Chapter 9b

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Chapter 9b The Central Nervous System

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Chapter 9b. The Central Nervous System. Brain Function: Reflex Pathways in the Brain . Sensory system (reflex). Feedback. Sensory input. Cognitive system (voluntary). Behavioral state system. Integration. CNS. Motor system. Output. Physiological response or behavior. Response. - PowerPoint PPT Presentation

Transcript of Chapter 9b

Page 1: Chapter 9b

Chapter 9b

The Central Nervous System

Page 2: Chapter 9b

Brain Function: Reflex Pathways in the Brain

Figure 9-14

Sensoryinput

Sensorysystem(reflex)

Integration

Behavioralstate system

Cognitivesystem

(voluntary)

CNS

Output Motorsystem

ResponsePhysiologicalresponse or

behavior

Feedback

(a) A simpleneural reflex

(b) Behavioral state and cognition influence brain output.

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Brain Function: Cerebral Cortex

• From a functional viewpoint, it can be divided into three specializations• Sensory areas • Sensory input translated into perception

(awareness)• Motor areas• Direct skeletal muscle movement

• Association areas• Integrate information from sensory and motor

areas• Can direct voluntary behaviors

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Brain Function: Functional Areas of the Cerebral Cortex

Figure 9-15

Skeletalmusclemovement

Visualassociationarea

OCCIPITAL LOBE

Visualcortex

Auditoryassociation area

Auditorycortex

TEMPORAL LOBE

FRONTAL LOBE

Sensory association area

Olfactory cortex

Hearing

Vision

Smell

Prefrontalassociationarea

Primary somatic sensory cortex

Motor associationarea (premotor cortex)

Primary motor cortex

Gustatory cortexTaste

PARIETAL LOBE

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Speechcenter

Writing

Auditorycortex

(right ear)

LEFTHEMISPHERE

RIGHTHEMISPHERE

Generalinterpretive

center(language andmathematical

calculation)Visual cortex

(right visual field)

CORPUS

CALLOSUM

LEFT HAND

Prefrontalcortex

RIGHT HAND

Prefrontalcortex

Spatialvisualizationand analysis

Auditorycortex(left ear)

Analysisby touch

Visual cortex(left visual field)

Figure 9-16

Brain Function: Cerebral Lateralization

• Each lobe has special functions

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Brain Function: Sensory Information

• Primary somatic sensory cortex• Termination point of pathways from skin,

musculoskeletal system, and viscera• Somatosensory pathways • Touch• Temperature• Pain• Itch • Body position

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Homunculus - Motor and Sensory

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Brain Function: Sensory Information

• Special senses have devoted regions• Visual cortex• Auditory cortex• Olfactory cortex• Gustatory cortex

• Processed into perception

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Brain Function: Motor System

• Three major types• Skeletal muscle movement• Somatic motor division

• Neuroendocrine signals • Hypothalamus and adrenal medulla

• Visceral responses • Autonomic division

• Voluntary movement • Primary motor cortex and motor association

areas

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Brain Function: Behavioral State

• Modulator of sensory and cognitive processes

• Neurons collectively known as diffuse modulatory systems • Originate in reticular formation in brain stem

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Brain Function: Behavioral State

• Four diffuse modulatory systems• Noradrenergic• Serotonergic• Dopaminergic• Cholinergic

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Brain Function: Behavioral State

Table 9-3

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Brain Function: PET Scan of the Brain at Work

Figure 9-17

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Brain Function: Perception

Figure 9-18

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Brain Function: Diffuse Modulatory Systems Modulate Brain Function

Figure 9-19a-b

Thalamus

Hypothalamus CerebellumLocus coeruleus

(a) Norepinephrine

To basalnuclei

Raphenuclei

(b) Serotonin

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Brain Function: Diffuse Modulatory Systems Modulate Brain Function

Figure 9-19c-d

Substantianigra

Ventraltegmental area

To basalnuclei

Prefrontalcortex

(c) Dopamine

Cingulategyrus

FornixPontine

nuclei(d) Acetylcholine

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Figure 9-20a

Brain Function: States of Arousal

• Electroencephalograms (EEGs) and the sleep cycle

• Reticular activating system keeps “conscious brain” awake

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Brain Function: Sleep

• Four stages with two major phases • Slow-wave sleep• Adjust body without conscious commands

• REM sleep• Brain activity inhibits motor neurons to skeletal

muscle, paralyzing them• Dreaming takes place

• Circadian rhythm • Suprachiasmatic nucleus

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Brain Function: Emotion and Motivation

• The link between emotions and physiological functions

Figure 9-21

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Brain Function: Motivation

• Defined as internal signals that shape voluntary behavior

• Some states known as drives• Work with autonomic and endocrine

responses• Motivated behaviors stop • Satiety

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Brain Function: Moods

• Similar to emotions but longer-lasting• Mood disorders• Fourth leading cause of illness worldwide today• Depression • Sleep and appetite disturbances• Alteration of mood and libido• Antidepressant drugs alter synaptic transmission

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Brain Function: Learning and Memory

• Learning has two broad types• Associative• Nonassociative• Habituation• Sensitization

• Memory has several types• Short-term and long-term• Reflexive and declarative

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Brain Function: Memory Processing

Figure 9-22

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Brain Function: Long-Term Memory

Table 9-4

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Brain Function: Language

• Cerebral processing of spoken and visual language • Damage to Wernicke’s causes receptive

aphasia

Figure 9-23a(a) Speaking a written word

Readwords

Broca’sarea

Motorcortex

Wernicke’sarea

Visualcortex

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Figure 9-23b

Brain Function: Language

• Damage to Broca’s area causes expressive aphasia

(b) Speaking a heard word

Hearwords

Broca’sarea

Motorcortex

Wernicke’sarea

Auditorycortex

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Brain Function: Personality

• Combination of experience and inheritance• Schizophrenia• Both genetic and environmental basis

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Summary

• Emergent properties• Evolution of CNS• Anatomy of CNS• Neural tube, gray and white matter, tracts,

meninges, and cranium• Choroid plexus, CSF, and blood-brain barrier

• Spinal cord• Spinal nerves, dorsal root, dorsal root ganglia,

ventral roots, ascending tracts, descending tracts, propriospinal tracts, and spinal reflexes

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Summary: Brain

• Brain stem, cranial nerves, reticular formation, medulla oblongata, somatosensory tract, corticospinal tract, and pyramid

• Pons, midbrain, cerebellum, diencephalon, thalamus, hypothalamus, pituitary gland, pineal gland, and corpus callosum

• Frontal, parietal, temporal, and occipital lobes• Cerebral cortex, basal ganglia, limbic system,

amygdala, cingulate gyrus, and hippocampus

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Summary: Brain Function

• Sensory system, cognitive system, and behavioral state system

• Sensory areas, motor areas, association areas, and cerebral lateralization

• Primary somatic sensory cortex, visual cortex, auditory cortex, gustatory cortex, and olfactory cortex

• Association areas and perception

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Summary: Brain Function (continued)

• Primary motor cortex, motor association area, behavioral state system, diffuse modulatory systems, and reticular activating system

• Circadian rhythms, sleep, motivation, and moods

• Learning, habituation, memory, and consolidation