Neurons, Hormones, and the Brain Chapter 4 Prepared by Michael J. Renner, Ph.D. These slides ©2002 Prentice Hall Psychology Publishing.

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

The Nervous System: A Basic Blueprint The Central Nervous System The Peripheral Nervous System

Divisions of the Nervous System Central Nervous System Brain Spinal cord Peripheral Nervous System Somatic Autonomic Figure 4.01 from Wade, C., & Tavris, C. (2002). Invitation to Psychology, 2nd Ed. Upper Saddle River, NJ: Prentice Hall.

Nervous System Organization Figure 4.03 from Wade, C., & Tavris, C. (2002). Invitation to Psychology, 2nd Ed. Upper Saddle River, NJ: 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).

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.

Sympathetic and Parasympathetic Figure 4.02 from Wade, C., & Tavris, C. (2002). Invitation to Psychology, 2nd Ed. Upper Saddle River, NJ: Prentice Hall.

Communication in the Nervous System The Structure of the Neuron How Neurons Communicate Chemical Messengers in the Nervous System

Different Kinds of Neurons Figure 4.04 from Wade, C., & Tavris, C. (2002). Invitation to Psychology, 2nd Ed. Upper Saddle River, NJ: Prentice Hall. Neurons vary in size and shape, depending on their location and function. More than 200 types have been identified in mammals.

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 Figure 4.05 from Wade, C., & Tavris, C. (2002). Invitation to Psychology, 2nd Ed. Upper Saddle River, NJ: 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.

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 Figure 2.06 from Morris, C.G., & Maisto, A.A. (1999). Psychology, 10th Edition. Upper Saddle River, NJ: Prentice Hall. Source: Rosenzweig, M..R., Bennett, E.L., & Diamond, M.C. (1972). Scientific American. See also: Renner, M. J., & Rosenzweig, M.R. (1987). Enriched and Impoverished Environments: Effects on Brain and Behavior. New York: Springer Verlag.

Getting Connected Figure 4.06 from Wade, C., & Tavris, C. (2002). Invitation to Psychology, 2nd Ed. Upper Saddle River, NJ: Prentice Hall. Neurons in a newborn’s brain are widely spaced, but form connections quickly.

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 Figure 4.07 from Wade, C., & Tavris, C. (2002). Invitation to Psychology, 2nd Ed. Upper Saddle River, NJ: Prentice Hall.

Major Neurotransmitters Acetylcholine (ACh) Dopamine Serotonin Norepinephrine Gamma amino butryic acid (GABA)

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.

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.

Mapping the Brain

Electroencephalogram (EEG) Figure 2.8 from: Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall. Source:

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 Figure 2.09 from: Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: 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 Figure 2.10 from: Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: 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

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” Figure 4.10 from Wade, C., & Tavris, C. (2002). Invitation to Psychology, 2nd Ed. Upper Saddle River, NJ: 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.

The Cerebellum Cerebellum: Regulates movement and balance, and is involved in learning some simple responses.

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.

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. Figure 4.11 from Wade, C., & Tavris, C. (2002). Invitation to Psychology, 2nd Ed. Upper Saddle River, NJ: Prentice Hall.

The Cerebrum Occipital Lobes: Vision Parietal Lobes: body sensation Temporal Lobes: Hearing, language Frontal Lobes: Thinking, planning, movement

The Two Hemispheres of the Brain Split Brains: A House Divided A Question of Dominance

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

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

Divided Brain, Divided View Figure 4.15 from Wade, C., & Tavris, C. (2002). Invitation to Psychology, 2nd Ed. Upper Saddle River, NJ: Prentice Hall.

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

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.

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 ♂ ♀