EXSC%224:%Week%of%1/23/17%%Textbook%Notes%Ch.%11.10%&%12.1%11.10$Neurons$act$together,$making$complex$behaviors$possible$• Neurons$are$organized$into$neuronal$pools$• Neuronal$pools$are$functional$groups$of$neurons$• Patterns$of$neural$processing$o Serial:$input$travels$along$one$pathway$to$a$specific$destination$o Parallel:$input$travels$along$several$different$pathways$to$be$integrated$in$different$CNS$regions$12.1$Folding$during$development$determines$the$complex$structure$of$the$adult$brain$• In$embryonic$development$the$nervous$system$starts$out$as$a$neural$tube$• Then$it$expands$into$three$primary$brain$vesicles$o Prosencephalon$(forebrain)$o Mesencephalon$(midbrain)$o Rhombencephalon$(hindbrain)$• These$develop$into$the$secondary$brain$vesicles$o Telencephalon$o Diencephalon$o Mesencephalon$o Metencephalon$o Myelencephalon$$• 4$Brain$regions$o cerebral$hemispheres$o diencephalon$o brain$stem$o cerebellum$• ventricles$o they$are$all$continuous$with$one$another$and$the$central$canal$of$the$spinal$cord$o 4$ventricles$§ 2$lateral$ventricles-they$are$separated$by$the$septum$pellucidum$(a$thin$membrane)$§ 3rd$ventricle-in$the$diencephalon,$communicates$with$the$lateral$ventricles$by$a$channel$called$the$interventricular$foramen$§ 4th$ventricle-connected$to$the$3rd$ventricle$by$the$cerebral$aqueduct$$Lecture%1/24%Notes%Neurotransmitter$receptors$• Two$types$o Channel$linked$(ionotropic)$receptors$§ Direct$§ Ligand$gated$ion$channels$§ Action$is$immediate$and$brief$§ Only$open$as$long$as$ligand$is$bound$to$the$channel$§ Properties$of$the$pore$itself$regulates$what$ions$can$go$through$it$§ Channels$usually$regulate$what$enters$based$on$the$size$of$the$ion$§ Excitatory$receptors:$receptors$are$channels$that$allow$an$influx$of$Na+$(depolarization)$§ Inhibitory:$receptors$allow$Cl-$influx$or$K+$efflux$(hyperpolarization)$o G-protein$linked$receptors$§ Indirect$§ Uses$second$messenger$systems$§ Not$an$ion$channel$or$pore$§ When$activated,$it$activates$a$series$of$steps$that$can$open$up$a$channel$in$the$membrane$1. Neurotransmitter$(1st$messenger)$binds$and$activates$receptor$2. Receptor$activates$small$G$protein$a. Not$embedded$in$the$membrane$b. Loses$a$GDP$and$picks$up$GTP$(energy$source)$3. G$protein$activates$adenylate$cyclase$4. Adenylate$cyclase$converts$ATP$to$cyclic$AMP$(cAMP)$the$2nd$messenger$5. cAMP$changes$membrane$permeability$by$opening$and$closing$ion$channels$a. cAMP$activates$enzymes$Neural$integration:$Neuronal$pools$• Functional$groups$of$neurons$that:$o Integrate$incoming$information$o Forward$the$processed$information$to$other$destinations$Patterns$of$neural$processing$• Serial$processing$• Ex:$reflexes-rapid,$auto-response$to$stimulus$that$always$has$the$same$response$• Reflex$arcs$(pathways)$have$5$essential$components$o Receptor$o Sensory$neuron$o Integration$center$o Motor$neuron$o Effector$• Parallel$processing$o Input$travels$along$several$pathways$o One$stimulus$promotes$numerous$responses$at$the$same$time$o Important$for$higher$level$mental$functioning$§ Ex/$smell$reminding$you$of$something$(pathways$involve$sensory$parts$of$the$brain$as$well$as$memory$center)$o Information$comes$in$and$moves$to$different$regions$of$the$brain$$$Simple$neuronal$pool$• Single$presynaptic$neuron$fiber$branches$and$has$synapses$with$several$neurons$in$the$pool$Types$of$circuits$in$neuronal$pools$• Diverging$circuit$o 1$incoming$fiber$stimulates$an$increasing$number$of$fibers$o may$affect$one$or$more$pathways$o common$in$sensory$and$motor$pathways$o also$known$as$amplifying$circuit$• converging$circuit$o opposite$of$divergent$circuit$o results$in$either$strong$stimulation$or$inhibition$o also$common$in$sensory$and$motor$systems$• reverberating$circuit$o chain$of$neurons$containing$collateral$synapses$with$previous$neurons$in$the$chain$o usually$common$with$basal$processes$(ex:$breathing)$o perpetually$activate$themselves$• parallel$after$discharge$circuit$o incoming$fiber$stimulates$several$neurons$in$parallel$arrays$to$stimulates$several$neurons$in$parallel$arrays$to$stimulate$a$common$output$cell$$Chapter$12:$The$cerebrum$part$1$In$development$• starts$as$a$hollow,$fluid-filled$tube$• all$the$nervous$system$will$come$from$this$• as$a$fetus$it$starts$becoming$something$• secondary$brain$vesicles$and$what$they$will$turn$into$o telencephalon$(new$brain):$cerebrum$o diencephalon$(new$brain):$thalamus,$hypothalamus,$and$epithalamus$o mesencephalon$(old$brain):$brainstem-midbrain$o metencephalon$(old$brain):$brainstem-pons,$and$cerebellum$o myelencephalon$(old$brain):$brainstem-medulla$oblongata$• brain$grows$fastest$during$fetal$development$• brain$grows$faster$than$the$skull$growing$around$it$so$it$folds$up$to$save$space$and$fit$o folds$result:$sulci,$gyri,$and$fissures$Gray$vs$white$matter$• gray:$neuron$cell$bodies$or$unmyelinated$axons$o cortex$over$cerebrum$and$cerebellum$o forms$nuclei$deep$in$the$brain$• white:$bundles$of$axons$(myelinated)$o forms$tracts$that$connect$parts$of$the$brain$o ascending$and$descending$tracts$in$the$spinal$cord$Ventricles$• fluid$contained$system$of$brain$and$spinal$cord$• 2$large$ones$in$right$and$left$hemispheres$• lateral$ventricles$produce$cerebrospinal$fluid$• lined$by$ependymal$cells$• connects$to$3rd$ventricles$which$connects$to$cerebral$aqueduct$and$the$4th$ventricle$• apertures$allow$fluid$to$leave$ventricles$and$surround$brain$• brain$is$floating$in$cerebrospinal$fluid$cerebral$hemisphere$• frontal$lobe$• parietal$lobe$• occipital$lobe$• temporal$lobe$• insula:$not$visible,$under$the$temporal$lobe$• 3$functional$areas$o motor$o sensory$o association$frontal$lobe$• has$the$motor$cortex$• responsible$for$cognition$(conscience$thought)$• no$sensory$processing$• front$of$brain$to$central$sulcus$• premotor$cortex:$stores$muscle$memory$• frontal$eye$field:$voluntary$eye$movement$• Broca’s$area:$speech$production$• Primary$motor$cortex:$voluntary$movement$starts$here$$Textbook%Notes%Ch.%12.2%&%12.3%12.2$The$cerebral$hemispheres$consist$of$cortex,$white$matter,$and$the$basal$nuclei$• Cerebral$hemispheres$o 83%$of$brain$mass$o form$superior$part$of$brain$o gyri=elevated$ridges$o sulci=shallow$grooves$o fissures=deeper$grooves$o 5$lobes$§ temporal$§ frontal$§ parietal$§ occipital$§