Neurogenesis Postnatally Flashcards
When is neurogenesis completed prenatally?
By 7 months of gestation
Is it possible to have new neurons?
Originally believed that no neurons were formed after early development
but later research suggested otherwise
When was it discovered that we can have new neurons later on in life?
In songbirds - there is a replacement of neurons in the singing area
Male birds sing to attract a female and a hate - they have more neurons during spring to attract more females, but this shrinks when the season is over
What regions do new neurons appear in?
Olfctory receptors continually replace dying ones - stem cells in the nose remain immature and periodically divide, as they get damaged easily
Hippocampus - neuorgenesis in adult mammals to facilitate learning
What does blocking the production of new neurons in the hippocampus do?
Impairs the formation of new memories
Where does neurogenesis not occur?
In the cerebral cortex - may be exceptions following injury or stroke
some mechanisms of recovery include new branches of axons and dendrites
What does regrowth of axons refer too?
Recovery is better in younger brains and is better in the periphery than the brain
destroyed cell bodies cannot be replaced, but damaged axons can grow back
What is recovery of axons known as?
Collateral sprouting
What does collateral sprouting refer too?
New branches formed by non-damaged axons that attach to vacant spots on dendrites and cell bodies
need the secretion of neurotrophins
after the first 2 weeks, rate of new synapses is very fast
Step by step of collateral sprouting
originally, 2 axons synapsing on a neuron
due to an injury, degeneration of a neuron
there is now empty space which wasn’t there before, the axon takes over the empty space and strengthens the connection with the neuron by sporting to fill the synapse
Reorganisation in the monkey cortex
Looked at what area responded to each finger in the somatosensory cortex
amputated finger 3
when they recorded the stimulation, the area that received input from finger 3 was taken over by finger 2 and 4 - shows that it has been reorganised
cortex previously responsive to finger 3 becomes responsive to finger 2 and 4
Why does our brain increase in size?
Increase in synapses
