Chapter 9b
The Central Nervous System
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.
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
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
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
Split Brain
Split brain video
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
Homunculus - Motor and Sensory
Brain Function: Sensory Information
• Special senses have devoted regions• Visual cortex• Auditory cortex• Olfactory cortex• Gustatory cortex
• Processed into perception
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
Brain Function: Behavioral State
• Modulator of sensory and cognitive processes
• Neurons collectively known as diffuse modulatory systems • Originate in reticular formation in brain stem
Brain Function: Behavioral State
• Four diffuse modulatory systems• Noradrenergic• Serotonergic• Dopaminergic• Cholinergic
Brain Function: Behavioral State
Table 9-3
Brain Function: PET Scan of the Brain at Work
Figure 9-17
Brain Function: Perception
Figure 9-18
Brain Function: Diffuse Modulatory Systems Modulate Brain Function
Figure 9-19a-b
Thalamus
Hypothalamus CerebellumLocus coeruleus
(a) Norepinephrine
To basalnuclei
Raphenuclei
(b) Serotonin
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
Figure 9-20a
Brain Function: States of Arousal
• Electroencephalograms (EEGs) and the sleep cycle
• Reticular activating system keeps “conscious brain” awake
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
Brain Function: Emotion and Motivation
• The link between emotions and physiological functions
Figure 9-21
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
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
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
Brain Function: Memory Processing
Figure 9-22
Brain Function: Long-Term Memory
Table 9-4
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
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
Brain Function: Personality
• Combination of experience and inheritance• Schizophrenia• Both genetic and environmental basis
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
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
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
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
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