A - B - C - D - E - F - G - H - I - J - K - L - M
 
O - P - Q - R - S - T - U - V - W - X - Y - Z

Acetylcholine…a common neurotransmitter, particularly involved in long term memory formation. Specifically released at neuromuscular junctions, it’s present at higher levels during sleep.

ACTH… also called corticotropin, this stress-related hormone is produced by the pituitary gland. It’s released into your system when you experience injury, emotion, pain, infections or other trauma.

Adrenaline…(also known as epinephrine) under stress, fear or excitement, this hormone is released from your adrenal gland into your bloodstream. When it reaches your liver, it stimulates the release of glucose for rapid energy. Abrupt increases caused by anger can constrict heart vessels, requiring the heart to pump with higher pressure. Also known as epinephrine.

Amygdala… an almond-shaped mass of gray matter located in the middle of the brain (anterior temporal lobe), that is thought to be the critical processor area for senses. It’s connected to the hippocampus, and plays a role in emotionally-laden memories. Contains a huge number of opiate receptor sites implicated in rage, fear and sexual feelings, and .is concerned with the expression and regulation of emotion and motivation.

Axon…the long fiber extending from the brain cell (neuron) that carries the output (an electrical nerve impulse) to other neurons. Can be up to a meter long. Axons build up a white fatty (lipoprotein) insulation called myelin.

Brain stem… located at the top of the spinal cord. Links the lower brain with the middle of the brain and cerebral hemispheres. Often referred to as the lower brain or reptilian brain in Paul McLean’s triune brain model.

Broca’s area… part of the left frontal lobe in the cerebrum. It converts thoughts into sounds (or written words) and sends the message to the motor area. Impulses go first to Wernicke’s area, in the right hemisphere, then to Broca’s area.

Cell migration...  The movement of a cortical neuron during development to its proper position on the cortical wall.

Cerebellum… a cauliflower-shaped structure located below the occipital area and next to the brain stem. The word is Latin for “Little Brain.” Traditionally, research linked it to balance, posture, coordination and muscle movements. It relays signals to the muscles from higher brain regions where decisions are made. Newer research has linked it to cognition, novelty and emotions.

Cerebral cortex…this is the newspaper-sized, ¼” thick, outermost layer of the cerebrum. It is wrinkled, six layers deep and packed with brain cells (neurons). It controls higher mental functions, such as thinking, planning, remembering, and analyzing. Cortex is Latin for “bark” or “rind.”

Cerebrum…this is the largest part of the brain, composed of the left and right hemisphere, joined by the corpus callosum. It has frontal, parietal, temporal (right and left) and occipital lobes.

Cingulate gyrus…this structure lies directly above the corpus callosum. It mediates communication between the cortex and the middle of the brain structures.

Corpus callosum…a white-matter bundle of about 200 million nerve fibers which connect the right and left hemispheres. Located in the middle of the brain.

Cortex...  Latin for Bark.  See CEREBRAL CORTEX.

Cortical ladders... a phrase often used to describe long glial cells in the cortex.  For normal development to occur, neurons must climb these cortical ladders at the right time, and must reach the right destinations.

Cortical neuron... a brain cell that is located in the cerebral cortex.

Critical period... a time span when a particular part of the brain is most apt to change and most vulnerable to environmental influences.

Dendrites…these are the strand-like, or hair-like, fibers emanating from the cell body. Similar to spider webs or cracks in a wall, they are the receptor sites for axons when they connect to make a synapse. Each neuron usually has many, many dendrites.

Dendritic tree... a network that forms as the number of dendrites in a neuron multiplies.  The growth of dendritic trees explains, in part, why individual neurons get bigger and heavier as the brain develops.

Dopamine…a powerful and common neurotransmitter primarily involved in producing a positive mood or feelings. Secreted by neurons in the substantia nigra, mid brain and hypothalamus, it plays a role in movements, too. It’s commonly in shortage in patients suffering from Parkinson’s Disease.

Endorphin…a natural opiate, this neurotransmitter is similar to morphine. It is produced in the pituitary gland. Protects against excessive pain and is released with ACTH and enkephalins into the brain.

Enkephalin…this morphine-like substance consists of five opiate-type amino acids. Released into the brain with ACTH and endorphins to combat pain.

Event Related Potential (ERD)…brain responses to some "event". An event may be sensory (sound, feel, taste, or visual) or mental (memory recognition).  Electrical signals are measured on the scalp using the electroencephalogram (EEG).  

Frontal lobes…one of four main areas of the cerebrum, the upper brain area. Controls voluntary movement, verbal expression, problem-solving, will power and planning. The other three areas of the cerebrum are the occipital, parietal and temporal (right and left).

GABA…gamma-aminobutyric acid, this neurotransmitter acts as an inhibitory agent, an “off” switch.

Glial…a non-neuronal cell, these are one of two types of brain cells (the other is a neuron). These outnumber neurons 10-1, and are also known as interneurons. In the cerebral cortex, long glial cells form “critical ladders” that neurons must climb to reach their proper positions during brain development.  This process is known as neuronal migration or cortical cell migration. They also carry nutrients, speed repair and may form their own communication network. They produce myelin and assist neurons in their migration to the cortex. Short for neuroglia.

Hemisphere, right and left... the two halves of the cerebrum.

Hippocampus…found deep in the temporal lobe, central to the middle of the brain area. It is crescent-shaped and has been shown to play an important role in organizing memories, as well as handling some visual and spatial information.

Hypothalamus…located in the bottom center of the mid-brain area. A complex thermostat-like structure that influences and regulates appetite, body temperature, hormone secretion, digestion, sexuality, circulation, emotions and sleep.

Lateralization…refers to the activity of using one hemisphere more than another. The term “relative lateralization” is more accurate since we are usually using at least some of the left and right hemisphere at the same time.

Limbic system…an older term coined by Dr. Paul McLean in the 1950’s. This is a group of connected structures in the mid brain area which include the hypothalamus, amygdala, thalamus, fornix, hippocampus and cingulate gyrus.

Lower brain…this is the lower portion of the brain composed of the upper spinal cord, medulla, pons and some believe the reticular formation. It sorts sensory information and regulates our survival functions like breathing and heart rate.

Medulla…located in the brain stem, it channels information between the cerebral hemispheres and the spinal cord. It controls respiration, circulation, wakefulness, breathing and heart rate.

Myelin…a fatty white (lipoprotein) shield that coats and insulates axons. Habits may be a result of myelinated axons.

Neural pathway... a series of synapses that forms a network in the brain.  These pathways can be activated by a particular experience.

Norepinephrine…(also known as noradrenaline) a common neurotransmitter, primarily involved in our arousal states: fight or flight, metabolic rate, blood pressure, emotions and mood.

Neurons…one of two types of brain cells. We have about 100 billion of these. Receives stimulation from its branches known as dendrites. Communicates to other neurons by firing a nerve impulse along an axon.

Neuronal migration...  see CELL MIGRATION.

Neuroplasticity...  the capacity of the brain to change or adapt in response either to experience or to damage.

Neurotransmitters…our brain’s biochemical messengers. It is believed that we have 50 - 100 types of them. These usually act as the stimulus that excites a neighboring neuron or an inhibitor to suppress activation.

Occipital lobe…located in the rear of the cerebrum. One of the five lobes of the upper brain with vision processing as a function. The other lobes are the frontal, parietal, and the two temporal.

Oxytocin…a peptide also known as the “commitment molecule.” It’s released during sex and pregnancy and influences “unlearning” and pair bonding.

Parietal lobe…the top of our cerebrum. One of five lobes of the upper brain. This area deals with reception of sensory information from the contralateral body side. It plays a part in reading, writing language and calculation. The other lobes are the frontal, occipital, and the two temporal.

Pons…located near the top of the brain stem, above the medulla. It’s a critical relay station for our sensory information.

Potentiation…the strengthening of a synapse for the making of learning. This strengthening can persist for a long time. This is known as long-term potentiation.

Pruning... a term often used to describe an important feature of brain development-the selective elimination of synapses. This usually occurs at around 24 months of age (the "terrible twos").

Reticular formation…a small structure, located at the top of the brain stem and bottom of middle of the brain area. It’s the regulator responsible for attention, arousal, sleep-awake, consciousness.

Serotonin…a common neurotransmitter, most responsible for inducing relaxation, regulating mood and sleep. Antidepressants (like Prozac) usually suppress the absorption of serotonin, making it more active.

Sheath... the myelin layer covering the axon referred to as the myelin sheath.

Synapse…the means by which neurons communicate. When an axon of one neuron releases neurotransmitters to stimulate the dendrites of another cell, the resulting junction point (actually a gap) where the reaction occurs is a synapse. The adult human has trillions of synapses.

Temporal lobes…located on the side of the cerebrum (in the middle of our upper brain, near our ears), it’s an area believed responsible for hearing, senses, language, learning and memory storage. The other major cerebrum areas are the frontal, parietal and occipital lobes.

Thalamus…located deep within the middle of the brain, it is a key sensory "relay station" receiving input from the body's sensory, motor, and other systems, dispatching them to the appropriate region of the cerebral cortex. Its functions are involved in hearing, muscle movement, retrieving memories.

Vasopressin…a stress-related hormone that is responsible partly for our aggression.

Vesicle... a small sac, usually containing fluid.  In a neuron, vesicles are containers for neurotransmitters.

Wernicke’s area…the upper back edge of the parietal and left temporal lobes. Here the brain converts thoughts into language.