Brain Bee Glossary

• Orexin Neurons


  Specialized neurons that provide an excitatory signal to the arousal system, particularly to the norepinephrine neurons. Orexin activation plays a critical role in preventing abnormal transitions into REM sleep during the day, as occurs in narcolepsy
• Olfactory Bulb


  A round, knoblike structure of the brain responsible for processing the sense of smell. Specialized olfactory receptor cells are located in a small patch of mucous membrane lining the roof of the nose. Axons of these sensory cells pass through perforations in the overlying bone and enter two elongated olfactory bulbs lying on top of the bone.
• Occipital Lobe


  One of the four subdivisions of the cerebral cortex. This lobe plays a role in processing visual information.
• Norepinephrine


  A catecholamine neurotransmitter produced both in the brain and in the peripheral nervous system. This transmitter is involved in arousal and sleep regulation, mood, and blood pressure.
• Nociceptors


  In animals, nerve endings that signal the sensation of pain. In humans, they are called pain receptors.
• Neurotransmitter


  A chemical released by neurons at a synapse for the purpose of relaying information to other neurons via receptors.
• Neuroscientist


  Scientists who specialize in the study of the brain and the nervous system
• Neuron


  A nerve cell specialized for the transmission of information and characterized by long, fibrous projections called axons and shorter, branchlike projections called dendrites.
• Neurogenesis


  The production and growth of new nerve cells during development and, in select brain regions, throughout life.
• Neural Induction


  The process during embryonic development whereby molecules trigger ectoderm tissue to become nerve tissue.
• Nerve Terminal


  The tip of the axon where neurotransmitters are released.
• Nerve Growth Factor


  A substance whose role is to guide neuronal growth during embryonic development, especially in the peripheral nervous system. This substance also probably helps sustain neurons in the adult.
• NMDA Receptors

  one of three major classes of glutamate receptors, which have been implicated in activities ranging from learning and memory to development and specification of nerve contacts in a developing animal.
• Myelin Sheath


  Compact fatty material that surrounds and insulates the axons of some neurons and accelerates the transmission of electrical signals.
• Myasthenia Gravis


  A disease in which acetylcholine receptors on muscle cells are destroyed so that muscles can no longer respond to the acetylcholine signal to contract. Symptoms include muscular weakness and progressively more common bouts of fatigue. The disease's cause is unknown but is more common in females than in males; it usually strikes between the ages of 20 and 50.
• Multiple Sclerosis (MS)


  An autoimmune disease in which the body's natural defenses attack the myelin sheath covering the axons of neurons in the central nervous system. Symptoms include numbness, clumsiness, and blurred vision.
• Mutations


  Changes in DNA, such as "misspellings" in the gene sequence or incorrect amounts of DNA, that can prevent a gene from functioning properly.
• Motor Unit


  A functional unit made up of an alpha motor neuron and all the muscle fibers it contains and controls, ranging from a few to a hundred or more.
• Motor Neuron


  A neuron that carries information from the central nervous system to muscle.
• Mitochondria


  Small cylindrical organelles inside cells that provide energy for the cell by converting sugar and oxygen into special energy molecules, called adenosine triphosphate (ATP).
• Migration


  The process whereby new neurons find their proper position in the brain.
• Hindbrain


  The most anterior segment of the brainstem. With the pons and medulla, this thing is involved in many functions, including regulation of heart rate, respiration, pain perception, and movement.
• Metabolism


  The sum of all physical and chemical changes that take place within an organism and all energy transformations that occur within living cells.
• Magnetoencephalography (MEG)


  A technique that can quantitatively measure the strength of activity in various regions of the brain at millisecond resolution.
• Magnetic Resonance Spectroscopy (MRS)


  Using the same machinery as MRI, MRS measures the concentration of certain chemicals, such as neurotransmitters, instead of blood flow
• Magnetic Resonance Imaging (MRI)


  A technique that uses magnetic fields to create a high-quality, three-dimensional image of organs and structures inside the body. This technology is noninvasive and does not expose the body to X-rays or other radiation.
• Long-Term Memory


  The final phase of memory, in which information storage may last from hours to a lifetime.
• Ion Channels

  Selectively permeable water-filled channels that pass through the cell membrane and allow ions or other small molecules to enter or leave the cell.
• Ions


  Electrically charged atoms or molecules.
• Inhibition


  A synaptic message that prevents a recipient neuron from firing.
• Interneuron


  A neuron that exclusively signals another neuron
• Hypothalamus


  A complex brain structure composed of many nuclei with various functions, including regulating the activities of internal organs, monitoring information from the autonomic nervous system, controlling the pituitary gland, and regulating sleep and appetite.
• Huntington's Disease


  A genetic disorder characterized by involuntary jerking movements of the limbs, torso, and facial muscles, often accompanied by mood swings, depression, irritability, slurred speech, and clumsinessBasal ganglia出问题，过度dopamine
• Hormones


  Chemical messengers secreted by endocrine glands to regulate the activity of target cells. They play a role in sexual development, calcium and bone metabolism, growth, and many other activities
• Homeostasis


  The normal equilibrium of body function.
• Hippocampus


  A seahorse-shaped structure located within the brain and considered an important part of the limbic system. One of the most studied areas of the brain, it is involved in learning, memory, and emotion.
• Hindbrain


  The most posterior part of the brain comprises the pons, medulla oblongata, and cerebellum.
• Hair Cells


  Sensory receptors in the cochlea that convert mechanical vibrations to electrical signals; they in turn excite the 30,000 fibers of the auditory nerve that carry the signals to the brainstem.
• Growth Cone


  A distinctive structure at the growing end of most axons. It is the site where new material is added to the axon.
• Gray Matter


  Portions of the brain that are gray in color because they are composed mainly of neural cell bodies, rather than myelinated nerve fibers, which are white.