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.

OCD

Obsessive-compulsive disorder (OCD) is an anxiety disorder characterized by unreasonable thoughts and fears (obsessions) that lead you to do repetitive behaviors (compulsions). With obsessive-compulsive disorder, you may realize that your obsessions aren't reasonable, and you may try to ignore them or stop them. But that only increases your distress and anxiety. Ultimately, you feel driven to perform compulsive acts in an effort to ease your stressful feelings. Obsessive-compulsive disorder often centers around themes, such as a fear of getting contaminated by germs. To ease your contamination fears, you may compulsively wash your hands until they're sore and chapped. Despite your efforts, thoughts of obsessive-compulsive behavior keep coming back. This leads to more ritualistic behavior — and a vicious cycle that's characteristic of obsessive-compulsive disorder.