) can also help tune circadian rhythms. Seasonal Impacts Major depressive disorder with seasonal pattern→ a unique type of depression that results from insufficient amount of daylight during the winter months Being outside helps your mind because it produces serotonin Light ○ Melatonin For people indigenous in the area of Alaska, they do not get affected. If someone randomly goes, then they will have problems and stuggle. Managing Circadian Rhythms Cortisol→ A hormones released by the adrenal glands that promotes arousal ○ High in the morning (when higher this is associated with higher blood pressure, higher heart rate, and mobilization of energy stores) Low at night ○ Stress Anxiety Cortisol is released during times of stress, if this happens at night it will be hard to sleep. ○ Helps keep you awake Growth hormone (GH) ○ Released during deep stages of sleep ○ Build muscle, bone mass, and maintain immune system function ○ Sleep deprivation will reduce their release Neural Correlates of Waking an Sleep REM sleep gets longer the more cycles happen ○ We wake up a couple times time at night from our nervous system ○ NREM gets smaller ○ NREM 1 and 2 are deep sleep Electrocephalogram (EEG) ○ Desynchronous brain activity  Every neuron doing their own thing A lucid awake brain, all areas of the brain are doing their own thing ○ Synchronous brain activity The neurons are firing in the same way Usually deep sleep ○ Gives surface level read on what the neurons in the cortex are doing ○ Gamma-BAT-D (order of waves in sleep) Alpha waves = calm awake brain, closed eyes and they start If you close your eyes and then do mental math then Beta will come in Gamma = processing sensory input, visual in particular Beta waves = awake brain, concentration, working, etc desinchronized, front of the brain, Theta waves = beginning of sleep, NREM Delta = largest and slowest (NREM 3 and 4) ○ Dreaming is NOT deep sleep ○ Sleep consists of alternating periods of REM and NREM When we fall asleep: Electrocephalogram ○ Stage 1 of NREM Hypnogogic jerk When you are falling asleep and you feel like you are falling More often in a non familiar place rather than at your bed Most of the time only experience one then the next time they go to REM right after Theta waves start to appear (replace alpha waves) Lasts 10-15 min ○ Stage 2 of NREM Sleep spindles Quick beta activity Ex. heater turns on and your brain hear it K-complexes Keeps you from waking up  Deep delta wave Theta waves become common In between stage but nervous system is still monitoring Watch environment as much as possible Our brain is still listening to what is around us When sound is processed beta waves get activated (sleep spindle), the brain will decide More theta activity ○ Stages 3 and 4 of NREM Start seeing more delta activity than before (deepest waves) Delta waves = deep sleep Hardest stage to wake up in Relying on the parasympathetic nervous system Brain, circulatory, everything is very slow In deep sleep antibodies are created, tissue is fixed Someone who does not sleep as good then they will get sick more often When wanting to build muscle you need good sleep ○ REM Rapid eye movement Usually about an hour and a half after you fall asleep (90min) You don't remember the dreams you were having because they were coming off the wrong stage when waking up Sympathetic arousal The brain itself never sleeps Paradoxical sleep→ when you look at the brain of someone who is having a dream they look awake in a lot of ways, two things are happening at the same time which should not be (awake brain and sleeping)  You need all the stages of REM, if it does not then the brain will try to steal from another one In an 8hr sleep a person usually experiences about 5 periods of REM REM deprivation can cause difficulty concentrating and irritability During REM heart rate, blood pressure, and breathing becomes rapid and irregular REM rebound→ increased amount of REM sleep following a period of REM deprivation Brain Networks Controlling Waking Parts of the brain that play a role in consciousness: Brainstem, hypothalamus, and basal forebrain Cholinergic meropontine nuclei (Acetocholine) (REM-on) ○ Thalamus Modulates sensory activity If a structure is active while you are awake then it is also active while we are dreaming (REM) REM-off structures ○ Not active during both awake and dreaming, only active while awake. Off in REM, active while awake ○ Locus coeruleus Norepinephrine ○ Anterior raphe nuclei Serotonin Daydreaming ○ Homosapiens spend half of their day daydreaming ○ Thinking internally, linked with problem solving ○ Default mode network (DMN) → a circuit that is active during uncofused thought daydreaming 50% of the day 5% less energy When not daydreaming the DMN decreases in activity  View intrinsic thought rather than external Peak in adulthood, low as a child or elder ○ Compeating networks DMN Focused activity In schizophrenia there is activity of both at the same time They are literally trying to think while daydreaming Both are fighting for control Both DMD and focused activity activated at the same time The Initiation and Control of NREM Sleep NREM sleep Hypothalamus ○ Preoptic area (POA) of the hypothalamus NREM-on Inhibits waking pathways, allowing sleep to occur Produces immediate sleep Sleep debt More sleep needed the more you use your body/brain Suppresses brain activity Thalamus ○ Synchronizes cortical activity ○ Facilitates the transition in the waves that are being produced, controlling synchronicity of neurons in the cortex, helps us transition from starters of being awake to sleeping Locus coeruleus and raphnei nuclei ○ Reduce activity REM Sleep Cholinergic mesopontine nuclei (REM-On) → thalamus ○ Waking and REM  As we see disenchronised activity, we see activity in the mesopontine nuclei (wakes you up) Pons ○ REM-on structure (on during REM) ○ Rostral pontine reticular formation In the brainstem, goes to superior colliculi Superior colliculi Eye movements Visually oriented reflex, turning head to movement quickly so fovea can see in more detail Facilitates eye movements in your sleep Muscular paralysis Motor cortex fully active Should be paralyzed while dreaming, so you don't act out your dream. Goes from the pontine reticular formation, to the medulla, then to the motor systems in the spinal cord. Your brain is not in a sleep state, some parts are just doing other things. Residual sleep paralysis→ when you wake up but you are still paralyzed During REM many structures become as active or even more active than when waking You are not paralyzed in all of sleep, only in REM sleep. Muscular inhibition is the strongest at the beginning of a REM period followed by a gradual decrease. ○ Having a memory of something that you don't know if it was a dream or not then this is because in your sleep the brain is close to being awake. Biochemical relates to sleep and waking Acetocholine ○ Released by pons and basal forebrain ○ Associated with waking and sleep ○ Cholinergic agonists like nicotine produce high levels of mental alertness, just like glutamate. Histamine ○ High during waking  ○ Low in NREM and REM Serotonin and norepinephrine ○ Higher waking ○ Drops in NREM and very low in REM ○ Drugs that release this cause a delay in sleepiness (ex. amphetamine) Adenosine ○ Accumulate throughout the day, if sleep is postponed it will still be accumulating ○ Adenosine induces sleep ○ During sleep the levels drop allowing you to wake up again Melatonin ○ Dark cycle release of melatonin helping for the unconsciousness to fall asleep ○ Melatonin is released about 2 hrs before you go to sleep ○ “Opening of the sleep gate” 2 hrs have passed, now you are very likely to fall asleep. Decrease on signals maintaining waking and action of melatonin Advantage of Sleep Memories are consolidated during sleep Perhaps… ○ NREM builds memories ○ REM strengthens memories… Body restoration ○ Immune system ○ Damage Mental health ○ Mood goes when you are tired ○ Someone chronically tired cannot control their mood ○ No good mental health if sleep deprived Getting Better Sleep Regular schedule ( go to bed at the same time and wake up the same time) Aerobic Exercise Diet ○ Avoid caffeine (ish)  Relax ○ Thoughts Hide time No light No provocation Dream content Familiar places Routine activities Rarely an active character ○ 15% of the time ○ Most of the time you are watching what is taking place Strangers (not real people) ○ The amygdala gives you the emotion that you know the people Negative dreams ○ 70% are nightmares Day’s activities ○ The more likely you think about something during the day the more likely you are to dream about it. Lucid dreaming→ dreamers are aware that they are dreaming and can control the content of their dream ○ Anxiety increases the likelihood ○ Looking at wedding band all day and asking if you are dreaming, then at night the brain will too Theories of dreaming Evolutionary Model of Dreaming ○ dreaming provides the advantage of consolidating memories during sleep rather than during waking ○ In NREM the memory is built, the synapses in it. During REM they are being replayed. ○ Threat simulation hypothesis→dreams provide practice for dealing with threats Sleep disorders Insomnia→ difficulty initiation or maintaining sleep enough to feel rested  ○ Onset insomnia→ difficulty getting to sleep at bedtime ○ Maintenance insomnia→ difficulty staying asleep during the night ○ The most common, specially in college students Narcolepsy→ sleep attacks, enter REM sleep immediately and wake up feeling refreshed. Occasionally REM paralysis. ○ 10-20 min ○ Every 2-3 hrs Apnea→total absence of airflow during sleep time ○ Person wakes up 100 of times at night Sleep talking→ not logical talking, in NREM Sleep walking→in NREM walking while asleep Lifetime and Sleep The younger you are the more time you will spend in REM Teens spend about 20% of life in REM and infants about 80% REM declines as people approach midlife Sleep decreases about 27 minutes per decade Produce lee melatonin as we get older Why sleep? Keeps us safe ○ In a secure location, safe from predators Restores our bodies ○ Reinforce the role of NREM restauration Memory consolidation and reconsolidation ○ Memories during the day can be strengthened at night, sorted, discarded, or embedded within existing memories Sleep and emotional regulation ○ Bad sleep can mean depression and anxiety ○ Sleep deprivation can cause the wrong use of emotion ○ People can be more reactive to negative stimuli Dreams Happen in both REM and NREM In REM they are more vivid, lengthy, complicated, and story like In NREM they are more like a short episode like an image with no emotion tied to it Activation synthesis theory→ dream contents reflect neural activity ○ If a person is sprinkled with water they would have dreams with water related themes Evolutionary Model of Dreaming→ dreaming provides the advantage of consolidating memories during sleep rather than during waking Threat simulation hypothesis→dreams provide practice for dealing with threats Nightmare→ REM dream with upsetting content Lucid dreaming→ dreamers are aware that they are dreaming and can control the content of their dream Sleep terror→ occurs during REM sleep, an individual is aroused, disoriented. frightened, inconsolable. There usually is a scream and unresponsiveness. No memory of sleep terror the next day. Sleep-Wake disorders Major depressive disorder with seasonal pattern→ a unique type of depression that results from insufficient amount of daylight during the winter months Delayed sleep wake phase disorder→ inability to go to sleep until later than desired time Advanced sleep wake phase disorder→ people become sleepy early in the evening Non 24 hours sleep wake disorder→ sleep does not conform to a 24 hr clock Insomnia→ difficulty initiation or maintaining sleep enough to feel rested ○ Onset insomnia→ difficulty getting to sleep at bedtime ○ Maintenance insomnia→ difficulty staying asleep during the night Narcolepsy→ sleep attacks, enter REM sleep immediately and wake up feeling refreshed. Occasionally REM paralysis. Catalepsy→ muscle paralysis from REM occurs when the person is completely awake. Does not cause loss in consciousness Sleep Paralysis→ feature of narcolepsy in which muscle paralysis occurs after REM (awake) Hypnotic hallucinations→ REM dream that happens before sleeping Hypnopnea→ REM dream that happens after sleeping Hyponea→ reduction of airflow during sleep  Apnea→total absence of airflow during sleep time Sudden infant death syndrome→ infant stops breathing and dies during sleep Sleep walking→in NREM walking while asleep REM sleep behavior disorder→ REM paralysis is absent Restless legs syndrome→ limb, like a leg, moves in regular intervals during sleep Chapter 13 Cognitive neuroscience Consciousness → awareness of ongoing experience. Can vary from high to low depending on what we are doing. Qualia→ what we experience that serves as elements of consciousness. Thalamus enables consciousness Posterior hot zone is the areas of the brain that help in consciousness Disorders of consciousness Coma→ A disorder of consciousness characterized by inability to wake, no evidence of sleep walking-rhythms, no response to light or pain, and inability to produce voluntary behavior. ○ When reticular formation is affected ○ Most of the time both hemispheres are damaged in the reticular formation to have a coma. Unresponsive wakefulness syndrome (UWS) → waking without consciousness, typical sleep cycles, ability to open and close eyes, scream and cry, aka vegetative state. Lack voluntary control over their bodies. ○ People have said that really it is conscious awareness without the ability to communicate.  Locked in syndrome→ perfect consciousness and cognition, paralyzed, except for the eyes and eyelids. Asymmetry Lateralization→ localization of function to one hemisphere of the brain ○ One side of the brain is better at doing some things that the other ○ Different gene expression in the spinal cord and in the two hemispheres ○ Hemisoherectomy→ when one side of the cortex is removed, usually in Rasmussen's syndrome which causes seizures in one side of the brain. ○ Advantages: Increase in cognitive capacity ( now the brain can simultaneously carry out functions that are specialized to the right and left sides of the brain Helps make behavior more predictable, usually attacking from the left helps that. IF someone attacks in from the right it's more of a surprise. Left side of the brain ○ language, ○ logic, ○ sequential Right side of the brain ○ emotional information (specifically negative emotion), ○ intuitive information, ○ facial recognition, ○ spatial relations, 3D shapes Contralateral ○ Visual fields ○ Auditory Sound in one ear is processed faster by opposite hemisphere ○ Sensory and motor information Split-Brain (corpus colusum cut in half) Commissures connecting left and right hemisphere ○ Last resort for severe seizures Don't clearly see anything different after after split ○ No changes in personality, intelligence, or speech  Provide a unique situation to study lateralization ○ Now, fMRI and DTI can be used on anyone to study it We are the only species with language Dichotic listening→ one hemisphere processes the other ear Stutter→ born with language on both sides, both sides arguing Development and Lateralization Genetics Maternal (moms gene tics influence lateralization) Prenatal position ⅔ of fetuses have their right ear facing their right side of the womb Most people have learning in their left side The right ear in that position gets info and its processed by the left hemisphere Lateralization and Handedness(spinal control) We are not dominant in one side of the brain over the other To determine handedness if you write with the right then your language is to the left hemisphere and vice versa. Language 90% right-handed ○ 96% of those, left hemisphere language 10% left-handed ○ 70% of those, left hemisphere language Lateralization and hearing Sound is initially contralateral Dichotic listening tasks→ simultaneously presenting different sounds to each ear. ○ Most of the time they say they heard the one that goes with the side their language is in. Lateralization and emotion More emotional display of responses when presented to their right side rather than their left. Right = avoidance of negative stimuli, left = processing of positive stimuli The right hemisphere ○ Facial emotion Lateralization and Music Right hemisphere and orbifrontal cortex ○ Prosody→ the emotional tone of language How we say the same things but can be emotionally different. Left hemisphere ○ Plantum temporale Perfect pitch, twice as large in the platinum temporarily compared to normal people without perfect pitch. Overall there are disorders that have asymmetry rather than lateralization. These can be schizophrenia, autism, bipolar disorder, etc. More common in left-handed people and both mixed-handedness. Handedness, language, spatial relations, dichotic listening, the processing of music and prosody, gender, are some psychological disorders that correlate with patterns of lateralization How do we communicate? Language: a system for communicating thought and feelings using arbitrary signals, such as sound, gestures, or written signals ○ Has a specific area of the brain ○ Not correlated with intelligence ○ In natural selection standing up right gave us the ability to have language and signals as it freed up our hands ○ In order to learn speech the Broca’s and Wernicke's areas must connect, this is where the apes have low connection and cannot learn language like humans Arcuate fasciculus→ band of fibers that connect Broca’s and Wernikie’s area. Damage can cause Conduction aphasia→ cannot repeat a sentence, name, trouble assembling speech to sound. Due to the problems in the transfer of information. ○ Frontal, temporal, parietal lobe as well as the cingulate cortex, the insula, and the basal ganglia FOXP2 gene: the mutated gene code with a direct implication in human communication and language ○ Allow us to create complex language ○ If someone has a mutation here they will have difficulties with language Size of basal ganglia was smaller than normal Other animals have the gene but it is different by a couple amino acids. Critical period hypothesis: between birth and 7 years old, it is theorized that learning a new language is easiest. ○ 4 languages in the critical period, learned with equal proficiency Dual stream model→ there are two pathways for language. One is from sound to meaning and the other is from sound to movement.  ○ Ventral→ sound to meaning ○ Dorsal→ sound to speech What if brain damage occurs? Aphasia: a disorder characterized by damage to the regions of the brain responsible for language (to either produce or understand language) ○ Mutism (expressing yourself in different times) is not aphasia ○ Deafness is not aphasia How is language produced? Broca’s area: the center for producing speech, located in the left inferior frontal region of the brain ○ You can understand what is being said but you cannot produce speech. Broca’s (non-fluent) aphasia: a condition characterized by the difficulty to produce speech (while still able to understand speech), can still understand it when spoken to. Anomia: the difficulty to recall object names ○ The “tip of the tongue” phenomenon How is language understood? Wernicke’s area: the center for decoding and interpreting speech, located in the temporal lobe Wernicke’s (fluent) aphasia: a condition characterized by continuous speech that does not make logical sense, although it “sounds normal”. ○ Made up words (neologisms) ○ No comprehension or written or spoken language Global Aphasia→ cannot comprehend, read, or write. Broca’s, Wernike’s, and the arcuate fasciculus is messed up. What is bilingualism? Bilingualism: the ability to maintain control of two languages ○ Fluency ○ Balanced vs. unbalanced bilinguals ○ Compound (both at the same time comfortably), coordinate (depending on the place), and subordinate bilinguals (filtered through your native language)  Phonology→ being able to hear and produce the sounds from a language (ex. Mimicking an accent) Study of nun where they were more likely to get dementia the less languages they knew. American Sign Language (ASL) → showed that people that had stopped functioning in the left hemisphere could still not sign even though ASL has a spatial aspect. Showing that language is language no matter how you put it, in words or signs it is all the same. What is code switching? Code-switching: the alternating use of multiple languages within a string of speech production ○ When alternating in the language (ex. spanglish) Switch cost: a phenomenon where "activating" the other language required more time and cognitive effort that staying with the same language’ Reading and Writing Disorders: Alexia→ can understand spoken language but cannot read or point to letters Agraphia→ not able to write Dyslexia→ difficulty learning to read despite normal intelligence. (developmental) Phonological awareness→ ability to discriminate between rapidly presented speech sounds Stutter→ repeat or prolonged speech sounds when speaking. To compensate the brain has more white matter to connect areas, normal intelligence. (developmental)