Apoptosis

Question 0

cells compete for connections

Answer 0

e.g. axons that arrive too late to find space on Post-Synaptic cell, cannot compete for Neurotrophins, DIE

axons often begin by branching widely, connecting to many sites; only a few are strengthened, maintained
-» so, each cell makes fewer, more selective connections as prenatal development progresses

redundancy probably serves to assure correct connections and allows for flexible adapting to local conditions

Question 1

Apoptosis

Answer 1

cell death

all neurons have SUICIDE GENES - brain chemistry and activation patterns determine if activated/not

during fetal development, the nervous system MASSIVELY OVERPRODUCES cells (up to 50% more than necessary to survive)

as cells compete for connections, “losers” die off (suicide genes are activated)

post development, most remaining STEM CELLS also die by the activation of their suicide genes