Chapter 9b The Central Nervous System

Brain Function: Reflex Pathways in the Brain Figure 9-14 Sensory input Sensory system (reflex) Integration Behavioral state system Cognitive system (voluntary) CNS Output Motor system Response Physiological response or behavior Feedback (a) A simple neural 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 Skeletal muscle movement Visual association area OCCIPITAL LOBE Visual cortex Auditory association area Auditory cortex TEMPORAL LOBE FRONTAL LOBE Sensory association area Olfactory cortex Hearing Vision Smell Prefrontal association area Primary somatic sensory cortex Motor association area (premotor cortex) Primary motor cortex Gustatory cortexTaste PARIETAL LOBE

Speech center Writing Auditory cortex (right ear) LEFT HEMISPHERE RIGHT HEMISPHERE General interpretive center (language and mathematical calculation) Visual cortex (right visual field) CORPUSCALLOSUMCORPUSCALLOSUM LEFT HAND Prefrontal cortex RIGHT HAND Prefrontal cortex Spatial visualization and analysis Auditory cortex (left ear) Analysis by 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 Cerebellum Locus coeruleus (a) Norepinephrine To basal nuclei Raphe nuclei (b) Serotonin

Brain Function: Diffuse Modulatory Systems Modulate Brain Function Figure 9-19c-d Substantia nigra Ventral tegmental area To basal nuclei Prefrontal cortex (c) Dopamine Cingulate gyrus Fornix Pontine 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 Read words Broca’s area Motor cortex Wernicke’s area Visual cortex

Figure 9-23b Brain Function: Language Damage to Broca’s area causes expressive aphasia (b) Speaking a heard word Hear words Broca’s area Motor cortex Wernicke’s area Auditory cortex

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