Sensory experience is capable of modifying neuronal connectivities in the brain, either by enhancing or diminishing the flow of information. Scientists from the Max Planck Institute for Developmental Biology (Tbingen, Germany) report in "Nature Neuroscience" (May 1998) that these two forms of plasticity differ in their molecular machinery.
Sensory experience during early postnatal development is essential for the optimization of neuronal connections in the brain. While genetic information is only sufficient for the development of the coarse pattern of connections between nerve cells, use-dependent modifications lead to the adaptation of neuronal connectivities to the individuals needs. The basic rules for these modifications are that connections which are rarely used are eliminated, and the flow of information along pathways which are regularily used are strengthened by addition of connections. These modifications of brain circuitries are also believed to underly the mechanisms of learning and forgetting in the mature brain.
The developing visual cortex is an excellent model system to study both forms of plasticity. In
this structure the information of both eyes converges and thereby allows depth-vision through
a comparison of the pictures seen by either eye. As shown by the pioneering studies by Drs.
Hubel and Wiesel in the 1970s, impairment of vision in one eye in infants leads to a severe
loss of connections from this eye to the cortex. This can result in almost complete blindness of
the affected eye within a short period of time. During early development, this loss of function
can be recovered by restoring vision in the deprived eye, leading to new formation of
connections carrying the ac
Contact: Christian Mller