Evolution of the brain and cognition

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Evolution of the brain and
cognition
PENG Gang 彭刚
Department of Linguistics, CUHK
[email protected]
• “Language as Shaped by the Brain” By Morten
Christiansen
• “Broca’s Area and the Evolution of Language”
by Tom Schoenemann
• …
• Part 1: Evolution of the human brain and
cognition
• Part 2: Brain, experience, and behavior
Sapir-Whorf Hypothesis updated (Adapted from Prof. Wang’s speech)
BEHAVIOR
LANGUAGE
EXPERIENCE
BRAIN
Different LANGUAGES
EXPERIENCES shape different BRAINS;
different brains produce different perceptions;
different perceptions produce different BEHAVIORS.
4
It is the cortical area just posterior to the auditory cortex
within the Sylvian fissure. It is a triangular region which forms
the heart of Wernicke’s area.
Brain asymmetry in adults
• Geschwind and Levitky found that the planum
temporale is larger on the left in 65% of
brains; on the right is only 11%. (100 adult
human brains, obtained at postmorten, and
free of significant pathology)
Geschwind, N., and Levitsky, M. (1968). Human brain: Left-right asymmetries in temporal speech
region. Science 161: 186-187.
Brain asymmetry in newborns
16 were adults and 14 were infants (which included 11 neonates)
whose postnatal ages were 1,1,1, 2,2, 6,11,13,19 and 21 days and 1,
2, 3 and 3 months with a median age of 12 days.
Witelson, S. F., and Pallie, W. (1973). Left hemisphere specialization for language in the
newborn: Neuroanatomical evidence of asymmetry. Brain 96: 641-646.
Musical ability and brain asymmetry
• Schlaug et al found that musicians with
absolute/perfect pitch revealed stronger leftward
planum temporale asymmetry than nonmusicians
or musicians with out perfect pitch.
Schlaug, Gottfried, Jaencke, L., Huang, Y. and Steinmetz, H. (1995). In vivo evidence of
structural brain asymmetry in musicians. Science 267:699–701.
Genetic advantage for East-Asia people
• Extremely rare in the U.S. and Europe, with an
estimated prevalence in the general
population of less than one in 10 000.
• Onset of musical training has been
consistently found to be an important factor
for AP.
Profita, Joseph and T.G. Bidder. (1988). Perfect pitch. American journal of medical genetics,
29:763–771.
Deutsch, Diana, Henthorn, T., Marvin, E. and Xu, H.-S. (2006). Absolute pitch among American
and Chinese conservatory students: Prevalence differences, and evidence for a speech-related
critical period. Journal of Acoustical Society of America 119:719–722.
Peng, Gang, Deutsch, Diana, Henthorn, Trevor, Su, Danjie, and Wang, William S-Y. (2013).
Language experience influences non-linguistic pitch perception. Journal of Chinese Linguistics.
Percentage correct
Tone
60
Nontone
Chance
40
20
0
2--5
6--9
≥10
Age of onset of musical training
Percentage correct responses on the test of AP, as a function
of age of onset of musical training for two language groups.
Peng, Gang, Deutsch, Diana, Henthorn, Trevor, Su, Danjie, and Wang, William S-Y. (2013).
Language experience influences non-linguistic pitch perception. Journal of Chinese Linguistics.
Genetic advantage to East Asian people?
Percentage correct
responses on the test of AP,
as a function of age of onset
of musical training and
fluency in speaking a tone
language. Those in groups
tone very fluent, tone fairly
fluent, and tone non- fluent
were all of East Asian ethnic
heritage. Those in group
nontone were Caucasian
and spoke only nontone
language.
Deutsch, Diana, K. Dooley, T. Henthorn and B. Head. (2009). Absolute pitch among students in
an American music conservatory: Association with tone language fluency. Journal of Acoustical
Society of America, 125:2398–2403.
• The answer to the above question is “NO”.
• In Schlaug et al’s study, musicians with AP
revealed stronger leftward planum temporale
asymmetry. How did such a stronger
asymmetry come from?
Postnatal musical training is probably the
important driving force!
Schlaug, Gottfried, Jaencke, L., Huang, Y. and Steinmetz, H. (1995). In vivo evidence of
structural brain asymmetry in musicians. Science 267:699–701.
Amazing brain plasticity
Four visibly but not
lexically distinguishable
colors, were taught to
subjects to exemplify,
respectively, four new
lexical categories,
named with
meaningless Mandarin
monosyllables.
Kwok, V., Niu, Z., Kay, P., Zhou K., Mo, L., Jin, Z., So, K.F. & Tan, L.H. (2011). Learning new color
names produces rapid increase in gray matter in the intact adult human cortex. Proc Natl Acad
Sci USA, 108(16): 6686-8
Amazing brain plasticity
Differences in gray matter volume between post- and pretraining scans, as
illustrated by images from axial (Left), sagittal (Center), and coronal (Right)
views. The region in the cerebral cortex surviving a whole-brain– based analysis
(P < 0.005 uncorrected) is V2/3 (X = −10, Y = −77, Z = 3; Z=3.58).One area in the
cerebellum(X=13,Y=−75,Z=−38;P<0.005 uncorrected; Z = 3.86) also shows a
volumetric difference. A small volume correction (20-mm) analysis of V2/3
indicated that the difference was significant at P < 0.05 FWE.
Is it a transient effect?
• Don’t know yet.
• It’s probable that long-term intensive postnatal training influences brain structure.
• The stronger leftward planum temporale
asymmetry for musicians may be partially due
to the training effect.
Sapir-Whorf Hypothesis updated (Adapted from Prof. Wang’s speech)
BEHAVIOR
LANGUAGE
EXPERIENCE
BRAIN
Different LANGUAGES
EXPERIENCES shape different BRAINS;
different brains produce different perceptions;
different perceptions produce different BEHAVIORS.
16
"Does use and exertion of mental power
gradually change the material structure of the
brain,
just as we see, for example, that much used
muscles become stronger? It is not improbable,
although the scalpel cannot easily demonstrate
this.”
Samuel Thomas Soemmering, 1791.
Quoted in Restak, R. (2003). The New Brain: How the Modern Age is Rewiring
your Brain. London, Rodale`
Kay, P., & Kempton, W. (1984). What is the Sapir-Whorf hypothesis? American Anthropologist,
17
86, 65–79.
Thank you! 谢谢!
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