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Introduction To Neuroscience


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Introduction To Neuroscience

  1. 1. Introduction to Neuroscience The Search for Consciousness and the Anatomical Basis of the Soul
  2. 2. History of Neuroscience <ul><li>Prehistory </li></ul><ul><ul><li>10,000 years ago, early hominids </li></ul></ul><ul><ul><li>Trepanation - making a therapeutic hole in the skull </li></ul></ul><ul><li>Ancient Egypt – </li></ul><ul><ul><li>5000 years ago; aware of symptoms of brain damage </li></ul></ul><ul><ul><li>Heart, not the brain believed to be the storehouse of memories and location of the soul </li></ul></ul>
  3. 3. Ancient Greece <ul><li>4th C. B.C. </li></ul><ul><ul><li>Brain is the organ of sensation </li></ul></ul><ul><li>Hippocrate s (460-379 BC) </li></ul><ul><ul><li>Brain is the seat of intelligence </li></ul></ul><ul><li>Aristotle (384-322 BC) </li></ul><ul><ul><li>Heart is the center of intellect </li></ul></ul><ul><ul><li>the brain serves to cool blood. </li></ul></ul>
  4. 4. The Romans <ul><li>Galen (130-200 AD) – </li></ul><ul><ul><li>A Greek, chief physician in Rome </li></ul></ul><ul><ul><li>As physician to gladiators, saw spinal cord & brain injuries </li></ul></ul><ul><ul><li>Dissected sheep to study brain </li></ul></ul><ul><ul><li>Tried to deduce functions: </li></ul></ul><ul><ul><ul><li>Cerebrum is soft - recipient of sensations; </li></ul></ul></ul><ul><ul><ul><li>Cerebellum is rather firm - must command the muscles; </li></ul></ul></ul><ul><ul><ul><li>Ventricles served to receive the vital humors via the nerves, which were hollow tubes like blood vessels. </li></ul></ul></ul><ul><ul><li>These ideas prevailed for the next 1500 years. </li></ul></ul>
  5. 5. Renaissance to the 19 th Century <ul><li>Andreas Vesalius (1514-1564 AD) </li></ul><ul><ul><li>Outstanding anatomist and medical illustrator </li></ul></ul><ul><ul><li>Made detailed studies of the bodies of criminals </li></ul></ul><ul><ul><li>Paid particular attention to the ventricles </li></ul></ul><ul><ul><li>Hydraulic view of brain function: Prevailing notion was that fluids forced out from the ventricles could &quot;pump you up&quot; </li></ul></ul><ul><li>White matter/Gray matter </li></ul><ul><ul><li>since white matter was continuous with the nerves, it carried information to and from the gray matter </li></ul></ul><ul><li>The bumps (gyri) and grooves (sulci and fissures) on the surface of the cerebral cortex have a repeatable pattern from individual to individual </li></ul>
  6. 6. Renee Descartes <ul><li>17th C. French philosopher </li></ul><ul><li>First to suggest substance dualism: material stuff & thinking stuff </li></ul><ul><li>Brain, ventricles, and nerves are tools of human behavior shared by higher animals </li></ul><ul><li>The mind is a uniquely human thing - a spiritual entity (soul) that communicates with the brain via the pineal gland </li></ul><ul><li>How do we perceive self - what creates brain consciousness? </li></ul><ul><ul><li>Descartes thought it was the pineal gland. </li></ul></ul><ul><li>Cartesian theater (Daniel Dennet) </li></ul><ul><ul><li>idea that there is a place in the brain where it all comes together - center of consciousness or soul. </li></ul></ul><ul><ul><li>100 billion neurons in the brain - not one center, but the way neurons are massively interconnected (parallel processing networks) = consciousness </li></ul></ul>
  7. 7. Major Developments of the 19 th Century <ul><li>Starting point of modern neuroscience </li></ul><ul><li>Injury to the brain disrupts sensations, movement, thought; causes death. </li></ul><ul><li>Brain communicates with the body via the nerves </li></ul><ul><li>Brain has substructures which probably perform different tasks </li></ul><ul><li>Brain operates like a machine and follows laws of nature (but the mind?) </li></ul>
  8. 8. Four Key 19 th C. Observations <ul><li>Major insight #1: </li></ul><ul><li>- Nerves as wires </li></ul><ul><li>Major insight #2: </li></ul><ul><li>- Localization of brain function </li></ul><ul><li>Major insight #3: </li></ul><ul><li>- The nervous system (and thus behavior) is governed by the principles of evolution by natural selection </li></ul><ul><li>Major insight #4: </li></ul><ul><li>- The neuron is the basic functional unit of the nervous system </li></ul>
  9. 9. Nerves as Wires <ul><li>Benjamin Franklin - Experiments and Observations on Electricity – 1751 </li></ul><ul><li>Luigi Galvani & Emil du Bois-Reymond - 1800 </li></ul><ul><ul><li>Electricity to nerves can make muscles twitch </li></ul></ul><ul><ul><li>Brain generates electricity </li></ul></ul><ul><li>Charles Bell & Francois Magendie – 1810 </li></ul><ul><ul><li>Dorsal roots carry sensory information </li></ul></ul><ul><ul><li>Ventral roots carry motor information </li></ul></ul><ul><ul><li>Nerve trunks are mixtures of fibers going in both directions </li></ul></ul>
  10. 10. Localization of Brain Function <ul><li>Charles Bell - 1811 </li></ul><ul><ul><li>proposed that motor fibers (ventral roots) originate in the cerebellum and sensory fibers (dorsal roots) in the cerebrum </li></ul></ul><ul><li>Marie-Jean-Pierre Flourens – </li></ul><ul><ul><li>used selective removal (ablation) to provide experimental evidence (largely from birds) that Galen and Bell were right. </li></ul></ul><ul><li>Franz Joseph Gall – </li></ul><ul><ul><li>Phrenology - behavior could be correlated with the size of different parts of the skull </li></ul></ul><ul><ul><li>Foreshadowed the localization of function to the cerebral cortex </li></ul></ul><ul><li>Paul Broca – neurologist </li></ul><ul><ul><li>Studied patient who could understand language, but not speak. </li></ul></ul><ul><ul><li>After patient’s death, found lesion in left frontal lobe (Broca's area) </li></ul></ul>
  11. 11. Evolution of Nervous Systems <ul><li>Charles Darwin - On the Origin of Species , 1859 </li></ul><ul><ul><li>Evolution by natural selection included behavior and the nervous system </li></ul></ul><ul><li>More advanced animals have same basic nervous system core as lower animals </li></ul><ul><ul><li>Basis of using animal models </li></ul></ul><ul><li>Nervous system is specialized for niche </li></ul><ul><ul><li>e.g. monkeys have well developed vision for their arboreal life and rats have poorly developed vision, but well developed vibrissae (whiskers) </li></ul></ul>
  12. 12. The Neuron <ul><li>The Neuron is the basic functional unit of the nervous system </li></ul><ul><li>Theodore Schwann – </li></ul><ul><ul><li>proposed cell theory in 1839 </li></ul></ul><ul><li>The major problem was to determine whether the network of nerve fibers in the brain were interconnected like a plumbing system or made up of distinct neurons. </li></ul>
  13. 13. Contemporary Neuroscience <ul><li>Molecular Neuroscience – </li></ul><ul><ul><li>biochemistry of the nervous system </li></ul></ul><ul><li>Cellular Neuroscience – </li></ul><ul><ul><li>cell biology of the nervous system </li></ul></ul><ul><ul><li>Structure/function at the level of individual neurons </li></ul></ul><ul><li>Systems Neuroscience – </li></ul><ul><ul><li>how do neural circuits work? </li></ul></ul><ul><ul><li>Sensory systems, motor systems, etc. </li></ul></ul><ul><li>Behavioral Neuroscience – </li></ul><ul><ul><li>how do systems of the brain interact to produce behavior? </li></ul></ul><ul><ul><li>Source of dreams? Mind altering drugs (foods)? </li></ul></ul><ul><li>Cognitive Neuroscience – </li></ul><ul><ul><li>How does the activity of the brain create the mind? </li></ul></ul><ul><ul><li>Descartes' Problem - self-awareness, mental imagery, language </li></ul></ul>
  14. 14. Nervous System Disorders <ul><li>The driving force behind neuroscience </li></ul><ul><li>More Americans are hospitalized with neurological and mental disorders than with any other disease group including heart disease and cancer </li></ul><ul><li>Alzheimer’s, Parkinson’s, Huntington’s : </li></ul><ul><ul><li>all caused by progressive degeneration of specific brain areas </li></ul></ul><ul><li>Parkinson’s– cripples voluntary movements </li></ul><ul><ul><li>afflicts 500,000 Americans </li></ul></ul><ul><li>Alzheimer’s – dementia </li></ul><ul><ul><li>affects over 3 x 10 6 Americans </li></ul></ul><ul><li>Stroke – the 3rd leading cause of death in the U.S. </li></ul><ul><ul><li>annual cost $25 billion </li></ul></ul>
  15. 15. Nervous System Disorders - Mood <ul><li>Mental disorders cost the U.S. $130 billion yearly </li></ul><ul><li>Depression & Schizophrenia – </li></ul><ul><ul><li>disorders of mood & thought </li></ul></ul><ul><ul><li>15 x 10 6 Americans will experience a major depressive illness in their lifetime </li></ul></ul><ul><ul><li>leading cause of suicide </li></ul></ul><ul><li>Schizophrenia – delusions, hallucinations – </li></ul><ul><ul><li>affects 2 x10 6 Americans </li></ul></ul><ul><li>Alcohol and drug addiction affect virtually every family – cost $150 billion/year </li></ul>
  16. 16. The Basics of Neuroscience <ul><li>The basic function of all nervous systems: </li></ul><ul><li>Stimulus and response </li></ul><ul><li>Example: Doorbell rings ( stimulus ) </li></ul><ul><ul><li>Receptors in the ear receive the stimulus </li></ul></ul><ul><ul><li>Conductors (nerves) carry the message to the brain </li></ul></ul><ul><ul><li>The brain interprets the message </li></ul></ul><ul><ul><li>Conductors (nerves) carry the message from brain to muscles </li></ul></ul><ul><ul><li>Effectors (muscles) are stimulated and you walk to the door! </li></ul></ul>
  17. 17. Picturing Stimulus & Response
  18. 18. Structures of Stimulus & Response <ul><li>3 types of structures are required :  </li></ul><ul><li>Receptors </li></ul><ul><ul><li>a group of cells or an organ that detects a stimulus and generates impulses that travel along conductors. </li></ul></ul><ul><li>Conductors </li></ul><ul><ul><li>nerve cells that carry the message to and from the brain and/or spinal cord </li></ul></ul><ul><li>Effectors </li></ul><ul><ul><li>structures that react to the original stimulus; muscles or glands </li></ul></ul>