Glossary of terms

A

actin: a cytoskeletal protein present in all cells
Epilepsy-induced brain cell damage prevented

astrocytes: star-shaped glial cells that fill in the space between neurons and maintain the extracellular environment with the right concentrations of chemicals to support neurons, such as taking up neurotransmitters released by neurons. Astrocytes are the most numerous glia, and the most mysterious. They now appear to be critically involved in neurogenesis.

axon: a long projection extending from the cell body, that carries the output of the neuron away from it
Imaging shows structural changes in mild traumatic brain injury

B

BDNF: see brain-derived neurotrophic factor

brain-derived neurotrophic factor: a neuropeptide important for neuronal growth, survival, differentiation, connectivity and synaptic plasticity. The gene controlling BDNF expression comes in two variants, one of which is linked to poorer memory.
Gene linked to poor episodic memory ; Meal skipping protects the nerve cells of mice

C

catecho-O-methyltransferase gene: codes for the enzyme that metabolizes neurotransmitters like dopamine and norepinephrine, and comes in two common versions (met and val -- met contains the amino acid methionine at a point in its chemical sequence where val contains a valine). The COMT gene, like the BDNF gene, has been implicated in schizophrenia as well as cognitive function.
Genes implicated in learning attitude

cerebrospinal fluid (CSF): a clear salty liquid which cushions the brain

COMT: see catecho-O-methyltransferase gene

CREB: adenosine 3',5'-monophosphate response element–binding protein; a protein implicated in keeping memories stable, and more recently seen to be involved in determining which neurons store memories
How memory networks are formed

CSF: see cerebrospinal fluid

D

dendrite: is a branched projection of a nerve cell that conducts electrical stimulation to the cell body; the name is derived from the Greek word for tree.
Epilepsy-induced brain cell damage prevented

dendritic spine: a small protrusion on the dendrites that receives input from synapses
Epilepsy-induced brain cell damage prevented

dopamine: a neurotransmitter associated with reward and motivation. Evidence suggests dopamine levels in the prefrontal cortex need to be neither too high nor too low for optimal functioning.
Gene predicts better outcome as cortex normalizes in teens with ADHD ; Novelty aids learning ; Key neural system at risk from fetal alcohol exposure ; December 2001 news report 2; Amphetamine helps or hinders cognitive function depending on your genes

dynamin: a key protein that plays a major role in nerve communication. also see syndapin
How brain cells communicate

E

enzymes: are a type of protein; they are responsible for catalyzing the chemical reactions in a living cell -- that is, they accelerate the rates of reactions.

ependymal cells: brain cells that provide the lining for the ventricles.

epidermal growth factor: a mitogen that stimulates proliferation of hippocampal progenitor cells

EGF: see epidermal growth factor

eIF2a: a protein implicated in long-term storage of memories
Mutation improves memory, may lead to memory-enhancing pill

F

FGF-2: see fibroblast growth factor-2

fibroblast growth factor-2: a mitogen that stimulates proliferation of hippocampal progenitor cells.

G

GABA: see gamma-aminobutyric acid

gamma-aminobutyric acid: an amino acid synthesized from glutamate, it's the major inhibitory neurotransmitter in the adult brain, that is, one that dampens neuronal activity. It appears to dwindle in old age.
Is a dwindling brain chemical responsible for age-related cognitive decline?

gene expression: typically, a the transcription of a gene’s DNA sequence produces a messenger RNA molecule, which guides the synthesis of a specific protein. The encoded protein carries out the gene's function.

glial cells or glia: support cells in the brain; There are about ten times as many glial cells as neurons in the brain. Little attention has been paid to them, but now researchers are beginning to think they are more important than realized. The name is derived from the Latin word for 'glue'. The most common glia are astrocytes; other glia in the brain are oligodendroglia.

glutamate: an amino acid, it's the most prevalent excitatory neurotransmitter in the adult brain
How whole-brain radiation might cause dementia ; Link between APOE and memory neurotransmitter

gray matter: brain tissue is divided into two types: gray matter and white matter. Gray matter is made up of the cell bodies of nerve cells. The volume of gray matter tissue is a measure of the density of brain cells in a particular region. (for more, see article)

H

HAR1F: a RNA gene that is active in nerve cells that appear early in embryonic development and play a critical role in the formation of the layered structure of the human cerebral cortex. One of two genes that make up HAR1 (human accelerated region 1).

I

interneurons: are neurons that connect with other neurons, as compared to sensory and motor neurons. Most neurons are interneurons.

L

long-term potentiation: a process of synaptic modification, by which stimulated synapses become more effective; thought to be key to the forming of declarative memory.
Fragile X syndrome -- A stimulating environment restores neuronal function in mice ; A natural chemical found in strawberries boosts memory in healthy mice ; Drug reverses aging effect on memory process

LTP: see long-term potentiation

M

MEF2: see myocyte enhancer factor 2

mGluR5: a glutamate receptor, an excess of which has been implicated in Fragile X syndrome. Fragile X, the leading cause of mental retardation, is characterized by loss of the FMR1 gene, which encodes the fragile X mental retardation protein (FMRP). FMRP and mGluR5 keep each other in check; without FMRP, mGluR5 increase excessively.
Fragile X retardation syndrome corrected in mice ; Fundamental defect in fragile X syndrome identified and corrected

microglia: brain cells that remove debris left by dead and dying neurons and glia.

mitogen: something that induces mitosis -- a form of cell division -- in cells

motor neurons: neurons that connect with muscles and direct movements

myelin: the sheathing that insulates axons and facilitates speedy communication among neurons.

myocyte enhancer factor 2 (MEF2): a protein that turns on and off genes that control dendritic remodeling, that is the growth and pruning of neurons. The MEF2 pathway could play a role in autism and other neurodevelopmental diseases.
Protein that controls how neurons change as a result of experience

N

neural precursor cells: early stage cells that give rise to mature neurons and glial support cells; often referred to as neural stem cells

neuroblasts: neural precursor cells midway in development between a stem cell and a fully developed neuron

neurogenesis: creation of new neurons; common in young brains, it has only recently been found to occur in adult brains, and then only in specific regions. (for more see article)

neurotransmitter: a messenger chemical in the brain; it is through neurotransmitters that neurons communicate with each other. Examples are GABA, glutamate, acetylcholine, dopamine, serotonin, norepinephrine.

neurotrophin: a molecule in the brain that normally promotes the growth and development of neurons and other brain cells but can also kill them, depending on how and where they bind to a cell. The family includes nerve growth factor (NGF) and BDNF.
Stem cells improved memory in mice after brain injury

norepinephrine: a neurotransmitter synthesized from dopamine
Why emotion enhances memory

O

oligodendrocyte: glia that in the central nervous system (the brain and spinal cord) provide the myelin sheathing that insulates axons.

oxytocin: a hormone involved in nurturing and social behaviors; often nicknamed the "cuddle hormone"; particularly important in maternal bonding. Releasing this hormone makes us feel secure and protected and lowers our stress level, but this effect seems to require us to to have experienced some affection during childhood. The area of the brain that acts as the receptor for oxytocin is also the reward centre associated with drug addictions.
Oxytocin may help treat two core autism symptoms

P

peptide: a compound of two or more amino acids linked by a peptide bond. Peptides differ from proteins by their size; peptides are shorter. Proteins can be broken down into peptides (this occurs during digestion).

precursor cells: see neural precursor cells

prion: a protein that by changing shape (and thus function), induces neighboring proteins to do so too. Research indicates prions can speed up neurogenesis. Malformed prions cause mad cow disease.

progenitor cells: multipurpose cells capable of proliferation but unable to self-renew like stem cells, and thus proliferate indefinitely.

proteins: are essential to living organisms; they are long chains of amino acids linked together by peptide bonds. Enzymes, hormones, and antibodies are all types of protein.

pyramidal neurons: one of two main classes of neurons found in the cerebral cortex; so-called because of the shape of their dendritic branchings. They are excitatory neurons, that is they promote neuron firing (rather than inhibit it)

R

RNA genes: produce RNA molecules with special properties and effects, rather than expressing a protein, which is what most genes do.

S

sensory neurons: neurons that connect to sensory surfaces, such as the skin or the retina.

serotonin: a neurotransmitter that plays an important role in regulating a number of mental processes including mood and memory
Possible genetic risk for fetal alcohol disorders; Ecstasy can harm the brains of first-time users

synapse: the site where one neuron makes contact with another
Brain connections strengthen during waking hours, weaken during sleep ; Why learning takes a while

synaptic plasticity: the ability of synapses to be altered resulting in a modification of synaptic transmission; onsidered to be the foundation of learning and memory
Stress hormone impacts memory, learning in diabetic rodents

synaptic transmission: the process of transfering information at a synapse

syndapin: a molecule that works with a key protein called dynamin to allow the transmission of messages between nerve cells
How brain cells communicate

T

U

ubiquitin carboxyl-terminal hydrolase gene: (UCHL1), involved with protein degradation; the UCHL1 protein is highly expressed throughout the brain, to the extent that it makes up perhaps as much as 2% of total soluble brain protein. Replaceable neurons (such as those found in the dentate gyrus and the olfactory bulb, where neurogenesis occurs), and neurons that die in people with diseases such as Alzheimer's and Parkinson's have unusually low levels of UCHL1. Rising levels of UCHL1 may be associated with a reduced risk of neuronal death.
One gene links neurogenesis with neurodegenerative diseases such as Alzheimer's

UCHL1: see ubiquitin carboxyl-terminal hydrolase gene

V

ventricles: the spaces in the core of the brain; cerebrospinal fluid is produced in the paired lateral ventricles, and flows out through a series of unpaired ventricles