Exam 4 Study GuideSleep:- Circadian rhythms- there are many circadian rhythms for many processes inthe body and the braino Awareness o Body temperatureo Hormone levels Growth hormones  Cortisol (a glucocorticoid-how awake you are)- Activity is very easy to monitor, especially in rodents that like to run at night- Revolutions of the wheel produce a mark on a strip of paper to show when the animals run- Analysis of activity shows that there is a free-running or endogenous rhythm that is entrained by light or some other cueo The endogenous rhythm last a little longer than 24 hours- Jet lag- traveling from west to east can induce a jet lag, your international clock does not match the external zeitgebero Takes a while to resynchronize o Traveling from east to west there is less jet lago Internal clock tends to run longo Easier to stay up late and sleep in late - Two major brain structures control circadian rhythms o Superchiasmatic nucleus in hypothalamus Receives input directly from retina The retinal ganglion cells do not receive input from rods or cones, but contain their own photopigment (melanopsin) o Pineal gland which secretes melatonin  Controlled by the sympathetic portion ofthe autonomic nervous  Secretes melatonin at night  Affects seasonally breeding mammals asthe hypothalamus becomes very sensitiveto the negative feedback from gonadhormones  In humans- may play a role in the timing ofsleep- Circadian rhythm involves a feedback loop in which proteins are first made and then combine- Combined protein, called a dimer for two proteins, inhibits the production of its component proteins- Dimer degrades and process begins anew - Ultradian rhythms- less than a day- Circannual rhythms- follow the course of a year - Different stages of sleep: use electrodes on surface of scalp to measure electrical potentials generated by brain o EGG= electroencephalogramo REM= rapid eye movemento SWS= slow wave sleep- Young adults show a progressive lengthening of REM sleep, while older adults often are awakened during sleep - Four areas for sleep and arousal:o Basal forebrain Generates slow wave sleep Releases GABA in tuberomammilary nucleus inthe hypothalamus  GABA in an inhibitory neurotransmitter-reduces brain activity Anesthetics work by making GABA receptorsmore sensitive o Brainstem System that controls wakefulness Reticular formation- runs the length of themedulla and projects to most of the rest of the brain- Responsible for maintaining alertness and arousal-orienting response  Locus coerulus- involved in vigilance Raphe Nuclei-inhibit the reticular formation and promotes sleep or drowsiness o A region of the pons that controls REM sleep Part of reticular formation in the pons Record PGO waves in the EEG These waves of electrical activity during REM sleep begin in the Pons, travel to the lateral geniculate then on the occipital cortex REM sleep inhibited by activity of the raphe nuclei o Hypothalamus Neurons that use the neuropeptide hypocretin are found in the lateral hypothalamus and project into other brain areas involved in sleep The hypocretin neurons may act as a switch that controls whether we are awake,in SWS, or in REM sleep Narcoleptics lose their hypocretin neurons- Sleep disorders:o Insomnia- inability to sleep a normal amount of time  Onset: inability to get to sleep Maintenance: inability to stay asleepo Sleep apnea- stop breathing during sleepo SIDS- have infants sleep on back instead of stomach reduce SIDS by 44% - Stages of sleep:o Awake-medullao Slow wave- basal forebraino REM- Ponso Cortical-hypothalamusEating:- 70% of calories go to basal metabolic rate- About 14% of caloric intake is used by the brain- Rate increased with weight, but decreases with ageo Performance increases glucose level until glucose gets too high then performance decreases- junk food- Glucose is the only fuel for the brain- The rest of the body can use glucose for fatty acids - Insulin is needed for the body both use glucose and to store it as glycogen o Insulin is created by the pancreas- hypothalamic nuclei involved in eating behavior o Ventromedial hypothalamus- don’t eat o Lateral hypothalamus- says eat- Feedback pathways for eating:- Gherlin-Growth releasing hormone/apatite stimulant- If Leptin is high you want to turn onventral medial hypothalamus …it signalsfat (opposite of Ghrelin)- When Leptin is on, want to turn offGhrelin and vice versa - Stress plays a role in hypothalamus- Stress increases glucocorticoids- Fluid in the body:o Most of the fluid is within cells o Some fluid is between cells and in the blood o A little fluid is in the cerebral ventricles - Sports drinks add salt to compensate for the loss during sweating- Hyponatremia from too much watero Nausea, headache, confusion, lethargy, fatigue, loss of appetite, restlessness, and irritability, muscle weakness, spasms or cramps, seizures - Hypovolemic thirst- baroreceptors in major blood vessels detect any pressure drop from fluid loss- Osmosensory- osmosensory neurons in the brain detect any increased osmolality of extracellularfluid- Three key components:o Hypothalamuso Pituitary o Adrenal glands- Vasopressin released pituitary acts on kidneys- Kidneys release rein to constrict blood vessels, activate adrenal and provide feedback to subfornical organ- Adrenals lease aldosterone to retain sodiumBrain Development- Zygote undifferentiated- single egg- Development- specification, genes - Layer formation- outer layer ectoderm- Become specialized by turning genes on and off- Stages of neural developmento Proliferation- cell divisiono Migration (neuroblasts)- eventually distorts into ventricleso Differentiation dendrites axons synapses- becomes a neuron Growing axon- CMA cell adhesion molecules Target- neurotrophic factors NGF (nerve growth factors)BDNF (brain derived neurotrophic factor)o Pruning and cell death- Ends functional cell or not This stage overlaps with threeo Myelination- doesn’t occur until connections are made - Timing:o Early- spinal cord reflexeso Late- proliferation Cerebellum- 2 yrs Olfactory bulb- life Dentate gyrus of hippocampus- lifeo Differentiation Cerebral cortex visual to prefrontalo Early synapses between motor neurons and muscles Neurons stop peliferating-forever - Visual cortex develops- first year- Prefrontal