Saving the Brain

I want to revisit the topic of neurogenesis (the growth of new neuron cells) because while it may be that adult brains can form new neurons, they can't do so to the degree found with brains experiencing the critical period.  The critical period occurs when between late embryonic stages and early life.  This is when massive amounts of new neurons are created and preliminary synapses are growing towards as many targets as possible.

The power of a single synapse is weak, but together in a
circuit their power is incredible. 

After the critical period, there is a massive reduction in the number of connections between neurons.  The ones that remain are typically efficient enough to handle all the mental processes but the ability to "rewire" after this period is severely reduced.

However, some recent research is leading us to believe that there may be a way to reopen the critical period  and at least partially rewire our brains.  In fact, some antidepressants seem to be doing just that.  There's now evidence that anti-depressants like fluoxetine work by increasing BDNF (brain derived neurotrophic factor) which is hallmark of the critical period.  Fluoxetine requires chronic usage to get these effects but perhaps the antidepressant allows for the creation of new synapses and connections.  Maybe the rewiring is changing how information is processed in the emotional centers of the brain, thus relieving the depression of the patient.

A pill that changes how your brain is wired-
scary or amazing?

There's still plenty of research and trails we have yet to undergo before we understand all the mechanisms.  But this offers hope that neuroplasticity can be raised to the high level of malleability found during the critical period.