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Chapter 14 Lecture Outline Copyright (c) The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 14-1.

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1 Chapter 14 Lecture Outline Copyright (c) The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 14-1

2 14-2 Central Nervous System overview of the brain meninges, ventricles, cerebrospinal fluid and blood supply hindbrain and midbrain forebrain integrative functions the cranial nerves Figure 14.1a Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Frontal lobe Occipital lobe Central sulcus Longitudinal fissure Parietal lobe (a) Superior view Cerebral hemispheres

3 14-3 Introduction to the Nervous System Aristotle: brain was ‘radiator’ to cool blood Hippocrates: “from the brain only, arises our pleasures, joys, laughter, and jests, as well as our sorrows, pains, griefs, and tears” cessation of brain activity - clinical criterion of death evolution of the CNS: spinal cord very little change, while brain has changed a great deal –greatest growth in areas of vision, memory, and motor control of the prehensile hand

4 14-4 Directional Terms and Landmarks rostral - toward the forehead caudal - toward the spinal cord three major portions: cerebrum, cerebellum, brainstem –cerebrum is 83% of brain volume –cerebellum contains 50% of the neurons; second largest brain region –brainstem the portion of the brain that remains if the cerebrum and cerebellum are removed Figure 14.1b Brainstem Cerebellum Cerebrum Spinal cord RostralCaudal Central sulcus Lateral sulcus Gyri (b) Lateral view Temporal lobe Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

5 14-5 Cerebrum longitudinal fissure – deep groove that separates cerebral hemispheres gyri - thick folds sulci - shallow grooves corpus callosum – thick nerve bundle at bottom of longitudinal fissure that connects hemispheres Figure 14.1a Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Frontal lobe Occipital lobe Central sulcus Longitudinal fissure Parietal lobe (a) Superior view Cerebral hemispheres

6 14-6 Cerebellum occupies posterior cranial fossa about 10% of brain volume contains over 50% of brain neurons Figure 14.1b Brainstem Cerebellum Cerebrum Spinal cord RostralCaudal Central sulcus Lateral sulcus Gyri (b) Lateral view Temporal lobe Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

7 14-7 Brainstem brainstem – what remains of the brain if the cerebrum and cerebellum are removed major components –diencephalon –midbrain –pons –medulla oblongata Figure 14.1b Brainstem Cerebellum Cerebrum Spinal cord RostralCaudal Central sulcus Lateral sulcus Gyri (b) Lateral view Temporal lobe Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

8 14-8 Median Section of the Brain Figure 14.2a Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. leaves Thalamus Hypothalamus Frontal lobe Corpus callosum Cingulate gyrus Optic chiasm Pituitary gland Mammillary body Midbrain Pons Central sulcus Parietal lobe Parieto–occipital sulcus Occipital lobe Pineal gland Habenula Posterior commissure Cerebral aqueduct Fourth ventricle Cerebellum (a) Epithalamus Anterior commissure Temporal lobe Medulla oblongata

9 14-9 Median Section of Cadaver Brain Figure 14.2b Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Corpus callosum Cingulate gyrus Lateral ventricle Thalamus Hypothalamus Midbrain Cerebellum Fourth ventricle Pons (b) Choroid plexus Pineal gland Occipital lobe Parieto–occipital sulcus Posterior commissure © The McGraw-Hill Companies, Inc./Dennis Strete, photographer Medulla oblongata

10 14-10 Gray and White Matter gray matter – the seat of neuron cell bodies, dendrites, and synapses –dull white color when fresh, due to little myelin –forms surface layer, cortex, over cerebrum and cerebellum –forms nuclei deep within brain white matter - bundles of axons –lies deep to cortical gray matter, opposite relationship in the spinal cord –pearly white color from myelin around nerve fibers –composed of tracts, bundles of axons, that connect one part of the brain to another, and to the spinal cord

11 Embryonic Brain Development Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. leaves (a) 19 days (c) 22 days Ectoderm Notochord Neural groove Neural fold Neural plate (b) 20 days (d) 26 days Somites Neural crest Neural crest Neural tube Figure 14.3

12 14-12 Embryonic Brain Development Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Diencephalon Mesencephalon Telencephalon Forebrain Pons Cerebellum Metencephalon Spinal cord Hindbrain Spinal cord Rhombencephalon Mesencephalon Prosencephalon (a) 4 weeks(b) 5 weeks (c) Fully developed Midbrain Myelencephalon (medulla oblongata) 4th week –forebrain –midbrain –hindbrain 5th week –telencephalon –diencephalon –mesencephalon –metencephalon –myelencephalon Figure 14.4

13 14-13 Meninges meninges – three membranes that envelop the brain –lie between the nervous tissue and bone –as in spinal cord: dura mater, arachnoid mater, pia mater –protect the brain and provide structural framework for arteries and veins dura mater –in cranial cavity - 2 layers –cranial dura mater is pressed closely against cranial bones no epidural space layers separated by dural sinuses – collect blood circulating through brain –folds inward to extend between parts of the brain

14 14-14 Meninges arachnoid mater and pia mater are similar to those in the spinal cord arachnoid mater –transparent membrane over brain surface –subarachnoid space separates it from pia mater below –subdural space separates it from dura mater above in some places pia mater –very thin membrane that follows contours of brain, even dipping into sulci –not usually visible without a microscope

15 14-15 Meninges of the Brain Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Subdural space Skull Pia mater Blood vessel Dura mater: Periosteal layer Meningeal layer Arachnoid mater Brain: Gray matter White matter Arachnoid villus Subarachnoid space Superior sagittal sinus Falx cerebri (in longitudinal fissure only) Figure 14.5

16 14-16 Meningitis meningitis - inflammation of the meninges –serious disease of infancy & childhood –especially between 3 months and 2 years of age caused by bacterial or viral invasion of the CNS by way of the nose and throat pia mater and arachnoid are most often affected signs include high fever, stiff neck, drowsiness, and intense headache and may progress to coma & death diagnosed by examining the CSF for bacteria –lumbar puncture (spinal tap) draws fluid from subarachnoid space between two lumbar vertebrae

17 14-17 Brain Ventricles Figure 14.6 a-b Lateral ventricles Central canal Lateral aperture Fourth ventricle Third ventricle Median aperture (a) Lateral view Caudal Interventricular foramen Cerebral aqueduct Rostral Lateral ventricle Third ventricle Cerebrum Lateral aperture Fourth ventricle Median aperture (b) Anterior view Interventricular foramen Cerebral aqueduct Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

18 14-18 Ventricles and Cerebrospinal Fluid ventricles – four internal chambers within the brain –two lateral ventricles – one in each cerebral hemisphere interventricular foramen - a tiny pore that connects to third ventricle –third ventricle – single medial space beneath corpus callosum cerebral aqueduct runs through midbrain and connects third to fourth ventricle –fourth ventricle – small triangular chamber between pons and cerebellum connects to central canal, runs down through spinal cord choroid plexus – spongy mass of blood capillaries on the floor of each ventricle

19 14-19 Ventricles of the Brain Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Choroid plexus Thalamus Gyrus Sulcus Caudate nucleus Frontal lobe White matter Lateral ventricle Temporal lobe Third ventricle Lateral sulcus Insula Lateral ventricle Occipital lobe (c) Rostral (anterior) Caudal (posterior) Longitudinal fissure Gray matter (cortex) Corpus callosum (anterior part) Septum pellucidum Corpus callosum (posterior part) Longitudinal fissure © The McGraw-Hill Companies, Inc./Rebecca Gray, photographer/Don Kincaid, dissections Figure 14.6c

20 14-20 Cerebrospinal Fluid (CSF) cerebrospinal fluid (CSF) – clear, colorless liquid that fills the ventricles and canals of CNS –made by ependyma – neuroglia that line the ventricles and cover choroid plexus brain produces and absorbs 500 mL/day –100 – 160 mL normally present at one time production begins with the filtration of blood plasma through the capillaries of the brain –ependymal cells modify the filtrate, so CSF has more sodium and chloride than plasma, but less potassium, calcium, glucose, and very little protein

21 14-21 Cerebrospinal Fluid (CSF) Circulation CSF continually flows through and around the CNS –driven by its own pressure, beating of ependymal cilia, and pulsations of the brain produced by each heartbeat CSF secreted in lateral ventricles flows through intervertebral foramina into third ventricle, then down the cerebral aqueduct into the fourth ventricle small amount of CSF fills the central canal of the spinal cord –all escapes through three pores median aperture and two lateral apertures leads into subarachnoid space CSF is reabsorbed by arachnoid villi –protrude through dura mater into superior sagittal sinus

22 14-22 Flow of Cerebrospinal Fluid Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Choroid plexus in fourth ventricle adds more CSF. CSF flows out two lateral apertures and one median aperture. CSF fills subarachnoid space and bathes external surfaces of brain and spinal cord. At arachnoid villi, CSF is reabsorbed into venous blood of dural venous sinuses CSF is secreted by choroid plexus in each lateral ventricle. CSF flows through Interventricular foramina into third ventricle. Choroid plexus in third ventricle adds more CSF. CSF flows down cerebral aqueduct to fourth ventricle. Arachnoid villus Superior sagittal sinus Arachnoid mater Subarachnoid space Dura mater Choroid plexus Third ventricle Cerebral aqueduct Lateralaper ture Fourth ventricle Median aperture Centralcanal of spinal cord Subarachnoid space of spinal cord Figure 14.7

23 14-23 Functions of CSF buoyancy –allows brain to attain considerable size without being impaired by its own weight –if it rested heavily on floor of cranium, the pressure would kill the nervous tissue protection –protects the brain from striking the cranium when the head is jolted –shaken child syndrome and concussions do occur from severe jolting chemical stability –flow of CSF rinses away metabolic wastes from nervous tissue and homeostatically regulates chemical environment

24 14-24 Blood Supply to the Brain brain is only 2% of the adult body weight, and receives 15% of the blood –750 mL/min neurons have a high demand for ATP, and therefore, oxygen and glucose, so a constant supply of blood is critical to the nervous system –10 second interruption of blood flow may cause loss of consciousness –1 – 2 minute interruption can cause significant impairment of neural function –4 minutes without blood causes irreversible brain damage

25 14-25 Brain Barrier System blood is also a source of antibodies, macrophages, bacterial toxins, and other harmful agents brain barrier system – strictly regulates what substances can get from the bloodstream into the tissue fluid of the brain two points of entry must be guarded: –blood capillaries throughout the brain tissue –capillaries of the choroid plexus

26 14-26 Brain Barrier System blood-brain barrier - protects blood capillaries throughout brain tissue –consists of tight junctions between endothelial cells that form the capillary walls –astrocytes reach out and contact capillaries with their perivascular feet –anything leaving the blood must pass through the cells, and not between them –endothelial cells can exclude harmful substances from passing to the brain tissue while allowing necessary ones to pass

27 14-27 Brain Barrier System blood barrier system is highly permeable to water, glucose, and lipid-soluble substances such as oxygen, carbon dioxide, alcohol, caffeine, nicotine, and anesthetics obstacle for delivering medications such as antibiotics and cancer drugs trauma and inflammation can damage BBS and allow pathogens to enter brain tissue –circumventricular organs (CVOs) – places in the third and fourth ventricles where the barrier is absent blood has direct access to the brain enables the brain to monitor and respond to fluctuations in blood glucose, pH, osmolarity, and other variables CVOs allow human immunodeficiency virus (HIV) to invade

28 14-28 Medulla Oblongata begins at foramen magnum of the skull extends for about 3 cm rostrally and ends at a groove between the medulla and pons all nerve fibers connecting the brain to the spinal cord pass through the medulla Figure 14.2a

29 14-29 Medulla Oblongata cardiac center –adjusts rate and force of heart vasomotor center –adjusts blood vessel diameter respiratory centers –control rate and depth of breathing reflex centers –for coughing, sneezing, gagging, swallowing, vomiting, salivation, sweating, movements of tongue and head

30 14-30 Medulla and Pons Diencephalon: Midbrain: Thalamus Infundibulum Mammillary body Cerebral peduncle Pyramid Anterior median fissure Pyramidal decussation Spinal cord (a) Anterior view Pons Medulla oblongata:

31 14-31 Pons Figure 14.2a Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. leaves Thalamus Hypothalamus Frontal lobe Corpus callosum Cingulate gyrus Optic chiasm Pituitary gland Mammillary body Midbrain Pons Central sulcus Parietal lobe Parieto–occipital sulcus Occipital lobe Pineal gland Habenula Posterior commissure Cerebral aqueduct Fourth ventricle Cerebellum (a) Epithalamus Anterior commissure Temporal lobe Medulla oblongata pons – anterior bulge in brainstem, rostral to medulla

32 14-32 Pons ascending sensory tracts descending motor tracts pathways in and out of cerebellum various roles –sensory – hearing, equilibrium, taste, facial sensations –motor – eye movement, facial expressions, chewing, swallowing, urination, and secretion of saliva and tears – sleep, respiration, and posture

33 14-33 Cerebellum 2nd largest part of the total brain right and left cerebellar hemispheres connected by vermis cortex of gray matter with folds (folia) contains more than half of all brain neurons, about 100 billion white matter branching pattern is called arbor vitae Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. leaves (b) Superior view Folia Anterior Posterior Anterior lobe Vermis Posterior lobe Cerebellar hemisphere Figure 14.11b

34 14-34 Cerebellar Functions monitors muscle contractions and aids in motor coordination evaluation of sensory input –comparing textures without looking at them –spatial perception and comprehension timekeeping center –predicting movement of objects –helps predict how much the eyes must move in order to compensate for head movements and remain fixed on an object hearing –distinguish pitch and similar sounding words planning and scheduling tasks lesions may result in emotional overreactions and trouble with impulse control

35 14-35 Midbrain –short segment of brainstem that connects the hindbrain to the forebrain –contains cerebral aqueduct –tectum – roof-like part of the midbrain posterior to cerebral aqueduct part involves visual attention, tracking moving objects, and some reflexes part receives signals from the inner ear –relays them to other parts of the brain

36 14-36 Midbrain -- Cross Section Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. leaves Tegmentum Cerebral peduncle: Cerebral crus Tectum Cerebral aqueduct Reticular formation Central gray matter Medial lemniscus Red nucleus Substantia nigra Posterior Anterior (a) Midbrain (c) Medulla (b) Pons Figure 14.9a

37 14-37 Reticular Formation reticular formation – loosely organized web of gray matter that runs vertically through all levels of the brainstem clusters of gray matter scattered throughout pons, midbrain and medulla has connections with many areas of cerebrum more than 100 small neural networks without distinct boundaries Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Visual input Reticular formation Thalamus Radiations to cerebral cortex Ascending general sensory fibers Descending motor fibers to spinal cord Auditory input Figure 14.10

38 14-38 Functions of Reticular Formation Networks somatic motor control –adjust muscle tension to maintain tone, balance, and posture –signals from eyes and ears go to cerebellum - motor coord. –gaze center – allow eyes to track and fixate on objects –central pattern generators – neural pools that produce rhythmic signals to the muscles of breathing and swallowing cardiovascular control pain modulation –origin of descending analgesic pathways – fibers act in the spinal cord to block transmission of pain signals to the brain sleep and consciousness –plays central role in states of alertness and sleep habituation –brain learns to ignore repetitive, inconsequential stimuli

39 14-39 The Diencephalon Diencephalon Mesencephalon Telencephalon Forebrain Pons Cerebellum Metencephalon Spinal cord Hindbrain (c) Fully developed Midbrain Myelencephalon (medulla oblongata) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. –the diencephalon encloses the third ventricle most rostral part of the brainstem has three major embryonic derivatives –thalamus –hypothalamus –epithalamus Figure 14.4c

40 14-40 Diencephalon: Thalamus thalamus – ovoid mass on each side of the brain perched at the superior end of the brainstem beneath the cerebral hemispheres –the “gateway to the cerebral cortex” – nearly all input to the cerebrum passes through; filters information on its way to cerebral cortex –plays key role in motor control by relaying signals from cerebellum to cerebrum –involved in the memory and emotional functions of the limbic system Figure 14.12a

41 14-41 hypothalamus – forms part of the walls and floor of the third ventricle infundibulum – a stalk that attaches the pituitary gland to the hypothalamus major control center of autonomic nervous system and endocrine system –plays essential roll in homeostatic regulation of all body systems Diencephalon: Hypothalamus Figure 14.2a leaves Thalamus Hypothalamus Frontal lobe Corpus callosum Cingulate gyrus Optic chiasm Pituitary gland Mammillary body Midbrain Pons Central sulcus Parietal lobe Parieto–occipital sulcus Occipital lobe Pineal gland Habenula Posterior commissure Cerebral aqueduct Fourth ventricle Cerebellum (a) Epithalamus Anterior commissure Temporal lobe Medulla oblongata Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

42 14-42 functions of hypothalamic nuclei –hormone secretion regulates growth, metabolism, reproduction, stress responses –autonomic effects influences heart rate, blood pressure, gastrointestinal secretions and motility, and others –thermoregulation monitors body temperature –food and water intake produce sensations of hunger, satiety, and thirst –rhythm of sleep and waking controls 24 hour circadian rhythm –memory receives signals from hippocampus –emotional behavior anger, aggression, fear, pleasure, and contentment Diencephalon: Hypothalamus

43 Cerebrum cerebrum – largest and most conspicuous part of the human brain –seat of sensory perception, memory, thought, judgment, and voluntary motor actions Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. leaves Thalamus Hypothalamus Frontal lobe Corpus callosum Cingulate gyrus Optic chiasm Pituitary gland Mammillary body Midbrain Pons Central sulcus Parietal lobe Parieto–occipital sulcus Occipital lobe Pineal gland Habenula Posterior commissure Cerebral aqueduct Fourth ventricle Cerebellum (a) Epithalamus Anterior commissure Temporal lobe Medulla oblongata Figure 14.2a

44 14-44 Cerebrum - Gross Anatomy two cerebral hemispheres divided by longitudinal fissure –connected by white fibrous tract: corpus callosum –gyri and sulci – increases amount of cortex in the cranial cavity –some sulci divide each hemisphere into five lobes named for the cranial bones that overlay them Frontal lobe Occipital lobe Central sulcus Longitudinal fissure Parietal lobe (a) Superior view Cerebral hemispheres Figure 14.1a,b Brainstem Cerebellum Cerebrum Spinal cord RostralCaudal Central sulcus Lateral sulcus Gyri (b) Lateral view Temporal lobe

45 14-45 Cerebrum - Lobes Figure Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Postcentral gyrus Occipital lobe Temporal lobe Lateral sulcus Frontal lobeParietal lobe Insula RostralCaudal Central sulcus Precentral gyrus

46 14-46 frontal lobe –voluntary motor functions –motivation, foresight, planning, memory, mood, emotion, social judgment, and aggression parietal lobe –receives and integrates general sensory information, taste and some visual processing occipital lobe - primary visual center of brain temporal lobe –hearing, smell, learning, memory, aspects of vision & emotion insula (hidden by other regions) –understanding spoken language, taste and sensory information from visceral receptors Functions of Cerebrum - Lobes

47 14-47 Cerebral Cortex neural integration is carried out in the gray matter of the cerebrum cerebral gray matter found in three places –cerebral cortex –basal nuclei –limbic system cerebral cortex – layer covering the surface of the hemispheres –only 2 – 3 mm thick –cortex constitutes about 40% of the mass of the brain Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. I II III IV V VI Cortical surface Stellate cells Small pyramidal cells Large pyramidal cells White matter Figure 14.15

48 14-48 Cerebral Cortex contains two principal types of neurons stellate cells –receive sensory input and process information on a local level pyramidal cells –include the output neurons of the cerebrum –only neurons that leave the cortex and connect with other parts of the CNS neocortex – six layered tissue that constitutes about 90% of the human cerebral cortex Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. I II III IV V VI Cortical surface Stellate cells Small pyramidal cells Large pyramidal cells White matter Figure 14.15

49 14-49 The Basal Nuclei basal nuclei – masses of cerebral gray matter buried deep in the white matter, lateral to the thalamus –receives input from the midbrain and the motor areas of the cortex –send signals back to both these locations –involved in motor control Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cerebrum Corpus callosum Lateral ventricle Thalamus Insula Optic tract Hypothalamus Third ventricle Pituitary gland Internal capsule Caudate nucleus Putamen Subthalamic nucleus Globus pallidus Lentiform nucleus Corpus striatum Figure 14.16

50 14-50 Limbic System limbic system – important center of emotion and learning main components are: –cingulate gyrus – arches over top of corpus callosum –hippocampus – in the medial temporal lobe - memory –amygdala – immediately rostral to the hippocampus – emotion limbic system structures have centers for both gratification and aversion –gratification – sensations of pleasure or reward –aversion –sensations of fear or sorrow Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Basal nuclei Amygdala Temporal lobe Fornix Hippocampus Medial prefrontal cortex Corpus callosum Cingulate gyrus Orbitofrontal cortex Thalamic nuclei Mammillary body Figure 14.17

51 14-51 Higher Brain Functions higher brain functions - sleep, memory, cognition, emotion, sensation, motor control, and language involve interactions between cerebral cortex and basal nuclei, brainstem and cerebellum functions of the brain do not have easily defined anatomical boundaries integrative functions of the brain focus mainly on the cerebrum, but involves combined action of multiple brain levels

52 14-52 The Electroencephalogram electroencephalogram (EEG) – monitors surface electrical activity of the brain waves –for studying normal brain functions like sleep & consciousness –in diagnosis of degenerative brain diseases, metabolic abnormalities, brain tumors, etc. brain waves – 4 types defined by amplitude (mV) & frequency (Hz) persistent absence of brain waves is common clinical and legal criterion of brain death Figure 14.18a Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © The McGraw-Hill Companies, Inc./Bob Coyle, photographer 1 second Alpha (  ) Beta (  ) Delta (  ) Theta (  ) (a) (b) Figure 14.18b

53 14-53 Brain Waves alpha waves 8 – 13 Hz –awake and resting with eyes closed and mind wandering –suppressed when eyes open or performing a mental task beta waves 14 – 30 Hz –eyes open and performing mental tasks –accentuated during mental activity and sensory stimulation theta waves 4 – 7 Hz –drowsy or sleeping adults –if awake and under emotional stress delta waves high amplitude, less than 3.5 Hz –deep sleep in adults

54 14-54 Sleep sleep occurs in cycles called circadian rhythms –events that reoccur at intervals of about 24 hours sleep - temporary state of unconsciousness from which one can awaken when stimulated –sleep paralysis - inhibition of muscular activity –coma or hibernation – states of prolonged unconsciousness where individuals cannot be aroused from those states by sensory stimulation restorative effect –brain glycogen and ATP levels increase in non-REM sleep –memories strengthened in REM sleep synaptic connections reinforced

55 14-55 Four Stages of Sleep Stage 1 –feel drowsy, close our eyes, begin to relax –often feel drifting sensation, easily awakened if stimulated –alpha waves dominate EEG Stage 2 –pass into light sleep –EEG declines in frequency but increases in amplitude –exhibits sleep spindles – high spikes

56 14-56 Four Stages of Sleep Stage 3 –moderate to deep sleep –about 20 minutes after stage 1 –theta and delta waves appear –muscles relax and vital signs (body temperature, blood pressure, heart and respiratory rate) fall Stage 4 –called slow-wave-sleep (SWS) – EEG dominated by low-frequency, high amplitude delta waves –muscles now very relaxed, vital signs at their lowest, and we become more difficult to awaken

57 14-57 Rhythm of Sleep about 5X a night, a sleeper backtracks from stage 3 or 4 to stage 2 –exhibits bouts of rapid eye movement (REM) sleep –also called paradoxical sleep; EEG resembles the waking state, but sleeper is harder to arouse than any other stage – vital signs increase, brain uses more O 2 than when awake –sleep paralysis stronger dreams occur in both REM and non-REM sleep –REM tend to be longer and more vivid parasympathetic nervous system active during REM sleep –constriction of the pupils –erection of the penis and clitoris

58 14-58 Necessity of Sleep sleep has a restorative effect, and sleep deprivation can be fatal to experimental animals –bed rest alone does not have the restorative effect of sleep…why must we lose consciousness? –sleep may be the time to replenish such energy sources as glycogen and ATP –REM sleep may consolidate and strengthen memories by reinforcing some synapses, and eliminating others

59 14-59 Sleep Stages Figure Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Awake Stage 1 Stage 2 Stage 3 Stage 4 EEG stages Time (min) Time (hr) (a) One sleep cycle (b) Typical 8-hour sleep period Stage REM Sleep spindles Stage 1 Drowsy Stage 2 Light sleep Stage 3 Moderate to deep sleep Stage 4 Deepest sleep REM sleep

60 14-60 Cognition cognition – mental processes by which we acquire & use knowledge –sensory perception, thought, reasoning, judgment, memory, imagination, and intuition studies of patients with brain lesions, cancer, stroke, and trauma yield information on cognition –parietal lobe association area – perceiving stimuli contralateral neglect syndrome – unaware of objects on opposite side of their body –temporal lobe association area – identifying stimuli agnosia – inability to recognize, and name familiar objects prosopagnosia – person cannot remember familiar faces –frontal lobe association area – planning our responses and personality – inability to execute appropriate behavior

61 14-61 Memory information management requires –learning – acquiring new information –memory – information storage and retrieval –forgetting – eliminating trivial information hippocampus – important memory-forming center –organizes sensory and cognitive information into a unified long- term memory –memory consolidation – the process of “teaching the cerebral cortex” until a long-term memory is established –long-term memories are stored in various areas of the cerebral cortex cerebellum – helps learn motor skills amygdala - emotional memory

62 14-62 Memory amnesia – defects in declarative memory – describing past events –not usually procedural memory – like ability to tie your shoes –anterograde amnesia – unable to store new information –retrograde amnesia – cannot recall things they knew before the injury

63 14-63 Lobotomy of Phineas Gage severe injury with metal rod injury to the ventromedial region of both frontal lobes extreme personality change –fitful, irreverent, grossly profane –opposite of previous personality prefrontal cortex functions –planning, moral judgment, and emotional control Figure Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

64 14-64 Emotion emotional feelings are interactions between prefrontal cortex and diencephalon prefrontal cortex - seat of judgment, intent, and control over expression of emotions feelings come from hypothalamus and amygdala amygdala receives input from sensory systems –one output goes to hypothalamus - somatic and visceral motor systems heart races, raises blood pressure, makes hair stand on end, induce vomiting –other output to prefrontal cortex - controlling expression of emotions ability to express love, control anger, or overcome fear

65 14-65 Sensation primary sensory cortex - sites where sensory input is first received association areas nearby that process and interpret –primary visual cortex is bordered by visual association area which interprets visual stimuli –multimodal association areas – receive input from multiple senses and integrate this into an overall perception Anterior Posterior (a) Precentral gyrus Central sulcus Postcentral gyrus Parietal lobe Frontal lobe Occipital lobe Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 14.22a

66 14-66 Special Senses special senses – in head, employ complex sense organs vision –visual primary cortex in far posterior region of the occipital lobe –visual association area – anterior and occupies all the remaining occipital lobe hearing –primary auditory cortex in the superior region of the temporal lobe and insula –auditory association area – temporal lobe deep and inferior to primary auditory cortex equilibrium taste and smell

67 14-67 The General Senses general (somesthetic, somatosensory, or somatic) senses – distributed over the entire body; relatively simple receptors –touch, pressure, stretch, movement, heat, cold, and pain ascending tracts bring general sensory information from the rest of the body –thalamus processes the input –selectively relays signals to the postcentral gyrus of cerebrum awareness of stimulation occurs in primary somesthetic cortex making cognitive sense of the stimulation occurs in the somesthetic association area because of decussation, the right postcentral gyrus receives input from the left side of the body and vice versa

68 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Thigh Shoulder Arm V (b) Insula Lateral sulcus Genitalia Toes Leg Hip Trunk Eye Nose Face Upper lip Lower lip Teeth, gums Tongue Thumb (I) Wrist Hand Forearm Neck Elbow II III IV Fingers I II III IV V LateralMedial Abdominal viscera Sensory Homunculus Figure 14.22b sensory homunculus – diagram of the primary somesthetic cortex which resembles an upside-down sensory map of the contralateral side of the body somatotopy – the point-to- point correspondence between an area of the body and an area of the CNS Viscerosensory area

69 14-69 Functional Regions of Cerebral Cortex Wernicke area Broca area Primary motor cortex Motor association area Prefrontal cortex Olfactory association area Primary somesthetic cortex Somesthetic association area Primary gustatory cortex Visual association area Primary visual cortex Primary auditory cortex Auditory association area Figure Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

70 14-70 Motor Control the intention to contract a muscle begins in motor association (premotor) area of frontal lobes –where we plan our behavior –program for action transmitted to neurons of the precentral gyrus (primary motor area) –neurons send signals to the brainstem and spinal cord –ultimately resulting in muscle contraction –precentral gyrus also exhibits somatotopy –motor homunculus has a distorted look because the amount of cortex devoted to a given body region is proportional to the number of muscles and motor units in that body region

71 14-71 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fingers Eye and eyelid Tongue Ankle Lips Face Jaw Pharynx Vocalization Salivation Mastication Swallowing Neck Brow V Hand Wrist Elbow Shoulder Trunk Knee Hip Toes IV III II Thumb (I) I II III IV V (b) LateralMedial Motor Homunculus Figure 14.23b

72 14-72 Motor Control –In addition to the cerebrum, the cerebellum is involved cerebellum –highly important in motor coordination –aids in learning motor skills –maintains muscle tone and posture –smoothes muscle contraction –coordinates eye and body movements –coordinates the motions of different joints with each other –ataxia – clumsy, awkward gait

73 14-73 Language language includes several abilities: reading, writing, speaking, and understanding words assigned to different regions of the cerebral cortex Wernicke area –recognition of spoken and written language; creates plan of speech –when we intend to speak, Wernicke area formulates phases according to learned rules of grammar –transmits plan of speech to Broca area Broca area –generates motor program for the muscles of the larynx, tongue, cheeks and lips –transmits program to primary motor cortex for commands to the lower motor neurons that supply relevant muscles

74 14-74 Language Centers Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. leaves Precentral gyrus AnteriorPosterior Speech center of primary motor cortex Primary auditory cortex (in lateral sulcus) Postcentral gyrus Angular gyrus Primary visual cortex Wernicke area Broca area Figure 14.25

75 14-75 Aphasia aphasia – any language deficit from lesions in same hemisphere (usually left) containing the Wernicke and Broca areas nonfluent (Broca) aphasia –lesion in Broca area –slow speech, difficulty in choosing words, using words that only approximate the correct word fluent (Wernicke) aphasia –lesion in Wernicke area –speech normal and excessive, but uses jargon that makes little sense –cannot comprehend written and spoken words anomic aphasia –can speak normally and understand speech, but cannot identify written words or pictures

76 14-76 Cranial Nerves the brain must communicate with the rest of the body –most of the input and output travels by way of the spinal cord –12 pairs of cranial nerves arise from the base of the brain –exit the cranium through foramina –lead to muscles and sense organs located mainly in the head and neck

77 14-77 Cranial Nerve Disorders Trigeminal neuralgia (tic douloureux) –recurring episodes of intense stabbing pain in trigeminal nerve area (near mouth or nose) –pain triggered by touch, drinking, washing face –treatment may require cutting nerve Bell palsy –degenerative disorder of facial nerve causes paralysis of facial muscles on one side –may appear abruptly with full recovery within weeks


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