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Right Brain Left Brain Psych 546-01 PowerPoint Presentation
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Right Brain Left Brain Psych 546-01

Right Brain Left Brain Psych 546-01

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Right Brain Left Brain Psych 546-01

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  1. Right Brain Left BrainPsych 546-01 • Dr David A Kaiser

  2. Syllabus

  3. LECTURE 1History of Laterality Neolithic Neurology (i.e. trephination)

  4. Corpus Callosum

  5. Aristotle: Right side is the origin of motion in all creatures (he was an exception, a left-hander) • Plato favored symmetry Plato Aristotle (427-347) (384-322)

  6. Andreas Vesalius (1514-1564) De Humani Corporis Fabrica (The Fabric of The Human Body) – 1543 Studied anatomy solely for structure

  7. Argued for general law of symmetry Symmetrical functioning between paired organs necessary because one had to be able to relate to the external world equally with both sides of body (1805). Cerebral Symmetry: Bichat Francois X. Bichat (1771-1802) Helped found Science of Histology

  8. Cerebral Localization (Mosaic): Franz Gall • Phrenology: Analysis of shapes and lumps of skull reveals personality and intellect. • Identified 27 major faculties like imitation, spirituality Franz Joseph Gall (1758-1828) • Noticed how verbally superior schoolmates had bulging eyes, and believed language abilities resided behind eyes (suborbital region of frontal lobe), overdeveloped in these few

  9. Cerebral Holism (Diffuse representation – Equipotentiality) • Pierre Flourens (1824) set up lab to attack Gall’s mind-brain equivalence, the materialistic heresies which undermined the unity of the soul, human immortality, free will, and the very existence of God • He demonstrated that main divisions of brain were responsible for largely different functions. • By removing cerebrum, all perceptions, motor function, and judgment were abolished. • Removal of cerebellum affected equilibrium and motor coordination. • Destruction of brain stem caused death. • Extensive and indiscriminate cortical lesions in birds and rabbits showed little behavioral change, which led him to believe that these functions are represented diffusely around the brain.

  10. Cerebral Localization: Bouillaud Vocal supporter of Gall and his theory of brain as plurality of organs. Bouillaud was “the soul of the doctrine of localization” for 50 years. From 1825 to 1860 he defended Gall in debates before French Academie de Medecine Localization remained highly polarizing - Mind has many faculties but brain must be unitary for soul to enter - Language was the faculty which separated man and beast, according to Descartes Jean-Baptiste Bouillaud (1796-1881) Bouillaud (1825): 100 patients with speech loss after frontal lesions

  11. Brain disease and speechlessness 1761, 1825, 1829-40 • Morgagni, Bouillaud, Andral • N =10, 25, 11 • 5 LHD (4 aphasic); 5 RHD (1 aphasic) • 11 LHD (8 aphasic); 14 RHD (4 aphasic) • 5 LHD (3 aphasic); 6 RHD (0 aphasic) • Speechlessness rates • 15 of 21 left brain damage (71%) • 5 of 25 right brain damage (20%) • Meta-analysis (n=46) reveals statistical patterns missed by smaller bins

  12. Swing back to Localization • Marc Dax (1836): LH damage associated with verbal memory deficits • (Son gave academy father’s memoirs, 1863) • Paul Broca (1861 and 1865) convincing evidence of anterior lesions, then speech laterality; Tan “Nous parlons avez l’hemispheregauche” Paul Broca (1824-1880)

  13. Right Hemisphere as Minor Brain Carl Wernicke (1874): other left-sided lesions lead to different speech problems Temporal lesion disturbs comprehension. Developed connectionism model of language and predicated conduction aphasia

  14. Right brain superiority for some functions “Leading hemisphere” hypothesis (1868) = brains are not mere duplicates - RH superiority for visual recognition

  15. Wilder Penfield, 1930s • Electrical stimulation lead to language disruption, others produce episodic memories

  16. George Ojemann • Electrical Stimulation reveals focal representation of language, but differs between individuals

  17. Korbinian Brodmann (1868-1918) (1906) - 52 cytoarchitectonic brain areas

  18. Last kicks of holism • Lashley’s Principle of Mass Action • Lesion size, and not location, determine behavioral consequence • Larger lesions have greater behavioral repercussions • No clear area-function specifications in rats • Refuted by Irle (1990) review of 283 monkey studies • Location important • And in fact, some lesions led to improved performance (possibly due to reciprocal inhibitory networks), with larger size leading to better performance for some functions EXCEPT Hologram theories of the brain and universe (Bohm, 1980) and Karl Pribram

  19. LECTURE 2Evolution of Handedness

  20. Nature vs Nuture • Evidence of cultural mechanisms or other environmental causes • Evidence of genetic basis • Evidence of right-handedness in early humans

  21. Aristotle: Right side is the origin of motion in all creatures • Plato favored symmetry Plato Aristotle (427-347) (384-322)

  22. Evidence from early humans • Evidence from early humans • tools, weapons, cave drawings • Stone tool manufacture 1.8 mya suggests right-handedness (twist of chips) • Tooth wear due to toothpicks 1.5 mya indicates right-handedness in Homo habilis • Preferential wear on cutting tools suggest right handedness • Refitting stone tools (c7000 BC) to the original rock to indicate clockwise (Rh) manufacture • Early art shows right handedness in sword use • Coren & Porac (1977) surveyed 5000 years of art depicting unimanual tool or weapon use – 93% Rhanded, and no systematic trends through time (but only 37 pieces prior to 3000 BC) • Hand outlines – 70% are of the left hand

  23. Rate of Right hand to carry out action in art across eras 8 % Left handed

  24. Biblical evidence • c1400 B.C. - Judges 20: Of the children of Benjamin, 700 of 26,000 were “restricted in their use of the right hand” • i.e., left-handed = 2.7% • Psalm 137 connects cunning of right hand and use of tongue (i.e., speech) If I forget thee, O Jerusalem, let my right hand forget her cunning. Let my tongue cleave to the roof of my mouth… • However Hebrew writing flows right to left, suggesting left-handedness • Philologic evidence: both Greek and Latin use same word stem for “ten” and “right” suggesting a left-to-right counting motion

  25. (Task) Hemisphericity & Hemispheric Dominance • Hemisphere which houses major higher functions (language vs spatial & emotion)\ • Handedness informs us of certain task hemisphericity such as speech • Dominance: Hemisphere which dominates individual’s cognition (or cognitive style)

  26. Visual Pathway

  27. Alcoholism Criminals Lawyers Autism Math prodigies Gifted children Immune disorders People having paranormal experiences Professional tennis & baseball players Recent Presidents Smokers Sleep difficulties Stutterers Vegetarians Artists Elevated Prevalence in:

  28. Distribution of Left Handedness • MZ =14.5% • DZ =14.0% • Single births = 8.5%

  29. Causes of Left Handedness • NUTURE (environmental) • Prenatal/perinatal brain injury • 7.3% in normal elementary schools • 18.2 % in special education facilities (in 1920, both) • Cultural or evolutionary pressure for right handedness • NATURE • Genetic (e.g., Annett’s 1974 right shift hypothesis) • Mirror twin

  30. Right Shift Hypothesis (Annett, 1974) • Genetic composition for asymmetry (right or left handedness) • Single dominant gene for right-shifting RS++ = right handed RS+- = right handed RS-- = half right, half left • Population made up of: • 70 % right handed, 20 % mixed, 10 % left handed

  31. Right Shift Hypothesis (Annett, 1974) • Rife (1940) Survey of offspring handedness given parental hand • R-R: 92.4% (total individuals: 1993) • R-L: 80.5% (174) • L-L: 45.5 % (11) • Meta-analysis from Ramaley (1913), Chamberlain (1928), and Annett (1973) found 139 LxL family children, 61 left handers (44%)

  32. Twin handedness ratesZazzo, 1960 • MZ (n=1210) • RR: 72 % RL: 24% LL 4% • DZ (n=1145) • RR: 76 % RL: 22% LL 2% • Twins(11.7 %) vs singletons (7.1%) (Davis & Annett, 1994)

  33. Wheat Washing: 6 Rh, 8 Lh Potato Washing: 0 Rh (+6), 1 Lh (+14) Mori (1975) reported hand preferences in 5 of these monkeys – all 5 maintained same preference 10 years later Simian Handedness:Watanabe & Kawai (1984)

  34. Gorilla Data (Shafer, 1993)

  35. Gorilla by Age Group vs Human Children (Shaffer, 1993)

  36. ...And Then There Was One • Sixteen Species of Extinct Humans • Ardipithecus ramidusAustralopithecus anamensisAustralopithecus afarensisAustralopithecus bahrelghazaliAustralopithecus aethiopicusParanthropus boiseiParanthropus robustusAustralopithecus africanusAustralopithecus garhiHomo rudolfensisHomo habilisHomo ergasterHomo erectusHomo antecessorHomo heidelbegensisHomo neanderthalensis • Homo sapiens

  37. Neoteny – Childlike features into adulthood

  38. Wada test • Used to determine whether psychosurgery (e.g., temporal lobectomy) can be done without risk to memory or speech. • Anaesthetic (sodium amytal) is injected into artery (via the catheter), paralyzing one hemisphere of the brain for about 3 minutes. • During this time,memory and speech are tested. The same is then done on other hemisphere.