EXSC%224:%Week%of%1/30/17%%Lecture%1/31%Notes%The$brainstem$$• has$3$regions:$o midbrain:$made$of$the$corpora$quadrigemina$and$cerebral$aqueduct$o pons$o medulla$oblongata$• is$responsible$for$physiological$needs:$heart$beat,$breathing$• it$is$continuous$with$the$spinal$cord$o information$is$either$being$relayed$to/from$the$spinal$cord$from/through$the$brain$stem$• the$brainstem$ends$where$the$medulla$exits$the$skull$midbrain$• superior-most$region$of$the$brainstem$• cerebral$peduncles$o contain$pyramidal$motor$tracts$o function$as$a$connection$o carry$descending$motor$information$o 80%$of$voluntary$motor$information$goes$through$here$• cerebral$aqueduct:$channel$between$3rd$and$4th$ventricles$• corpora$quadrigemina$of$tectum$o made$of$2$superior$colliculi$and$2$inferior$colliculi$o reflex$centers$o superior$colliculi:$visual$reflexes$§ ex/$turn$head$when$you$see$something$out$of$the$corner$of$your$eye$o inferior$colliculi:$auditory$reflexes$§ ex/$you$jolt$and$look$around$when$you$hear$a$loud$bang$• superior$cerebellar$peduncles$o connect$cerebellum$to$midbrain$and$transmits$this$information$to$higher$processing$centers$• red$nuclei=group$of$cells$involved$with$motor$functioning$pons$• forms$part$of$the$anterior$wall$of$the$4th$ventricle$• some$nuclei$of$the$reticular$formation$here$help$maintain$the$normal$rhythm$of$breathing$• has$middle$cerebellar$peduncle$• has$fibers$of$the$pyramidal$tract$that$are$associated$with$the$crus$cerebri$peduncles$• pontine$nuclei:$cardio-respiratory$centers$exist$to$regulate$breathing$and$heart$rate$medulla$oblongata$• has$2$pyramids:$ventral$longitudinal$ridges$formed$by$pyramidal$tracts$• decussation$of$pyramids-crossover$of$corticospinal$tracts$• has$the$medial$lemniscus$• autonomic$reflex$centers$o cardiovascular$center$§ heart$rate/force$§ blood$vessel$diameter$o respiratory$centers$§ generate$respiratory$rhythm$§ control$rate$and$depth$of$breathing$with$pontine$centers$o additional$centers$regulate$§ vomiting$§ hiccupping$§ swallowing$§ coughing$§ sneezing$Cerebellum$• 11%$of$the$mass$of$the$brain$• subconsciously$provides$précising$timing$and$appropriate$patterns$of$skeletal$muscle$contraction$• fine$tunes$motor$movements$in$real$time$• refines$motor$paths$• smooth$coordinated$muscle$contraction$• proprioception:$awareness$of$body’s$position$and$momentum$• recognizes$and$predicts$sequences$of$events$during$complex$movements$• plays$role$in$non-motor$word$association$and$puzzle$solving$• anterior$lobe=ventral$surface$• posterior$lobe=dorsal$surface$• right$side$of$cerebellum$receives$information$from$the$right$side$of$the$body$(epsilateral)$Functional$brain$systems$• Networks$of$neurons$that$work$together$and$span$wide$areas$of$the$brain$o Limbic$system$o Reticular$formation$Limbic$system$• Emotional$or$affective$brain$o Amygdala:$emotional$center,$recognizes$angry$or$fearful$facial$expressions,$assesses$danger,$and$elicits$the$fear$response$§ Helps$store$emotional$memories$§ Helps$pick$out$appropriate$emotion$o Cingulate$gyrus:$plays$a$role$in$expressing$emotions$via$gestures,$and$resolves$mental$conflict$o Hippocampus:$memory$§ Vital$role$in$learning$§ If$damaged,$can’t$learn$new$information.$May$be$able$to$learn$implicit$information$like$how$to$do$things$but$not$explicit$information$like$someone’s$name$• Puts$emotional$responses$to$odors$o Ex:$skunks$smell$bad$Reticular$formation$• Clusters$of$cell$bodies$in$all$3$sections$of$the$brain$stem$• Three$broad$columns$along$the$length$of$the$brain$stem$o Raphe$nuclei$o Medial$group$of$nuclei$o Lateral$group$of$nuclei$• Vital$role$in$basic$regulation$(blood$pressure,$heart$rate,$breathing)$• RAS$(reticular$activating$system)$$o Sends$impulses$to$the$cerebral$cortex$to$keep$it$conscious$and$alert$o Filters$out$repetitive$and$weak$stimuli$(about$99%$of$all$stimuli)$o Severe$injury$results$in$permanent$unconsciousness$(coma)$o has$a$role$in$helping$keep$you$alert$and$conscious$(when$inhibited,$you$lose$consciousness)$• Motor$function$o Helps$control$coarse$limb$movements$o Reticular$autonomic$centers$regulate$visceral$motor$functions$o Vasomotor$o Cardiac$o Respiratory$centers$Consciousness$• Self-awareness$• Brain$knows$it$exists$• Fainting$is$a$loss$of$consciousness$o It$is$a$mechanism$used$by$the$body$so$that$the$head$gets$in$line$with$the$heart$so$that$blood$is$not$having$to$be$pumped$up$against$gravity$memory$• Storage$and$retrieval$of$information$• Two$stages$of$storage$• Short-term%memory$(STM,$or$working$memory)—temporary$holding$of$information;$limited$to$seven$or$eight$pieces$of$information$• Hippocampus$is$not$needed$for$short$term$memory$• STM$codes$about$10$pieces$of$information$max$• Long-term%memory%(LTM)$has$limitless$capacity$• Hippocampus$helps$in$the$conversion$of$information$from$short$term$to$long$term$memory$• Sensory$input$comes$in$and$goes$through$the$hippocampus$• Factors$that$affect$transfer$from$STM$to$LTM$• Emotional$state:$best$if$alert,$motivated,$surprised,$and$aroused$• Rehearsal:$repetition$and$practice$$• Association:$tying$new$information$with$old$memories$$• Automatic$memory:$subconscious$information$stored$in$LTM$$Lecture%2/2%Notes%Protection$of$the$brain$• Bone$(skull)$• Membranes$(meninges)$o Cover$and$protect$the$CNS$o Made$of$connective$tissue$o Protect$blood$vessels$and$enclose$venous$sinuses$o Contain$cerebrospinal$fluid$(CSF)$o Form$partitions$in$the$skull$o Meningitis=inflammation$of$the$meninges$o 3$layers$§ dura$mater:$periosteal$and$meningeal$layer$§ arachnoid$mater:$loose$covering,$has$fiber-like$projections$• subarachnoid$space:$space$between$the$arachnoid$and$pia$maters,$filled$with$cerebrospinal$fluid$• arachnoid$villus:$1$way$valve$that$allows$CSF$to$exit$space$and$enter$circulation$§ pia$mater:$really$tight$on$the$cortex$of$the$brain,$delicate,$fine$• Watery$cushion$(cerebrospinal$fluid)$o Manufactured$at$the$2$lateral$ventricles$and$the$4th$ventricle$o Produce$150$mL$per$day$o Naturally$generates$pressure$to$push$itself$through$the$ventricle$system$o When$it$gets$to$the$4th$ventricle$it$can…$§ Keep$descending$to$the$central$canal$of$the$spinal$cord$and$exit,$then$come$back$up$an$ascending$pathway$§ OR$it$can$go$through$an$aperture$and$enter$the$subarachnoid$space$directly$o