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.
How blueberries help the aging brain
;
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
chandelier cells:
named for their structural resemblance to an old-fashioned candlestick.
A rare type of GABAergic neuron (one that releases gamma aminobutyric
acid (GABA)) found in the cerebral cortex that is strongly connected to
many excitatory pyramidal cells.
Chandelier cells may help explain human cognition
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 blueberries help the aging brain
; 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
Acne drug may help those with Fragile X
syndrome ; 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.
Circadian clock may be critical for remembering what you learn
;
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).
homocysteine:
is a homologue of the naturally-occurring amino acid cysteine, produced from
methionine. Elevated levels of homocysteine are associated with a greatly
increased risk for coronary heart disease, stroke, vascular dementia, and
Alzheimer's disease. Levels of homocysteine in the blood are strongly influenced
by diet -- high levels are particularly associated with deficiencies in vitamin
B12 and
folate -- lifestyle factors such as smoking,
and genetic factors.
B-vitamin deficiency may cause vascular cognitive impairment
; Folic acid
supplementation may improve cognitive performance ;
Diet rich in foods
with Vitamin E may reduce Alzheimer’s disease risk
; High
homocysteine levels may double Alzheimer's risk ;
High homocysteine levels are associated with decreased memory capability after
age 60
I
interneurons: are neurons that connect with other neurons, as compared to sensory and motor neurons. Most neurons are interneurons.
K
KIBRA: a gene implicated in human memory. The gene is expressed in the
hippocampus, and those with one variant - the T-allele - appear to need less
brain activity to remember the same amount of information compared to those with
the C-allele. The gene has also been implicated in Alzheimer's risk.
Memory gene linked to late-onset Alzheimer's
;
'Memory gene' identified
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
methionine:
is one of the essential amino acids that we require from
food. Broken down, it produces homocysteine; B-vitamins are required to
convert homocysteine back to methionine. High levels of methionine can be found
in sesame seeds, Brazil nuts, fish, meats, and dairy products. Most
fruits and vegetables contain very little -- spinach, potatoes, and
boiled corn are some of the exceptions. Methionine is also found in beta-amyloid,
and has been suggested as being
the source of the toxic free radicals produced by
amyloid-beta peptides.
B-vitamin deficiency may cause vascular cognitive impairment
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
;
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.
Brain slows at 40, starts body decline
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 (the 3rd ventricle; the cerebral aqueduct, in the midbrain; the 4th ventricle, in the hindbrain)
W
white matter: Brain
tissue is divided into two types: gray matter and
white matter. White matter is made up of the axons of neurons -- the
long filaments that extend from the cell bodies and carry the electrical
signals that carry the messages between neurons. It's the
myelin sheathing that makes it look white. There
are three major white matter systems, which all connect to form one
continuous system: cortical white matter; the
corpus callosum; the
internal capsule.
Brain slows at 40, starts body decline
; Occasional memory loss tied to lower brain volume
; Drinking alcohol associated with smaller brain volume
; Intelligence and rhythmic accuracy go hand in hand
; Imaging shows structural changes in mild traumatic brain injury
; Age-related changes in the
brain's white matter affect cognitive function ;
Gray matter may
decline from adolescence, but white matter keeps growing until our late
forties
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