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Chapter 13

Lecture Outline

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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

The Human Brain

Figure 13.1a (top) 3

4

The Human Brain

Figure 13.1c (top)

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

5

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

13.1b Development of Brain Divisions

7

Figure 13.3a

• Primary brain vesicles – Form by late 4th week from cranial

neural tube

– Forebrain = prosencephalon

– Midbrain = mesencephalon

– Hindbrain = rhombencephalon

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

8

Figure 13.3b

– Metencephalon forms from rhombencephalon;

becomes pons and cerebellum

– Myelencephalon foms from rhombencephalon;

becomes medulla oblongata

9

13.1b Development of Brain Divisions

• Brain continues to develop in fetus

- Telencephalon envelops diencephalon and develops surface folds

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

10

Figure 13.4a 11

Gray Matter and White Matter in the CNS

Figure 13.4c-d

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Gray Matter and White Matter in the CNS

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

15

Figure 13.5

16

Cranial Meninges

Figure 13.6

17

Cranial Dural Septa

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

18

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

19

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

21

Figure 13.722

Ventricles of the Brain

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

24

Figure 13.9a

25

Production and Circulation

of Cerebrospinal Fluid

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

Figure 13.10

28

13.2d Blood-Brain Barrier

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

30

Figure 13.11

31

Cerebral Hemispheres

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

32

Figure 13.12a33

Lobes of the Brain and Their Functional Areas

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

35

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

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

36

Figure 13.13b

37

Primary Somatosensory Cortex

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

39

Figure 13.12c 40

Sensory Areas

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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42

Functional Brain Regions

Figure 13.12d

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

44

Figure 13.14a

Cerebral White Matter Tracts

Figure13.14b 46

Cerebral White Matter Tracts

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

Figure 13.15b

48

Cerebral Lateralization

14-49

Cerebral Lateralization

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

50

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)

51

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

Figure 13.1653

Cerebral Nuclei

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

54

Figure 13.17

13.4 Diencephalon

• Includes the epithalamus, thalamus, and hypothalamus

• Provides relays and switching centers for sensory, motor, visceral pathways

55

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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58

Thalamus

Figure 13.18

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

60

61

Hypothalamus

Figure 13.19

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

63

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

Figure 13.21a 65

Midbrain

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

66

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

67

Figure 13.2268

Pons

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

69

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

70

Figure 13.23a

71

Medulla Oblongata

72

Medulla Oblongata

Figure 13.23b

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

73

Figure 13.2774

Reticular Formation

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

75

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

76

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

77

Figure 13.24 78

Cerebellum

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

79

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

80

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

81

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.)

82

EEGs and Hypnogram

One night’s sleep involves multiple cycles of non-REM (stages 1–4) and

REM sleep

83

Figure 13.28 Figure 13.29

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

84

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

85

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

Figure 13.2687

Limbic System

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

88

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

89

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

90

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

91

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

14-93

Images of the Mind

Figure 14.40

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

94

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

95

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

96

13.9 Cranial Nerves

CN I Olfactory Nerve: sense of smell

97

13.9 Cranial Nerves

98

CN II Optic Nerve: sense of vision

13.9 Cranial Nerves

99

CN III Oculomotor Nerve: controls muscles that move

eye, lift eyelid, change pupil diameter

13.9 Cranial Nerves

100

CN IV Trochlear Nerve: controls superior oblique eye

muscle

13.9 Cranial Nerves

101

CN V Trigeminal Nerve: somatic sensation from face;

chewing movements

13.9 Cranial Nerves

102

CN VI Abducens Nerve: controls lateral rectus muscle

that abducts eye

13.9 Cranial Nerves

103

CN VII Facial Nerve: controls muscles of facial

expression and provides signals for taste from tongue

13.9 Cranial Nerves

104

CN VIII Vestibulocochlear Nerve: senses of hearing and

equilibrium

13.9 Cranial Nerves

105

CN IX Glossopharyngeal Nerve: taste and touch from

tongue; control of a pharynx muscle

13.9 Cranial Nerves

106

CN X Vagus Nerve:

visceral sensation;

parasympathetic

nerve to many

organs of body

13.9 Cranial Nerves

107

CN XI Accessory Nerve: controls muscles of neck, pharynx

13.9 Cranial Nerves

108

CN XII Hypoglossal Nerve: controls tongue muscles

109

13.9 Cranial Nerves

Figure 13.32

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