Flashcards in Developmental Plasticity Deck (32):
Define: developmental plasticity
the changes in the brain’s neural structure in response to experience during its growth and development.
At what time does the brain have the most plasticity?
during foetal stage, infancy, childhood and adolescence (but it still has plasticity in adulthood).
Why does the young brain have more plasticity than the old brain?
because until synaptic pruning, there are more synapses in the brain than ever needed so there are the most chances for learning to occur.
Is developmental plasticity influenced both by genes and experience?
Yes; experience particularly in synaptogenesis and synaptic pruning (check)
Synaptogenesis and synaptic pruning
the process of forming new synapses.
WHen does synaptogenesis occur most rapidly?
after birth during infancy (increases tenfold) and into infancy
What is a purpose of synaptogenesis?
to allow to infant to respond to a new stream of constant environmental input
Define: synaptic pruning
The process of eliminating synaptic connections.
Adults have __% less synapses than 4 year oldsq
What factors affect the amount of synaptic pruning?
The area of the brain
The amount of experience (connections that are frequently used are retained and strengthened; if not they die)
SYnaptic pruning is complete in the visual cortex at __; and in the frontal lobe at __
What are the 5 stages of developmental plasticity?
the unborn baby’s neurons divide and multiply. 250,000 cells are produced per minute.
newly formed neurons move to their predestined location
In migration, the location of the neurons determines what?
Their function - to which they adapt
What else happens in migration?
Brain structures are formed.
Define: circuit formation
axons of new neurons grow out towards target cells and form synapses with them
Example of circuit formation?
Eg. axons for motor neurons grow out to spinal cord and form synapses with other motor neurons.
Define: circuit pruning
THe elimination (via death) of excess neurons and synapses.
What is the purpose of circuit pruning?
TO eliminate neurons which are in a circuit by mistake (eg. do not fire at the same time, so dies) or are no longer used (see synaptogen)
When does circuit pruning occur?
In infancy/childhood, then again in adolsecence.
Process in which axons of neurons are covered in myelin.
fatty white substance that coats some axons, which prevents interference from electrical messages in other neurons and increases the rate of neural transmission within a neuron.
Is myelination required for the brain to become fully developed?
When does myelination occur?
Begins in birth, ends in late adolescence/beyond
IN what order does myelination occur?
o The lower brain structures are myelinated first, then the occipital, temporal and parietal lobes (OTP), and finally the frontal lobe – specifically the prefrontal cortex.
Describe the numbers of neurons and synapses in birth, childhood and adulthood.
Babies are born with 100 billion nerve cells, each with 2500 synaptic connections. This increases to 15,000 connections in late childhood and decreases to 8,000 connections in adulthood.
Describe the development of brain structures during adolescence.
Cerebellum: more neurons and synapses
Amygdala: more active
Corpus callosum: thickens; more connections linking the two hemispheres. and increases the number of connections
Describe the method of Rozenweig's studies
25-day-old rat pups were randomly allocated to 3 environmental conditions:
Impoverished condition: single rat housed in a standard cage
Standard condition: 3 rats housed in a standard cage with food and water
Enriched condition: 10-12 rats housed in a large cage with many stimulus objects – providing many informal learning opportunities.
Kept in cages for 80 days, and brains were dissected
Describe the findings of Rozenweig's findings
Changes to brain occurred:
• Thicker and heavier cerebral cortices (later studies found they were 10% heavier)
• More acetylcholine
• Neuronal changes, including:
o Longer/bushier dendrites
o Bigger existing synapses
o New synapses (later studies found there were 20% more)