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Chapter 14 Lecture Outline

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

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

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 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 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Rostral Caudal Central sulcus Gyri Cerebrum Lateral sulcus Temporal lobe Cerebellum Brainstem Figure 14.1b Spinal cord (b) Lateral view

5 Cerebrum Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cerebral hemispheres 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 Frontal lobe Central sulcus Parietal lobe Occipital lobe Longitudinal fissure (a) Superior view Figure 14.1a

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

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

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

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

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. Neural plate Neural crest Neural crest leaves Neural fold Ectoderm Neural groove Notochord (a) 19 days (b) 20 days Neural crest Neural tube Somites (c) 22 days (d) 26 days Figure 14.3 14-11

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

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

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

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

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 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 Flow of Cerebrospinal Fluid
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Arachnoid villus 8 Superior sagittal sinus Arachnoid mater 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. 1 2 3 4 5 6 7 8 CSF is secreted by choroid plexus in each lateral ventricle. CSF flows through Interventricular foramina into third ventricle. Choroid plexus in third CSF flows down cerebral aqueduct to fourth ventricle. Subarachnoid space Dura mater 1 2 Choroid plexus 3 Third ventricle 7 4 Cerebral aqueduct Lateralaper ture Fourth ventricle 6 5 Median aperture 7 Centralcanal of spinal cord Figure 14.7 Subarachnoid space of spinal cord

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 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 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 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 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 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 Medulla Oblongata cardiac center vasomotor center respiratory centers
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 Medulla and Pons Diencephalon: Thalamus Infundibulum Mammillary body
Midbrain: Thalamus Infundibulum Mammillary body Cerebral peduncle Pyramid Anterior median fissure Pyramidal decussation Spinal cord (a) Anterior view Pons Medulla oblongata:

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

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 Cerebellum 2nd largest part of the total brain
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Anterior leaves Vermis Anterior lobe Posterior lobe Cerebellar hemisphere Folia Posterior Figure 14.11b (b) Superior view 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

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

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. Radiations to cerebral cortex Thalamus Auditory input Visual input Reticular formation Ascending general sensory fibers Descending motor fibers to spinal cord Figure 14.10

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 The Diencephalon the diencephalon encloses the third ventricle
most rostral part of the brainstem has three major embryonic derivatives thalamus hypothalamus epithalamus 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. Figure 14.4c

40 Diencephalon: Thalamus
Figure 14.12a 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

41 Diencephalon: Hypothalamus
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 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 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

42 Diencephalon: Hypothalamus
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

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

44 Cerebrum - Gross Anatomy
Cerebral hemispheres Rostral Caudal Central sulcus Gyri Cerebrum Frontal lobe Lateral sulcus Central sulcus Temporal lobe Cerebellum Parietal lobe Brainstem Spinal cord Occipital lobe Figure 14.1a,b Longitudinal fissure (b) Lateral view (a) Superior view 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

45 Cerebrum - Lobes Figure 14.13 Postcentral gyrus Occipital lobe
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Postcentral gyrus Occipital lobe Temporal lobe Lateral sulcus Frontal lobe Parietal lobe Insula Rostral Caudal Central sulcus Precentral gyrus Figure 14.13

46 Functions of Cerebrum - Lobes
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

47 Cerebral Cortex Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 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 Figure 14.15 Cortical surface I Small pyramidal cells II III Stellate cells IV Large pyramidal cells V VI White matter

48 Cerebral Cortex contains two principal types of neurons stellate cells
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 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 Figure 14.15 Cortical surface I Small pyramidal cells II III Stellate cells IV Large pyramidal cells V VI White matter

49 The Basal Nuclei Figure 14.16
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cerebrum Corpus callosum Lateral ventricle Thalamus Internal capsule Caudate nucleus Corpus striatum Putamen Lentiform nucleus Insula Third ventricle Globus pallidus Hypothalamus Subthalamic nucleus Optic tract Pituitary gland Figure 14.16 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

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 Limbic System Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Medial prefrontal cortex Corpus callosum Fornix Cingulate gyrus Thalamic nuclei Orbitofrontal cortex Mammillary body Basal nuclei Hippocampus Amygdala Temporal lobe Figure 14.17

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 The Electroencephalogram
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Alpha () Beta () Theta () Delta () Figure 14.18a 1 second (a) (b) Figure 14.18b © The McGraw-Hill Companies, Inc./Bob Coyle, photographer 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

53 Brain Waves alpha waves 8 – 13 Hz beta waves 14 – 30 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 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 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 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 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 O2 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 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 Sleep Stages Awake Sleep spindles Stage 1 Drowsy REM sleep Stage
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Awake Sleep spindles Stage 1 Drowsy REM sleep Stage Stage 2 Light sleep Stage 3 Moderate to deep sleep Stage 4 Deepest sleep 10 20 30 40 50 60 70 Time (min) (a) One sleep cycle Awake REM REM REM REM REM Stage 1 EEG stages Stage 2 Stage 3 Stage 4 1 2 3 4 5 6 7 8 Time (hr) Figure 14.19 (b) Typical 8-hour sleep period

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 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 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 Lobotomy of Phineas Gage
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 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 14.20

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 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 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Anterior Frontal lobe Precentral gyrus Central sulcus Postcentral gyrus Parietal lobe Occipital lobe Posterior (a) Figure 14.22a

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 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 Sensory Homunculus Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 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 Neck Hip Arm Trunk Shoulder II Elbow Thigh III IV Hand Wrist V Forearm Leg V IV I III II Thumb (I) Toes Fingers Genitalia Eye Nose Face Upper lip Teeth, gums Lower lip Tongue Abdominal viscera Viscerosensory area Lateral sulcus Insula Lateral Medial (b) Figure 14.22b 14-68

69 Functional Regions of Cerebral Cortex
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Primary somesthetic cortex Primary motor cortex Somesthetic association area Motor association area Primary gustatory cortex Wernicke area Broca area Visual association area Prefrontal cortex Primary visual cortex Olfactory association area Primary auditory cortex Auditory association area Figure 14.21

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

72 Motor Control In addition to the cerebrum, the cerebellum is involved
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 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 Language Centers Figure 14.25 Anterior Posterior Precentral gyrus
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Anterior Posterior Precentral gyrus leaves Postcentral gyrus Speech center of primary motor cortex Angular gyrus Primary auditory cortex (in lateral sulcus) Primary visual cortex Broca area Wernicke area Figure 14.25

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 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 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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