The Myth of Using Only 10% of Our Brain

1. FEM 4100 Brain & human BehaviorTopic 1: Introduction

2. True or False? • Do we use only 10% of our brains? False: There is no scientific evidence to suggest that we use only 10% of our brains.

3. Where Did the 10% Myth Begin? • The 10% statement may have been started with a misquote of Albert Einstein or the misinterpretation of the work of Pierre Flourens in the 1800s. • It may have been William James who wrote in 1908: "We are making use of only a small part of our possible mental and physical resources" (from The Energies of Men, p. 12).

4. Where Did the 10% Myth Begin? • Perhaps it was the work of Karl Lashley in the 1920s and 1930s that started it. Lashley removed large areas of the cerebral cortex in rats and found that these animals could still relearn specific tasks. • We now know that destruction of even small areas of the human brain can have devastating effects on behavior. • That is one reason why neurosurgeons must carefully map the brain before removing brain tissue during operations for epilepsy or brain tumors: they want to make sure that essential areas of the brain are not damaged.

5. Why Does the Myth Continue? • Somehow, somewhere, someone started this myth and the popular media keep on repeating this false statement (see the figures). Soon, everyone believes the statement regardless of the evidence. I have not been able to track down the exact source of this myth, and I have never seen any scientific data to support it. • According to the believers of this myth, if we used more of our brain, then we could perform super memory feats and have other fantastic mental abilities - maybe we could even move objects with a single thought. Again, I do not know of any data that would support any of this.

6. What Does it Mean to Use Only 10% of Your Brain? • What data were used to come up with the number - 10%? • Does this mean that you would be just fine if 90% of your brain was removed? • If the average human brain weighs 1,400 grams (about 3 lb) and 90% of it was removed, that would leave 140 grams (about 0.3 lb) of brain tissue. • That's about the size of a sheep's brain.

7. What Does it Mean to Use Only 10% of Your Brain? • It is well known that damage to a relatively small area of the brain, such as that caused by a stroke, may cause devastating disabilities. • Certain neurological disorders, such as Parkinson's Disease, also affect only specific areas of the brain. • The damage caused by these conditions is far less than damage to 90% of the brain.

8. What Does it Mean to Use Only 10% of Your Brain? • Perhaps when people use the 10% brain statement, they mean that only one out of every ten nerve cells is essential or used at any one time? • How would such a measurement be made? • Even if neurons are not firing action potentials, they may still be receiving signals from other neurons.

9. True or False? • Your brain makes a painkiller similar to heroin True: Naturally produced chemicals called endorphins are closely related to heroin

10. True or False? • Is Laughter the Best Medicine? • True: It may be a good way for people to relax because muscle tension is reduced after laughing. • There are some cases when a good deep laugh may help people with respiratory problems by clearing mucus and aiding ventiliation. • Perhaps laughing can also help cardiac patients by giving the heart a bit of a workout. • Some hospitals even have their own "Humor Rooms," "Comedy Carts," and clown kids in attempts to speed a patient's recovery and boost morale.

11. False: However, laughter is NOT ALWAYS good medicine. • There are a few cases when laughing actually CAUSED a heart attack or a stroke. • Also, immediately after abdominal surgery, people should not laugh too hard because they could tear out their stitches accidentally. • Care should also be used in patients with broken ribs. So, try not to be too funny around these people.

12. Research has shown that parts of the limbic system are involved in laughter. • The limbic system is a primitive part of the brain that is involved in emotions and helps us with basic functions necessary for survival. • Two structures in the limbic system have been shown to play a role in laughter: the amygdala and the hippocampus. • Humans may be "tuned" for laughter much in the same way that songbirds are "tuned" for song -- especially their own specific family song. (While birdsong of one species may sound the same to you and me, there are subtle differences among the birds' songs.) • Certain nerve cells in the songbird's brain "fire" in response to hearing his song.

13. Perhaps humans have specialized nerve cells that respond to laughter. • After all, laughter is a specialized vocalization, and we are "tuned" to respond to vocalizations with language. • We use our brain for many things. • Laughter is yet another part of human behavior that the brain regulates. • It helps us clarify our intentions and provides an emotional context to our conversations. • Laughter, then, is used as a signal for being part of a group--it signals acceptance and positive interactions. • It clues the listener in to the emotional tone of the conversation and the speaker's intentions. • This may be one reason it is more difficult to interpret the meaning of an e-mail or letter--emotional clues about the sender's tone are missing.

14. Did You Know? • Laughter is contagious. • Since 1950, TV has exploited this by adding "laugh tracks" to sitcoms. • People laugh more readily upon hearing others laugh. • When you hear others laugh, you actually think the TV show is more humorous. • Babies start to laugh at about 4 months of age. • Babies who are born blind and deaf can laugh, so the ability to see or hear is not required for laughter.

15. True or False? • Many things that happen to us leave no record in memory True: Most of the information around us never reaches memory, and what does reach memory often gets distorted

16. True or False? • You are born with all the brain cells you will ever have False: Recent research shows that some parts of the brain continue producing new cells throughout life

17. The Brain vs. The Computer • How does the brain compare to the computer?? • Some people say that the computer is better than the brain; some people say that the brain is better than the computer. • Perhaps, it is best to say that the brain is better at doing some jobs and the computer is better at doing other jobs.

18. The Brain vs. The Computer • Similarity Both use electrical signals. • Difference The brain uses chemicals to transmit information; the computer uses electricity. Even though electrical signals travel at high speeds in the nervous system, they travel even faster through the wires in a computer.

19. The Brain vs. The Computer • Similarity Both transmit information. • Difference A computer uses switches that are either on or off ("binary"). In a way, neurons in the brain are either on or off by either firing an action potential or not firing an action potential. However, neurons are more than just on or off because the "excitability" of a neuron is always changing. This is because a neuron is constantly getting information from other cells through synaptic contacts. Information traveling across a synapse does NOT always result in a action potential. Rather, this information alters the chance that an action potential will be produced by raising or lowering the threshold of the neuron.

20. The Brain vs. The Computer • Similarity Both have a memory that can grow. • Difference Computer memory grows by adding computer chips. Memories in the brain grow by stronger synaptic connections.

21. The Brain vs. The Computer • Similarity Both can adapt and learn. • Difference It is much easier and faster for the brain to learn new things. Yet, the computer can do many complex tasks at the same time ("multitasking") that are difficult for the brain. For example, try counting backwards and multiplying 2 numbers at the same time. However, the brain also does some multitasking using the autonomic nervous system. For example, the brain controls breathing, heart rate and blood pressure at the same time it performs a mental task.

22. The Brain vs. The Computer • SimilarityBoth need energy. • Difference The brain needs nutrients like oxygen and sugar for power; the computer needs electricity to keep working. • SimilarityBoth can be damaged. • Difference It is easier to fix a computer - just get new parts. There are no new or used parts for the brain. However, some work is being done with transplantation of nerve cells for certain neurological disorders such as Parkinson's disease. Both a computer and a brain can get "sick" - a computer can get a "virus" and there are many diseases that affect the brain. The brain has "built-in back up systems" in some cases. If one pathway in the brain is damaged, there is often another pathway that will take over this function of the damaged pathway.

23. True or False? Both center patches are the same shade of gray

25. True: The patch on the right appeared darker due to perceptual contrast with its background

26. True: The patch on the right appeared darker due to perceptual contrast with its background

27. True or False? • Intelligence is a purely genetic trait that does not change throughout a person’s life False: Intelligence is the result of both heredity and environment, and may change throughout your life

28. True or False? • Repeated exposure to the same face leads us to like it less False: Familiar people (and their faces) are generally liked more than less familiar people

29. Four Major Themes • Why study the brain? • History of brain study • Disciplines of neuroscience (study of the brain) • Clinical implications

30. Why study the brain? “The more you use your brain, the more brain you will have to use.” • George A. Dorsey “Brain: an apparatus with which we think we think.” • Ambrose Bierce

31. Why study the brain? • The human brain is packed solid with billions of nerve cells each communicating with thousands of preselected listeners over miles and miles of living wires (the nervous system) which operates the whole body

32. History of brain study WHAT IS THE BRAIN?? • Analysis by analogy • Explore the mind problem • The roots of dualism • The pneuma theory • Descardes & the brain • The scientific method • The rise of experimentation in psychology • Exploring the nervous system • Brain-behavior relation

33. Analysis by analogy • The ancient wondered – why can a thought / an emotion be experienced but not seen or touched • Found that inanimate was attributable to a spirit of vital force that could be neither seen or understood (known as animism today) • People view themselves in the dualistic term, with mind traditionally seen as an entity distinct from the physical world of matter and governed by entirely separate sets of principles • Roots of dualisme – writing of the Greek philosopher Anaxagoras • Plato elaborate on the concept, maintaining that the mind, or soul – the instrument with which knowledge is pursued – superior to the physical body & sense

34. Analysis by analogy • The Pneuma Theory • Aristotle explained various animal functions, including movement, as being the result of"pneuma," a spiritual breath (literally) that was carried to the various organs to activate them, and that caused the limbs to move • The theory which attributed the functions of mind to invisible spirits, emerged during the rise of Greek civilization • Hippocrates (5 century, B.C.) theorized that the brain was the controlling mechanism of all mental & emotional faculties • Galen, Greek physician (129–201 A.D.) • recognized that muscles were responsible for movement in both humans and animals • suggested that the inability to vocalize is a proof of the relationship between the nervous system & behavior (based on research on a pig’s larynx)

35. Analysis by analogy • The Pneuma Theory • Leonardo da Vinci (1452–1519) discarded Aristotle's pneuma theory of motive force; he clearly understood that muscles were activated by nerves that ramified through them and caused them to contract, pulling the tendons and attached bones • Luigi Galvani, Italian physician (1790) – discovered that electric current applied to the muscle of a frog produce muscle movement, correctly theorized that the nerves are capable of conducting electricity (identified that the nature of pneuma was a unique substances he called animal electricity)

36. Analysis by analogy • Rene Descartes (1596-1650)& the brain • Rejected the Greek notion that human fate is subject to the whim of invisible & unknowable force • Theorize that many behaviors formerly thought to be beyond the scope of conventional scientific investigation • eg. Basic sensory experiences – could be explained mechanistically, the same way you might explain the working of a complicated machine • What is the effect of Descartes thoughts on British empirism – John Locke, David Hume, etc??

37. Evolution of The Scientific Method • Behaviorism (John Watson) • Structuralism (Wundt) • Identify the building blocks of consciousness • Used introspection • Functionalism (James) • Identify the ways the mind adapts to the world • Influenced by Darwin’s ideas • Gestalt psychology (Wertheimer) • The whole is greater than the sum of its parts

38. Evolution of The Scientific Method • Psychodynamic theory (Freud) • We are influenced by the unconscious mind • We may try to suppress urges • Psychoanalysis

39. Disciplines of Neuroscience • Neuroanatomy • Structure of the nervous system • Neurochemistry • Chemical bases of neural activity • Neuroendocrinology • Interactions between the nervous system and the endocrine system • Neuropathology • Nervous system disorders • Neuropharmacology • Effects of drugs on neural activity

40. Disciplines of Neuroscience • Neurophysiology • Functions and activities of the nervous system • Neuroscience • Interdisciplinary field that focuses on the brain and its role in psychological processes • Biopsychology • The specialty in psychology that studies the interaction of biology, behavior, and the environment • Physiological Physiology • Understanding the human consciousness

41. What is Biopsychology? • “the scientific study of the biology of behavior” • psychobiology, behavioral biology, behavioral neuroscience • psychology: the scientific study of behavior • Hebb (1949) proposed that psychological phenomena might be produced by brain activity

42. Biopsychology is an integrative discipline • Knowledge from other disciplines of neuroscience is applied to the study of behavior • Each discipline studies a different aspect of the nervous system that informs our understanding of what produces and controls behavior

43. Biopsychological Research • Human and nonhuman subjects • Experiments and nonexperiments • Pure and applied research

44. Human and nonhuman subjects • Why use nonhumans? • Simpler brains makes it more likely that brain-behavior interactions will be revealed • Comparative approach – gain insight by making comparisons with other species • Fewer ethical restrictions

45. Divisions of Biopsychology • Six major divisions • Each has a different approach, but there is much overlap • Physiological psychology, psychopharmacology, neuropsychology, psychophysiology, cognitive neuroscience, comparative psychology

46. Divisions of Biopsychology • Physiological psychology • Neural mechanisms of behavior • Direct manipulation of the brain • Psychopharmacology • Effects of drugs on the brain • Neuropsychology • Brain damage in humans

47. Divisions of Biopsychology • Psychophysiology • Relation between physiological activity and psychological processes • Cognitive neuroscience • Neural bases of cognition • Comparative psychology • Comparing different species to understand evolution, genetics, and adaptiveness of behavior

48. Figure 1.6 (summary)

49. Converging Operations: revelations from brain damages • Using multiple approaches to address a single question • Korsakoff’s syndrome – a condition characterized by severe memory loss and most commonly seen in alcoholics • Is Korsakoff’s the result of the toxic effects of alcohol on the brain?

50. Converging Operations • Jimmie G. – an alcoholic with Korsakoff’s • Korsakoff’s is also seen in malnourished persons who had little or no alcohol • Thiamine-deficient rats exhibit memory deficits • Alcohol accelerates the development of brain-damage in thiamine-deficient rats