2fitb Flashcards
3 parts of hindbrain
pons, cerebellum, medulla oblongata
4 main sections of cerebral cortex
the frontal lobe, the
parietal lobe, the occipital lobe, and the temporal lobe.
Overall the nervous system is __
a vast biological computing
device formed by a network of gray matter regions
interconnected by white matter tracts.
Somatic nerves in the __
region are related to __; those in
the __ region serve the __; and those in the
__ regions interact with the __
Somatic nerves in the cervical
region are related to the neck and arms; those in
the thoracic region serve the chest; and those in the
lumbar and sacral regions interact with the legs
In the __, the glia
that make the __ are called __, and in the
__, they are known as __.
In the brain, the glia
that make the sheath are called oligodendrocytes, and in the
peripheral nervous system, they are known as Schwann cells.
Nerve impulses involve __. The flow of
ions creates __.
The ability of a neuron to generate an
electrical impulse depends on __
Nerve impulses involve the opening and
closing of ion channels. The flow of
ions creates an electrical current that produces
tiny voltage changes across the neuron’s cell
membrane.
The ability of a neuron to generate an
electrical impulse depends on a difference in
charge between the inside and outside of the
cell.
When a nerve impulse begins, __ occurs on the
cell’s membrane, as the neuron switches from __.
The change, called __, then __. In this way, a neuron
may be able to __.
When these voltage changes reach
the end of an axon, they trigger __
When a nerve impulse begins, a dramatic
reversal in the electrical potential occurs on the
cell’s membrane, as the neuron switches from an
internal negative charge to a positive charge state.
The change, called an action potential, then passes
along the axon’s membrane at speeds up to several
hundred miles per hour. In this way, a neuron
may be able to fire impulses multiple times every
second.
When these voltage changes reach
the end of an axon, they trigger the release
of neurotransmitters
When
the neurotransmitter is in place (in receptor), this interaction __ and __, such as (3)
When
the transmitter is in place, this interaction alters the target
cell’s membrane potential and triggers a response from the
target cell, such as the generation of an action potential, the
contraction of a muscle, the stimulation of enzyme activity,
or the inhibition of neurotransmitter release.
Much less is known about ACh in the
brain. Recent discoveries suggest that it may be
critical for __
normal attention, memory, and sleep.
ACh is synthesized in __.
When an action potential arrives at the nerve
terminal, __, and __. On __, this action __.
ACh is then broken down by the enzyme
__ and resynthesized in the
nerve terminal.
ACh is synthesized in axon terminals.
When an action potential arrives at the nerve
terminal, electrically charged calcium ions
rush in, and ACh is released into the synapse,
where it attaches to ACh receptors on the target
cells. On voluntary muscles, this action opens
sodium channels and causes muscles to contract.
ACh is then broken down by the enzyme
acetylcholinesterase and resynthesized in the
nerve terminal.
__ and __ act as
__ signals, activating, among others, __ (NMDA) receptors which, in developing animals,
have been implicated in activities ranging from __.
Glutamate and aspartate act as
excitatory signals, activating, among others, N-methyl-d-aspartate (NMDA) receptors which, in developing animals,
have been implicated in activities ranging from learning
and memory to development and specification of nerve
contacts.
In the brain, serotonin has been
identified as an important factor in __
sleep quality, mood,
depression, and anxiety.
Researchers also have identified
genes that code for receptors and are involved in the signaling
mechanisms of trophic factors. These findings are expected to
result in a greater understanding of how trophic factors work
in the brain. This information should also prove useful for
the
design of new therapies for brain disorders of development and
for degenerative diseases, including Alzheimer’s disease and
Parkinson’s disease.
6 classes of steroid hormones
androgens, estrogens, progestins, glucocorticoids,
mineralocorticoids, and vitamin D
The brain contains receptors for __ hormones and the six classes of
__ hormones, which are synthesized from __. The receptors are found
in __.
The brain contains receptors for thyroid hormones
(those produced by the thyroid) and the six classes of
steroid hormones, which are synthesized from cholesterol. The receptors are found
in selected populations of neurons in the brain and relevant
organs in the body.
__ and __ hormones bind to
__ that in turn __. This can result in __.
Thyroid and steroid hormones bind to
receptor proteins that in turn bind to DNA and regulate the
action of genes. This can result in long-lasting changes in
cellular structure and function.
The brain has receptors for many hormones; for
example, the __ hormones (4). These hormones are taken
up from __ and act to affect __.
The brain has receptors for many hormones; for
example, the metabolic hormones insulin, insulin-like
growth factor, ghrelin, and leptin. These hormones are taken
up from the blood and act to affect neuronal activity and
certain aspects of neuronal structure.
In response to stress and changes in our biological
clocks, such as day and night cycles and jet lag, hormones
__. In
the brain, hormones __ as well as
__. As a result, the circuitry of
the brain and its capacity for neurotransmission are changed
over a course of hours to days.
hormones
enter the blood and travel to the brain and other organs. In
the brain, hormones alter the production of gene products
that participate in synaptic neurotransmission as well as
affect the structure of brain cells.
Reproduction in females is a good example of a regular,
cyclic process driven by circulating hormones and involving
a feedback loop: The __ in the __ produce
__, a __ that
acts on cells in the __. In both males and females,
this causes two hormones — __ — to be __.
The neurons in the hypothalamus produce
gonadotropin-releasing hormone (GnRH), a peptide that
acts on cells in the pituitary. In both males and females,
this causes two hormones — the follicle-stimulating hormone
(FSH) and the luteinizing hormone (LH) — to be released
into the bloodstream.
The endocrine system works in large part by acting on
__, which controls __. __. This is referred to as __.
The endocrine system works in large part by acting on
neurons in the brain, which controls the pituitary gland. The
pituitary gland secretes factors into the blood that act on
the endocrine glands to either increase or decrease hormone
production. This is referred to as a feedback loop.
Sexual differentiation of the brain is caused by sex
hormones acting in fetal and early postnatal life, although
recent evidence suggests __. Scientists
have found statistically and biologically significant
differences between the brains of men and women that are
similar to sex differences found in experimental animals.
These include differences in __ and__.
Sexual differentiation of the brain is caused by sex
hormones acting in fetal and early postnatal life, although
recent evidence suggests genes on either the X or Y
chromosome may also contribute to this process. Scientists
have found statistically and biologically significant
differences between the brains of men and women that are
similar to sex differences found in experimental animals.
These include differences in the size and shape of brain
structures in the hypothalamus and the arrangement of
neurons in the cortex and hippocampus.
Scientists have identified a new class of neurotransmitters
that are gases. These molecules — __ — do not act like other neurotransmitters. Being
gases, they are not __. Instead,
they are __.
Scientists have identified a new class of neurotransmitters
that are gases. These molecules — nitric oxide and carbon
monoxide — do not act like other neurotransmitters. Being
gases, they are not stored in any structure, certainly not in
storage structures for classical and peptide transmitters. Instead,
they are made by enzymes as they are needed and released
from neurons by diffusion.
Rather than __,
these gas neurotransmiters simply __.
Rather than acting at receptor sites,
these gases simply diffuse into adjacent neurons and act upon
chemical targets, which may be enzymes.Rather than acting at receptor sites,
these gases simply diffuse into adjacent neurons and act upon
chemical targets, which may be enzymes.
several diseases that most scientists
once thought were purely disorders of adult function,
such as __, are now being considered in
developmental terms; that is, such disorders may occur
because __
several diseases that most scientists
once thought were purely disorders of adult function,
such as schizophrenia, are now being considered in
developmental terms; that is, such disorders may occur
because pathways and connections to the brain did
not form correctly early in life.
by applying knowledge about __, __ is now viewed as a future possibility
by applying knowledge about how connections
form during development, regeneration following injury
to the brain is now viewed as a future possibility
common associated symptoms of ASD?
include intellectual
disabilities, seizures, and gastrointestinal problems.
Based mainly on __, ASDs are thought to
be __; already, more than __ genes have been
linked to increased risk for autism. ASD is typically diagnosed based on
behavioral symptoms detected in children about __ years
of age.
Based mainly on twin studies, ASDs are thought to
be highly genetic; already, more than 100 genes have been
linked to increased risk for autism; three
__ can detect differences in children between __
and __ years old, a time when many affected children exhibit
__.
very sensitive measures of social engagement and interaction; 1, 2; abnormal, accelerated growth of the brain
In
addition, recent evidence indicates that some forms of autism
may be due to __, either __
In
addition, recent evidence indicates that some forms of autism
may be due to dysregulation of the immune system, either in
the mother or the child.
Brain alterations in autism are subtle; there is no obvious
change such as in Down syndrome or Alzheimer’s disease.
There is speculation that abnormal development of certain
regions of the brain involved in __ leads to __
There is speculation that abnormal development of certain
regions of the brain involved in language, cognition, and
social communication leads to abnormal connections with
other parts of the brain
Although no cure exists and no drugs for the major
symptoms of autism have been developed, many affected
children respond very well to __, with earlier interventions leading
to better outcomes.
specialized behavioral therapies
based on learning theory
ADHD is characterized by
excessively inattentive, hyperactive, or impulsive behaviors
Neuroscientists have found that
almost all abused drugs produce pleasure by
activating a specific network of neurons called the brain reward system.
The circuit is normally involved in an important type of
learning that helps us stay alive. It evolved to mediate the
pleasurable and motivating effects of natural rewards, such as
eating when we are hungry or drinking when we are thirsty.
Indeed, when a reward produces feelings of pleasure, we
learn to repeat the actions that got us the reward in the first
place. Drugs can activate this same system, thus promoting
continued drug use.
In
addition to the brain reward system, brain regions that
are changed by drugs include those involved in __. These latter brain systems are
important in __.
In
addition to the brain reward system, brain regions that
are changed by drugs include those involved in executive
functions and judgment. These latter brain systems are
important in inhibiting behavior and in decision-making.
__
are standard responses of the brain and body to drugs.
Tolerance and dependence
are standard responses of the brain and body to drugs.
(4) are
equally effective in treating the more than __
people addicted to nicotine.
Nicotine
gum, the transdermal patch, nasal spray, and inhalers are
equally effective in treating the more than one million
people addicted to nicotine.
In addition, animal research has shown that alcohol
works by __
activating the endogenous opioid system. This
means that susceptible individuals may feel an opioid-like
euphoria from their own endorphins when they drink.
Opiates create effects like those elicited by the naturally
occurring opioid peptides. They __ —
important medical uses.
relieve pain, depress
breathing, cause nausea and vomiting, and stop diarrhea
opiate addiction medication
methadone, naloxone, naltrexone, buprenorphine
methadone
helps opiate addicts rehabilitate themselves by preventing
withdrawal symptoms that can motivate continued drug
use.
naloxone
available medications
that act as antagonists at opioid receptors; that is, they can
curb the allure of opiates by blocking the opiate receptors
so that opiates produce no pleasurable effects when they are taken. The blockers alone are sometimes useful for addicts
who are highly motivated to quit.
naltrexone
available medications
that act as antagonists at opioid receptors; that is, they can
curb the allure of opiates by blocking the opiate receptors
so that opiates produce no pleasurable effects when they are taken. The blockers alone are sometimes useful for addicts
who are highly motivated to quit. In addition, scientists are
developing a long-lasting version of naltrexone that needs to
be taken only once a month.
buprenorphine
Another medication used to treat heroin addiction,
buprenorphine, causes a weaker effect on the receptors than
methadone and creates only a limited high, which deters an
addict from abusing the medication itself.
__ users often go on binges, consuming a large
amount of the drug in just a few days. A __ occurs
after this period of intense drug-taking, resulting in such
symptoms as __. These symptoms may come from __. __ are in clinical trials.
Cocaine users often go on binges, consuming a large
amount of the drug in just a few days. A crash occurs
after this period of intense drug-taking, resulting in such
symptoms as emotional and physical exhaustion and
depression. These symptoms may come from an actual
shutdown, or crash, in dopamine and serotonin function, as
well as an increased response of the brain systems that react
to stress. Vaccines to produce antibodies to cocaine in the
bloodstream are in clinical trials.
Alzheimer’s patients usually die from
pneumonia or some other complication of
immobility
In the earliest stages, the clinical diagnosis of
possible or probable Alzheimer’s can be made with greater
than __ percent accuracy. As the course of the disease
progresses, the accuracy of diagnosis at Alzheimer’s research
centers exceeds __ percent. final confirmation of the
diagnosis requires __
80; 90; final confirmation of the
diagnosis requires examination of brain tissue, usually
obtained at autopsy.
what causes the clinical symptoms of Alzheimer’s?
damage to neural systems that transmit acetylcholine, somatostatin, monoamines, and glutamate; these systems are critical for attention, memory, learning, higher cognitive abilities
Microscopic examination of brain tissue from people
who died from Alzheimer’s shows (2) and where?
amyloid plaques and tau tangles (also called fibrillary tanges); in brain regions important for
memory and intellectual functions
how do genes cause Alzheimer’s?
Genes that cause dominant Alzheimer’s
appear to do so by causing beta amyloid plaques to
accumulate.
Experimental therapies in models of other
neurodegenerative diseases — __,
for example — have been effective in mice with the disease
but not in humans.
amyotrophic lateral sclerosis
Over the past several decades, scientists have shown
that in primate models of Parkinson’s,
there are specific
regions in the basal ganglia, the group of cellular structures
deep in the brain, that are abnormally overactive. Most
important, they found that surgical deactivation or
destruction of these overactive structures — the pallidum
and subthalamic nucleus — can greatly reduce symptoms of
Parkinson’s disease (pallidotomy)
what does MPTP stand for
(1-methyl-4-phenyl-1, 2, 3, 6
tetrahydropyridine
2 phobias mentioned
- acrophobia, fear of heights
- agoraphobia, fear of open spaces
anxiety disorders include
OCD; panic disorder; phobias;
social anxiety disorder; generalized anxiety disorder; PTSD
New therapies for brain tumors are being developed
in clinical trials. Many of these trials focus on
targeted
therapy — treatment aimed at the biologic characteristics
of tumors.
brain tumor targeted therapies (6)
- vaccines
- monoclonal antibodies
- anti-angiogenic therapy
- immunotherapy
- gene therapy
- target delivery of substances
Researchers are exploring the role of __ in the
origin of brain tumors
stem cells
MS: While many medications and therapies
are available to control symptoms such as __, no treatments
are available for __.
While many medications and therapies
are available to control symptoms such as muscle stiffness
(spasticity), pain, fatigue, and mood swings, as well as
bladder, bowel, or sexual dysfunction, no treatments
are available for the nerve degeneration that causes the
progression of the disease.
how long have steroids been used to treat MS?
3 decades
MS: Because the (3) are
commonly affected, symptoms such as (3) often occur.
Because the spinal cord, cerebellum, and optic nerve are
commonly affected, symptoms such as numbness, clumsiness,
and blurred vision often occur.
However MS can affect many
other brain areas, including __ and __, so
symptoms may also include __.
However MS can affect many
other brain areas, including bundles of myelinated nerve fibers
(white matter) and areas rich in neurons (gray matter), so
symptoms may also include slurred speech, weakness, loss of
coordination, pain, uncontrollable tremors, loss of bladder
control, memory loss and other cognitive problems, depression,
and fatigue.
HIV: In developing
countries, however, only about __ percent of the people
who need therapy are receiving such treatment.
36
HAND also affects those __,
though __.
HAND also affects those receiving the
modern combination antiretroviral treatment (CART),
though not to the same degree.
Each year, about
__ new __ injuries are reported, caused mostly by __.
Each year, about
12,000 new spinal cord injuries are reported, caused mostly by motor
vehicle accidents, sports injuries, violence, and falls.
The leading causes
of traumatic brain injury are
falls and motor-vehicle related
events.
No magic bullet has yet been found, but doctors have
discovered methods to stave off severe neurological damage
caused by head and spinal cord injuries and to improve
neurological function. This is accomplished by
working to
prevent secondary pathogenesis, or damage that occurs after
the initial insult; support regeneration and repair; and refine
and optimize rehabilitation techniques.
In general, patients who arrive
in the emergency room and are diagnosed with a severe
head injury are
monitored for pressure on the brain from
bleeding or swelling.
A recent pilot clinical trial for
patients with moderate to severe closed-head injury found
that __. Those in the
moderately injured group had __.
A recent pilot clinical trial for
patients with moderate to severe closed-head injury found
that the hormone progesterone cut the number of deaths
in severely injured patients by 50 percent. Those in the
moderately injured group had improved functional recovery
30 days after injury.
Often moderate pain
is treated by combining
a mild opioid, such as codeine,
with aspirin or an NSAID.
how do NSAIDs work?
NSAIDs work by inhibiting the cyclo-oxygenase
(COX) enzymes that make the inflammatory and painproducing
chemical prostaglandin.
b/c NSAIDs are __, they also are effective for treating
injuries or conditions such as __
b/c NSAIDs are anti-inflammatory, they also are effective for treating
injuries or conditions such as arthritis and postoperative
pain.
4 types of neuropathic pain
- diabetic neuropathy
- neuralgia
- phantom limb pain
- post-stroke pain
For some neuropathic pain
conditions in which a light touch
to the skin can produce severe pain,
topical lidocaine may be effective.
The finding that \_\_ receptors are concentrated in the \_\_ led to the use of injections of \_\_ into \_\_, without causing \_\_
The finding that opioid receptors are concentrated in the spinal cord led to the use of injections of morphine and other opioids into the cerebrospinal fluid in which the spinal cord is bathed, without causing paralysis, numbness, or other severe side effects.
Because
adverse side effects of drugs arise from __ — for
example, __ — new analgesics that target only
the __ may have fewer side effects.
Because
adverse side effects of drugs arise from the widespread
location of the molecules targeted by analgesics — for
example, constipation results from morphine’s action on
opioid receptors in the gut — new analgesics that target only
the nociceptor may have fewer side effects.
Among the many
nociceptor targets are __— one
of which is activated by __, the pungent ingredient
in hot peppers, and another by __ — as well as a
variety of __ and __
Among the many
nociceptor targets are specialized receptor channels — one
of which is activated by capsaicin, the pungent ingredient
in hot peppers, and another by mustard oil — as well as a
variety of acid-sensing sodium and calcium ion channels.
idiopathic
arising
from an uncertain cause
Seizures occur because of
sudden, disorderly discharges
of interconnected neurons in the brain that temporarily
alter one or more brain functions.
epilepsy types
idiopathic and symptomatic,
generalized and partial
Many antiepileptic drugs are available. Their principal
targets are
either ion channels or neurotransmitter receptors.
Until recently, if you or a loved one had a stroke, your
doctor would tell your family there were few treatment
options outside of
physical or speech therapy
A stroke occurs when __. As a result, __, causing __.
A stroke occurs when a blood vessel bringing oxygen
and nutrients to the brain bursts or is clogged by a blood
clot or some other particle. As a result, the brain is deprived
of blood, causing the death of neurons within minutes.
Depending on its location, a stroke can cause
many
permanent disorders, such as paralysis on one side of the
body and loss of speech.
Stroke tends to occur more in __ and
__ as well as in __
Stroke tends to occur more in males and
African Americans as well as in those with risk factors.
Another
promising possibility for improving recovery after stroke is
through the use of __. Some animal studies have
shown that __. Administration of
__ might further enhance the benefits of __
Another
promising possibility for improving recovery after stroke is
through the use of neural stem cells. Some animal studies have
shown that an injection of stem cells helps recovery even if
administered several days after the injury. Administration of
growth factors might further enhance the benefits of stem cell
transplantation
Other experimental therapies (for stroke) under investigation may
lead to even bigger payoffs for patients in the future. Some
strategies target __. In this way,
the vicious cycle of __ can be slowed.
Other experimental therapies (for stroke) under investigation may
lead to even bigger payoffs for patients in the future. Some
strategies target mechanisms inside the neuron. In this way,
the vicious cycle of local damage followed by a widening
fringe of biochemical-induced neuronal death can be slowed.
Emerging clinical evidence suggests that, following a
stroke affecting movement in one arm,
encouraging use
of the weakened arm by temporarily restricting use of the
unaffected arm may help functional recovery.
In the future,
__ may be treated with trophic factors or
their genes.
In the future,
Alzheimer’s disease, Parkinson’s disease, and amyotrophic
lateral sclerosis (ALS) may be treated with trophic factors or
their genes.
In an interesting twist on growth factor therapy,
researchers have demonstrated that
neutralizing molecules
that stop or inhibit growth can help repair damaged
nerve fiber tracts in the spinal cord.
the engineered antibody approach has shown some promise in
treating Alzheimer’s disease, although it also carries risks,
such as
increased inflammation when the brain reacts to
the antibodies against its proteins.
engineered antibody therapies have produced promising
preliminary results for
Huntington’s, Parkinson’s, and
Alzheimer’s diseases, as well as neurodegenerative disorders (ex: vCJD, which has been lined to mad cow disease)
New leads for drugs to treat __
have recently been described using high-throughput methods.
New leads for drugs to treat Alzheimer’s and prion diseases
have recently been described using these methods.
Performing activities related to vision involves about __ percent of the human
brain — __.
Performing
these activities involves about 30 percent of the human
brain — more than for any other sense.
Vision has been studied intensively. As a result,
neuroscientists may know more about it than any other
sensory system.
Most information about initial stages of
visual __, or __, comes from studies of __ and
__, whereas visual __ has been mostly studied in
__ and __.
Most information about initial stages of
visual transduction, or how light is converted into electrical
signals, comes from studies of Drosophila (fruit flies) and
mice, whereas visual processing has been mostly studied in
monkeys and cats.
scientists have learned that
the medial temporal region is closely connected to
widespread areas of the cerebral cortex, including the
regions responsible for thinking and language.
In 1900, for example, the average life expectancy was about
__ years. At that time, __, or __ percent
of the population, were older than age __, and they were
typically in ill health. By 2007, life expectancy reached
approximately __ years, and today, more than __
people, or almost __ percent of the population, are older
than age __.
In 1900, for example, the average life expectancy was about
47 years. At that time, three million people, or 4 percent
of the population, were older than age 65, and they were
typically in ill health. By 2007, life expectancy reached
approximately 78 years, and today, more than 39 million
people, or almost 13 percent of the population, are older
than age 65.
The term
dementia includes a number of different diseases, of which
Alzheimer’s disease is the most common. Other dementias
include (3)
cerebrovascular disease, Pick’s disease, and Lewy
body disease.
We now know that the brain reaches its maximum
weight near age __, and subtle changes in the brain’s
chemistry and structure begin __ for most people.
We now know that the brain reaches its maximum
weight near age 20, and subtle changes in the brain’s
chemistry and structure begin at midlife for most people.
Brain tissue can respond to damage or loss of neurons
in several ways:
The remaining healthy neurons are able
to expand their dendrites and fine-tune their connections
with other neurons. If the cell body of the neuron remains intact, a damaged brain neuron can readjust by inducing
changes in its axon and dendrites.
Increasingly, both physical and mental exercise
is viewed as an effective means of slowing the effects
of brain aging, perhaps by
altering the levels of certain
neurotropic factors that are beneficial to brain functioning.
Treatments for brain disorders such as __ and __
and target
__. The advances in medicine that led to this
type of treatment were made possible by studies using __ and __
Treatments for brain disorders such as Parkinson’s disease
and attention deficit hyperactivity disorder (ADHD) target
the synapse. The advances in medicine that led to this
type of treatment were made possible by studies using rats
and mice.
Following
the discovery that chemicals and other molecules are
transported within neurons, methods have been developed
to __. This can be
done by __, allowing __
Following
the discovery that chemicals and other molecules are
transported within neurons, methods have been developed
to visualize brain activity and precisely track nerve fiber
connections within an animal’s nervous system. This can be
done by injecting a radioactive amino acid into brain cells, allowing activities in the nervous system to show up on film.
another technique used to visualize brain activity and precisely track nerve fiber
connections:
In another technique, the enzyme horseradish peroxidase
is injected and taken up by nerve fibers that later can be
identified under a microscope.
what does PET measure?
energy consumption in the brain. or to produce maps of changes in local cerebral blood flow (CBF).
what does PET stand for?
Positron emission Tomography
what is PET based on?
Rings of detectors around the subject’s head
record the timing and position of gamma particles emitted
when positrons, positively charged particles, undergo radioactive decay in the brain
PET process
Small amounts of a radioisotope are introduced into the
blood, which then carries the radioisotope to different brain
areas. The radioisotope shows up in the brain in proportion to
how hard local neurons are working. Computers build threedimensional
images of changes in blood flow based on the
amount of radiation emitted in different brain regions. The
more brain activity, the more vivid the picture that is created.
PET contributions
- how drugs affect the brain
- what happens while people are working on diff activites
- understanding certain brain disorders, such as stroke, depression, Parkinson’s
- measure changes in neurotransmitter release
- revealed marked changes in the depressed brain
what does SPECT stand for
single photon emission computed
tomography
SPECT compared to other brain imaging technique
similar to PET, but its pictures are
not as detailed. SPECT is much less expensive than PET
SPECT process
the tracers it uses break down at a slower rate and
do not require a nearby particle accelerator, typical of those
used in nuclear physics, to produce them. this is why it’s cheaper than PET
MRI process
patient is exposed
to a powerful, steady magnetic field. Different atoms in the
brain resonate to different frequencies of magnetic fields.
A background magnetic field lines up all the atoms in the
brain. Then a second magnetic field, oriented differently
from the background field, is turned on and off many times
a second; at certain pulse rates, particular atoms resonate to
and line up with this second field. When the second field is
turned off, the atoms that were lined up with it swing back
to align with the background field. As they swing back, they
create a signal that can be picked up and converted into an
image.
what does MRI stand for
magnetic resonance imaging
what do MRIs reveal?
MRIs tell scientists when
structural abnormalities first appear in the course of a disease,
how they affect subsequent development, and precisely
how their progression correlates with mental and emotional
aspects of a disorder. In some instances, they can even reveal
minute changes that occur over time.
what do MRIs not use ?
X-rays or other raidation
different MRI procedure
A different MRI procedure can also assess the path of
fiber tracts in the brain; that is, the connectivity between regions. This technology, referred to as diffusion tensor
imaging, takes advantage of diffusion rates of water, which
tend to be higher along fiber tracts, to produce highresolution
images of how areas may connect in the brain.
what does MRS stand for
magnetic resonance spectroscopy
MRS vs other brain imaging technique
MRS, a technique related to MRI, uses the same machinery
but measures the concentration of specific chemicals — such
as neurotransmitters — in different parts of the brain instead
of blood flow.
what does MRS measure
the molecular and metabolic changes that occur in the
brain
what is MRS ideal for and why
Because it is noninvasive,
MRS is ideal for studying the natural course of a disease or its
response to treatment.
MRS contributions
this technique has already provided new information
about brain development and aging, Alzheimer’s disease,
schizophrenia, autism, and stroke.
what is fMRI often preferred for and why
Given fMRI’s temporal
and spatial resolution, as well as its noninvasive nature, this
technique is often preferred for studies investigating dynamic
cognitive and behavioral changes.
what does fMRI stand for
Functional Magnetic Resonance Imaging
what does fMRI measure
This technique compares brain activity under
resting and active conditions.
fMRI process
It combines the high-spatial
resolution, noninvasive imaging of brain anatomy offered
by standard MRI with a strategy for detecting increases in
blood oxygen levels when brain activity brings fresh blood
to a particular area of the brain — a correlate of neuronal
activity.This technique allows for more detailed maps of
brain areas underlying human mental activities in health
and disease.
what does MEG stand for
Magnetoencephalography
what does MEG measure
MEG is a
recently developed technique that reveals the source of weak
magnetic fields emitted by neurons.
MEG process
An array of cylindershaped
sensors monitors the magnetic field pattern near
the patient’s head to determine the position and strength
of activity in various regions of the brain
MEG vs other brain imaging techniques
In contrast with
other imaging techniques, MEG can characterize rapidly
changing patterns of neural activity — down to millisecond
resolution — and can provide a quantitative measure of the
strength of this activity in individual subjects. Moreover, by
presenting stimuli at various rates, scientists can determine
how long neural activation is sustained in the diverse brain
areas that typically respond.
combination of 2 imaging techniques
- One of the most exciting developments in imaging is
the combined use of information from fMRI and MEG. The
former provides detailed information about the areas of brain
activity while an individual is engaged in a particular task,
whereas MEG tells researchers and physicians when certain
areas become active. - when TMS is used with fMRI, a
functional correlation between a region and a behavior can
be established.
types of optical imaging
event-related optical signal, TMS, NIRS
optical imaging process
Optical
imaging relies on shining weak lasers through the skull to
visualize brain activity.
optical imaging unique
These techniques are inexpensive
and relatively portable. They are also silent and safe: Because
only extremely weak lasers are used, these methods can be
used to study everyone, even infants.
what does NIRS stand for
near infrared spectroscopy
NIRS process
technicians shine lasers
through the skull at near infrared frequencies, which renders the skull transparent. Blood with oxygen in it absorbs
different frequencies of light from blood in which the oxygen
has been consumed. By observing how much light is reflected
back from the brain at each frequency, researchers can track
blood flow. Diffuse optical tomography is then used to create
maps of brain activity
what does NIRS measure
blood flow
event-related optical signal
records how light scatters in response to rapid cellular
changes that arise when neurons fire, potentially assessing
neural activity lasting milliseconds. similar to NIRS
what does TMS stand for
transcranial magnetic stimulation
TMS process
works
by inducing electrical impulses in the brain. This is
accomplished by altering magnetic fields through the use
of an electromagnetic coil that emits powerful magnetic
pulses while held against the scalp.
reptitive TMS
Repetitive TMS is being
used to investigate the role of specific brain regions during
behavior, and it can be combined with other neuroimaging
techniques.
Early mapping techniques
allowed scientists to track down the genes responsible for
several neurological conditions. These include:
HTT, RB1, DMD
There are
now very early interventional studies for some neurological
conditions, such as
Angelman syndrome and tuberous
sclerosis complex.
Many
genetic changes have been associated with autism, or more
specifically, with conditions that can include autism or
autism-like features as symptoms. Such conditions include
tuberous sclerosis complex, due to mutations in the genes
TSC1 and TSC2, as well as Rett syndrome, associated with
the MECP2 gene.
vision: Scientists know much about __, but relatively less about the __ and __
Scientists know much about the way cells encode visual
information in the retina, but relatively less about the lateral geniculate nucleus and the visual cortex.
how does the visual process begin, and how long ago was this discovered?
About 60 years ago,
scientists discovered that each vision cell’s
receptive field is activated when light hits
a tiny region in the center of the field
and inhibited when light hits the area
surrounding the center. If light covers the
entire receptive field, the cell responds
weakly. Thus, the visual process begins by
comparing the amount of light striking any
small region of the retina with the amount
of surrounding light.
Although the visual processing mechanisms are not
yet completely understood, recent findings from anatomical
and physiological studies in __ suggest that
visual signals are fed into at least three separate processing
systems. One system appears to process information mainly
about shape; a second, mainly about color; and a third,
movement, location, and spatial organization.
Human
psychological studies support the findings obtained through
animal research. These studies show that the perception of
movement, depth, perspective, the relative size of objects,
the relative movement of objects, shading, and gradations in
texture all depend primarily on contrasts in __ rather than __
light intensity
rather than on color.
strabismus
condition in which the eyes are not properly aligned with each other and point
in different directions. It is also termed squint, cross-eye, or
walleye
path of sound waves
- collected by the external ear (pinna and external auditory canal)
- funneled to the tympanic membrane (eardrum) to make it vibrate
- malleus (hammer), attached to the eardrum, transmits the vibration to the incus (anvil), which passes the vibration to the stapes (stirrup)
- stapes push on oval window
the part
of the brain involved in perceiving sound?
superior temporal gyrus, or auditory cortex
how was therapy for strabismus developed?
Information from research in cats and monkeys has
improved the therapy for strabismus
why does food “taste” diff when we have a head cold?
Actually, what is really being affected is the flavor of
the food, or the combination of taste and smell. That’s because
only the taste, not the food odors, are being detected. Taste itself
is focused on distinguishing chemicals that have a sweet, salty,
sour, bitter, or umami taste (umami is Japanese for “savory”).
Touch is the sense by which we determine the
characteristics of objects: __. We do this
through __.
Touch is the sense by which we determine the
characteristics of objects: size, shape, and texture. We do this
through touch receptors in the skin.
The transmission of this
information is highly topographic, meaning that
the body is represented in an orderly fashion at different levels of the
nervous system. Larger areas of the cortex are devoted to
sensations from the hands and lips; much smaller cortical
regions represent less sensitive parts of the body
Neurologists measure sensitivity by
determining the
patient’s two-point threshold, the distance between two points
on the skin necessary in order for the individual to distinguish
two distinct stimuli from just one. This method involves
touching the skin with calipers at two points. Not surprisingly,
acuity is greatest in the most densely nerve-packed areas of the
body. The threshold is lowest on the fingers and lips.
Prostaglandins also
contribute to
the clinical condition of allodynia, in which
innocuous stimuli can produce pain, as when sunburned skin is
touched.
comparison of the two types of fibers that transmit pain and itch messages
The myelinated nerve fibers are very painsensitive,
and they probably evoke the sharp, fast pain that is produced by, for example, a pinprick. C fiber-induced pain, by
contrast, is generally slower in onset, dull, and more diffuse.
In the ascending system, pain and itch impulses are relayed from
the
spinal cord to several brain structures, including the thalamus
and cerebral cortex.
if awakened during slow wave sleep,
most people recall only fragmented thoughts,
not active dreams.
why can movement concide w/ dreams?
Interestingly, our motor cortex nerve cells
fire as rapidly during REM sleep as they do during waking
movement, a fact that explains why movement can coincide
with dreams.
what causes the hallmark signs of REM sleep?
Internal activation during REM comes from
a cyclically active REM sleep generator made up of neurons in
the brainstem. Signals from these neurons cause the forebrain
to become excited and lead to the rapid eye movements and
muscle suppression — hallmark signs of this state. In the
absence of external input, forebrain excitation from internal
sources is the driving force behind the vivid dreams experienced
during REM sleep
Why do we get sleepy? There are two main determining
factors:
the circadian system (time of day or night) and how long
we have been awake.
Orexin activation plays a critical role in
preventing abnormal
transitions into REM sleep during the day, as occurs in
narcolepsy.
Specialists now define stress as
any external
stimulus that threatens homeostasis — the normal equilibrium
of body function.
A stressful situation activates __. how was this studied?
- 3 major communication systems in the brain: voluntary nervous system, autonomic nervous system, neuroendocrine system
- through experiments, primarily with rats,
mice, and nonhuman primates such as monkeys
sympathetic nervous system
causes arteries supplying blood to the muscles
to relax in order to deliver more blood, allowing greater
capacity to act. At the same time, blood flow to the
skin, kidneys, and digestive tract is reduced. The stress
hormone epinephrine, also known as adrenaline, is
quickly released into the bloodstream. The role of
epinephrine is to put the body into a general state of
arousal and enable it to cope with the challenge.
parasympathetic nervous system
helps regulate
bodily functions and soothe the body once the stressor has
passed, preventing the body from remaining in a state of
mobilization too long. If these functions are left mobilized
and unchecked, disease can develop. Some actions of this branch appear to reduce the harmful effects of the
emergency branch’s response to stress.
neuroendocrine system
maintains the body’s
internal functioning. Various stress hormones travel through
the blood and stimulate the release of other hormones,
which affect bodily processes such as metabolic rate and
sexual function
Stress also can contribute to sleep loss when
people get caught in a vicious cycle:
elevated glucocorticoids
delaying the onset of sleep, and sleep deprivation raising
glucocorticoid levels.
2 man made glucocorticoids
hydrocortisone, prednisone
importance of motor units
If the (alpha) motor neurons die, which can happen in certain diseases, such as amyotrophic lateral sclerosis (ALS), a person is no longer able to move.
The brain can control not only the actions of motor
neurons and muscles but even
the nature of the feedback
received as movements occur
Flexion withdrawal occurs very rapidly and without
your attention because
these responses are built into systems of
neurons that are located within the spinal cord itself
Evidence suggests that as we learn to walk, speak, or play
a musical instrument,
the necessary, detailed control
information is stored within the cerebellum, where it can
be called upon by commands from the cerebral cortex.
Another brain region that is crucial for coordinating
and adjusting skilled movement is the cerebellum.
A disturbance of cerebellar function leads to
poor
coordination of muscle control, disorders of balance
and reaching, and even difficulties in speech, one of
the most intricate forms of movement control.
brain regions important for voluntary movement
motor cortex, basal ganglia, thalamus, cerebellum, neuron groups in midbrain and brainstem
Dysfunction of the basal ganglia can lead to serious
movement disorders:
The neurotransmitter dopamine,
which helps control movement, is supplied to the
basal ganglia by the axons of neurons located in the
substantia nigra, a midbrain cell group. People with
Parkinson’s disease experience degeneration of the nigral neurons. The supply of dopamine is depleted,
resulting in the hallmark symptoms of Parkinson’s —
tremor, rigidity, and akinesia, the inability to move.
mvmnt control: In addition to the motor cortex, movement control
involves the interaction of many other brain regions,
including the basal ganglia, thalamus, cerebellum, and
__. Scientists know that the __ and __ have widespread connections
with __ and __ areas of the __
In addition to the motor cortex, movement control
involves the interaction of many other brain regions,
including the basal ganglia, thalamus, cerebellum, and
a large number of neuron groups located within the
midbrain and brainstem — regions that send axons
to the spinal cord. Scientists know that the basal
ganglia and thalamus have widespread connections
with motor and sensory areas of the cerebral cortex.
How exactly are memories
stored in brain cells?
memory involves a persistent
change in synapses, the connections between neurons.
In animal studies, researchers found that such changes
occur in the short term through biochemical events that
affect the strength of the relevant synapses. Turning on
certain genes may lead to modifications within neurons
that change the strength and number of synapses,
stabilizing new memories.
what’s LTP
Another important model for the study of memory is the
phenomenon of long-term potentiation (LTP), a long-lasting
increase in the strength of a synaptic response following
stimulation. LTP takes place as
a result of changes in the strength of synapses at contacts
involving N-methyl-d-aspartate (NMDA) receptors.
LTP molecular fnctions
- Ca2+ released into synapse, activating cAMP in the postsynaptic neuron
- cAMP activates several kinds of enzymes, some of which increase the number of synaptic receptors, making the synapse more sensitive to neurotransmitters. cAMP also activates CREB.
the molecular cascade leading to protein synthesis is essentail to
Many studies have shown that the molecular cascade
leading to protein synthesis is not essential to initial learning
or to maintaining short-term memory; however, this cascade
is essential for long-term memory.
Researchers
once believed that all aspects of language ability were
governed only by the left hemisphere. but
Recognition of
speech sounds and words, however, involves both left and right temporal lobes. In contrast, speech production
is a strongly left-dominant function that relies on frontal
lobe areas but also involves posterior brain regions in
the left temporal lobe. These appear to be important
for accessing appropriate words and speech sounds.
Neurological illnesses
affect more than __ million Americans annually and
cost more than __ to treat.
Neurological illnesses
affect more than 50 million Americans annually and
cost more than $500 billion to treat.
More than __ disorders of the brain and nervous system
result in more hospitalizations than any other disease group,
including heart disease and cancer
1,000
mental disorders strike __ adults a year at a cost of __
mental disorders strike 44 million adults a year at a cost of $148
billion.
discovering how to delay the onset of Alzheimer’s
disease by __ years could save __ in annual health
care costs.
discovering how to delay the onset of Alzheimer’s
disease by five years could save $50 billion in annual health
care costs.
if
one twin gets the disease, the probability the other will
also be affected is
between 30 percent and 60 percent,
indicating that there are environmental factors at play
as well.
neuroscientists have discovered that many of the
toxic venoms used by animals can be adapted into new
pharmacological treatments. For example,
the poison of a
puffer fish, tetrodotoxin (TTX), halts electrical signaling in
nerve cells. However, in discrete, targeted doses, TTX can be
used specifically to shut down those nerve cells involved in
sending constant signals of chronic pain
As neurons are produced, they move from
the neural
tube’s ventricular zone, or inner surface, to near the border of
the marginal zone, or outer surface.
how does the brain form?
at the time migration starts to occur (3 -4wk after conception), the ectoderm starts to thicken and build up along
the middle. As the cells continue to divide, a flat neural
plate grows, followed by the formation of parallel ridges,
similar to the creases in a paper airplane, that rise across its
surface. Within a few days, the ridges fold in toward each
other and fuse to form a hollow neural tube. The top of the
tube thickens into three bulges that form the hindbrain, the
midbrain, and the forebrain. Later in the process, at week
seven, the first signs of the eyes and the brain’s hemispheres
appear
neuronal migration mechanisms
- most common (90 percent of migration in humans): glia
- inhibitory interneurons
Once the neurons reach their
final location,
they must make the proper connections so
that a particular function, such as vision or hearing, can
emerge. Unlike induction, proliferation, and migration, which
occur internally during fetal development, the next phases of
brain development are increasingly dependent on interactions
with the environment.
Neurons become interconnected through
(1) the growth
of dendrites — extensions of the cell body that receive signals
from other neurons and (2) the growth of axons — extensions
from the neuron that can carry signals to other neurons. Axons enable connections between neurons at considerable
distances to develop.
A combination of signals also determines the type of
neurotransmitters that a neuron will use to communicate
with other cells. For some cells, such as __, the
type of neurotransmitter is fixed, but for other neurons, it is
not. Scientists found that when certain immature neurons
are maintained __, they
produce the neurotransmitter __. In contrast, if
the same neurons are maintained__, they produce the neurotransmitter
__.
A combination of signals also determines the type of
neurotransmitters that a neuron will use to communicate
with other cells. For some cells, such as motor neurons, the
type of neurotransmitter is fixed, but for other neurons, it is
not. Scientists found that when certain immature neurons
are maintained in a dish with no other cell types, they
produce the neurotransmitter norepinephrine. In contrast, if
the same neurons are maintained with specific cells, such as
cardiac, or heart, tissue, they produce the neurotransmitter
acetylcholine
. Just as genes turn on and off signals to regulate
the development of specialized cells, a similar process leads
to the production of specific neurotransmitters. Many
researchers believe that the signal to engage the gene, and
therefore the final determination of the chemical messengers
that a neuron produces, is influenced by
by factors coming from
the location of the synapse itself.
when does neuron apoptosis occur?
Apoptosis is activated if a neuron loses its
battle with other neurons to receive life-sustaining chemical
signals called trophic factors. These factors are produced
in limited quantities by target tissues. Each type of trophic
factor supports the survival of a distinct group of neurons.
For example, nerve growth factor is important for sensory
neuron survival.
after a critical period,
connections diminish in number
and are less subject to change, but the ones that remain are
stronger, more reliable, and more precise. These turn into
the unique variety of sensory, motor, or cognitive “maps”
that best reflect our world.
Heightened activity in the
critical period may, however, also contribute to
an increased
incidence of certain disorders in childhood, such as epilepsy.
2 types of plasticity
Plasticity can be categorized as experienceexpectant
or experience-dependent.
