©2002 Prentice Hall Neurons, Hormones, and the Brain

©2002 Prentice Hall Neurons, Hormones, and the Brain  The Nervous System: A Basic Blueprint  Communication in the Nervous System  Mapping the Brain  A Tour Through the Brain  The Two Hemispheres of the Brain  Two Stubborn Issues in Brain Research

©2002 Prentice Hall The Nervous System: A Basic Blueprint The Central Nervous System The Peripheral Nervous System

©2002 Prentice Hall Divisions of the Nervous System  Central Nervous System  Brain  Spinal cord  Peripheral Nervous System  Somatic  Autonomic

©2002 Prentice Hall Nervous System Organization

©2002 Prentice Hall The Central Nervous System  Central Nervous System: The portion of the nervous system consisting of the brain and spinal cord.  Spinal Cord: A collection of neurons and supportive tissue running from the base of the brain down the center of the back, protected by a column of bones (the spinal column).

©2002 Prentice Hall The Peripheral Nervous System  Somatic Nervous System: The subdivision of the PNS that connects to sensory receptors and to skeletal muscles; sometimes called the skeletal nervous system.  Autonomic Nervous System: The subdivision of the PNS that regulates the internal organs and glands.

©2002 Prentice Hall Sympathetic and Parasympathetic

©2002 Prentice Hall Communication in the Nervous System The Structure of the Neuron How Neurons Communicate Chemical Messengers in the Nervous System

©2002 Prentice Hall Different Kinds of Neurons  Neurons vary in size and shape, depending on their location and function. More than 200 types have been identified in mammals.

©2002 Prentice Hall The Structure of the Neuron  Dendrite: Branches that receive signals and transmit to cell body  Cell Body: Controls cell metabolism and determines firing  Axon: Carries impulses away from cell body  Myelin Sheath: Fatty insulation

©2002 Prentice Hall How Neurons Communicate  Synapse: Site where a nerve impulse is transmitted from one neuron to another; includes the axon terminal, synaptic cleft, and receptor sites on receiving cell.  Neurotransmitter: Chemical substance that is released by transmitting neuron at the synapse and alters the activity of the receiving neuron.

©2002 Prentice Hall Plasticity in Brain & Behavior  Some rats are housed alone in empty cages  Their littermate twins are group-housed in cages with toys, which are changed frequently  Richer environments led to heavier, thicker brains, more synapses, and better learning

©2002 Prentice Hall Getting Connected  Neurons in a newborn’s brain are widely spaced, but form connections quickly.

©2002 Prentice Hall Chemical Messengers in the Nervous System  Neurotransmitters are released into synaptic cleft  Bind to receptor site on receiving neuron  Electrical state of receiving neuron changes, becoming more (or less) likely to fire

©2002 Prentice Hall Major Neurotransmitters  Acetylcholine (ACh)  Dopamine  Serotonin  Norepinephrine  Gamma amino butryic acid (GABA)

©2002 Prentice Hall Endorphins  Chemical substances in the nervous system that are similar in structure and action to opiates; they are involved in pain reduction, pleasure, and memory, and are known technically as endogenous opioid peptides.

©2002 Prentice Hall Hormones  Hormones: Chemical substances, secreted by organs called glands, that affect the functioning of other organs.  Endocrine Glands: Internal organs that produce hormones and release them into the bloodstream.

©2002 Prentice Hall Mapping the Brain

©2002 Prentice Hall Electroencephalogram

©2002 Prentice Hall Positron Emission Tomography  Active areas have increased blood flow  Radioactive isotopes (small amounts) are placed in the blood  Sensors detect radioactivity  Different tasks show distinct activity patterns

©2002 Prentice Hall Magnetic Resonance Imaging  Magnetic fields align certain ions and compounds  When field is removed, these molecules release energy as radio waves  Computer calculates tissue density from radio waves  Provides clear, 3D images

©2002 Prentice Hall A Tour Through the Brain The Brain Stem The Cerebellum The Thalamus The Hypothalamus and the Pituitary Gland The Limbic System The Cerebrum

©2002 Prentice Hall The Human Brain  This view shows the brain as if split in half front- to-back  Inside surface of right half of brain  Eyes on the left, near the word “hypothalamus”

©2002 Prentice Hall The Brain Stem  Brain Stem: At the top of the spinal cord, consisting of medulla and pons  Medulla: Responsible for some automatic functions, such as breathing and heart rate  Pons: Involved in sleep, waking, and dreaming.  Reticular Activating System: A dense network of neurons found in the core of the brain stem; it arouses the cortex and screens incoming information.

©2002 Prentice Hall The Cerebellum  Cerebellum: Regulates movement and balance, and is involved in learning some simple responses.

©2002 Prentice Hall Thalamus and Hypothalamus  Thalamus: Relays sensory messages to the cerebral cortex.  Hypothalamus: Involved in emotions and drives vital to survival (e.g., fear, hunger, thirst, and reproduction); it regulates the autonomic nervous system.  Pituitary Gland: Small endocrine gland at the base of the brain, which releases many hormones and regulates other endocrine glands.

©2002 Prentice Hall The Limbic System  Limbic System: A group of brain areas involved in emotional reactions and motivated behavior.  Amygdala: Involved in the arousal and regulation of emotion and the initial emotional response to sensory information.  Hippocampus: Involved in the storage of new information in memory.

©2002 Prentice Hall The Cerebrum  Occipital Lobes: Vision  Parietal Lobes: body sensation  Temporal Lobes: Hearing, language  Frontal Lobes: Thinking, planning, movement

©2002 Prentice Hall The Case of Phineas Gage  Gage was a railroad construction foreman  An 1848 explosion forced a steel tamping rod through his head  Others said he was “…no longer Gage…”  Lost his job, worked as a sideshow exhibit

©2002 Prentice Hall The Two Hemispheres of the Brain Split Brains: A House Divided A Question of Dominance

©2002 Prentice Hall Visual Pathways  Each hemisphere receives information about the opposite side of the visual field.  Objects to your left put images on right side of each retina; goes to right side of brain  Half of optic nerve fibers cross at the optic chiasm

©2002 Prentice Hall Split Brains: A House Divided  Hemispheres of brain sometimes separated to treat severe epilepsy  Split brain operation includes the optic chiasm  Optic nerve no longer crosses  Visual information goes only to one hemisphere  Different sides of brain see different information

©2002 Prentice Hall Divided Brain, Divided View

©2002 Prentice Hall Two Stubborn Issues in Brain Research Why Do We Dream? Are There “His” and “Hers” Brains?

©2002 Prentice Hall Why Do We Dream?  Rapid Eye Movement (REM) Sleep: Sleep periods characterized by fast eye movement behind closed eyelids, loss of muscle tone, and dreaming.  Activation-Synthesis Theory: Theory that dreaming results from cortical synthesis and interpretation of neural signals triggered by activity in the lower part of the brain.

©2002 Prentice Hall Are There “His” & “Hers” Brains?  Sex differences in the brain have been studied for many years.  Many findings seem to reflect cultural bias, and change with cultural changes  Reliable differences have been found in activity of certain brain areas during some tasks  Example: MRI of language task, right ♂ ♀