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brain structure

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  • 1. Brain Structure and Function
  • 2. “If the human brain were sosimple that we couldunderstand it, we would be sosimple that we couldn’t”-Emerson Pugh, The Biological Origin of HumanValues (1977)
  • 3. Phineas Gage• September 13th, 1848• Phineas 25 years old• Rutland & BurlingtonRailroad, Cavendish, VT• Paving the way for new RR tracks• “Tamping Iron”– 1.25in x 3ft
  • 4. • Accident– Quick Recovery• Months later: “No longer Gage”– Before: capable, efficient, best foreman, well-balancedmind– After: extravagant, anti-social, liar, grossly profane• Stint with P.T Barnum• Died 12 years laterPhineas Gage
  • 5. Evolution of the BrainReptilian  Paleomammalian  Neomammalian
  • 6. The Brain• Brainstem–responsible forautomatic survivalfunctions• Medulla–controls heartbeatand breathing
  • 7. BRAINSTEM  Heartrate and breathingCEREBELLUM Coordinationand balanceParts of the BrainamygdalapituitaryhippocampusTHALAMUS Relaysmessages
  • 8. Reticular Formation•Widespread connections•Arousal of the brain asa whole•Reticular activatingsystem (RAS)•Maintainsconsciousness andalertness•Functions in sleep andarousal from sleep
  • 9. The Cerebellum–helps coordinatevoluntarymovement andbalance
  • 10. The Limbic System• Hypothalamus, pituitary, amygdala, and hippocampus alldeal with basicdrives, emotions, andmemory• Hippocampus  Memoryprocessing• Amygdala  Aggression(fight) and fear (flight)• Hypothalamus Hunger, thirst, bodytemperature, pleasure;regulates pituitary gland
  • 11. The Limbic System Hypothalamus neural structure lyingbelow (hypo) thethalamus; directs severalmaintenance activities eating drinking body temperature helps govern theendocrine system via thepituitary gland linked to emotion
  • 12. The Limbic System
  • 13. The Limbic System• Amygdala–two almond-shaped neuralclusters that arecomponents ofthe limbic systemand are linked toemotion and fear
  • 14. Charles WhitmanAugust 1st, 1966
  • 15. The Brain• Thalamus– the brain’s sensoryswitchboard, locatedon top of thebrainstem– it directs messages tothe sensory receivingareas in the cortexand transmits repliesto the cerebellum andmedulla
  • 16. The Cerebral Cortex• Cerebral Cortex–the body’sultimate controland informationprocessingcenter
  • 17. The lobes of the cerebral hemispheres
  • 18. The lobes of the cerebral hemispheresPlanning, decisionmaking speechSensoryAuditoryVision
  • 19. The Cerebral Cortex• Frontal Lobes–involved in speaking andmuscle movements and inmaking plans and judgments–the “executive”• Parietal Lobes–include the sensory cortex
  • 20. The Cerebral Cortex• Occipital Lobes–include the visual areas, whichreceive visual information from theopposite visual field• Temporal Lobes–include the auditory areas, each ofwhich receives auditory informationprimarily from the opposite ear
  • 21. The Cerebral Cortex• Frontal (Forehead to top)  Motor Cortex• Parietal (Top to rear)  Sensory Cortex• Occipital (Back)  Visual Cortex• Temporal (Above ears)  Auditory Cortex
  • 22. Motor/Sensory Cortex• Contralateral• Homunculus• Unequalrepresentation
  • 23. Sensory Areas – Sensory HomunculusFigure 13.10
  • 24. The Cerebral Cortex Aphasia impairment of language, usually caused by lefthemisphere damage either to Broca’s area(impairing speaking) or to Wernicke’s area(impairing understanding) –see clips Broca’s Area an area of the left frontal lobe that directs themuscle movements involved in speech Wernicke’s Area an area of the left temporal lobe involved inlanguage comprehension and expression
  • 25. Language Areas• Broca Expression• Wernicke Comprehensionand reception• AphasiasLEFT HEMISPHERE
  • 26. Paul Broca [1800s]• Suggested localization
  • 27. Techniques to examine functionsof the brain1. Remove part ofthe brain & seewhat effect it hason behavior2. Examine humanswho have sufferedbrain damage
  • 28. 3. Stimulate thebrain4. Record brainactivity
  • 29. Brain Lateralization
  • 30. Our Divided Brains• Corpus collosum –large bundle ofneural fibers(myelinatedaxons, or whitematter) connectingthe twohemispheres
  • 31. Hemispheric SpecializationLEFTSymbolic thinking(Language)DetailLiteral meaningRIGHTSpatial perceptionOverall pictureContext,metaphor
  • 32. Contra-lateraldivision of labor• Right hemispherecontrols left side ofbody and visual field• Left hemispherecontrols right side ofbody and visual field
  • 33. Split Brain Patients• Epileptic patients had corpus callosum cutto reduce seizures in the brain• Lives largely unaffected, seizures reduced• Affected abilities related to naming objectsin the left visual field
  • 34. Brain Plasticity
  • 35. Brain Plasticity• The ability of the brain toreorganize neural pathwaysbased on new experiences• Persistent functional changes inthe brain represent newknowledge• Age dependent component• Brain injuries
  • 36. Environmental influences onneuroplasticityImpoverished environmentEnriched environment
  • 37. Sensation and Perception
  • 38. Sensation• The process by which the centralnervous system receives input fromthe environment via sensory neurons• Bottom up processing
  • 39. Perception• The process by which the braininterprets and organizes sensoryinformation• Top-down processing
  • 40. The psychophysics of sensation• Absolute threshold  the minimumstimulation needed to detect a stimulus with50% accuracy• Subliminal stimulation  below theabsolute threshold for conscious awareness– May affect behavior without consciousawareness• Sensory adaptation/habituation diminished sensitivity to an unchangingstimulus
  • 41. The five major senses• Vision – electromagnetic– Occipital lobe• Hearing – mechanical– Temporal lobe• Touch – mechanical– Sensory cortex• Taste – chemical– Gustatory insular cortex• Smell – chemical– Olfactory bulb– Orbitofrontal cortex– Vomeronasal organ?
  • 42. The sixth sense• Vestibular  balance and motion– Inner ear• Proprioceptive  relative position of bodyparts– Parietal lobe• Temperature  heat– Thermoreceptors throughout the body, sensory cortex• Nociception  pain– Nociceptors throughout the body, sensory cortexAnd the seventh…and eighth…and ninth…
  • 43. Thresholds of the five major senses
  • 44. The RetinaThe retina at theback of the eyeis actually partof the brain!Rods –brightnessCones – color