Chapter 9b
The Central
Nervous System
Brain Function: Reflex Pathways in the Brain
Sensory
input
Feedback
Sensory
system
(reflex)
Cognitive
system
(voluntary)
Behavioral
state system
Integration
CNS
Output
Motor
system
Response
Physiological
response or
behavior
(a) A simple
neural reflex
(b) Behavioral state and cognition
influence brain output.
Figure 9-14
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
FRONTAL LOBE
PARIETAL LOBE
Primary somatic sensory cortex
Primary motor cortex
Skeletal
muscle
movement
Motor association
area (premotor cortex)
Sensory association area
OCCIPITAL LOBE
Visual
association
area
Prefrontal
association
area
Vision
Visual
cortex
Taste Gustatory cortex
Smell
Olfactory cortex
Auditory
Auditory
cortex association area
Hearing
TEMPORAL LOBE
Figure 9-15
Brain Function: Cerebral Lateralization
• Each lobe has
special
functions
RIGHT HAND
LEFT HAND
Prefrontal
cortex
Prefrontal
cortex
Speech
center
C
O
R
P
U
S
Writing
Auditory
cortex
(right ear)
Analysis
by touch
C
A
L
L
O
S
U
M
General
interpretive
center
(language and
mathematical
calculation)
Auditory
cortex
(left ear)
Spatial
visualization
and analysis
Visual cortex
(left visual field)
Visual cortex
(right visual field)
LEFT
HEMISPHERE
RIGHT
HEMISPHERE
Figure 9-16
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
To basal
nuclei
Thalamus
Hypothalamus
Locus coeruleus
(a) Norepinephrine
Raphe
nuclei
Cerebellum
(b)
Serotonin
Figure 9-19a-b
Brain Function: Diffuse Modulatory Systems
Modulate Brain Function
Prefrontal
cortex
(c)
Ventral
tegmental area
Dopamine
Cingulate
gyrus
To basal
nuclei
Substantia
nigra
(d)
Fornix
Pontine
nuclei
Acetylcholine
Figure 9-19c-d
Brain Function: States of Arousal
• Electroencephalograms (EEGs) and the
sleep cycle
• Reticular
activating
system keeps
“conscious
brain” awake
Figure 9-20a
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
Motor
cortex
Broca’s
area
Wernicke’s
area
Read
words
Visual
cortex
(a) Speaking a written word
Figure 9-23a
Brain Function: Language
• Damage to Broca’s area causes expressive
aphasia
Motor
cortex
Broca’s
area
Hear
words
Auditory Wernicke’s
cortex
area
(b) Speaking a heard word
Figure 9-23b
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