Nervous system is made up of gray and white matter.  Brain consists of neuronal cells-neurons .Every cell has a body ("gray matter") and the cable-like processes- that extend from the cell bodies ("white matter"). Our skills and abilities are correlated with density of neuronal cells (white matter) while the speed of information processing is governed by a gray matter.

The structural brain-scan study has shown the age –dependent changes in gray matter volume and distribution. Different learning and memory problems are the results of   decreased gray matter in particular regions of the brain. Although the amount of gray matter is the arbiter of knowledge, however, the number of connections between neurons is also important.

 It is very interesting that with age gray matter declines starting  from adolescence  while  white matter keeps growing all the time. If we lose connections we lose everything. This is true for life as well as for our brain function. A number of neurological diseases are the results of impaired connections or their complete lose.