Study Guides (248,151)
United States (123,290)
Psychology (300)
PSB 2000 (145)
All (109)

Introduction to Brain and Behavior [NOTES] Part 9 -- I got a 92% in the course

11 Pages
Unlock Document

PSB 2000
All Professors

Circadian rhythms  Endogenous Rhythms  Circadian rhythms: rhythms that last about a day; human’s last around 24 h • Waking and sleeping • Hormone secretion • Urine production • Eating and drinking • Sensitivity to drugs  Age is an important factor • People around 20 like to go to bed late and wake up late → Not just leaned  Why? To prepare for changes in environment before they occur • Sunrise/Sunset • Temperature changes (day to night, seasonal)  Zeitgeber  A stimulus that can affect or reset the biological clock • Bright light: when you get up in the middle of the night to go to the bathroom/get a drink of water, you don’t turn the lights back on because it wakes you up some  Examples • Temperature • Exercise • Noise • Meals • Bright light  Jet lag  Problem is that our endogenous rhythm doesn’t match external time  Easier to travel West (stay up later than normal and “sleep in”) than East (have to go to bed early and wake up early)  Flight attendants on long trips across several time zones for > 5 years  • Smaller than average hippocampus: adjusting to jet-lag is stressful, and stress increases stress hormones and these can be toxic to the hippocampus especially • Some memory impairment  Shift work: people who work out-of-synch with regular sleep-wake cycle  Duration of sleep depends on when you go to bed (sleep less if you go to bed in the morning or afternoon)  For those who work night shift, try to sleep during day, but it is difficult • Other circadian rhythms (like temperature) do not adjust to new attempted sleep- wake cycle • You can’t just choose to be nocturnal  Lighting conditions can be helpful, but do not override basic drive to sleep at night and be active in day  Biological clock: Suprachiasmatic nucleus  Main control center for sleep and temperature circadian rhythms; cells fluctuate their activity every 24 hours  Brain transplants that prove the SCN contains a clock: • Hamsters with mutant gene causing 20 hour (instead of 24 hour) rhythm remove SCN from normal adult hamsters  replace with SCN tissue from fetal mutant hamsters  adult recipients produce 20 hour rhythm  Clock genes:  Activated, transcribed, proteins are made, bound together, and then the proteins go back to the nucleus and tell the nucleus to stop (negative feedback, takes 24 hours)  Makes proteins: per, time, clock  Small amount in the morning, increase as the day goes on  High levels (in association with another protein, “clock”) “make flies sleepy” and negatively feedback to turn genes off  Cycle begins again in the morning  Light disrupts the process: bright light flash in the night inactivates tim and resets clock  Some sleep disorders linked to problem with these genes  How does light impact the biological clock?  Retinohypothalamic pathway: • Projection that goes directly from the retina to the SCN providing it with information about light; from the retina to the hypothalamus  Melatonin  Hormone secreted by pineal gland; starting 2-3 hours before bedtime; peaks around bedtime; makes us sleepy  Pineal gets information about light (indirectly) from retina and SCN and melatonin feeds back SCN • Taken in afternoon, melatonin phase-advances the biological clock • Melatonin seems to make the cells of SCN more sensitive zeitgebers  Tumor here can make people stay awake for days  Pineal is critical for seasonal rhythms • As nights get longer, releases more melatonin  acts on many regions of the brain to change behavior and physiology to prepare for winter • As days get longer (spring), releases less melatonin; antigonadotropic; less of it means more reproductive behavior ( more important in seasonal breeders than humans…and in the interest of full disclosure, some seasonal breeders are fertile when the days are longer; others when the days are shorter) Study Questions • Define circadian rhythm and zeitgeber. Know examples of each. What is the purpose of endogenous rhythms? • Circadian rhythms: rhythms that last about a day • Sleep cycle, urine production, hormone secretion, sensitivity to drugs • Zeitgeber: a stimulus that can effect or reset the biological clock • Temperature, exercise, noise, bright light, food • What are jet lag and shift work, and what are some effects of these situations on people? • Jet lag: moving from West to East and throwing off your circadian rhythm because you lost three hours of your day • Some hippocampus damage due to stress hormones; some memory impairment • Shift work: working overnight rather than during the day • It’s impossible to just decide to be nocturnal so the night shift is very difficult to adjust to; other circadian rhythms cannot adjust as well • What is the significance of the suprachiasmatic nucleus (SCN)? What is the behavioral result of a lesion of the SCN? How did brain transplants help prove the role of the SCN? • It is the main control center for sleep and temperature circadian rhythms; it can alter length of your day; brain transplants can alter the length of your circadian rhythm • What are some genes and proteins involved in sleep, and how are they involved? • Melotonin: peaks at bedtime; makes us sleepy • Clock genes: increase as the day goes on, makes you sleepy, bright light can interrupt it • What is the retinohypothalamic pathway? In what way does it contribute to circadian rhythms? From what retinal cells does it project and where does it go? • Pathway that goes right from the retina to the SCN that provides information about light Sleep  Function of sleep  Energy conservation • When we would be relatively inefficient • Probably “original” purpose (even bacteria have circadian rhythms) • Species differ in their amount of sleep depending on how much time they devote to hunting/gathering, and how safe they are (inquiring minds) • But sleep deprivation affects cognitive processes much more than physical ones  Restoration • GABA is released during sleep and sleep deprivation increases GABA in neurons • Deprivation: dizziness, bad concentration, hand tremors, irritability, hallucinations • Low metabolic demands, so brain can rebuild proteins and replenish glycogen stores • But this really just requires rest, not just sleep → Cramming and pulling an all-nighter is not as effective as studying as then going to sleep  Memory • Learn something  sleep  have better performance • Brain areas active during learning = brain areas active during sleep • Short term memory can “take out the trash”; also “hardwire” traces destined for long- term memory storage • Genes that are upregulated during sleep belong to the neurotrophin family, as well as genes for synaptic physiology  What makes us sleep?  Melatonin (circadian)  Clock genes/proteins  Accumulation of a chemical  Neural control; hypothalamus • Part of the hypothalamus is inhibitory to wakefulness promoting regions in the brainstem and forebrain • The wakefulness and sleep promoting regions in the brain directly inhibit one another; provides for a quick transition  Stages of sleep  4 stages of non-REM sleep • 3&4 are slow wave  Stage 1 is very similar to being awake – alpha; brain activity is still high but is declining  Stage 2: brain activity still decreasing; K complexes – which serve to protect a person from being awakened by a sudd
More Less

Related notes for PSB 2000

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.