Brain

The brain is a pinkish-grey, wrinkled organ that fills the skull — looking, for all the world, like a huge walnut. It is hard to believe, from its appearance, that this ugly lump of jelly contains the mechanisms of thought, perception, will, and consciousness, that it is the seat of our personality. Its 100,000 million nerve cells, each with an average of 100,00 connections from other neurons, makes the human brain the most complicated and least understood object in the known universe. The vertebrate brain is the large anterior portion of the central nervous system . The "cranial vault" of the skull encases the brain in most vertebrates. In invertebrates, the enlarged and specialized anterior ganglion of the central nervous system is often referred to as a brain, although not all scientists regard it as a true brain.

Concentration impairment

Concentration difficulty is a decreased ability to focus your thoughts on something. Concentration difficulties can be related to difficulty staying awake, impulsiveness, intrusive thoughts or concerns, overactivity, or inattention. They can be caused by medical, cognitive or psychological problems or may be related to sleep disorders or medications, alcohol or drugs. Concentration difficulties may be long-term, established conditions, as in the case of attention deficit disorder, or they may arise as a result of illness or another event.