How the Human Brain Creates New Synapses: Theory of Recovery

The human brain changes throughout our lives. New connections are continually created while synapses that are no longer in use begin to degenerate. Now, scientists have discovered a new theory that may explain the synapse formation in the visual cortex, which could lead to a better understanding of how our thought processes work.

Neuroplasticity, which is the ability for our brains to change, plays a key role in learning processes. It enables the brain to recover from injuries and even compensate for the loss of functions. Even the adult brain can make new connections that are constantly formed and organized. In order to get a better look at the visual cortex, the researchers created models and studied the principles according to which neurons form new connections and abandon existing synapses.

"A neuron that no longer receives any stimuli loses even more synapses and will die off after some time," said Markus Butz, one of the researchers, in a news release. "We must take this restriction into account if we want the results of our simulations to agree with observations."

The visual cortex has a property called retinotopy, which makes it particularly suitable for demonstrating the new growth rule. This property means that points projected beside each other onto the retina are also arranged beside each other when they are projected onto the visual cortex, just like on a map. If areas of the retina are damaged, the cells onto which the associated mages are projected receive different inputs.

"In our simulations, you can see that areas which no longer receive any input from the retina start to build crosslinks, which allow them to receive more signals from their neighboring cells," said Butz.

The findings reveal a little bit more about the plasticity of the human brain. Not only that, but the discoveries may have implications for the future. Structural plasticity plays an important role during the early rehabilitation phase of patients affects by neurological diseases, so any findings concerning how the brain recovers could help with that process. In addition, the findings are of relevance for the Human Brain Project, an ongoing effort to map the brain.

The findings are published in the journal PLOS Computational Biology.