DEVELOPMENT 11 03 2013 you are Long Neuro tube in uterus Brain produced first body comes second Fluid filled Cells of divide brain dividing Ventricles Long neuro tube becomes the ventricles Fluid filled spaces with walls that get bigger divide neurogenesis until front divides on itself and creates a brain 3200 genes make your brain always need these genes on seems insufficient o Epigenetic stuff happening to the genome opening closing allowing genes to be read Abusive parent example inherit an epigenetic control over a behavior gene more likely to abuse your children histones decide which genes get turned on and when o Lamarck genetics passed down and abusive gene Not actually true Can pick up an acquired trait and pass it down Proliferation Making more cells o Most neurons produced in first half of pregnancy b w Embryonic Day ED 42 125 o Neurons produced before most glial cells w in a region Neural Tube o Wall of cells in ventricular zone Cells being born here Radio glia rope from inside of outside of neuro Once no longer needed turn to astrocytes Migrating cells crawl up radio glia and settle on tube highway top layer Neocortex o 6 layers Brain size o Related to time and of cycles during proliferation in ventricular zone Man 22 4 hours 20 cycles Growth of brain just takes waiting Two times the cells 4 times neurons o Thickness of cortex only 6 layers As thick as it can get Need room for myelinated fibers Chimpanzee s tried it more cells o Larger brain Smart brain is NOT putting in more cells NO ROOM Cant get rid of the extra cells we do o Humans fewer cells with fancier connections b c of more room o We have complex wiring others don t Parahippocampal thickening have room for it Cortex increases with size over time w high IQ Superior Frontal thinning Cortex decreases with size over time not high IQ Size of brain correlates with lifespan in animals Initial slower growth longer cytogenic period Cost of brain power very metabolically active growth balanced against cost to maintain other body processes high brain power reduced gut size birth canal decreased fertility humans whales dolphins when born we only have senses we have more folding to fit bigger sheets of cortex folds occur at location of specific functions the more complicated regions are larger regions o hands and face o every species motor before senses vision in back Neuron number neurons wiring complexity intelligence size doesn t correlate intelligence bigger brains take longer to communicate o ex elephants have huge brains no myelin slow Maturation of synapses If a pathway isn t being used we get rid of it When younger lots of pathways When older less pathways o Flexible o Efficient Maturation of Myelin Primary motor sensory myelinate first Association cortex myelinate last Frontal paritetal Myelination finishes 20 25 in females 25 30 in males o Smaller brains Fast initial growth Neurogenesis terminates earlier in development Corpus Callosum Interconnects hemispheres Gets proportionally smalls as cortex size increases o Decreased connections Allow less cooperation of tasks w each other Specialize in specific tasks Thinking w out words Control of only right hand Disadvantage Stroke cancer produce big deficits Glutamate Pathological activation of glutamate receptors o By binding to NMDA receptor it induces death of a synapse Allows to much calcium to activate Killing a synapse kills the whole neuron Both sides of pathway die Responsible for apoptosis o Why our brains work better than chimps Glutamate gets rid of unused pathways PNS Loves to regenerate o Myelin sheath in PNS can remain intact after injury o Helps guide regrowing nerve axon to correct site Cancer kills long axons Patients lose feeling in hands feet o Injured neurons in PNS Can die for many different reasons Have many different results Motor neuron injury Muscle will atrophy Will slowly regenerate Physical therapy Mixed rewiring of axonal regeneration Kills synapse Neuromas Chronic pain o Most common complaint of pain around the world Collateral sprouting after neural degeneration One neuron injured other will share function Finger CNS Depends on stem cells o Pluripotent Make them into the cell desired for functioning Stem cells o Originate in proliferative zone throughout life o Guided on migration by glia New neurons in hippocampus o Forms memories o Anti depressant drugs stimulate production Regrowth discouraged in CNS o Creates rewiring issues o Spinal Cord Injuries Astrocytes glial cells block the area severed Can t recombine or regrow together Developmental Disorders Autism Prevalence o Regional differences in US o Inflexible synaptic spines Make it hard to learn LTP isn t working b w neurons o Low functioning autistics different folding patter of gyri Mostly in frontal inferior Broca s area o High functioning autistics Different folding pattern of gyri o Acetylcholine Autistics don t pay attention very well Lack of interest in faces Fusiform gyrus has less acetylcholine Place for recognizing faces CARDIAC RHYTHMS SLEEP 11 03 2013 plikCircadian Rhythms Rhythm controlled by light coming into eyes Through suprachiasmatic nuclei SCN o Above pituitary o Tells us it s day time o Seasonal Affective Disorder SAD Less light coming into eyes Less neuronal activity making someone depressed o Damage to SCN Disrupts sleep wake patterns traveling east is harder than traveling west disrupts biorhythms typically biorhythms 25 hours long Output Rhythms o Physiology o Behavior Lizards o Small cortex o Skulls have holes to let in light Pineal gland o Controlled by SCN o Produces melatonin o Melatonin reset bio clock Great for jetlag Sleep Biorhythms of sleep o Cell repair o Body cools at night Surge of melatonin during night SCN controls many other things besides melatonin Brain stops defending you against temperature changes To wake up body warms you up All of this is less when we get older o Depressed people wake up too early Body warms too soon o Eating before bed Surge of energy from 1 3am from food processing Wake up hot o Growth hormones released Helps body healing o Potassium levels up and down o Cortisol increases Stress hormone Goes up as we get closer to waking up Sleep time o More sleep correlates losing weight o Too much time awake means more calories Muscle metabolism goes up during sleep Fat burning increases during sleep Less likely to resist insulin o No light Sleep biorhythms disconnect from each other Cold at the wrong time during sleep Bio clock