BIO & ENVIRO FOUNDATIONS 2: (WK9):

NATURE & NURTURE:

  • innateness = genetic blueprints

  • epigenesis = two-way interactions - genes & environments

  • slower development than other mammals

  • more brain development outside womb

PRENATAL BRAIN DEVELOPMENT:

  • neurons = born (neural tube), migrate, differentiate (final form)

  • 6-18 weeks for cerebral cortex

  • active migration, passive migration

  • myelination = formation of the isulating myelin sheath around some axons

    • begins prenatally & continues into early adulthood

    • formation of myelin sheath speeds up and increases information processing

POST-NATAL BRAIN DEVELOPMENT:

  • increase in size, complexity and reach of dendritic tree, number of synpases and neuural connections

PLASTICITY:

  • at birth, the brain is plastic

  • if there is brain damage, other areas take over the function of it

  • brain growth increases specialisation

  • the adult brain is characterised by specialised cortical regions

MODULES:

  • localisation of perceptual, motor & cognitive (approx same region as the cortex)

  • differentiation of cerebral cortrex into diff structures, diff functional units or modules

  • e.g. broca & wernicke’s area

INNATE MODULARITY VS MODULARISATION:

  • Fodor (1983) - innate

    • humans are born with innate capacity to develop information processing systems to make sense of the world

    • environmental influences function through evolution

  • Karmiloff-Smith (1992) - modularisation

    • modules are a product of development, human mind becomes modular

    • limited amount of innately specified constraints on the mind would produce modular adult minds

EVIDENCE FOR MODULARISATION:

  • PET scans (Peterson)

    • native english speakers, responses to written english words, pseudo words, nonsense strings etc.

    • specific region of left visual cortex - only responded to eng words or pseudo words

  • EEG with deaf participants (Neville)

    • regions of temporal lobe now dominated by visual input

  • EEG increasing localisation (Milles)

    • processing of known words initially spread over a relatively large area of the cortex

    • narrows irrespective of maturational age

SELF-ORGANISATION:

  • initially neural systems is undifferentiated (random)

  • small adaptive changes - order to systems

  • redundant neural pathways are eliminated, surviving become separated

  • newborn visual preference for bright & dim stimuli was affected by previous exposure to an auditory stimulus

ADULTHOOD AND AGING:

  • brain loses 5-10% of weight on average between 20 and 90, and brain volume also decreases

  • this affects cognitive functioning in older adults