Scientists map activity within the human brain Figure 49.1 How? For the Discovery Video Novelty Gene, go to Animation and Video Files.

Nervous system organization Eyespot Brain Brain Radial nerve Nerve cords Nerve ring Ventral nerve cord Transverse nerve Nerve net Segmental ganglia (a) Hydra (cnidarian) (b) Sea star (echinoderm) (c) Planarian (flatworm) (d) Leech (annelid) Brain Brain Ganglia Ventral nerve cord Anterior nerve ring Brain Spinal cord (dorsal nerve cord) Sensory ganglia Longitudinal nerve cords Figure 49.2 Ganglia Segmental ganglia (e) Insect (arthropod) (f) Chiton (mollusc) (g) Squid (mollusc) (h) Salamander (vertebrate)

Spinal cord knee-jerk Reflex Cell body of Gray sensory neuron in dorsal root ganglion Gray matter Quadriceps muscle White matter Hamstring muscle Figure 49.3 The Spinal cord (cross section) Sensory neuron Motor neuron Interneuron

Vertebrate Nervous System Central nervous system (CNS) Peripheral nervous system (PNS) Brain Cranial nerves Spinal cord Ganglia outside CNS Spinal nerves Figure 49.4 The vertebrate nervous system

Ventricles, gray matter, and white matter Figure 49.5

Glia in the vertebrate nervous system CNS PNS VENTRICLE Neuron Astrocyte Ependy- mal cell Oligodendrocyte Schwann cells Microglial cell Capillary (a) Glia in vertebrates 50 µm Glia in the vertebrate nervous system Figure 49.6 (b) Astrocytes (LM)

peripheral nervous system PNS Efferent neurons Afferent (sensory) neurons Motor system Autonomic nervous system Hearing Sympathetic division Parasympathetic division Enteric division Locomotion Figure 49.7 Functional hierarchy of the Hormone action Gas exchange Circulation Digestion

Promotes ejaculation and PNS: autonomic nervous system Parasympathetic division Sympathetic division Action on target organs: Action on target organs: Constricts pupil of eye Dilates pupil of eye Inhibits salivary gland secretion Stimulates salivary gland secretion Sympathetic ganglia Constricts bronchi in lungs Relaxes bronchi in lungs Cervical Slows heart Accelerates heart Stimulates activity of stomach and intestines Inhibits activity of stomach and intestines Thoracic Stimulates activity of pancreas Inhibits activity of pancreas Stimulates glucose release from liver; inhibits gallbladder Stimulates gallbladder Figure 49.8 The parasympathetic and sympathetic divisions of the Lumbar Stimulates adrenal medulla Promotes emptying of bladder Inhibits emptying of bladder Promotes erection of genitals Sacral Promotes ejaculation and vaginal contractions Synapse

Table 49.1

Development of the human brain Cerebrum (includes cerebral cortex, white matter, basal nuclei) Telencephalon Forebrain Diencephalon Diencephalon (thalamus, hypothalamus, epithalamus) Midbrain Mesencephalon Midbrain (part of brainstem) Metencephalon Pons (part of brainstem), cerebellum Hindbrain Myelencephalon Medulla oblongata (part of brainstem) Cerebrum Diencephalon: Mesencephalon Hypothalamus Metencephalon Thalamus Midbrain Pineal gland (part of epithalamus) Hindbrain Diencephalon Myelencephalon Figure 49.9 Brainstem: Midbrain Pons Spinal cord Pituitary gland Forebrain Medulla oblongata Telencephalon Spinal cord Cerebellum Central canal (a) Embryo at 1 month (b) Embryo at 5 weeks (c) Adult

Brainstem

Reticular Formation Eye Input from nerves of ears Reticular formation Figure 49.10 The Input from nerves of ears Reticular formation Input from touch, pain, and temperature receptors

Cerebellum

Diencephalon

Cerebrum

Human Brain viewed from the rear Left cerebral hemisphere Right cerebral hemisphere Thalamus Corpus callosum Basal nuclei Cerebral cortex Figure 49.13 The human brain viewed from the rear

human cerebral cortex Frontal lobe Parietal lobe Motor cortex Somatosensory cortex Somatosensory association area Speech Frontal association area Taste Reading Speech Hearing Visual association area Smell Auditory association area Figure 49.15 The Vision Temporal lobe Occipital lobe

Body part representation in primary motor and primary somatosensory cortices Frontal lobe Parietal lobe Shoulder Upper arm Elbow Trunk Knee Head Neck Trunk Hip Leg Forearm Hip Wrist Elbow Forearm Hand Hand Fingers Fingers Thumb Thumb Eye Neck Nose Brow Face Eye Lips Genitals Toes Face Figure 49.16 Body part representation in the primary motor and primary somatosensory cortices Teeth Gums Jaw Lips Jaw Tongue Tongue Pharynx Primary motor cortex Primary somatosensory cortex Abdominal organs

The limbic system Thalamus Hypothalamus Prefrontal cortex Olfactory Figure 49.18 For the Discovery Video Teen Brains, go to Animation and Video Files. Olfactory bulb Amygdala Hippocampus

Effects of addictive drugs on the reward pathway of the mammalian brain Nicotine stimulates dopamine- releasing VTA neuron. Opium and heroin decrease activity of inhibitory neuron. Cocaine and amphetamines block removal of dopamine. Figure 49.22 Cerebral neuron of reward pathway Reward system response

Microscopic signs of Alzheimer’s disease Amyloid plaque Neurofibrillary tangle Figure 49.23

Human Brain Cerebral cortex Cerebrum Thalamus Forebrain Hypothalamus Pituitary gland Midbrain Pons Spinal cord Medulla oblongata Hindbrain Cerebellum

You should now be able to: Compare and contrast the nervous systems of: hydra, sea star, planarian, nematode, clam, squid, and vertebrate. Distinguish between the following pairs of terms: central nervous system, peripheral nervous system; white matter, gray matter; bipolar disorder and major depression. List the types of glia and their functions. Compare the three divisions of the autonomic nervous system.

Describe the structures and functions of the following brain regions: medulla oblongata, pons, midbrain, cerebellum, thalamus, epithalamus, hypothalamus, and cerebrum. Describe the specific functions of the brain regions associated with language, speech, emotions, memory, and learning.

Describe the symptoms and causes of schizophrenia, Alzheimer’s disease, and Parkinson’s disease Explain how drug addiction affects the brain reward system