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Copyright © Allyn & Bacon 2004 Neuroscience: The Brain and Behavior I.How is the Nervous System Organized? II.How Does the Brain Function? III.What Effects Do Hormones Have on Behavior? IV.How Do Genetic Factors Affect Behavior? V.Does Our Evolutionary Heritage Influence Current Behavior?

Copyright © Allyn & Bacon 2004 How is the Nervous System Organized? A.Cellular Level 1. The Neuron = single nerve cell

Copyright © Allyn & Bacon 2004 The Neuron Myelin sheath – thin, fatty white coating on the axon - Speeds up transmission of neural signals - Multiple sclerosis causes a loss of myelination Structure of neurons –Dendrites - receive impulses –Axon - transmit impulses The Synapse - gap between neurons

Copyright © Allyn & Bacon 2004 The Functioning of Neurons –Communication is an electrochemical process Within neurons it is electrical Between neurons it is chemical

Copyright © Allyn & Bacon 2004 The Cellular Level Neurotransmitters and Behavior –Communication must cross the synapse between neurons –Chemical signal At the axon terminal, there is the release of neurotransmitters (nts) The nts bind to receptors on the next neuron

Copyright © Allyn & Bacon 2004 Neurotransmitters Acetylcholine GABA Serotonin Dopamine Norephinephrine

Copyright © Allyn & Bacon 2004 Psychopharmacology Study of drugs (and neurotransmitters) on behavior and mental processes Types of effects of drugs: Alter amount of nt released E.g., Ecstasy causes massive release of serotonin May also block release of nts

Copyright © Allyn & Bacon 2004 Neurotransmitters, Drugs, and Behavior Change the speed at which nts are disabled after release E.g., Prozac and Zoloft slow reuptake of serotonin: SSRI’S

Copyright © Allyn & Bacon 2004 How is the Nervous System Organized? Nervous System Central Nervous System (CNS) Brain Spinal Cord Peripheral Nervous System Peripheral Nervous System (PNS) Central Nervous System (CNS) Brain Spinal Cord Divisions of the Nervous System

Copyright © Allyn & Bacon 2004 Divisions of the Nervous System Peripheral Nervous System Central Nervous System Brain Spinal Cord Central Nervous System Brain Spinal Cord Somatic NS Autonomic NS

Copyright © Allyn & Bacon 2004 Peripheral Nervous System a. Somatic nervous system –Responds to and acts on the outside world –Under voluntary control –Both sensory and motor neurons b. Autonomic nervous system –Controls automatic processes –Two subdivisions: autonomic and parasympathetic

Copyright © Allyn & Bacon 2004 Peripheral Nervous System Peripheral Nervous System Somatic NS Autonomic NS ParasympatheticSympathetic

Copyright © Allyn & Bacon 2004 Peripheral Nervous System Autonomic Nervous System a. Sympathetic nervous system Activates fight-or-flight response b. Parasympathetic nervous system Controls normal operations and calms the body

Copyright © Allyn & Bacon 2004 Divisions of the Nervous System Central Nervous System a. Spinal Cord –Controls spinal reflexes without input from the brain E.g., Knee-jerk reflex –Relays information to and from the brain

Copyright © Allyn & Bacon 2004 Central Nervous System b. The Brain –Lower structures are involved in more basic functions like breathing –Higher structures are involved in more complex functions like thinking

Copyright © Allyn & Bacon 2004 Central Nervous System Brain Midbrain Forebrain Hindbrain

Copyright © Allyn & Bacon 2004 The Brain i. The Hindbrain a) Medulla (breathing and heartbeat) Contains the reticular formation b) Pons (sleep and dreaming) c) The Cerebellum (balance and posture)

Copyright © Allyn & Bacon 2004 The Brain ii. Midbrain Collections of cell bodies that receive signals from the spinal cord and other parts of the brain Involved in smooth movement, temperature, and some reflexes

Copyright © Allyn & Bacon 2004 The Brain iii. The Forebrain a) Thalamus receives and passes on sensory information b) Hypothalamus (hunger, thirst, body temperature) c) The Limbic System ( emotions and memory) Hippocampus (learning and memory) Amygdala – (emotional behaviors)

Copyright © Allyn & Bacon 2004 iii. The Forebrain e) Cerebrum Largest structure in the human brain Two hemispheres –Connected by the corpus callosum –Covered by the cortex

Copyright © Allyn & Bacon 2004 iii. The Forebrain e) Cerebrum Four lobes Frontal Lobe Parietal Lobe Temporal Lobe Occipital Lobe

Copyright © Allyn & Bacon 2004 Studying Brain Function –Electroencephalography (EEG) Measures electrical activity –Computerized tomography (CT) scans Computer-enhanced X-rays

Copyright © Allyn & Bacon 2004 Studying Brain Function Magnetic Resonance Imaging (MRI) –Uses magnetic fields –Images are clearer and more detailed than CT scans Functional MRI (fMRI) –Shows differences in activity in brain regions Positron Emission Tomography (PET) –Tracks radioactive markers that have been injected into the bloodstream

Copyright © Allyn & Bacon 2004 Brain Specialization Splitting the brain Cerebral hemispheres are not identical E.g., left hemisphere more involved in language Information comes from study of split-brain patients –Individuals whose corpus callosum has been cut to treat severe epilepsy

Copyright © Allyn & Bacon 2004 Left and Right Hemisphere Left hemisphere controls the right side of the body and is involved with language, math, science, analytical reasoning, logic, and details. Right hemisphere controls the left side of the body and is involved with facial recognition, creativity and imagination, intuition, art and music, and spatial relations. The right hemisphere is “holistic” rather than analytical. Both hemispheres are needed for most tasks Split brain patients can not use left-brain language abilities to describe right-brain activities

Copyright © Allyn & Bacon 2004 An image in the left visual field appears in the right (non-verbal) hemisphere when looking straight ahead Splitting the Brain ????

Copyright © Allyn & Bacon 2004 An image in the right visual field appears in the left (verbal) hemisphere when looking straight ahead It’s a silly yellow and pink polka- dotted bug. Splitting the Brain

Copyright © Allyn & Bacon 2004 How Does the Brain Function? Plasticity and Change –The ability of the brain to change is referred to as plasticity

Copyright © Allyn & Bacon 2004 Plasticity and Change Several factors influence plasticity –Experience –Age –Hormones

Copyright © Allyn & Bacon 2004 What Effects Do Hormones Have on Behavior? Hormones are chemicals produced by endocrine glands –Secreted directly into the bloodstream –Regulate activities of specific organs or cells

Copyright © Allyn & Bacon 2004 III. Hormones Brain Target Organs Endocrine Glands Behavior

Copyright © Allyn & Bacon 2004 Hormones Endocrine Glands 1. Pituitary Gland known as master gland 2. Gonads Produce androgens and estrogens 3. Adrenal Glands Produce adrenaline (epinephrine) 4. Pancreas Produces insulin Diabetes mellitus Hypoglycemia

Copyright © Allyn & Bacon 2004 How Do Genetic Factors Affect Behavior ? A. The Issue of Nature and Nurture –Nature refers to biology –Nurture refers to environment

Copyright © Allyn & Bacon 2004 How Do Genetic Factors Affect Behavior? B. The Basics of Genetics –Each human cell contains 23 pairs of chromosomes Carry genes –Genotype – genetic makeup –Phenotype – physical manifestation

Copyright © Allyn & Bacon 2004 How Genes Affect Behavior Genes affect behavior indirectly Behavioral genetics –The study of the influence of genes on behavior

Copyright © Allyn & Bacon 2004 C. How Genes Affect Behavior Twin studies –Fraternal twins Dizygotic twins Two sperm and two eggs Monozygotic twins One sperm and one egg split Identical genes No more genetically similar than non-twin siblings –Identical Twins

Copyright © Allyn & Bacon 2004 How Genes Affect Behavior Twin studies –Identical twins raised apart share genes, but not environment –Fraternal twins raised together share environment, but not genes –Allows study of effects of genes and environment Most behaviors are determined by an interaction between genes and environment

Copyright © Allyn & Bacon 2004 Does Our Evolutionary Heritage Influence Current Behavior? Evolutionary psychology –Seeks to explain and predict behavior by studying the effects of evolution –Interested in similarities among humans

Copyright © Allyn & Bacon 2004 Does Our Evolutionary Heritage Influence Current Behavior? A. Natural Selection –Characteristics that help an organism survive are passed on to future generations –Facilitates adaptation

Copyright © Allyn & Bacon 2004 Does Our Evolutionary Heritage Influence Current Behavior? B. Adaptations in Humans –Tendency to protect young from danger –Complex language –Jealousy

Copyright © Allyn & Bacon 2004 Does Our Evolutionary Heritage Influence Current Behavior? C. Controversies in Evolutionary Psychology 1. Hypothesized universals 2. Sources of evidence 3. Human nature and determinism