VL16 Brain development

• lifespan development

• neural mechanisms

• environmental differences

• mental health

• Hippocampal formation

• parahippocampal cortex

• perirhinal cortex

• entorhinal cortex

• midbrain modulation

  • ventral tegmental area

  • substantia nigra

  • corpus striatum

• frontal lobe

• parietal lobe

• occipital lobe

• over protracted period of time

• complex interaction

  • molecular, cellular & environmental elements and systems

• progressive -> structures/systems that emerge set the stage for development of subsequent systems

• key concepts

  • neural plasticity

  • progressive differentiation and commitment

  • sources of developmental constraint

• adaptive

• adjusting to biological & environmental contingencies on all levels

• evident in young organisms but continuous until adulthood

Example: face processing

• gradual elaboration of neural systems

• distinct cell types

• patterns of connections

• different functions within neural network

Period of

• ovum 2 weeks -> week 1 germinal -> conception & zygote implanted in uterine wall

• embryo 8 weeks

• fetus 36 weeks

• cell division

• migration

• differentiation -> embryonic stem cells are no longer equivalent and interchangeable

• cell death

growth of physical structures & body

week 3

• heart & ZNS

weeks 4 & 5

• heart, arm, leg eye

weeks 6

• teeth, ear

week 7-8

• brain, ear, palate

week 8

• external genitalia bis 12

week 20-36: brain

• stabilization of neural elements and systems

• experience-expectant plasticity

• plasticity decline when neural elements become commited to particular systems

• genetics

• environment

• time

• pleiotropy

• polygenic

• no prescription of developmental processes but:

  • availability & quantity at right time constrains development

• genes can have multiple phenotypic effect

  
  

• multiple genes for one phenotype

• development = adaptation to contingencies of environment

• no normal development when no typical environmental input

• experience-expectant plasticity —> without expected input no normal development

• experience-dependent plasticity

environment effects on brain within normal range

• brain development is temporally constrained

• failure at earlier steps —> catastophic failure of brain development

• critical / sensitive periods —> when system is particularly plastic for certain type of experience

• no change with develppment

• volume quadruples but increases in

  • fiber bundles

  • dendrites

  • myelinization

• formation of neurons & migration almost entirely prenatal

• exception: adult neurogenesis in hippocampus and olfactory bulb

increased

• size and complexity of dendritic tree

• density of synaptic contacts between cells

• steady increase in synaptic density in human cerebral cortex

• age dependent when peak density is reached

  • sensory areas earlier than prefrontal

• synaptic pruning -> synaptic loss after initial overproduction

• more myelinated with development

• neuronal signal transmission is sped up