Evolving brains

Download Evolving brains

Post on 14-Apr-2017

192 views

Category:

Education

0 download

Embed Size (px)

TRANSCRIPT

  • 10/23/12

    1

    Discovery: Psychopaths have 11% less prefrontal volume than healthy subjects.

    Conclusions? What should we conclude regarding the biology of criminal behavior?

  • 10/23/12

    2

    what is it for?

  • 10/23/12

    3

    what is it for?

    the case of the sea squirt

    Tadpole phase w/ brain Sessile adult

    phase w/out brain

  • 10/23/12

    4

    Mind = software

    computational metaphor

    Brain = hardware

    Brain/mind as: 1- information processor 2- represents the world 3- predictive engine

    TRAIT YES NO modularity x cell types x neurochemistry x size x laterality x size-function relations x interfaces between modules x symbolic representations x abstraction from sensation/percept x recursive/combinatorial operations x

    uniquely human brain?

  • 10/23/12

    5

    a. functional specialization 1. phylogenetic patterns

    2. adaptive design

    outline

    b. size

    a. ecological pressures b. social pressures

    3. development

    Neurochemical

    Neurons Cortical Regions/lobes

    Inter-cortical connections

    Psychological states

    the brains mechanisms

  • 10/23/12

    6

    comparative brain evolution

    Motor

    AuditorySomatosensory

    Vision

    Space Planning, decision

    parietal

    occipital temporal

    frontal

  • 10/23/12

    7

    granny cells

    modularity & swiss army knives:

    Danook shows off his swiss army knife

    Fodor Tooby & Cosmides

  • 10/23/12

    8

    Domain-specific Fast, automatic processing

    Dedicated neural architecture

    Characteristic breakdown

    Informationally encapsulated

    signatures of a module

    a face module fast, automatic

    domain-specific

    informationally encapsulated

    dedicated architecture

    characteristic breakdown

  • 10/23/12

    9

    prosopagnosia:

    questions & main points:

    Q: what other systems of the brain might be modular?

    Q: what systems of the brain are most certainly NOT modular?

  • 10/23/12

    10

    a. functional specialization 1. phylogenetic patterns

    2. adaptive design

    outline

    b. size

    a. ecological pressures b. social pressures

    3. development

    comparative size differences

  • 10/23/12

    11

    Log (Body Weight)

    Log (Brain Weight)

    1g 10 kg 100,000kg.01g

    100kg

    Primates/DolphinsOther MammalsSmarter???

    brain size: comparative differences

    No one, I presume, doubts that the large proportion which the the size of mans brain bears to his body, compared to the same proportion in the gorilla or orang, is closely connected with his higher mental powers On the other hand, no one supposes that the intellect of any two animals or of any two men can be accurately gauged by the cubic contents of their skulls.

    C. Darwin, 1871

    hominidae brain evolution

    brain capacity (cubic centimeters)

  • 10/23/12

    12

    unlocking the genes thru microcephaly

    hominid brain evolution: size again

  • 10/23/12

    13

    Brain size fallacies

    BIG brain

    SMALL body

    Selection The Chihuahua Fallacy

  • 10/23/12

    14

    decreases in brain size

    dec. inc. mix

    phylogenetic changes in brain size

    smaller brains

    larger brains

    only animal eaters

    implications of domestication studies : selection on X can lead to other, unanticipated changes

    targeted selection can lead to extremely fast evolution

    domestication in humans?

  • 10/23/12

    15

    questions & main points: Q: why do we plot the relationship between brain and body size?

    Q: what can we infer about the increase in brain size over hominid evolution?

    Q: selection can cause both increases and decreases in brain size. this reflects important aspects of the species ecology and social environment.

    a. functional specialization 1. phylogenetic patterns

    2. adaptive design

    outline

    b. size

    a. ecological pressures b. social pressures

    3. development

  • 10/23/12

    16

    our approach

    Problems of mechanism can be tackled in isolation, but are best carried out as solutions to adaptive problems. Adaptive solutions are always designed in light of mechanistic constraints.

    How microchiropteran bats capture prey

    design of a predators brain:

  • 10/23/12

    17

    Bat biosonar

    100 300

    Frequency (Hertz)

    SoundPressureLevel(dB)

    0

    100 Best frequency

    neural tuning curves:

    Sound Pressure

    Level (dB)

    Frequency (Hertz)

  • 10/23/12

    18

    co-evolutionary arms races:

    Howler monkeys-folivores Spider monkeys-frugivores

    ecology & brain design

  • 10/23/12

    19

    questions & main points: Q: tamarins specialize on insects, marmosets on sap. what would you expect in terms of neural/cognitive specializations?

    brain design is a reflection of social and ecological factors

    due to these socioecological pressures, two distantly related species may have more similarly structured brains than two closely related species living in different environments.

    a. functional specialization 1. phylogenetic patterns

    2. adaptive design

    outline

    b. size

    a. ecological pressures b. social pressures

    3. development

  • 10/23/12

    20

    how mating systems select for sex differences in spatial ability

    brain design for spatial memory:

    Hippocampus

  • 10/23/12

    21

    Meadow & Prairie

    Polygamous Monogamous

    voles

    Female boundaries

    Male boundaries

    Typical polygamous mammal

    Typical monogamous mammal

  • 10/23/12

    22

    Average day range (meter2) 0 1000

    Polygamous meadow voles

    Monogamous prairie voles

    Female

    Male

    Female

    Male

    home range, mating system, & sex diffs:

    Maze performance

    Prairie voles (monog.): No sex differences

    Meadow voles (polyg.): Sex differences -- Males faster

    mating system & maze running:

  • 10/23/12

    23

    hippocampus: a key area for memory

    Hippocampal volume (mm ) 0 35

    Polygamous meadow voles

    Monogamous prairie voles

    3

    Female

    Male

    Female

    Male

    hippocampal volume

  • 10/23/12

    24

    comparative applications

    Food caching (storing) birds

    Parasitic cuckoo birds

    Log [Avg. Group Size]

    0

    100

    0 10 Neocortex ratio prosimians

    monogamous anthropoids

    polygamous anthropoids

    hominoids

    social life & brain size

  • 10/23/12

    25

    Environment of Evolutionary Adaptedness (EEA)

    Hunter-gatherers as windows into our past, and especially, the kinds of social and ecological problems that we faced.

    the hyper-social brain:

  • 10/23/12

    26

    questions & main points: Q: among humans, what careers might favor greater spatial ability, and would this be evident from the neuroanatomy?

    selection for both overall brain size and particular specializations, based on socioecology and experience

    a. functional specialization 1. phylogenetic patterns

    2. adaptive design

    outline

    b. size

    a. ecological pressures b. social pressures

    3. development

  • 10/23/12

    27

    Extreme nurture: blank slates & silly putty

    Let us then suppose the mind to be, as we say, white paper void of all characters, without any ideas. Whence comes it by that vast store which the busy and boundless fancy of man has painted on it with almost endless variety? Whence has it all the materials of reason and knowledge? To this I answer, in one word, from EXPERIENCE. John Locke

  • 10/23/12

    28

    1. Innate = fixed, experience irrelevant 2. Innate = universal 3. Innate = early onset

    false inferences about nativism:

    4. Animal behavior = instinctive; Human behavior = learned

    the undebatable issues: Account for the processes that take a fertilized egg

    to some end state in adulthood, replete with species-typical capacities

    The starting state must entail certain genetic givens --- some endowment that has evolved to provide each species with its unique signature

    What mechanisms channel the relevant experiences to cause change over development?

    How is experience mapped into changes in the neural circuitry, to cause stable changes in perception and knowledge of the world?

  • 10/23/12

    29

    Level ofSkill

    Onset ofExperience

    normal environment

    added experience

    developmental path-1:

    Level ofSkill

    Onset ofExperience

    developmental path-2:

  • 10/23/12

    30

    Level ofSkill

    Onset ofExperience

    developmental path-3:

    Level ofSkill

    Onset ofExperience

    developmental path-4:

  • 10/23/12

    31

    Level ofSkill

    Onset ofExperience

    developmental path-5:

    Magn