Presentation on theme: "Chapter 14 The Central Nervous System"— Presentation transcript:
1Chapter 14 The Central Nervous System Overview of the brainMeninges, ventricles, cerebrospinal fluid & blood supplyHindbrain and midbrainForebrainHigher brain functionsThe cranial nervesHippocampus & memory: People with damage to hippocampus can remember everything up to the brain damage. Could show clip from batman II. This indicates that sites of long term memory are located elsewhere in the game. Synaptic plasticity allows some synapses to harden, like when you’ve learned something so well you can do it automatically, like tying your shoes.Have groups of four students make a diagram that illustrates what parts of the body are controlled by the cerebrum, cerebellum, diencephalon, & Brain stem.Obtain PET, MRI, or other scans of normal and abnormal brains and get the students to predict the appearance of abnormal brains by first just looking at the normal ones.
2Brain – Directional Terms and Landmarks Size is not correlated to intelligence; Neanderthals had bigger brainsRostral (toward the forehead) - Caudal (toward the cord)Major parts of the brain - cerebrum, cerebellum, brainstemcerebrum is 83% of brain volume; cerebellum contains 50% of the neuronsbrain weighs 3 to 3.5 pounds
3Brain Longitudinal fissure separates 2 cerebral hemispheres. gyri are the folds and sulci the groovessurface layer of gray matter is called cortex;bundles of axons (white matter) are called tracts
9Regions of the cerebrum are specialized for different functions
10Meninges Dura mater -- outermost, tough membrane Closest to boneArachnoid mater is spider web filamentous layerPia mater is a thin vascular layer adherent to contours of brain
11Meningitis Inflammation of the meninges Serious disease of infancy and childhoodbetween 3 months and 2 years of ageBacterial and virus invasion of the CNS by way of the nose and throatpia mater and arachnoid are most likely to be affectedSigns include high fever, stiff neck, drowsiness and intense headache and may progress to comaDiagnose by examining the CSF, “Spinal Tap”
14Ventricles and Cerebrospinal Fluid Internal chambers within the CNSlateral ventricles found inside cerebral hemispheresthird ventricle is single vertical space under corpus callosumcerebral aqueduct runs through midbrainfourth ventricle is small chamber between pons & cerebellumcentral canal runs down through spinal cordHydroencephalitis can result from blockages at the foramen
15Cerebrospinal FluidClear liquid fills ventricles and canals & bathes its external surface (in subarachnoid space)Brain produces & absorbs about 500 ml/day- produced by ependymal cells lining the ventriclesfiltration of blood through choroid plexusFunctionsbuoyancy -- floats brain so it neutrally buoyantprotection -- cushions from hitting inside of skullchemical stability -- rinses away wastes
17Blood-Brain and Blood-CSF Barriers Blood-brain barrier is tightly joined endotheliumpermeable to lipid-soluble materials (alcohol, O2, CO2, nicotine and anesthetics)circumventricular organs in 3rd & 4th ventricles at breaks in the barrier where blood has direct accessmonitoring of glucose, pH, osmolarity & other variationsallows route for HIV virus to invade the brain
18Diagram depicting the main subdivisions of the embryonic vertebrate brain. These regions will later differentiate into forebrain, midbrain and hindbrain structures.
19Simple brain of our ancestors Forebrain, midbrain, hindbrain became subdivided during evolution
20Size increases with body size Brain size is constant function of body weight in fish, amphibians, reptilesLarger relative to body weight in birds, mammalsIncreasing complexity of forebrainSize of cerebrum = level of sophisticationCell bodies of the cerebrum are in the cortex (outer part) making surface area important
22Neural PathwaysBundles of nerves connecting distant parts of the brain.Corpus Callosum (huge body)million nerve fibersHot area to argue: do males/females have different sized C.C. & does this morphological difference lead to personality differences?Would a smaller C.C. in males mean they stay focused on a single task while females can multi-task?
23Hindbrain: Medulla Oblongata extension of spinal cordAscending & descending nervetracts – data conductionCardiac center adjusts rate &force of heart beatVasomotor center adjusts blood vessel diameterRespiratory centers control rate & depth of breathingReflex centers for coughing, sneezing, gagging, swallowing, vomiting, salivation, sweating, movements of tongue & head
24Medulla Oblongata Axons cross in medulla So right side of brain controls left side of body & vice versa
27Pons Bulge in the brainstem, rostral to the medulla Tracts of nerves go through itPathways in & out of cerebellumNuclei concerned with sleep, hearing, balance, taste, eye movements, facial expression, facial sensation, respiration, swallowing, bladder control & posture
28Cerebellum Muscle coordination, awareness of time, memory and emotion Involved in learning and remembering motor responses
29Midbrain, Cross Section Centers for the receipt and integration of several types of sensory information.-Superior colliculi – visual-Inferior colliculi - auditorySends info to forebrain.
30Reticular Activating System Regulate balance & posturerelaying information from eyes & ears to cerebellumgaze centers allow you totrack moving objectIncludes cardiac & vasomotor centersOrigin of descending analgesic pathwaysRegulates sleep & arousalinjury leads to irreversible comageneral anesthetics blocks this systemHabituation – acts as a sensory filter
31Diencephalon: Epithalamus Epithalamus includes thepineal gland (endocrine system) and the choroid plexus (CSF production).*The pineal gland produces melatonin, which is regulated in a circadian rhythm.Pineal Gland*In birds, the pineal gland is on the surface of the brain,directly under the skull and contains the photoreceptorsto regulate their biological clock.
32Diencephalon: Thalamus Gateway to cortexReceives nearly all sensory information on its way to cerebral cortexintegrate & directs information to appropriate areamain output center for motor info leaving the cerebrumInterconnected to limbic system so involved in emotional & memory functionsArousal, eye movements, taste, smell, hearing
34The Hypothalamus and Circadian Rhythms Animals exhibit all kinds of rhythmic behavior.-seasonal – migration, reproduction, hibernation-daily or circadian – sleep/wake cycles, activity cycles• External cues – light/dark cycle, magnetic fields, seasonal changes.• Internal cues – “biological clock”; in mammals, the suprachiasmatic nucleus (SCN)-produces specific proteins in response to changing light/dark cycles.-regulates hormone release, hunger, motor activity, etc.
35Limbic System Loop of cortical structures surrounding deep brain amygdala, hippocampus, fornix & cingulate gyrusAmygdala important in emotions and hippocampus in memory -- rest are not sure
36Cerebrum -- Gross Anatomy Cerebral cortex is 3mm layer of gray matter with extensive folds to increase surface area ---- divided into lobes
37Functions of Cerebrum Lobes Frontal contains voluntary motor functions and areas for planning, mood, smell and social judgementParietal contains areas for sensory reception & integration of sensory informationOccipital is visual center of brainTemporal contains areas for hearing, smell, learning, memory, emotional behaviorCan make a drawing on your hand
38EEG and Brain WavesElectroencephalogram records voltage changes from postsynaptic potentials in cerebral cortexDifferences in amplitude & frequency distinguish 4 types of brain waves
39Brain Waves & Sleep States of consciousness can be correlated with EEG 4 types of brain wavesalpha occur when awake & resting with eyes closedbeta occur with eyes open performing mental taskstheta occur during sleep or emotional stressdelta occur during deep sleepSleep is temporary state of unconsciousnesscoma is state of unconsciousness with no possible arousalreticular formation seems to regulate state of alertnesssuprachiasmatic nucleus acts as biological clock to set our circadian rhythm of sleep and waking
40Stages of Sleep Non-REM sleep occurs in stages 4 stages occurring in first 30 to 45 minutes of sleepstage 1 is drifting sensation (would claim was not sleeping)stage 2 still easily arousedstage 3 vital signs change -- BP, pulse & breathing rates dropreached in 20 minutesstage 4 is deep sleep -- difficult to arouseseems to have a restorative effectREM sleep occurs about 5 times a nightrapid eye movements under the eyelids, vital signs increase, EEG resembles awake person, dreams and penile erections occurmay help sort & strengthen information from memory
41Sleep Stages and Brain Waves Brain waves change as we pass through 4 stages of sleepalpha wavessleep spindlesthetadelta waves
42Sleep StagesNotice how REM sleep periods become longer and more frequent in the second half of the night
43CognitionCognition is mental processes such as awareness, perception, thinking, knowledge & memory75% of brain is association areas where integration of sensory & motor information occursExamples of effects of brain lesionsparietal lobe -- contralateral neglect syndrometemporal lobe -- agnosia (inability to recognize objects) or prosopagnosia (inability to recognize faces)frontal lobe -- problems with personality (inability to plan & execute appropriate behavior)
44MemoryInformation management requires learning, memory & forgetting (eliminating the trivia)pathological inability to forget have trouble with reading comprehensionanterograde amnesia -- can not store new dataretrograde amnesia -- can not remember old dataHippocampus is important in organizing sensory & cognitive information into a memorylesion to it causes inability to form new memoriesCerebellum helps learn motor skillsAmygdala important in emotional memory
45EmotionPrefrontal cortex controls how emotions are expressed (seat of judgement)Emotions form in hypothalamus & amygdalaartificial stimulation produces fear, anger, pleasure, love, parental affection, etc.electrode in median forebrain bundle in rat or human and a foot pedalpress all day to the exclusion of food (report a quiet, relaxed feeling)Much of our behavior is learned by rewards and punishments or responses of others to them
46Somatosensory CortexSomesthetic signals travel up gracile and cuneate fasciculi and spinothalamic tracts of spinal cordSomatosensory area is postcentral gyrus
47Sensory HomunculusDemonstrates that the area of the cortex dedicated to the sensations of various body parts is proportional to how sensitive that part of the body is.
48Special SensesOrgans of smell, vision, hearing & equilibrium project to specialized regions of the brainLocationstaste is lower end of postcentral gyrussmell is medial temporal lobe & inferior frontal lobevision is occipital lobehearing is superior temporal lobeequilibrium is mainly the cerebellum, but to unknown areas of cerebral cortex via the thalamus
49Sensory Association Areas Association areas interpret sensory informationSomatosensory association area (parietal lobe)position of limbs, location of touch or pain, and shape, weight & texture of an objectVisual association area (occipital lobe)identify the things we seefaces are recognized in temporal lobeAuditory association area (temporal lobe)remember the name of a piece of music or identify a person by his voice
50Motor ControlIntention to contract a muscle begins in motor association (premotor) area of frontal lobesPrecentral gyrus (primary motor area) processes that order by sending signals to the spinal cordpyramidal cells called upper motor neuronssupply muscles of contralateral side due to decussationMotor homunculus is proportional to number of muscle motor units in a region (fine control)
52Input and Output to Cerebellum Smooth muscle contractions, maintains muscle tone & posture, coordinates motions of different joints, aids in learning motor skills & coordinates eye movements
53Language Includes reading, writing, speaking & understanding words Wernicke’s area permits recognition of spoken & written language & creates plan of speechangular gyrus processes text into a form we can speakBroca’s area generates motor program for larynx, tongue, cheeks & lipstransmits that to primary motor cortex for actionAffective language area lesions produce aprosodiasame area as Broca’s on opposite hemisphere
56AphasiaAny language deficit resulting from lesions in same hemisphere as Wernicke’s & Broca’s areasLesion to Broca’s = nonfluent aphasiaslow speech, difficulty in choosing wordsentire vocabulary may be 2 to 3 wordsLesion to Wernicke’s = fluent aphasiaspeech normal & excessive, but makes little senseAnomic aphasia = speech & understanding are normal but text & pictures make no senseOthers = understanding only 1st half of words or writing only consonants
57Cerebral Lateralization Left hemisphere is categorical hemispherespecialized for spoken & written language, sequential & analytical reasoning (math & science), analyze data in linear wayRight hemisphere is representational hemisphereperceives information more holistically, perception of spatial relationships, pattern, comparison of special senses, imagination & insight, music and artistic skillHighly correlated with handedness91% of people right-handed with left side is categoricalLateralization develops with agetrauma more problems in males since females have more communication between hemisphere (corpus callosum is thicker posteriorly)