Evolutionen och den mnskliga hjrnan

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The Frontal Lobes
Development, Function and Pathology
Course given at the INS Summer Institute in
Xylocastro 2004
Jarl Risberg Department of Clinical Neuroscience
Lund University, Sweden
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Lecture 1

• Developmental aspects
• Phylogenesis and ontogenesis

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Chimpanzee
Man
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Homo sapiens Lucy
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Arguments for the water ape hypothesis

• East Africa was dominated by wetlands
• Upright position was mainly disadvantageous on
  the savanna
• No fur
• Body fat
• Sweat glands
• Innate swimming ability
• Plenty of nutritious seafood

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Two perspectives on hominin evolution
Begun, D.R. Science, 303, 1478-80, 2004
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Early hominid sexual dimorphism
Robust hominids
Gracile hominids
Spencer Larsen C., PNAS, 100, 9103-4, 2003
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Homo habilis
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Stringer C., Nature, 423, 692-5, 2003
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The 46 Chromosomes of Man
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DNA bases
A adenosine T thymine C cytosine G guanine
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Chimpanzee
Man
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Brain weight in grams
Encephalization quotient
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Mutation of the MYH16 gene 2.4 m years ago
g
Pennisi E., Science, 3003, 1957, 2004
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Astonishing quick development of artistic skills
40.000 years ago
Sinclair A., Nature, 426, 774-5, 2003
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Adolphs R., Nature Reviews Neuroscience, 4,
165-178, 2003
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Allman J., 1999
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Allman J., 1999
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Allman J., 1999
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Changes in percent body fat in human infants
Leonard et al., Comp. Biochem. Physiol., 136,
5-15, 2003
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Survival of the fattest

• Fat babies were the key to evolution of the large
  human brain.
• The fattest infants became mentally the fittest
  adults.
• Body fat in infants provided fuel store for the
  brain.
• Fresh- and salt-water shorelines provided the
  food supply for evolving body fat and larger
  brains in human infants.

Cunnane Crawford, Comp. Biochem. Physiol., 136,
17-26, 2003
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Allman J., 1999
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Diet quality in humans compared to other primates
Leonard et al., Comp. Biochem. Physiol., 136,
5-15, 2003
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Do you think
Humans have lager frontal lobes than
other primates?
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Semendeferi et al., Nature Neuroscience, 5,
272-6, 2002
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Semendeferi et al., Nature Neuroscience, 5,
272-6, 2002
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Brodmanns areas
10
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Larger area 10 in humans than in apes
Semendeferi et al., Am. J. Phys. Anthropol., 114,
224-241, 2001
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Brodmanns areas
44
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Asymmetric area 44 in great apes
Cantalupo Hopkins, Nature, 414, 505, 2001
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Chimpanzee
Man
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Chimpanzee
Man
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Rakic, P., 1990
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Duman et al. 2001
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Two trends of cortical development
Archicortical trend
Paleocortical trend
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Andreasen N.C., 2001
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New born
2 years
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Order of myelination of the human cortex
based on Flechsig P., 1920
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Fuster J., 2003
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Activity-dependent synapse stabilization
Hua Smith, Nature Neuroscience, 7, 327-332,
2004
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Sequential model
Concurrent model
Hua Smith, Nature Neuroscience, 7, 327-332, 2004
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Lemur
Macaque
Gibbon
Chimpanzee
Man
Post-reproductive phase
Year
Adult
Youth
Childhood
Birth
Weeks
Pregnancy length