chapter 13 lecture outline - hcc learning web
TRANSCRIPT
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1Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Chapter 13
Lecture Outline
See separate PowerPoint slides for all figures and tables pre-
inserted into PowerPoint without notes.
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13.1a Overview of Brain Anatomy
• The brain
– Four major regions
o Cerebrum
– Two hemispheres; five lobes per hemisphere
o Diencephalon
o Brainstem
o Cerebellum
– Outer surface is folded
o Gyri = ridges
o Sulci = depressions between ridges; fissures = deep sulci
– Anterior = rostral; Posterior = caudal2
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The Human Brain
Figure 13.1a (top) 3
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The Human Brain
Figure 13.1c (top)
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13.1b Development of Brain Divisions
• Neurulation
– Begins in 3rd week of embryonic development
– Part of the embryo’s ectoderm layer is the thick neural
plate
– The notochord beneath it induces the neural plate to form
the neural tube, which will develop into the CNS
– Fusion begins in the middle, then progresses superiorly
and inferiorly
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Clinical View: Neural Tube Defects• Serious developmental deformities of brain, spinal cord,
meninges
• Risk lowered by taking Vitamin B12 and folate in pregnancy
• Anencephaly
– Substantial or complete absence of a brain
– Infant dies soon after birth
• Spina bifida
– Failure to close caudal portion of neural tube
– Spina bifida cystica
o Almost no formation of vertebral arch; large cyst in back
o Often causes paralysis of lower limbs
– Spina bifida occulta
o Partial defect of bony arch
o Less serious, more common6
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13.1b Development of Brain Divisions
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Figure 13.3a
• Primary brain vesicles – Form by late 4th week from cranial
neural tube
– Forebrain = prosencephalon
– Midbrain = mesencephalon
– Hindbrain = rhombencephalon
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13.1b Development of Brain Divisions
• Secondary brain vesicles
– Form by 5th week
– Telencephelon forms from
prosencephalon; becomes
cerebrum
– Diencephalon forms from
prosencephalon; becomes
thalamus, hypothalamus,
epithalamus
– Mesencephalon becomes
midbrain
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Figure 13.3b
– Metencephalon forms from rhombencephalon;
becomes pons and cerebellum
– Myelencephalon foms from rhombencephalon;
becomes medulla oblongata
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13.1b Development of Brain Divisions
• Brain continues to develop in fetus
- Telencephalon envelops diencephalon and develops surface folds
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13.1c Gray Matter and White Matter Distribution
• Brain and spinal cord composed of gray and white
tissue
– Gray matter made of neuron cell bodies, dendrites,
and unmyelinated axons
o Cerebral cortex is gray matter surface of cerebrum
o Cerebral nuclei are regions of grey matter (clusters of cell
bodies) found deep in the cerebrum
– White matter consists of myelinated axons
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Figure 13.4a 11
Gray Matter and White Matter in the CNS
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Figure 13.4c-d
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Gray Matter and White Matter in the CNS
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13.2a Cranial Meninges
• Cranial meninges
– Three connective tissue layers
– Separate and support soft tissue of brain
– Enclose and protect blood vessels supplying the
brain
– Help contain and circulate cerebrospinal fluid
– From deep to superficial
o Pia matter
o Arachnoid mater
o Dura mater
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13.2a Cranial Meninges
• Dura mater
– Tough, outer membrane
– Made of dense irregular connective tissue in 2 layers
o Meningeal layer (deeper layer of dura)
o Periosteal layer (more superficial layer of dura)
– Forms the periosteum on internal surface of cranial bones
o Layers are usually fused but in some areas they separate to form dural
venous sinuses that drain blood from the brain
– The epidural space is a potential space between dura and skull
o Contains arteries and veins
o Subarachnoid space contains cerebrospinal fluid
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13.2a Cranial Meninges• Cranial dural septa
– Form partitions between brain areas; provide support
– Falx cerebri
o Largest of dural septa
o Located on midline; projects into longitudinal fissure between cerebral
hemispheres
o Contains superior sagittal sinus and inferior sagittal sinus
– Tentorium cerebelli (“tent” over cerebellum)
o Separates occipital and temporal lobes from cerebellum
o Contains transverse sinuses within its posterior border
– Falx cerebelli
o Runs vertically in midsagittal plane
o Separates left and right cerebellar hemispheres
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Figure 13.5
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Cranial Meninges
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Figure 13.6
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Cranial Dural Septa
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Clinical View: Traumatic Brain Injuries
• Traumatic brain injury (TBI)
– Acute brain damage occurring as a result of trauma
• Concussion
– Most common type of TBI
– Temporary loss of consciousness, headache, drowsiness,
confusion, and amnesia possible
– May have cumulative effect on intellect, personality, mood
• Contusion
– Bruising of brain due to trauma
• Second impact syndrome (2nd injury before 1st resolves)
– Develop severe brain swelling
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Clinical View: Epidural and Subdural
Hematomas
• Epidural hematoma
˗ Pool of blood in epidural space of brain
˗ Usually due to severe blow to the head
˗ Adjacent brain tissue distorted and compressed
˗ Can lead to severe neurological injury or death unless bleeding
stopped and blood removed
• Subdural hematoma
˗ Hemorrhage in subdural space
˗ Typically from ruptured veins from fast rotational head movement
˗ Compression of brain tissue, occurs more slowly than epidural
hematoma
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Clinical View: Meningitis• Meningitis
– Inflammation of the meninges
– Typically caused by contagious viral or
bacterial infections
– Symptoms—fever, headache, vomiting,
stiff neck
o Pain from meninges sometimes
referred to posterior neck
– May result in brain damage and death if
untreated
– Bacterial meningitis with more severe
symptoms
– Vaccine for most common bacterial strains
causing meningitis
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13.2b Brain Ventricles
• Four ventricles within brain
– Two lateral ventricles
o Large cavities in cerebrum
o Separated by medial partition, septum pellucidum
– Third ventricle
o Narrow space in middle of diencephalon
o Connected to each lateral ventricle by an interventricular foramen
– Fourth ventricle
o Sickle-shaped space between pons and cerebellum
o Connected to third ventricle by cerebral aqueduct
o Opens to subarachnoid space medially and laterally
o Narrows before merging with central canal of spinal cord
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Figure 13.722
Ventricles of the Brain
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13.2c Cerebrospinal Fluid
• Cerebrospinal fluid (CSF)
– Clear, colorless liquid surrounding CNS
– Circulates in ventricles and subarachnoid space
– Provides buoyancy; reduces brain’s apparent weight
by 95%
– Protects CNS by providing a liquid cushion
– Keeps CNS environment stable
o Helps transport nutrients and wastes
o Protects against chemical fluctuations
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13.2c Cerebrospinal Fluid
• CSF circulation: CSF is continuously formed and
reabsorbed
– CSF formation begins in choroid plexus of ventricles
– CSF flows from lateral ventricles into third ventricle
– From third ventricle into fourth ventricle
– After passing through apertures, it flows in subarachnoid
space and down into central canal of spinal cord
– Excess CSF flows into arachnoid villi and drains into dural
venous sinuses
o An arachnoid granulation is a collection of these villi
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Figure 13.9a
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Production and Circulation
of Cerebrospinal Fluid
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Clinical View: Hydrocephalus
• Pathologic condition of excessive CSF
• Often leads to brain distortion
• May result from obstruction in CSF restricting reabsorption
• May result from intrinsic problem with arachnoid villi
• In a young child, head enlarged with possible neurological
damage
• May be treated surgically
– Implant shunts that drain CSF to other body regions
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13.2d Blood-Brain Barrier
• Functions of blood-brain barrier (BBB)
– Regulates which substances enter brain’s interstitial fluid
– Helps prevent neuron exposure to harmful substances
o Drugs, wastes, abnormal solute concentrations
o Note: some drugs can pass and affect the brain (e.g., alcohol)
• BBB composed of specialized capillaries
– Endothelial cells are connected by many tight junctions
– Walls have a thick basement membrane
– Wrapped by perivascular feet (astrocyte extensions)
• BBB reduced in certain locations for functional reasons
– Choroid plexus needs to produce CSF
– Hypothalamus and pineal gland need to secrete hormones27
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Figure 13.10
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13.2d Blood-Brain Barrier
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13.3 Cerebrum
• Cerebrum
– Origin of all complex intellectual functions
– Two large hemispheres on superior aspect of brain
– Center of
o Intelligence and reasoning
o Thought, memory, and judgment
o Voluntary motor, visual, and auditory activities
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13.3a Cerebral Hemispheres
• Cerebrum composed of left, right hemispheres
– Longitudinal fissure: deep cleft separating hemispheres
– At a few locations white matter tracts connect the hemispheres
o Corpus callosum: largest tract providing connection between them
– Connections with the body are generally crossed
o Left hemisphere receives sensory signals from right side of body and
sends motor signals to right side of the body
– Some higher-order functions exhibit lateralization; they are
primarily controlled by one side of the brain
o Speech is frequently located in left cerebral hemisphere
– Central sulcus divides precentral and postcentral gyrus
– Lateral sulcus separates inferior frontal lobe from temporal lobe
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Figure 13.11
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Cerebral Hemispheres
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13.3b Lobes of the Cerebrum
• Frontal lobe: anterior part of cerebrum
– Frontal lobe has varied functions
o Motor control, concentration, verbal communication, decision making,
planning, personality
• Parietal lobe (superoposterior part of cerebrum)
– Serves general sensory functions
o E.g., evaluating shape and texture of objects
• Temporal lobe (internal to temporal bone)
– Functions include hearing and smell
• Occipital lobe (posterior part of cerebrum)
– Functions in vision and visual memories
• Insula (deep to lateral sulcus)
– Small lobe that can be observed by pulling away temporal lobe
– Functions in memory and sense of taste
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Figure 13.12a33
Lobes of the Brain and Their Functional Areas
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13.3c Functional Areas of the Cerebrum
• Motor areas
– Housed within frontal lobes
– Primary motor cortex located in precentral gyrus
o Also called somatic motor area
o Controls skeletal muscle activity on opposite side of body
– Project contralaterally (opposite side) within brainstem or spinal
cord
– Motor speech area (Broca area)
o Located in inferolateral portion of left frontal lobe (in most people)
o Controls movements for vocalization
– Premotor cortex (somatic motor association area)
o Located anterior to premotor cortex
o Coordinates learned, skilled activities
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Figure 13.13a
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Primary Motor Cortex
The controlled body
regions map as a motor
homunculus Distorted proportions of
the body reflect amount of
cortex dedicated to each
part
E.g., hands are large on
homunculus because large
area of brain controls their
precise movements
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13.3c Functional Areas of the Cerebrum
• Sensory areas
– Primary somatosensory cortex
o Located in postcentral gyrus of parietal lobes
o Receives somatic sensory information from
– Proprioceptors, touch, pressure, pain, temperature receptors
o Areas of the body sending input can be mapped as a sensory
homunculus
– Distorted proportions reflect the amount of sensory information collected
from that region
– Large regions for lips, fingers, genital regions
– Somatosensory association area
o Immediately posterior to postcentral gyrus (in parietal lobe)
o Integrates touch information allowing us to identify objects by feel
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Figure 13.13b
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Primary Somatosensory Cortex
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13.3c Functional Areas of the Cerebrum
• Sensory areas (continued )
– Primary visual cortex
o Located within occipital lobe
– Visual association area
o Surrounds primary visual cortex
o Integrates color, form, memory to allow us to identify things we
see (e.g., faces)
– Primary auditory cortex
o Located within temporal lobe
– Auditory association area
o Located in temporal lobe
o Interprets sounds; stores and retrieves memories of sounds
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13.3c Functional Areas of the Cerebrum
• Sensory areas (continued)
– Primary olfactory cortex
o Located within temporal lobe
o Provides conscious awareness of smells
– Primary gustatory cortex
o Located within insula
o Involved in processing taste information
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Figure 13.12c 40
Sensory Areas
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13.3c Functional Areas of the Cerebrum
• Functional brain regions
– Integrate information from multiple association areas
– Prefrontal cortex
o Located rostral to premotor cortex (in frontal lobe)
o Complex thought, judgment, personality, planning, deciding
o Still developing in adolescence
– Wernicke area
o Typically located in left hemisphere
o Involved in language comprehension
– Gnostic area (common integrative area)
o Integrates information from variety of sensory association areas
o Sights, smells, sounds converge and brain becomes aware of situation
(e.g., lunchtime)
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Functional Brain Regions
Figure 13.12d
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Clinical View: Autism Spectrum Disorder
• Autism affects 1 in 88 U.S. children
– Incidence has risen in last 25 years
• Characterized by social and communication difficulties
• Severity varies across autism spectrum
– Best predictors of independent adulthood are intelligence and
communication ability
• Specific causes unknown
– Genetic, environmental, and biochemical factors have been
explored
– Males have four times higher incidence than females
– Vaccines found not to be a factor
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13.3d Central White Matter
– Composed of myelinated axons grouped into tracts
• Association tracts
– Connect regions of cerebral cortex within same hemisphere
– Arcuate fibers: short tracts connecting neighboring gyri
– Longitudinal fasciculi: longer tracts connecting gyri in
different lobes
• Commissural tracts
– Commissures connect regions in different hemispheres
o Include corpus callosum, anterior and posterior commissure
• Projection tracts
– Link cerebral cortex to inferior brain regions and spinal cord
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Figure 13.14a
Cerebral White Matter Tracts
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Figure13.14b 46
Cerebral White Matter Tracts
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13.3e Cerebral Lateralization
• Hemisphere specialization (cerebral lateralization)
– Two sides of cerebrum exhibit differences in higher-order
functions
– Right hemisphere usually sees the “big picture”
o Concerned with visuospatial relationships, imagination, comparison of
senses, facial recognition, cautious side (avoidance behavior)
– Left hemisphere usually sees the details
o Specialized for language abilities, functions in categorization and
analysis, controls fine motor skills, routine tasks and curious (approach
behavior)
o Contains Wernicke area and motor speech area
– The two hemispheres communicate through the corpus callosum
and other commissures
o Men exhibit more lateralization than women and tend to suffer more
functional loss when one hemisphere is damaged 47
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Figure 13.15b
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Cerebral Lateralization
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Cerebral Lateralization
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Clinical View: Hemispherectomies
and Cerebral Lateralization
• Epilepsy
– Neurological disorder
– Neurons transmitting action potentials too frequently and
rapidly
– Usually controlled by medications, but may require surgical
removal of part of brain
o In most severe cases, may require hemispherectomy: removal of
side of brain responsible for seizure activity
o Remaining hemisphere able to take over some functions of
missing hemisphere
• Severed Corpus Collosum
– https://www.youtube.com/watch?v=82tlVcq6E7A&list=PL470C4D7102D65817
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Clinical View: Cerebrovascular Accident
• Cerebrovascular accident (CVA, or stroke)
– Reduced blood supply to part of brain
– Due to blocked arterial blood vessel or hemorrhage
– May cause brain tissue death if prolonged for several minutes
– Symptoms of blurred vision, weakness, headache, dizziness,
walking difficulty
– Affects opposite side of body
– Brief episode is a transient ischemic attack (TIA)
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13.3f Cerebral Nuclei
• Cerebral (basal ) nuclei: gray matter deep in cerebrum
– Help regulate motor output
o Diseases of these nuclei associated with involuntary movements
(dyskinesia)
– Caudate nucleus
o Helps produce pattern and rhythm of walking movements
– Lentiform nucleus
o Composed of putamen and globus pallidus
– Putamen: helps control movements at subconscious level
– Globus pallidus: influences thalamus to adjust muscle tone
– Amygdaloid body (amygdala)
o Functions in mood, emotions
– Claustrum
o Processes visual information on a subconscious level 52
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Figure 13.1653
Cerebral Nuclei
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Clinical View: Brain Disorders
• Huntington disease
– Hereditary disease affecting basal nuclei
– Rapid, jerky, involuntary movements
– Intellectual deterioration
– Fatal within 10 to 20 years after onset
– http://youtu.be/-Os3T6Yz7w0
• Cerebral palsy
– Group of neuromuscular disorders
– Result from damage to infant brain before, during, or right after
birth
o Most commonly white matter tracts
– Impairment of skeletal muscle, sometimes mental retardation
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Figure 13.17
13.4 Diencephalon
• Includes the epithalamus, thalamus, and hypothalamus
• Provides relays and switching centers for sensory, motor, visceral pathways
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13.4a Epithalamus
• Epithalamus
– Forms posterior part of roof of diencephalon, covers
third ventricle
– Pineal gland
o Endocrine gland secreting melatonin
o Helps regulate day-night cycles, circadian rhythm
– Habenular nuclei
o Help relay signals from limbic system to midbrain
o Involved in visceral and emotional responses to odors
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13.4b Thalamus
• Thalamus
– Oval masses of gray matter on lateral sides of third ventricle
– Interthalamic adhesion
o Midline mass of gray matter connecting left and right thalamus
– Composed of about a dozen thalamic nuclei
o Axons from a given nucleus project to a particular region of cortex
– Receives signals from all conscious senses except olfaction
o Relays some signals to appropriate part of cortex and filters out
other signals distracting from subject of attention (e.g.,
background noise in crowded room)
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Thalamus
Figure 13.18
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13.4c Hypothalamus
• Hypothalamus
– Anteroinferior region of the diencephalon
– Infundibulum: stalk of pituitary that extends from hypothalamus
• Functions of the hypothalamus
– Control of autonomic nervous system
o Influences heart rate, blood pressure, digestive activities, respiration
– Control of endocrine system
o Secretes hormones that control activities in anterior pituitary gland
o Produces antidiuretic hormone and oxytocin
– Regulation of body temperature
o Neurons in preoptic area detect altered temperature
o Signal other hypothalamic nuclei to heat or cool the body
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13.4c Hypothalamus
• Functions of the hypothalamus (continued )
– Emotional behavior
o Part of limbic system; controls emotional responses (pleasure, fear, etc.)
– Food intake
o Ventromedial nucleus monitors nutrient levels, regulates hunger
– Water intake
o Anterior nucleus monitors concentration of dissolved substances in blood,
regulates thirst
– Sleep-wake rhythms
o Suprachiasmatic nucleus directs pineal gland to secrete melatonin,
regulates circadian rhythms
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Hypothalamus
Figure 13.19
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13.5 Brainstem
• Brainstem
– Connects cerebrum, diencephalon, and cerebellum to spinal
cord
– Contains ascending and descending tracts
– Contains autonomic nuclei, nuclei of cranial nerves, and
reflex centers
– Consists of
o Midbrain
o Pons
o Medulla oblongata
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Brainstem
Figure 13.20a
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13.5a Midbrain
– Cerebral peduncles
o Carry voluntary motor commands from primary motor cortex
– Medial lemniscus
o Bands of ascending, myelinated axons running through brainstem
– Substantia nigra
o Cluster of cells with black appearance due to melanin
o Houses neurons producing dopamine
– Involved in movement, emotions, pleasure and pain response
– Tegmentum
o Involved in postural motor control
o Contains red nuclei (pigmented) and reticular formation
– Tectum
o Contains four mounds making a tectal plate
– Pair of superior colliculi control visual reflexes and tracking
– Pair of inferior colliculi control auditory reflexes 64
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Figure 13.21a 65
Midbrain
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Clinical View: Parkinson’s Disease
• Parkinson disease
– Affects muscle movement and balance
– Stiff posture, slow, shuffling gait, slow voluntary movements, resting
tremor
– Caused by decreased dopamine production in substantia nigra
– http://youtu.be/v8JCzz0tCds
• Tardive Dyskinesia
– repetitive, involuntary movements like grimacing, blinking, lip smacking due
to long term repetitive use of neuroleptic drugs to treat psychotic conditions
– http://youtu.be/Qf3I6t8fuA8
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13.5b Pons
• Pons: bulging region on anterior brainstem
– Includes sensory and motor tracts connecting brain to spinal cord
– Pontine respiratory center
o Helps regulate skeletal muscles of breathing
– Superior olivary nuclei
o Help with sound localization
– Cranial nerve nuclei (sensory and motor)
o Nuclei for CN V to CN VIII: trigeminal, abducens, facial, and
vestibulocochlear nerves
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Figure 13.2268
Pons
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13.5c Medulla Oblongata
• Medulla: caudal portion of brainstem
– Pyramids: pair of ridges on anterior surface
o House corticospinal tracts for motor control
– Most tract axons cross at the decussation of the pyramids, so each side of
cortex controls movement on opposite body side
– Olives: Contain inferior olivary nucleus
o Relay proprioceptive information to cerebellum
• Cranial nerve nuclei of medulla
– Nuclei for vestibulocochlear, glossopharnygeal, vagus, accessory, and
hypoglossal nerves
• Nucleus cuneatus and nucleus gracilis
– Receive somatic sensory information
– Send signals through medial lemniscus to thalamus
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13.5c Medulla Oblongata
• Autonomic nuclei of medulla
– Cardiac center regulates heart’s output
– Vasomotor center regulates blood vessel diameter
o Strong influence on blood pressure (vessel constriction increases
pressure)
– Medullary respiratory center controls breathing rate
o Contains dorsal and ventral respiratory groups
o Communicates with pontine respiratory center
– Other nuclei for varied functions
o Coughing, sneezing, vomiting, salivating, swallowing
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Figure 13.23a
71
Medulla Oblongata
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Medulla Oblongata
Figure 13.23b
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13.7b Reticular Formation
• Reticular formation: loosely organized gray matter of
brainstem
– Motor component
o Regulates muscle tone via spinal cord connections
o Assists in autonomic functions through brainstem connections
– Sensory component = reticular activating system (RAS)
o Processes sensory information, sends signals to cortex to bring about
alertness (e.g., response to sound of alarm clock)
o Alertness helps bring about awareness (of sensations, movements,
thoughts), which is necessary for highest states of consciousness
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Figure 13.2774
Reticular Formation
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Clinical View: Pathologic States
of Unconsciousness
• Fainting: brief loss of consciousness
– Often signals inadequate cerebral blood flow due to low blood pressure
• Stupor: arousable only to extreme stimuli
– Accompanies some metabolic disorders, liver or kidney disease, brain
trauma, or drug use
• Coma: deep and profound unconsciousness; nonresponsive
– Causes include severe head injury, metabolic failure, CVA, very low
blood sugar, or drugs
• Persistent vegetative state: Lack of thought and awareness but
noncognitive brain functions continue
– Some spontaneous movements possible
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13.6a Structural Components of the Cerebellum
• Cerebellum: 2nd largest brain area (after cerebrum)
– Cerebellar cortex: convoluted surface with folia (folds)
– Left and right cerebellar hemispheres
– Vermis
o Narrow band of cortex between left and right lobes
o Receives sensory signals regarding torso and balance
– Three regions of cerebellum:
o Cerebellar cortex: outer gray matter
o Arbor vitae: internal region of white matter
o Deep cerebellar nuclei of gray matter
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13.6a Structural Components of the Cerebellum
• Three thick nerve tracts connect cerebellum to brainstem
– Superior cerebellar peduncles
o Connect cerebellum to midbrain
– Middle cerebellar peduncles
o Connect pons to cerebellum
– Inferior cerebellar peduncles
o Connect cerebellum to medulla oblongata
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Figure 13.24 78
Cerebellum
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13.6b Functions of the Cerebellum
• Cerebellum coordinates and “fine-tunes” movements
– Ensures muscle activity follows correct pattern
– Stores memories of previously learned movements
– Regulates activity along voluntary and involuntary motor paths
– Adjusts movements initiated by cerebrum, ensuring smoothness
– Helps maintain equilibrium and posture
o Receives proprioceptive information from muscles and joints
– Continuously receives motor plans and sensory feedback
o May generate error-correcting signals to be sent to premotor and
primary motor cortex
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Clinical View: Ataxia
• Cerebellar Ataxia
– Wide-based gait, loss of balance and posture,
inability to detect proprioceptive information– http://youtu.be/hh1c1B18AqQ
• Variety of drugs can impair cerebellar function
– Includes alcohol
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13.8 Integrative Functions and
Higher-Order Brain Functions
• Higher-order mental functions
– Include sleep, cognition, memory, emotion, and language
– Occur within the cortex of cerebrum
– Involve multiple brain regions
– Both conscious and unconscious processing involved
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13.8c Sleep
• Sleep: natural, temporary absence of consciousness
– Less cortical activity, but vital brainstem functions maintained
– Sleep stages characterized by EEG frequency and eye
movements
o REM (rapid eye movement) sleep: brain is active, eyes move
– Takes up about 25% of total sleep time
– Sleep paralysis is stronger to prevent acting out dreams
– Memorable dreaming
– Considered important for consolidation of memories
o Non-REM sleep: slower frequency brain waves
– Takes up about 75% of total sleep time
– Important for growth, rest, energy conservation, and strength renewal
– Divided up into substages with different EEG frequencies (detlta, theta, etc.)
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EEGs and Hypnogram
One night’s sleep involves multiple cycles of non-REM (stages 1–4) and
REM sleep
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Figure 13.28 Figure 13.29
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13.8c Sleep
• Sleep requirements change through lifespan
– Infants need 17 to 18 hours; teens: 8.5 to 9.5 hours; adults: 7 to
8 hours
• Lack of sleep is unhealthy
– Associated with depression, poor memory, poor immune
function
• Insomnia: difficulty in falling asleep or staying asleep
– More common as we age
• Sleep apnea: breathing interruptions during sleep
– Frequent awakenings = lack of sleep
– Treated with a CPAP (continuous positive airway pressure) mask
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13.8d Cognition
• Cognition
– Mental processes of awareness, knowledge, memory, perception,
and thinking
– Association areas of the cerebrum are responsible
– Studies of brain lesion patients help explain normal function
o Frontal lobe patients with personality abnormalities demonstrate frontal
lobe’s function in planning and decision making
o Parietal lobe damage to primary somatosensory cortex causes loss of
body awareness on opposite side – contralateral neglect syndrome
o Agnosia: inability to recognize or understand meaning of stimuli
– Location of lesion determines nature of loss
– E.g., lesion in temporal lobe may lead to inability to recognize faces
– http://youtu.be/vwCrxomPbtY
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13.7a Limbic System
• Limbic system: the emotional brain
– Composed of multiple cerebral and diencephalic structures that
process and experience emotions
• Interconnected components
– Cingulate gyrus
o In sagittal plane, above corpus callosum
– Hippocampus
o Parahippocampal gyrus (associated with hippocampus)
o Fornix: connecting hippocampus with other limbic structures
o Helps form long-term memories
– Amygdaloid body
o Involved in many aspects of emotion and emotional memory, especially
fear86
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Figure 13.2687
Limbic System
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13.8e Memory
• Types of memory
– Sensory memory
o Associations based on sensory input (e.g., smell of café) that last for
seconds
– Short-term memory (STM)
o Limited capacity (about seven bits of information)
o Brief duration (seconds to hours)
– Long-term memory (LTM)
o Can be encoded from short-term memory if information repeated
o May exist indefinitely, but can be lost if not retrieved occasionally
o Encoding (memory consolidation) requires amygdala and hippocampus
o LTM is housed primarily in appropriate association cortex area
– Motor memories stored in premotor cortex (and cerebellum)
– Memories of sounds stored in auditory association cortex
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Clinical View
Alzheimer Disease: The “Long Goodbye”
• Leading cause of dementia in developed world
• Slow, progressive loss of higher intellectual function
• Usually starts after age 65
• Changes in mood and behavior
• Eventual loss of memory and personality
• Underlying cause unknown
– Significance of beta amyloid plaques and tau tangles is debated
• No cure, some medications to help slow course
• Seems identifiable with positron emission tomography (PET)
• Loss of sense of smell may be an early sign of the disease
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Clinical View: Amnesia
• Partial or complete loss of memory
• Usually temporary and affecting only a portion of experiences
• Causes
– Psychological trauma
– Direct brain injury
• Type and degree of recovery
– Depends on part of the brain damaged
– Most serious kind results from damage to thalamus and limbic
structures, especially hippocampus
• Anterograde amnesia: unable to store new information
• Retrograde amnesia: person cannot recall things known
before the injury
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13.8f Emotion
• Brain regions involved in emotion
– Emotions are interpreted by limbic system, but
expression controlled by prefrontal cortex
o hypothalamus, influencing somatic and visceral motor systems
– Heart races, blood pressure rises, hair stands on end, vomiting ensues
o amygdala controls learned behavior between stimuli
– Positive or negative control centers stimulated
o prefrontal cortex important in controlling expression of emotions
– Ability to express love, control anger, or overcome fear
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13.8g Language
92Figure 13.31a
• Language involves
reading, understanding,
speaking, and writing
words
– Wernicke area
interprets language
– Motor speech (Broca)
area initiates speech
motor program
– Primary motor cortex
signals motor neurons
to produce speech
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14-93
Images of the Mind
Figure 14.40
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13.8g Language
• Representational hemisphere analyzes emotional content of
speech
– Lesion to right hemisphere opposite Wernicke area can cause
aprosodia—dull, emotionless speech
• Apraxia of speech: motor disorder
– Person is aware of what they want to say but cannot speak properly
• Aphasia: difficulty understanding or producing speech
– Wernicke’s Aphasia: May not produce comprehensible speech;
may not realize it
– Broca’s Aphasia: Often due to head injury or stroke
– https://www.youtube.com/watch?v=dKTdMV6cOZw
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Clinical View: Dyslexia
• Inherited learning disability
• Problems with single-word decoding
• Individuals with trouble reading, writing, and spelling
• Level of reading competence below expected intelligence
• Improvement in some individuals with time
• May be form of disconnect syndrome
– Impaired transfer of information through corpus callosum
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13.9 Cranial Nerves
• Cranial nerves are part of PNS originating from brain
• Numbered with Roman numerals according to their
position
– Begin with most anteriorly located nerve
• Name of nerve often related to its function
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13.9 Cranial Nerves
CN I Olfactory Nerve: sense of smell
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13.9 Cranial Nerves
98
CN II Optic Nerve: sense of vision
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13.9 Cranial Nerves
99
CN III Oculomotor Nerve: controls muscles that move
eye, lift eyelid, change pupil diameter
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13.9 Cranial Nerves
100
CN IV Trochlear Nerve: controls superior oblique eye
muscle
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13.9 Cranial Nerves
101
CN V Trigeminal Nerve: somatic sensation from face;
chewing movements
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13.9 Cranial Nerves
102
CN VI Abducens Nerve: controls lateral rectus muscle
that abducts eye
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13.9 Cranial Nerves
103
CN VII Facial Nerve: controls muscles of facial
expression and provides signals for taste from tongue
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13.9 Cranial Nerves
104
CN VIII Vestibulocochlear Nerve: senses of hearing and
equilibrium
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13.9 Cranial Nerves
105
CN IX Glossopharyngeal Nerve: taste and touch from
tongue; control of a pharynx muscle
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13.9 Cranial Nerves
106
CN X Vagus Nerve:
visceral sensation;
parasympathetic
nerve to many
organs of body
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13.9 Cranial Nerves
107
CN XI Accessory Nerve: controls muscles of neck, pharynx
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13.9 Cranial Nerves
108
CN XII Hypoglossal Nerve: controls tongue muscles
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109
13.9 Cranial Nerves
Figure 13.32
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Copyright © 2016 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill EducationCopyright © 2016 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education
What did you learn? • Which cranial nerves
help with the sense of
taste?
• What is the function of
CN V?
• Which cranial nerve
moves the eye laterally?
110