The Brain

1. The Brain Carolyn R. Fallahi, Ph. D. Dr. Carolyn R. Fallahi

2. Phrenology • The idea that specific mental processes are located in, or associated with, discrete parts of the brain can be traced back to the early 1800s when a German physician, Franz Gall, invented phrenology. Dr. Carolyn R. Fallahi

3. Phrenology • Phrenology was the study of the bumps on the skull which could reveal our mental abilities and character traits. Dr. Carolyn R. Fallahi

4. Phrenology Dr. Carolyn R. Fallahi

5. Neurons and neural impulses • A Neuron is defined as an individual nerve cell in the nervous system. The neuron is the simplest element of the nervous system. Dr. Carolyn R. Fallahi

6. The Cell body • A neuron is made up of the following: • Cell body – central part of the nerve cell. Contains the cell’s control center. Dr. Carolyn R. Fallahi

7. The Nucleus • Nucleus – helps feed the neuron and keep it alive (the cell’s control center). Dr. Carolyn R. Fallahi

8. Dendrites • Dendrites – small branches off the cell body which receive messages from other neurons. Dr. Carolyn R. Fallahi

9. Axons • Axons are small branches at the other end of the neuron that carries messages away from the axon and transmits those messages to the next neuron. Axon tracts stretch-grown to 5 cm. Axon tracts (middle) bridge two populations of neurons (top and bottom). Dr. Carolyn R. Fallahi

10. Axon Terminals Dr. Carolyn R. Fallahi

11. Synapse Dr. Carolyn R. Fallahi

12. Neural Transmission • When the neuron is stimulated, it generates an impulse that travels down the axon and into the axon terminals where it causes the release of specialized chemicals. • These chemicals are called neurotransmitters. They travel a small distance across a synapse to the next neuron. Dr. Carolyn R. Fallahi

13. Neural Transmission • Neurons are long sacs filled with fluid on the inside and bathed in fluid on the outside. • The liquid on the inside consists of chemicals with either a positive or negative charge === this called ions. • If inside the cell is more negatively charged, then the overall cell is negative. • Negative cells are attracted to positive charged ions. Dr. Carolyn R. Fallahi

14. Neural Transmission • Neurons are linked together in complex chains. • There is a gap between the axon of one neuron and the dendrite of another – this is called the synpase. • Neural messages cross this gap depending on chemical substances that are called neurotransmitters. Dr. Carolyn R. Fallahi

15. Multiple Sclerosis and Guillain-Barre Syndrome • The myelin sheath is a layer of fatty cells that insulates the axons of some neurons. • Their purpose is to help speed the impulses of that neuron. • They are important for the normal transfer of information in the human nervous system. • With MS – the myelin sheaths of axon bundles in the brain, spinal cord and optic nerves hardens or develops lesions around those bundles. Dr. Carolyn R. Fallahi

16. The Myelin Sheath Dr. Carolyn R. Fallahi

17. Guillain-Barre Syndrome • This is a more common demyelinating disease that attacks the myelin of the peripheral nerves that innervate muscle and skin. • Often the disease develops from minor infectious illnesses or even inoculations. • It seems to result from a faulty immune reaction in which the body attacks its own myelin as if it were a foreign substance. • The symptoms come directly from the slowing of action potential conduction in the axons that innervate the muscle. Dr. Carolyn R. Fallahi

18. The Addicted Brain • The human brain is the world’s most prolific manufacturer and user of drugs • Biochemistry of addiction. • The role of neurotransmitters in mediating thoughts and feelings, particularly pain and pleasure. • A rat b/c addicted to cocaine and once addicted, will choose cocaine over food and thus starve to death. Dr. Carolyn R. Fallahi

19. Endorphins • Endorphins was coined from endogenous morphine and refers to the brain’s natural painkillers. • Pert & Snyder – 2 researchers – identified “opiate receptors” in the brain. • The discovery of endorphins grew out of the curiosity of 2 British pharmacologists, Hans Kosterlitz and John Hughes. In 1975, they isolated a substance from the brain of pigs that had the same actions as morphine. They named it enkephalin. Dr. Carolyn R. Fallahi

20. Endorphins • Later, the brain opioids were discovered. The group as a whole was named endorphins. • Research now looks at how natural opioids are produced by the brain, the pituitary gland, and other tissues in response to pain,stress, or other vigorous exercise. Dr. Carolyn R. Fallahi

21. Parkinson’s Disease • Parkinson’s disease was named after James Parkinson, a London physician who first described its “involuntary tremulous motion” in 1817 • It was hoped that Parkinson’s might be alleviated by replacing the chemical. It was thought that the tremors of Parkinson’s disease resulted from the death of nerve cells that produced dopamine, and thus the affliction became the first illness attributed to neurotransmitter deficiency. Dr. Carolyn R. Fallahi

22. Facts about the Brain: • At birth, the brain has all the brain cells or neurons that it will ever have. • Brain neurons do not regenerate. • The environment modifies brain structure. • Neural plasticity – ability to change its structure and function in response to external experiences. Dr. Carolyn R. Fallahi

23. Brain Research • At birth, humans do not yet possess a fully operational brain. • Environment affects how genes work; genes determine how the environment is interpreted. • Dr. Marion Diamond at the U. of California-Berkley, 1960s. Dr. Carolyn R. Fallahi

24. More Facts about Brain • The brain develops in an integrated fashion over time. • Learning is gradual. For ex…a baby doesn’t learn how to talk in one week. • The brain is curious and seeks connections between the new and the known. Dr. Carolyn R. Fallahi

25. More Facts about Brain • IQ is not fixed at birth. • Intervention programs can prevent children from having low IQs. • Some abilities are acquired more easily during certain sensitive periods. Dr. Carolyn R. Fallahi

26. Premature Infants For example…. Maternal smoking Alcohol use Infant malnutrition Lead poisoning Policies We spend 7x more on care for elderly than on children from birth to 5 years old. Applications of Brain Research Dr. Carolyn R. Fallahi

27. Brain Research • The role of nutrition of brain function. • How brain chemicals affect mood, personality, and behavior. • The connection between mind/brain and the body. Dr. Carolyn R. Fallahi

28. At Birth: 100 billion neurons 1 trillion glial cells – honeycomb that protects & nourishes the neurons Lay out circuits in place. Sensory experiences change brain structure. Deprivation of stimulating environment leads to decreased brain development. Malleable brain, e.g. stroke, epilepsy The developing brain B – 3 Years Dr. Carolyn R. Fallahi

29. 100,000 genes in human DNA Some 50,000 genes appear to be dedicated to constructing and maintaining the nervous system. Experience kicks in. The connections lends the growing brain exceptional flexibility & resilience. Genes and the Brain Dr. Carolyn R. Fallahi

30. Neural circuitry & stress • Children who are physically abused – brains tuned to danger. • Emotional deprivation – marked reduced activity in the left frontal lobe. • Physical, emotional abuse / neglect – child’s brain is forgiving – for a time. Dr. Carolyn R. Fallahi

31. Emotional deprivation early in life • The patterns of brain activity displayed by these children closely tracked the ups and downs of their mother’s depression. • At the age of three, children whose mothers were more severely depressed or whose depression lasted longer continued to show abnormally low readings. Dr. Carolyn R. Fallahi

32. Eye • Children born with a cataract will become permanently blind in that eye if the clouded lens is not promptly removed. Why? The brain’s visual centers require sensory stimulus to maintain their tentative connections. • Critical period for the eye is 3 years old. • Same holds true for hearing. Dr. Carolyn R. Fallahi

33. Language • Many linguists believe that language skills unfold according to a strict, biologically defined timetable. • Let’s examine this notion with the case of Genie. Dr. Carolyn R. Fallahi

34. Plasticity • Brains greatest growth spurt decreases at about 10 years old. • By 18, the brain declines in plasticity but increases in power. • Potential for greatness is encoded in the genes; but whether potential is realized involves how patterns are etched by experience in critical years. Dr. Carolyn R. Fallahi

35. Politics of Biology • Addictive disorders, sexual orientation, criminality? Due to nature/nurture. • Research: finding a new gene for lots of things. E.G., shyness, tendency to divorce, lack of happiness, etc. • Implications for belief in genes: decreases sense of responsibility for ailments. E.G., alcoholism – victim or have control? Dr. Carolyn R. Fallahi

36. Politics of Biology • Research for years…to identify genetic roots for aggression, violence, criminality. • 1965 study found imprisoned criminals were more likely than other people to have extra Y chromosome. • Research did not turn out to be accurate. XYY men were less intelligent but not aggressive. Dr. Carolyn R. Fallahi

37. Genetics & Psychiatric Disorders • Schizophrenia – past view…resulting from mothers who were apathetic toward their children. New view: genetics. • Takes guilt away. • Managed care issues – if due to biology – will only pay for drug therapy. • Homosexuality studies. LeVay (1991). Dr. Carolyn R. Fallahi

38. Introduction • The split brain research – reported by Gazzaniga (1967) • Right versus left hemispheres: • Left brain controls the ability to use language • Right brain controls spatial relationships, especially those needed for artistic activities Dr. Carolyn R. Fallahi

39. Split brain research cont’d • Many people believe that each half, or “hemisphere” of your brain may actually be a completely separate mental system with its own individual abilities for learning, remembering, perceiving the world, and even feeling emotions. Dr. Carolyn R. Fallahi

40. Research split brain pioneered by Roger W. Sperry (1913-1994). • Sperry was a prominent brain researcher and received a nobel peace prize in 1981 in physiology. • He is best known for his research on “Split brain” patients, demonstrating how the two halves of the brain functioned. • He was responsible for overturning the widespread belief that the left brain was dominant by showing that several cognitive abilities were localized in the right brain. Dr. Carolyn R. Fallahi

41. Sperry • He also provided experimental proof for the specificity of the reconnection of regenerating severed neurons in newts, which later led to new theories on how neurons grow. • Sperry was born in Hartford, CT in 1913. • Sperry’s famous split brain experiments started with the problem of interocular transfer. Dr. Carolyn R. Fallahi

42. Sperry • Interocular transfer: if one learns with one eye how to solve a problem then, with that eye covered and using the other eye, one already knows how to solve the problem. This is called “interocular transfer of learning.” • The question is….how can the learning with one eye appear with the use of the other? Sperry split the optic chiasm so the right eye goes to the right cerebral hemisphere and the left eye to the left hemisphere and also cut the corpus callosum between the two hemispheres. Dr. Carolyn R. Fallahi

43. Sperry • He did this in cats which created the “split brain cat.” The cat could be trained with the right eye to distinguish a triangle from a square while the left eye was covered. • After the cat learned the problem, Sperry tested the left eye with the right eye covered. The split brain cat had to learn all over again. The learning curve for the left eye (and left hemisphere) was very similar to the learning curve for the right eye. Dr. Carolyn R. Fallahi

44. Sperry • Since the cat had to learn all over from the beginning with the second eye, the cat could be trained to pick the square instead of the triangle when using the second eye. Each hemisphere has developed a different memory about what is correct. Dr. Carolyn R. Fallahi

45. Sperry • Sperry’s experiments with cats and later with monkeys paved the way for cutting the corpus callosum in humans as a treatment for severe epilepsy. • After the patients recovered from the operation and were no longer having seizures, they were generally willing to come to the Sperry lab, taking part in experiments extending over several decades. Dr. Carolyn R. Fallahi

46. Sperry • What these famous studies taught us: • 1. Socialness • 2. Lack of Interhemispheric Transfer • 3. Hemispheric specialization effects • 4. Compensary phenomena Dr. Carolyn R. Fallahi

47. Corpus Callosum • The corpus callosum is a structure made up of approximately 200 million nerve fibers. • This structure allows the two hemispheres of your brain to be in constant communication with one another. Dr. Carolyn R. Fallahi

48. Split brain research • Our increased knowledge of the specialized functioning of the 2 hemispheres allows us to better treat victims of stroke or head injury. By knowing the location of the damage, we can predict what deficits are likely to exist as the patient recovers. We can plan appropriate relearning and rehab strategies to make the recovery as quick as possible. Dr. Carolyn R. Fallahi