One Simple Rule Could Regulate Structural Neuroplasticity

October 10, 2013 | The processes by which synapses are formed, organized and pruned in the brain are still being uncovered as neuroscientists seek to construct working models of neural growth and development. Now, Dr. Markus Butz of Research Center Juelich and Dr. Arjen von Ooyen of VU University Amsterdam have proposed a simple homeostatic rule to explain the brain’s structural plasticity – the long-term process by which new connections are established and damage to the brain is repaired. Drs. Butz and von Ooyen theorize that neurons regulate their total electrical activity at a predetermined level. When a neuron experiences activity below that threshold, it builds new synaptic contacts with nearby cells, increasing its firing rate; when its electrical activity exceeds that threshold, synapses are allowed to degenerate. However, the homeostatic pattern falls off when a neuron experiences no electrical activity – in this case the neuron will stop building synapses and eventually die. Using computer simulations that follow this simple rule, Butz and von Ooyen were able to recreate observed patterns of neural reorganization in mice and monkeys with visual cortex damage, although the model has not yet been used predictively. Structural plasticity should not be confused with the short-term process of synaptic plasticity, which has long been understood to follow a different regulatory rule by which a neuron that persistently stimulates another cell will tend to grow a closer synaptic connection to that cell – or “Cells that fire together, wire together.” PLOS Computational Biology