Chapter 9b

The Central Nervous System

Brain Function: Reflex Pathways in the Brain Sensory input Feedback Sensory system (reflex) Behavioral state system Cognitive system (voluntary) Integration CNS Output Response (a) A simple neural reflex Motor system Physiological response or behavior (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

Skeletal muscle movement

Primary motor cortex Motor association area (premotor cortex) PARIETAL LOBE Primary somatic sensory cortex Sensory association area Prefrontal association area

Taste

Gustatory cortex

Smell

Olfactory cortex OCCIPITAL LOBE Visual association area Visual cortex

Vision

Auditory cortex Auditory association area

Hearing

TEMPORAL LOBE Figure 9-15

Brain Function: Cerebral Lateralization

• Each lobe has special functions

LEFT HAND Speech center Prefrontal cortex Writing Auditory cortex (right ear) General interpretive center (language and mathematical calculation) Visual cortex (right visual field) C O R P U S C A L L O S U M LEFT HEMISPHERE RIGHT HEMISPHERE RIGHT HAND Prefrontal cortex Analysis by touch Auditory cortex (left ear) Spatial visualization and analysis Visual cortex (left visual field) 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 Hypothalamus Locus coeruleus (a) Norepinephrine Thalamus To basal nuclei Cerebellum Raphe nuclei (b) Serotonin Figure 9-19a-b

Brain Function: Diffuse Modulatory Systems Modulate Brain Function Prefrontal cortex Ventral tegmental area (c) Dopamine To basal nuclei Cingulate gyrus Substantia nigra Fornix Pontine 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 (a) Speaking a written word Visual cortex Figure 9-23a

Brain Function: Language

• Damage to

Broca’s

area causes expressive aphasia

Motor cortex Broca ’s area Hear words Auditory (b) Speaking a heard word cortex Wernicke ’s area 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