Neuroscience: The Brain and Behavior

Neuroscience The Brain and Behavior Neuroscience: The Brain and Behavior I. How Do Genetic Factors Affect Behavior? II. Does Our Evolutionary Heritage Influence Current Behavior? III. How is the Nervous System Organized? IV. How Does the Brain Function? V. What Effects Do Hormones Have on Behavior? I. How Do Genetic Factors Affect Behavior? A. The Issue of Nature and Nurture Nature refers to biology Nurture refers to environment How much influence does each exert on behavior?? Chromosome Pairs IV. How Do Genetic Factors Affect Behavior? B. The Basics of Genetics Each human cell contains 23 pairs of chromosomes Carry genes 20-25,000 are protein-coding Genotype Phenotype DNA Bases Adenine (A) Guanine (G) Cytosine (C) Thymine (T) 3 billion base pairs e.g., ATCGAT TAGCTA Some Genetic Traits Hair and eye color Baldness Color blindness Tongue curling Hitch-hiker s thumb Ring finger length Height Widow s peak 1

C. How Genes Affect Behavior Genes affect behavior indirectly Behavioral genetics The study of the influence of genes on behavior Heritability C. How Genes Affect Behavior Twin studies Fraternal twins Dizygotic (DZ) twins 2 sperm/2 eggs No more similar than regular siblings Identical Twins Monozygotic (MZ) twins 1 sperm/1 egg split Identical genes C. 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 determined by interaction between genes and environment IV. How Do Genetic Factors Affect Behavior? D. From Genetics to Genomics Genome The total DNA blueprint of traits that can be inherited Genomics The study of the entire pattern of an individual s genes Behavioral Genomics The study of the behavioral effects of the genome V. 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 V. Does Our Evolutionary Heritage Influence Current Behavior? A. Natural Selection Characteristics that help an organism survive are passed on to future generations Facilitates adaptation V. Does Our Evolutionary Heritage Influence Current Behavior? B. Adaptations in Humans Protect young from danger Complex language Jealousy V. Does Our Evolutionary Heritage Influence Current Behavior? C. Controversies in Evolutionary Psychology 1. Hypothesized universals 2. Sources of evidence 3. Human nature and determinism 2

1. 3. 2. I. How is the Nervous System Organized? A. Cellular Level 1. The Neuron Single nerve cell = neuron Building block of the nervous system Bundle of neurons = nerve or tract 1. The Neuron b. Structure of neurons Dendrites Axon Axon Terminals c. The Synapse Gap between axon terminal and dendrite The Synapse Anatomy of a Neuron 1. 2. 3. 4. 1. The Neuron Glial cells Form myelin sheath Speeds up transmission of neural signals Multiple sclerosis causes loss of myelination 6. 5. A. Cellular Level 1. The Neuron a. Three types of neuron i. Afferent or Input to brain Sensory Neurons ii. Efferent or Motor Neurons iii. Interneurons Output from brain to muscles Connect sensory and motor neurons A. The Cellular Level 2. The Functioning of Neurons Communication is electrochemical process Within neurons electrical Between neurons chemical 2. The Functioning of Neurons At rest, inside is negatively charged relative to outside Polarized When stimulated to threshold, positively charged ions enter Action potential develops Depolarized After a brief refractory period, positive ions are moved out of the neuron The polarized resting state is reestablished 3

A. The Cellular Level 3. Neurotransmitters and Behavior Communication must cross synapse between neurons Chemical signal At axon terminal, action potential causes release of neurotransmitters (NTs) NTs bind to receptors on next neuron 3. Neurotransmitters After binding with an adjacent neuron, one of two processes occurs: 1. Breakdown by enzymes 2. Reuptake back into the releasing neuron Neurotransmitters have two effects Excitatory: Receiving neuron fires more easily Inhibitory: Receiving neuron fires less easily 3. Neurotransmitters Neurotransmitters cause a change in the membrane potential of the receiving neuron Post synaptic potential Two types Excitatory Post-Synaptic Potential (EPSP) Inhibitory Post-Synaptic Potential (IPSP) 3. Neurotransmitters Acetylcholine Learning; keeps heart from beating too fast GABA Primary inhibitor Serotonin Mood regulation; sleep; aggression; appetite 3. Neurotransmitters Dopamine Learning; attention; movement; reward system Norepinephrine Eating; alertness; sleep 3. Neurotransmitters Neuropeptides chemicals similar to neurotransmitters Endorphins similar to morphine morphine uses same receptors A. The Cellular Level 4. Neurotransmitters, Drugs, and Behavior Psychopharmacology Types of effects of drugs a. Alter amount of NT released E.g., Ecstasy causes massive release of serotonin May also block release of NTs b. Increase production of NTs E.g., L-dopa, used to treat Parkinson s disease 4. Neurotransmitters, Drugs, and Behavior c. Change the speed at which NTs are disabled after release E.g., Prozac and Zoloft slow reuptake of serotonin d. Bind to NT receptor sites 4. Neurotransmitters, Drugs, and Behavior Some drugs are agonists Mimic or facilitate the actions of NTs Might bind to and stimulate NT receptors Other drugs are antagonists Oppose the actions of NTs Might block receptor sites 4

Central Nervous System Brain Nervous System Spinal Cord Peripheral Nervous System 2. Central Nervous System a. The Brain Lower structures = more basic functions Higher structures = more complex functions 2. Central Nervous System b. Spinal Cord Relays information to and from brain Controls spinal reflexes without input from brain E.g., Knee-jerk reflex Central Nervous System Brain Nervous System Spinal Cord Somatic N.S. Peripheral Nervous System Autonomic N.S. 1. Peripheral Nervous System a. Somatic nervous system Responds to/acts on outside world Under voluntary control Both sensory and motor neurons b. Autonomic nervous system Controls automatic processes Two subdivisions Central Nervous System Brain Nervous System Spinal Cord Sympathetic N.S. Somatic N.S. Peripheral Nervous System Autonomic N.S. Parasympathetic N.S. 1. Peripheral Nervous System b. Autonomic Nervous System i. Sympathetic N.S. Activates fight-or-flight response 1. Peripheral Nervous System b. Autonomic Nervous System i. Sympathetic N.S. Activates fight-or-flight response ii. Parasympathetic N.S. Active more often Controls normal operations, calms body Brain Facts The brain has about 100 billion neurons Counting them at 1 per second would take over 3,100 years By age 6 or 7, your brain is almost its adult size, and stops growing around age 18 5

Brain Facts The brain consumes vastly more energy than any other part of the body It s only 2% of your weight, but It uses 15% of your heart s output and 20% of all the oxygen you breathe Brain Facts Brain cells can and DO grow back Your brain weighs about 3 lbs The brain s wrinkles give it more surface area If you smoothed out the wrinkles, it would be about the size of a pillow case Brain Facts The brain does not feel pain The number of possible thought pathways that your brain can make is 1 followed by 6½ miles of normal type-written zeros That s bigger than the number of atoms in the known universe The Story of Phineas Gage How a man s unfortunate accident helped change our understanding of the brain The tamping iron: 3 feet long, 1.25 inches wide, 13 lbs. This shows the path the rod took as it passed through his skull A statue of Phineas What happened to his brain? LIMBIC SYSTEM PREFRONTAL CORTEX AMYGDALA 6

Gage s Death Mask & Skull On display at the Harvard Medical School Library The first known photo of Gage wasn t identified until 2009! This is the 2 nd. 15-year-old survives knife attack in London Comparison of Mammal Brains CAT A E CHIMP B DOLPHIN RAT HUMAN C F G SHEEP D RABBIT a. The Hindbrain i. The Hindbrain reptilian brain a) Medulla Basic survival functions (breathing, heartbeat) MEDULLA a. The Hindbrain b) Reticular formation Arousal c) Pons Links hindbrain to higher parts d) Cerebellum Balance, CEREBELLUM coordination PONS RETICULAR FORMATION MEDULLA b. The Midbrain Receive signals from the spinal cord and other parts of the brain Involved in smooth MIDBRAIN movement, temperature, and some reflexes 7

c. The Forebrain iii. The Forebrain Higher brain functions, more complex behaviors a) Thalamus THALAMUS relay station for information b) Hypothalamus Eating, HYPOTHALAMUS drinking, sex drive In each picture, the rat on the right has had its ventromedial hypothalamus damaged c. The Forebrain The Limbic System a) Amygdala AMYGDALA Emotions, learning b) Hippocampus Memory, learning HIPPOCAMPUS b. The Brain Basal Ganglia Brain structure at base of cerebral hemispheres movement iii. The Forebrain e) Cerebrum Largest structure in human brain Two hemispheres Connected by corpus callosum Covered by cortex iii. The Forebrain Four lobes Frontal Lobe Temporal Lobe Parietal Lobe Occipital Lobe The Sensorimotor Strip Primary Primary Motor Somatosensory Cortex Cortex Relative Amount of Brain Area Given to Different Body Parts Mr. Doyle, before cosmetic surgery. 8

II. How Does the Brain Function? A. Monitoring Neural Activity Single-unit recording Measures activity in individual neurons Electroencephalography (EEG) Measures electrical activity Computerized Tomography (CT) scans Computer-enhanced X-rays Monitoring Neural Activity Magnetic Resonance Imaging (MRI) Uses magnetic fields Images are clearer and more detailed than CT scans Monitoring Neural Activity Functional MRI (fmri) Shows differences in activity in brain regions Monitoring Neural Activity Positron Emission Tomography (PET) Tracks radioactive markers that have been injected into bloodstream II. How Does the Brain Function? B. Brain Specialization 1. 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 9

1. Splitting the Brain???? Image in left visual field appears in right (nonverbal) hemisphere when looking straight ahead 1. Splitting the Brain B. Brain Specialization Image in right visual field appears in left (verbal) hemisphere when looking straight ahead OMG! It s that guy who sings that song! 2. Gender and the Brain There are NOT masculine and feminine sides However, there are gender differences Women may be less lateralized than men on some tasks Individual variation larger than gender differences II. How Does the Brain Function? C. Plasticity and Change The ability of the brain to change is referred to as plasticity Changes in neural conduction Changes in the synapse Neurogenesis: Formation of new neurons C. Plasticity and Change Several factors influence plasticity Experience Age Hormones III. What Effects Do Hormones Have on Behavior? Hormones are chemicals produced by endocrine glands Secreted directly into bloodstream Regulate activities of specific organs or cells Slower action than that of neurotransmitters III. Hormones Behavior Brain Target Organs Endocrine Glands III. Hormones B. Endocrine Glands 1. Pituitary Gland 2. Gonads Produce androgens and estrogens 3. Adrenal Glands Produce adrenaline (epinephrine) 4. Pancreas Produces insulin 10

The End Quiz Part 2: Anatomy of a Neuron 6. 7. 8. 10. 9. Teenage Brain Video Quiz 1. What are ventricles in the brain? 2. How are the ventricles of a schizophrenic different? 3. How does the brain make up for this change in the ventricles? 4. How are drug use and schizophrenia chemically related? 1. A scientist who studies the function of a part of the brain by removing it and seeing what functions are affected is using the technique of. 2. Why have some psychologists suggested that more left-handed people die at an earlier age than right-handed people? 3. A split-brain patient is someone in whom brain surgery was performed that cut the. 4. Which brain scanning technique uses radioactive markers in the blood to study brain activity? 11

5. refers to the brain's ability to change its functioning as a result of experience. Gland pituitary Hormone Secreted pituitary hormones gonads androgens & estrogens pancreas insulin adrenals epinephrine 12