2 Neuroscience2.10 Neurodevelopment and neuroplasticity
2.10 Neurodevelopment and neuroplasticity
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Written by Resident Doctor Committee · Published
Building the brain
Neurodevelopment forms the nervous system, and plasticity changes it through experience, injury and treatment.
Process | Timing |
|---|---|
Neural tube closes | Around day 28 |
Neurones migrate radially, building cortex inside out | Mainly first two trimesters |
Synaptogenesis, gliogenesis and most neuronal apoptosis | Earlier development |
Synaptic pruning removes surplus synapses | Adolescence, its most characteristic process; earlier in sensory than prefrontal cortex |
Association pathways myelinate | Continues into adulthood |
Failed neuronal migration can cause lissencephaly or heterotopia.
In adolescence cortical grey matter volume falls while white matter volume rises, reflecting pruning and myelination.
Neurodevelopmental model of schizophrenia
Weinberger, and Murray and Lewis, proposed in 1987 that early disturbances become clinically apparent years later.
Prenatal infection, famine and obstetric complications are associated with risk, and motor or cognitive differences can precede illness.
Two-hit models combine early liability with later influences such as cannabis or adversity.
Levels of plasticity
Level | Example |
|---|---|
Cellular | CREB-driven gene transcription |
Synaptic | NMDA-dependent long-term potentiation (Bliss and Lømo 1973) |
Structural | Dendritic spine growth in skill learning |
Network | Cortical map expansion after amputation |
Behavioural | Fear extinction, motor skill acquisition |
Injury at different ages
The Kennard principle holds that a focal early lesion recovers better, with language shifting right after left-hemisphere damage.
Diffuse early injury does worse than the adult equivalent because it corrupts skills not yet acquired.