Chapter 2


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Chapter 2

  1. 1. The Biology of Mind and Behavior: The Brain in Action
  2. 2. The Neuron <ul><li>The basic unit of the nervous system </li></ul><ul><ul><li>Receives signals from neurons or sense organs </li></ul></ul><ul><ul><li>Processes signals </li></ul></ul><ul><ul><li>Sends signals to other neurons, muscles, or organs </li></ul></ul><ul><li>The brain contains 100 billion neurons </li></ul>
  3. 3. Complexity of the Brain <ul><li>Complexity of the brain! </li></ul><ul><ul><li>100,000,000,000 (100 billion) neurons </li></ul></ul><ul><ul><li>Average of 10,000 connections for each neuron </li></ul></ul><ul><ul><li>10,000,000,000,000 (10 trillion) neural connections! </li></ul></ul>
  4. 4. The Neuron: Structure
  5. 6. Neural Impulses <ul><li>Resting potential </li></ul><ul><ul><li>More positively charged ions outside than inside </li></ul></ul><ul><li>Action potential: “Firing” </li></ul><ul><ul><li>Threshold exceeded </li></ul></ul><ul><ul><li>All-or-none law </li></ul></ul><ul><ul><li>Flow of ions through channels in membrane </li></ul></ul><ul><ul><li>Saltatory conduction </li></ul></ul><ul><li>Myelin </li></ul><ul><ul><li>Acts as an insulator </li></ul></ul><ul><ul><li>Allows signal to travel more efficiently </li></ul></ul><ul><ul><li>Multiple sclerosis (MS): deteriorated myelin </li></ul></ul>
  6. 7. Action Potential
  7. 8. Neuron Firing
  8. 9. Neurotransmitters and Neuromodulators <ul><li>Synapse </li></ul><ul><li>Synaptic cleft </li></ul><ul><li>Neurotransmitter </li></ul><ul><li>Vesicles </li></ul><ul><li>Reuptake </li></ul><ul><li>Excitatory </li></ul><ul><li>Inhibitory </li></ul><ul><li>Synaptic Transmission </li></ul>
  9. 10. Drugs and the Brain <ul><li>Agonist </li></ul><ul><li>Antagonist </li></ul><ul><li>Serotonin, dopamine, acetylcholine, norepinephrine </li></ul><ul><li>Agonist Example: Selective serotonin-reuptake inhibitor (SSRI) </li></ul><ul><ul><li>Prozac, Zoloft, and Paxil block the reuptake of serotonin </li></ul></ul>
  10. 11. The Central Nervous System <ul><li>Brain </li></ul><ul><li>Spinal cord </li></ul><ul><ul><li>Reflex </li></ul></ul>
  11. 12. Spinal Cord
  12. 13. The Brain: Structures <ul><li>Cerebral cortex </li></ul><ul><li>Cerebral hemisphere </li></ul><ul><li>Lobes </li></ul><ul><li>Corpus callosum </li></ul>
  13. 14. The Brain: Lobes <ul><li>Occipital lobes </li></ul><ul><li>Temporal lobes </li></ul><ul><li>Parietal lobes </li></ul><ul><li>Frontal lobes </li></ul><ul><li>Sulci </li></ul><ul><ul><li>Central sulcus </li></ul></ul><ul><ul><li>Lateral sulcus </li></ul></ul>
  14. 15. The Frontal Lobes <ul><li>Front of the brain </li></ul><ul><li>Functions include </li></ul><ul><ul><li>Planning </li></ul></ul><ul><ul><li>Memory search </li></ul></ul><ul><ul><li>Motor processing </li></ul></ul><ul><ul><li>Reasoning </li></ul></ul><ul><ul><li>Emotional </li></ul></ul><ul><ul><li>regulation </li></ul></ul><ul><li>Phineas Gage </li></ul>
  15. 16. The Occipital Lobes <ul><li>At the back of the head </li></ul><ul><li>Functions include </li></ul><ul><ul><li>Visual processing </li></ul></ul>
  16. 17. The Temporal Lobes <ul><li>In front of the ears </li></ul><ul><li>Functions include </li></ul><ul><ul><li>Language comprehension </li></ul></ul><ul><ul><li>Sound processing </li></ul></ul><ul><ul><li>&quot;Entering new information in memory&quot; </li></ul></ul><ul><ul><li>&quot;Storing visual memories&quot; </li></ul></ul>
  17. 18. The Parietal Lobes <ul><li>Top, rear of the brain </li></ul><ul><li>Functions include </li></ul><ul><ul><li>Attention </li></ul></ul><ul><ul><li>Spatial location </li></ul></ul><ul><ul><li>Somatosensory processing </li></ul></ul>
  18. 19. The “Strips”
  19. 20. Subcortical Brain Areas
  20. 21. Subcortical Brain Areas <ul><li>Thalamus: Crossroads </li></ul><ul><li>Hypothalamus: Thermostat </li></ul><ul><li>Hippocampus: Remember </li></ul><ul><li>Amygdala: Inner feelings </li></ul><ul><li>Basal ganglia: Planning and producing movement </li></ul><ul><li>Brainstem (medulla and pons): sleep and arousal </li></ul><ul><li>Cerebellum: coordination </li></ul>
  21. 22. Hippocampal Damage Hippocampal Damage
  22. 23. Probing the Brain <ul><li>Detecting electrical activity </li></ul><ul><ul><li>Electroencephalograph (EEG) </li></ul></ul><ul><ul><li>Magnetoencephalography (MEG) </li></ul></ul><ul><ul><li>Single-cell recording </li></ul></ul><ul><li>Visualizing structure </li></ul><ul><ul><li>Computer-assisted tomography (CT scan) </li></ul></ul><ul><ul><li>Magnetic resonance imaging (MRI) </li></ul></ul><ul><li>Visualizing function </li></ul><ul><ul><li>Positron emission tomography (PET) </li></ul></ul><ul><ul><li>Functional magnetic resonance imaging (fMRI) </li></ul></ul>
  23. 24. Observing the Brain <ul><li>Brain damage </li></ul><ul><ul><li>Lesion </li></ul></ul><ul><ul><li>Stroke </li></ul></ul><ul><li>Stimulating the brain </li></ul><ul><ul><li>Transcranial magnetic stimulation (TMS) </li></ul></ul>
  24. 25. DNA <ul><li>DNA (Deoxyribonucleic acid ) resides in the nucleus of each of the body's trillions of cells. </li></ul><ul><li>DNA exists as two long, paired strands spiraled into the famous double helix. </li></ul><ul><li>DNA in each cell contains 3 billion base pairs of proteins (adenine, guanine, cytosine, thymine). </li></ul><ul><li>The 3 billion base pairs are organized into 23 pairs of chromosomes (one set of pair inherited from the mother and one from the father). </li></ul>
  25. 26. Genes <ul><li>The DNA in each chromosome contains many genes. </li></ul><ul><li>Each gene is a stretch of DNA that contains a particular set of instructions, usually coding for a particular protein. </li></ul><ul><li>There are between 30,000 – 50,000 human genes. </li></ul>
  26. 27. How Genetically Complex are Humans Relative to Other Species? <ul><li>Number of Genes: </li></ul><ul><ul><li>Human - ~30,000 </li></ul></ul><ul><ul><li>Mouse - ~30,000 </li></ul></ul><ul><ul><li>Fruit Fly - 13,600 </li></ul></ul><ul><ul><li>Plant - 25,500 </li></ul></ul>
  27. 28. How Genetically Diverse are Humans from other Species? <ul><li>Genetically identical to Humans: </li></ul><ul><li>Chimpanzees ~ 98.5% </li></ul><ul><li>Mice ~ 85.0% </li></ul>
  28. 29. Genes and the Brain <ul><li>Genotype: Sum total of your particular set of genes. </li></ul><ul><li>Phenotype: The observable structure of behavior of an organism. </li></ul><ul><li>Mutations (physical changes to genes can produce different behaviors) </li></ul><ul><ul><li>Fat mice </li></ul></ul><ul><li>The environment matters </li></ul><ul><ul><li>Pruning (losing unused neural connections) </li></ul></ul><ul><ul><li>Plasticity (the brains ability to change with </li></ul></ul><ul><ul><li>experience: pruning or neural growth) </li></ul></ul>
  29. 30. Three Ways Genes and the Environment Interact <ul><li>Passive interaction: Genetically shaped tendencies of parents or siblings produce an environment that is passively received by the child. </li></ul><ul><li>Evocative (or reactive ) interaction: Genetically influenced characteristics draw out behaviors from other people. </li></ul><ul><li>Active interaction: People choose, partly based on genetic tendencies, to put themselves in specific situations and to avoid others. </li></ul>
  30. 31. Behavioral Genetics <ul><li>DNA </li></ul><ul><li>Heritability </li></ul><ul><li>Twin studies </li></ul><ul><ul><li>Monozygotic (identical) </li></ul></ul><ul><ul><li>Dizygotic (fraternal) </li></ul></ul><ul><ul><li>Adoption studies </li></ul></ul>
  31. 32. Evolution and the Brain <ul><li>Evolution </li></ul><ul><li>Natural selection </li></ul><ul><li>Adaptation </li></ul><ul><li>Reproduction of the fittest </li></ul>
  32. 33. Genetic Testing <ul><li>DNA testing is useful </li></ul><ul><ul><li>innocence or guilt; disease risk; preventive treatment or adjust their lifestyle; paternity. </li></ul></ul><ul><li>Genetic “blueprints” cost as little as $985 </li></ul><ul><ul><li>find out if your risk for 18 diseases, including Alzheimers. </li></ul></ul><ul><li>Soon it may be economically possible to construct a complete genetic map for every individual in the United States. </li></ul><ul><li>Potential uses and abuse </li></ul>
  33. 34. More Questions on Genetics <ul><li>Would you want to know about your risk for a disease that has no current preventive treatment or cure? Why? </li></ul><ul><li>Would the information improve or diminish your quality of life? Why? </li></ul><ul><li>Should potential employers, insurance companies, or the government have access to this information? Why? </li></ul><ul><li>Should potential employers, insurance companies, or the government be able to administer these tests prior to you being hired or insured? Why? </li></ul><ul><li>Because it is clear that the ability to gather this information is rapidly approaching, should steps be taken to limit who has access to this information or to limit how it is used? What kind of steps? </li></ul><ul><li>Do the potential benefits of having this information outweigh the drawbacks? Why? </li></ul>