Brain

Image of the brain. Source: NIH.

Lobes of the brain. Source: Wikimedia Commons.

The brain is the center of the nervous system. It is the source of intelligence and behavior, and controls almost all body functions. The human brain's unique abilities separate humans from other animals.

Other Names

• Encephalon
• Grey matter
• Cranium
• Mind

Description

The brain is a spongy, three-pound structure which is the seat of the nervous system.^[1]

The brain contains gray matter and white matter. Gray matter refers to the cells making up the brain, such as neurons. White matter is made of axons, which are wire-like projections from the nerve cells that transmit messages in the brain.

The brain is divided into several parts:

• Brainstem
  • The brainstem includes the pons, medulla, midbrain, and upper part of the spinal cord
• Cerebellum
• Cerebrum
  • The cerebrum contains the lobes of the brain. These are the occipital, parietal, frontal, and temporal lobes.
  • Other parts of the cerebrum include the thalamus, hypothalamus, optic chiasm, and basal ganglia.

There are many smaller areas of the brain with specific names.

Role of the Brain in the Body

The brain controls numerous functions in the body, including physiologic processes such as heart rate, blood pressure, and hormone release, as well as behavioral processes such as learning and emotion.

• The brainstem controls body functions necessary for survival such as breathing, heart rate, and blood pressure. Within the brainstem, the medulla controls breathing and heart rate; the midbrain relays signals for movement and is involved in vision, hearing, and eye movement; and the pons is involved in control of movement and analysis of sensory information
• The cerebellum coordinates balance and movement.
• The frontal lobe controls higher functions such as personality, reasoning, planning, parts of speech, movement, emotions, and problem solving.
• The occipital lobe helps the brain understand visual information received from the eyes.
• The parietal lobes are important for understanding language and spatial relationships. They also function in movement and the recognition and perception of stimuli.
• The temporal lobes are involved in memory and processing sensory information.

How It Works

The brain is composed of billions of neurons, which are cells that transmit information. Synapses are the points where the neurons communicate with each other. Nerve impulses are transmitted when ion channels open and allow minerals such as calcium to enter or exit the cell.^[1]

Neurons release chemicals called neurotransmitters in order to send signals. Examples of neurotransmitters are acetylcholine, dopamine, serotonin, epinephrine, and amino acids such as glutamine.

Diseases of the Brain

Many diseases and injuries can affect the brain.

Injuries

• Traumatic brain injury
• Subarachnoid hemorrhage

Conditions

• Alzheimer disease
• Cancers, such as gliomas
• Parkinson disease
• Seizure
• Stroke

Related Professions

• A neurologist is a medical doctor with special training in the nervous system.

• A neurosurgeon is a surgeon who specializes in treatment of diseases of the nervous system.

• A psychiatrist is a medical doctor with training in behavioral problems that result from brain disorders.

History

How the brain was named

The word brain comes from Old English brægen and has been in use since before the 12th century.^[2]

Research

Brain plasticity, or its ability to change, is an important area of research. Researchers are studying the way the brain changes with experience in order to learn how to help patients in rehabilitation after diseases such as stroke.^[3]

Related Videos

Dr. Peter Bandettini, a Biophysicist at the National Institutes of Health, describes what his work entails and how it relates to the brain.


Holding a real brain, seeing the effects of alcohol or drugs on the brain, learning how neurons fire in the brain. All things that only NIH researchers might do, right? Eye-on-NIH found that people around the country and students in Washington DC got some insight on what neurologists do in a fun and fascinating environment:


Human imaging studies have for the first time identified brain circuitry associated with social status. Caroline Zink is a Ph.D. researcher with the National Institute of Mental Health's Genes Cognition and Psychosis Program. She explains that different brain areas are activated when a person moves up or down in a pecking order, or social hierarchy.

References

1. ↑ ^{1.0 1.1} Society for Neuroscience. Brain facts: A primer on the brain and nervous system. PDF
2. ↑ Merriam-Webster Online. Brain.
3. ↑ Cecatto RB, Chadi G. The importance of neuronal stimulation in central nervous system plasticity and neurorehabilitation strategies. Funct Neurol. 2007 Jul-Sep;22(3):137-43. Abstract

External Links

National Institute of Neurological Disorders and Stroke

Bryn Mawr Brain Structure Information Page