Neuropsychology OptionWeek 5

1
Neuropsychology Option Week 5

• 2nd Lecture

2
T.H. Huxley (1863, 1874)
So far as cerebral structure goes therefore, it
is clear that man differs less from the
Chimpanzee or the Orang, than these do even from
the monkeys, and that the difference between the
brains of the Chimpanzee and of Man is almost
insignificant, when compared with that between
the Chimpanzee brain and that of a Lemur.
(Darwin, 1871/1901, p. 312)
Every principal gyrus and sulcus of a
chimpanzees brain is clearly represented in that
of a man.
3
Human brain
4
Chimpanzee brain
The chimpanzee brain is less than a third the
size of a typical human brain, but superficially
looks similar
5
Huxleys comparisons
So far as cerebral structure goes therefore, it
is clear that man differs less from the
Chimpanzee or the Orang, than these do even from
the monkeys, and that the difference between the
brains of the Chimpanzee and of Man is almost
insignificant, when compared with that between
the Chimpanzee brain and that of a Lemur.
(Darwin, 1874/1901, p. 312)
6
Huxley (1871)

• Every principal gyrus and sulcus of a
  chimpanzees brain is clearly represented in that
  of a man
• This second claim is probably misleading, since
  the reverse is certainly not true, and it maybe
  that the 21st century conclusion is radically
  different from the 19th century one, when more is
  known about the genetics of the difference
  between human and chimpanzee brains (Culotta,
  2005).

7
Mikkelsen et al, (2005)
8

• Caceres et al. (2003) applied a variety of
  genetic techniques to the cortical tissue
  (removed post-mortem) of humans, chimpanzees and
  rhesus macaques.
• These suggested that humans and chimpanzees are
  more similar to each other than to the macaques,
  which is as expected,
• but also that there were dozens of genes that
  were expressed very differently in human and
  chimpanzee cortex, with 90 of these being
  expressed more actively in humans than in
  chimpanzees, which suggested that
• The human is brain is characterized by elevated
  levels of neuronal activity.
• As a contrast, comparing gene expressing in the
  human and chimpanzee heart and liver revealed
  very little difference of this kind.

9
Sherwood, C. C., et al. (2006). Evolution of
increased glia-neuron ratios in the human frontal
cortex. PNAS, 103(37), 13606-13611.

• the human glia-neuron ratio in the prefrontal
  region did not differ significantly from
  predictions based on brain size.
• Further analyses of glia-neuron ratios across
  frontal areas in a humans, chimpanzees, and
  macaque monkeys showed that regions involved in
  specialized human cognitive functions, such as
  "theory of mind" (area 32) and language (area 44)
  have not evolved differentially higher
  requirements for metabolic support.
• Taken together, these findings suggest that
  greater metabolic consumption of human
  neocortical neurons relates to the energetic
  costs of maintaining expansive dendritic arbors
  and long-range projecting axons in the context of
  an enlarged brain.
• Sherwood et al. (1) provide support for the idea
  that the human brain is more or less a large
  hominoid (ape) brain and can be understood in
  that context.

10
Sense of Smell

• A minor confirmation by genetic analyses is that
  the human sense of smell is reduced by comparison
  to the chimpanzee
• both humans and chimpanzees have less sense of
  smell that dogs or mice
• This can be assessed by counting olfactory
  receptor genes and the proportion of these which
  are inactive (pseudogenes).
• Humans have a significantly higher proportion of
  these than chimpanzees (Gilad et al., 2005).

11
Olfactory receptor genes Linda Buck Nobel 2004
12

• Although further detailed distinctive features of
  the human brain may be expected, it is also the
  case that there are some features of the human
  brain, in particular the organization of the
  visual system, where the details in the human
  brain differ very little from those in
  chimpanzees (e.g. Cola et al., 2005 bottom of p
  2 of handout)
• Thus, in the aspects of organization we
  examined, the inferior pulvinar of chimpanzees
  closely resembles that of humans and monkeys

13
Functional differences language

• Apart from looking at neurophysiological or
  genetic details, it is possible to give
  hypothetical answers to both the how? and why?
  questions by making assumptions about the new
  psychological capacities subserved by human brain
  evolution,
• The origin of humans was accompanied by the
  emergence of new behavioural and cognitive
  functions, including language and specialized
  forms of abstract representation. (Caceres et
  al., 2003).

14

• The two most frequently appealed to candidates
  for new psychological capacities are language and
  an enhanced capacity for social cognition.
• Language remains a strong candidate for a human
  specialization because chimpanzee abilities
  appear to be so limited (see weeks 10 and 11
  Psychobiology II).
• There are however several very different
  suggestions as to how this human specialization
  arose.

15
Chomsky pic in guardian
16
(No Transcript)
17
(No Transcript)
18

• Hauser et al. (2002) for instance, although
  considering other possibilities, favour the
  notion that recursion is the key uniquely human
  component of language,
• but paradoxically from a Darwinian point of view,
  they argue that recursion probably evolved for
  reasons other than language.
• Recursion is illustrated by Chomskys well-known
  sentence colourless green ideas furiously
  sleep, which we understand as a grammatically
  correct sentence even though it makes little
  sense.
• The sequence I will say a very, very long
  sentence I will say a very, very, very long
  sentence and so on is a simpler illustration
  that a principle for combining just a few words
  can generate an infinite number of possible
  utterances.

19
Gentner, T. Q., et al. (2006). Recursive
syntactic pattern learning by songbirds. Nature,
440(7088), 1204-1207
Humans regularly produce new utterances that are
understood by other members of the same language
community. The recursive, hierarchical embedding
of language units (for example, words or phrases
within shorter sentences) that is part of the
ability to construct new utterances minimally
requires a 'context-free' grammar.
Recent hypotheses make the central claim that the
capacity for syntactic recursion forms the
computational core of a uniquely human language
faculty
Here we show that European starlings (Sturnus
vulgaris) accurately recognize acoustic patterns
defined by a recursive, self-embedding,
context-free grammarThus, the capacity to
classify sequences from recursive,
centre-embedded grammars is not uniquely human.
20
They used 8 recorded starling rattles and 8
warbles to make up a total of 4096 stimuli
21
 ii) Darwinian evolution of all parts of the
human language system

• The Hauser et al. (2002) suggestion tends to
  minimize the role of human evolution because a
  large part of the language system is held to be
  shared with other species, while the uniquely
  human part, recursion, they would prefer not to
  be an adaptation (i.e. not evolved by Darwinian
  selection).
• Pinker and Jakendoff (2005) supply a lengthy
  argument against the Hauser et al. (2002)
  position, since they had both previously put
  forward the position that human language is a
  system of co-adapted traits that evolved by
  natural selection for the purpose of
  communicating ideas

22
ii) Darwinian evolution of all parts of the human
language system

• Pinker and Jakendoff believe that the capacity of
  the human brain to handle recursion evolved by
  natural selection, but that many other aspects of
  brain capacity necessary for language,
  particularly for conceptual structure, speech
  perception and speech production, needed to be
  shaped by natural selection as well.
• Pinker and Jakendoff (2005) are also able to
  appeal to genetic evidence that was not available
  10 years ago.

23
Genes and Language BBC October 01
24
Pinker comments October 2001
25
Wellcome foxp2
26
National Geographic
27
No sign of Foxp2
28
Liegeois 03
29
Nature 2002

• Language is a uniquely human trait likely to have
  been a prerequisite for the development of human
  culture. The ability to develop articulate speech
  relies on capabilities, such as fine control of
  the larynx and mouth, that are absent in
  chimpanzees and other great apes. FOXP2 is the
  first gene relevant to the human ability to
  develop language. A point mutation in FOXP2
  co-segregates with a disorder in a family in
  which half of the members have severe
  articulation difficulties accompanied by
  linguistic and grammatical impairment. This gene
  is disrupted by translocation in an unrelated
  individual who has a similar disorder. Thus, two
  functional copies of FOXP2 seem to be required
  for acquisition of normal spoken language. We
  sequenced the complementary DNAs that encode the
  FOXP2 protein in the chimpanzee, gorilla,
  orang-utan, rhesus macaque and mouse, and
  compared them with the human cDNA. We also
  investigated intraspecific variation of the human
  FOXP2 gene. Here we show that human FOXP2
  contains changes in amino-acid coding and a
  pattern of nucleotide polymorphism, which
  strongly suggest that this gene has been the
  target of selection during recent human
  evolution.

30
FOXP2 a)

• Pinker and Jakendoff (p. 218) are able to make
  the point that The possibility that the affected
  people are impaired only in recursion is a
  non-starter.
• Instead the expression pattern of FOXP2 in both
  mice and humans suggests that it is involved in
  the development of circuits for motor control
  necessary in vocalization (Lai et al., 2003 Shu
  et al., 2005).
• The fact that there are homologies between humans
  and mice in this respect could be taken to
  support Hauser et al.s point about some aspects
  of human language having a long evolutionary
  history,

31
FOXP2 b)

• the more conventional Darwinian position would be
  to say that motor control for vocalization has a
  long evolutionary history, but that the uniquely
  human capacity for speech will have necessitated
  special brain mechanisms for the co-ordination of
  articulatory organs which are not shared with
  other species.

32

• Lai et al. (2003). FOXP2 expression during brain
  development coincides with adult sites of
  pathology in a severe speech and language
  disorder. Brain, 126, 2455-2462.
• the homologous pattern of FOXP2/Foxp2 expression
  in human and mouse argues for a role for this
  gene in development of motor-related circuits
  throughout mammalian species. Overall, this study
  provides support for the hypothesis that
  impairments in sequencing of movement and
  procedural learning might be central to the
  FOXP2-related speech and language disorder

33
shu
Shu et al. (2005). Altered ultrasonic
vocalization in mice with a disruption in the
Foxp2 gene. Proceedings of the National Academy
of Sciences of the United States of America,
102(27), 9643-9648

• our findings support a role for Foxp2 in
  cerebellar development and in a developmental
  process that subsumes social communication
  functions in diverse organisms.

34
Teramitsu, I., White, S. A. (2006). FoxP2
regulation during undirected singing in adult
songbirds. Journal of Neuroscience, 26(28),
7390-7394. (not on handout) Our data suggest
that FoxP2 is important not only for the
formation but also for the function of vocal
control circuitry. (In zebra finches)
35
iii) Emergence of language from a number of
language ingredients

• Elman (1999, 2005) provides yet another account
  of language, which is Darwinian in that it
  emphasises that
• species-specific biological factors play a
  critical role in the ability of humans to acquire
  and process language (1999, p. 1)
• but which differs from the account given by
  Pinker in predicting a lack of any genetic
  control of specific cortical micro-circuitry for
  language. Instead
• language is simply the result of a number of
  tweaks and twiddles which produce changes in
  humans in such things as vocal tract control,
  sociality, imitation and shared attention.

36
Emergence of language from a number of language
ingredients -b)

• These traits then interact to produce the unique
  human capacity for language.
• this account comes from the connectionist
  tradition and the emergentist aspect leads to
  the expectation that there will be complex
  developmental trajectories

• but tweaks and twiddles are entirely consistent
  with Darwinian processes, and changes in vocal
  tract control presumably would need to be brought
  about by something like changes to FOXP2.

37
Elman, 1999, 2005
38
Functional differences social cognition and
theory of mind

• An alternative function role for the large brains
  of primates has been suggested to be social
  cognition (Jolly 1966 Humphrey, 1976 Barrett
  Henzi, 2005).
• This has the advantage of applying to the large
  brains of non-human primates, as well as,
  putatively, to humans, but the disadvantage that
  it does not by itself explain human tool using,
• although the social transmission of tool using
  skills may have been a crucial component of the
  success of this strategy.

39
Functional differences social cognition and
theory of mind

• Current work on social cognition includes
  evidence that chimpanzees and other great apes
  appear to have skills which might be regarded as
  precursors to a theory of mind,
• for instance the ability to understand both human
  (Call et al., 2004) and conspecific (Tomasello et
  al., 2003) psychological states,
• but also points to the severe limitations of
  chimpanzees social cognition by comparison with
  the human case.
• In particular, chimpanzees can show understanding
  of what a conspecific has or has not seen when
  competing for contested food, but the often show
  surprisingly weak social-cognitive skills in
  tasks which require social co-operation (Hare
  Tomasello, 2004).

40
Blindfolds picture
41
Box 1 of tomasello, call and hare
Tomasello, Call and Hare (2003)
42
Box 1 text
Tomasello, Call and Hare (2003)
43
Box 2 diagram
Tomasello, Call and Hare (2003)
44
Bod 2 text
Tomasello, Call and Hare (2003)
45
Warneken, F., Chen, F., Tomasello, M. (2006).
Cooperative activities in young children and
chimpanzees. Child Development, 77(3), 640-663.
Human children 18 or 24 months of age and 3 young
chimpanzees interacted in 4 cooperative
activities with a human adult partner. The human
children successfully participated in cooperative
problem-solving activities and social games,
whereas the chimpanzees were uninterested in the
social games. As an experimental manipulation, in
each task the adult partner stopped participating
at a specific point during the activity.
All children produced at least one communicative
attempt to reengage him, perhaps suggesting that
they were trying to reinstate a shared goal. No
chimpanzee ever made any communicative attempt to
reengage the partner.
These results are interpreted as evidence for a
uniquely human form of cooperative activity
involving shared intentionality that emerges in
the second year of life.
46
Warneken et al., 2006. Top row, problem solving
tasks, bottom row social tasks
Above, alternative trapdoor task for chimps
47
Functional differences cultural learning and
invention

• Tomasello Rakoczy (2003) have argued that there
  are two (initial) stages of uniquely human
  social cognition.
• The first stage is observable in one year olds,
  who have an understanding of other persons as
  intentional agents,
• This enables them to take part in pretend play,
  and is important as a prerequisite for shared
  attention and early social and linguistic
  learning.
• The second stage is the Theory of Mind
  belief-desire psychology which normally starts
  around 4 years of age, but which is dependent on
  several years of linguistic communication.
• These early stages of uniquely human social
  cognition form the basis enable the cultural
  ratchet of social and technological innovation
  (Tomasello et al., 1993 Tomasello, 1999)

48
T and rakoczy
And so if we imagine a human child born onto a
desert island, somehow magically kept alive by
itself until adulthood, it is possible that this
adults cognitive skills would not differ very
much perhaps a little but not very much, from
those of other great apes. (121)
49
Tomasello, M., Carpenter, M., Call, J., Behne,
T., Moll, H. (2005). In search of the uniquely
human - Response. Behavioral and Brain Sciences,
28(5), 721-735
Human beings are the worlds experts at mind
reading. As compared with other species, humans
are much more skillful at discerning what others
are perceiving, intending, desiring, knowing, and
believing.
Our hypothesis for this something additional is
shared intentionality. We propose that human
beings, and only human beings, are biologically
adapted for participating in collaborative
activities involving shared goals and socially
coordinated action plans
50
Tomasello, M., Carpenter, M., Call, J., Behne,
T., Moll, H. (2005). In search of the uniquely
human - Response. Behavioral and Brain Sciences,
28(5), 721-735
Our attempt was to propose a theory of the
social-cognitive and social-motivational bases of
humans ability and propensity to live in this
local, that is, this cultural, way which no
other species does focusing on such things as
the ability to collaborate and to create shared
material and symbolic artifacts
Some. provided alternative magic bullets for
explaining the key features of human cognitive
and social uniqueness.But, in nearly all of
these cases, we find that these alternative
accounts basically sneak in through the back door
one or another form of shared intentionality as a
kind of hidden premise.
51
Saxe, R. (2006). Uniquely human social cognition.
Current Opinion in Neurobiology, 16(2), 235-239.
Recent data identify distinct components of
social cognition associated with five brain
regions
Yellow and red dorsal (shared attn) and ventral
(empathy) medial prefrontal cortex.
Green,blue, purple extrastiate and
temporal-parietal areas for others beliefs and
intentions
Whiteposterior cingulate, general social
cognition
52
Amodio, D. M., Frith, C. D. (2006). Meeting of
minds the medial frontal cortex and social
cognition. Nature Reviews Neuroscience, 7(4),
268-277. listed in week 4 handout
53
Conclusion

• There is of course no reason to have to choose
  between language and social cognition as the
  drivers of human uniqueness
• language has social functions (Dunbar, 1993)
• and Bloom (2000) suggested that theory of mind
  capacities lie behind what happens when children
  learn the meaning words.
• But in both cases the functional differences are
  at present better understood than the
  neurophysiological details of the special
  features of the human brain which cause the
  functional differences.