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Evolving brains

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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?
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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?

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3

what is it for?

the case of the sea squirt

Tadpole phase w/ brain Sessile adult

phase w/out brain

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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?

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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 brain’s mechanisms

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comparative brain evolution

Motor

AuditorySomatosensory

Vision

Space Planning, decision

parietal

occipital temporal

frontal

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granny cells

modularity & swiss army knives:

Danook shows off his swiss army knife

Fodor Tooby & Cosmides

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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

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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?

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a. functional specialization 1. phylogenetic patterns

2. adaptive design

outline

b. size

a. ecological pressures b. social pressures

3. development

comparative size differences

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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 man’s 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)

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unlocking the genes thru microcephaly

hominid brain evolution: size again

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Brain size fallacies

BIG brain

SMALL body

Selection The Chihuahua Fallacy

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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?

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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

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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 predator’s brain:

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Bat biosonar

100 300

Frequency (Hertz)

SoundPressureLevel(dB)

0

100 Best frequency

neural tuning curves:

Sound Pressure

Level (dB)

Frequency (Hertz)

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co-evolutionary arms races:

Howler monkeys-folivores Spider monkeys-frugivores

ecology & brain design

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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

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how mating systems select for sex differences in spatial ability

brain design for spatial memory:

Hippocampus

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Meadow & Prairie

Polygamous Monogamous

voles

Female boundaries

Male boundaries

Typical polygamous mammal

Typical monogamous mammal

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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:

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hippocampus: a key area for memory

Hippocampal volume (mm ) 0 35

Polygamous meadow voles

Monogamous prairie voles

3

Female

Male

Female

Male

hippocampal volume

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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

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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:

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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

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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

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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?

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Level ofSkill

Onset ofExperience

normal environment

added experience

developmental path-1:

Level ofSkill

Onset ofExperience

developmental path-2:

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Level ofSkill

Onset ofExperience

developmental path-3:

Level ofSkill

Onset ofExperience

developmental path-4:

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Level ofSkill

Onset ofExperience

developmental path-5:

Magnitudeof Trait

Low

High

1 NEnvironments

norm of reaction:

Norm of reaction: the extent to which a genotype exhibits phenotypic variation in different environments.

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Thinking about others’ thoughts

a theory of mind (ToM):

• Eye direction detector (at birth?)

• Shared attention/seeing-knowing (14 mos)

• Pretense (18-24mos)

• Appearance-reality (3 yrs)

• Personal beliefs & desires (3 yrs)

• Intentionality detector (14 mos)

• False beliefs (4 yrs)

• Beliefs about beliefs about beliefs (>5yrs)

Ontogeny of ToM:

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This is Sally This is Anne

Sally puts her ball in the basket

Sally goes away

Anne moves the ball to her box

Where will Sally look for her ball?

Sally & Anne: understanding false beliefs

Does the chimpanzee have a ToM?

D. Premack Sarah

D. Povinelli self-recog seeing-knowing

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Hare et al. (2000, 2001)

Perspective: seeing as knowing

Flombaum & Santos, 2005

seeing as knowing: rhesus monkeys

#Subjects

25

0

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autism and mindblindess:

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Temple Grandin By MARC HAUSER Thursday, Apr. 29, 2010

BACK N

What do neurologists, cattle and McDonald's have in common? They all owe a great deal to one woman, a renowned animal scientist born with autism, Temple Grandin. Though she didn't utter a word until close to her fourth birthday, substituting screams for phonemes, she splashed onto the stage of public awareness in 1995, thanks to the vivid, sensitive writing of the famed neurologist Oliver Sacks. Little was known about autism at the time except that people so afflicted appeared socially isolated, emotionally fragile and difficult to engage. But as with many psychological disorders, autism is a spectrum, and Temple, 62, is on one edge. Living on this edge has allowed her to be an extraordinary source of inspiration for autistic children, their parents — and all people. She is also a source of hope for another mammal: the cow. Using her unique window into the minds of animals, she has developed corrals for cattle that improve their quality of life by reducing stress. And though the fast-food industry continues to use cattle in its patties, it has come to appreciate the ethics and compassion of a Grandin burger.

The 2010 TIME 100

Stephen Wiltshire: Autistic savant

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motion primitives:

Autistics can properly interpret perceptual events (e.g., seeing), but not mental states (e.g., wanting, believing).

seeing vs wanting: perception vs mental states

Johnny

Which one is Johnny looking at?

Which one does Johnny want?

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emotional & imitative deficits:

Autistics have difficulty with self-reflective, social emotions (empathy)

Autistics have difficulty with imitation

mirror neurons:

Mirror neurons fire both when a macaque monkey acts in a particular way and when this same individual watches someone else acting in the same way.

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questions & main points: • Q: what is the hardware vs software distinction in light of the computational metaphor?

• many conserved neurophysiological features

• a small set of uniquely human neurocognitive features generative comp; symbols, interfaces, abstract

• domain-specificity and adaptations for particular cognitive problems

• ecological and social pressures and neural design

• fallacies of brain size


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