Chapter 5 Flashcards
Although conventional X-ray photography is not useful
for visualizing the brain, contrast X-ray techniques are.
____ ____ _____ involve injecting into one compartment of the body a substance that absorbs X-rays either
less than or more than the surrounding tissue. The injected
substance then heightens the contrast between the compartment and the surrounding tissue during X-ray photography.
Contrast X-ray techniques
One contrast X-ray technique, ____ _____,
uses the infusion of a radio-opaque dye into a cerebral
artery to visualize the cerebral circulatory system during
X-ray photography (see Figure 5.1).
____ _____ are most useful for
localizing vascular damage, but the displacement of
blood vessels from their normal
position also can indicate the location of a tumor.
cerebral angiography, Cerebral angiograms
In the early 1970s, the study of the living human brain was revolutionized by the introduction of computed tomography. \_\_\_\_ \_\_\_\_ is a computer assisted X-ray procedure that can be used to visualize the brain and other internal structures of the living body.
Computed
tomography (CT)
The success of computed tomography stimulated the development of other techniques for obtaining images of the
inside of the living body. Among these techniques is
____ _____ _____ a procedure in
which high-resolution images are constructed from the
measurement of waves that hydrogen atoms emit when
they are activated by radio-frequency waves in a magnetic
field.
magnetic resonance imaging (MRI)
In addition to providing relatively high ___ ____ (the ability to detect and represent differences in
spatial location), MRI can produce images in three dimensions.
spatial resolution
____ ____ ____ was the first brain imaging technique to provide images of brain activity
(functional brain images) rather than images of brain structure (structural brain images).
Positron emission tomography (PET)
In one common version of
PET, radioactive _______ is injected into the
patient s carotid artery (an artery of the neck that feeds
the ipsilateral cerebral hemisphere). Because of its similarity to glucose, the primary metabolic fuel of the brain,
_____ is rapidly taken up by active (energyconsuming) cells. However, unlike glucose, ______
cannot be metabolized; it therefore accumulates in active
neurons or in associated astrocytes
2-deoxyglucose (2-DG)
____ _____ produce images representing
the increase in oxygen flow in the blood to active areas of
the brain. ____ _____ is possible because of two attributes of oxygenated blood (see Raichle & Mintun,
2006). First, active areas of the brain take up more oxygenated blood than they need for their energy requirements, and thus oxygenated blood accumulates in active
areas of the brain. Second, oxygenated blood has magnetic properties (oxygen influences the effect of magnetic
fields on iron in the blood).
Functional MRI (fMRI)
The signal recorded by
fMRI is called the ____ _____ (the blood-oxygen-level dependent signal).
BOLD signal
Another technique that is used to monitor the brain activity of human subjects is magnetoencephalography
(MEG). MEG measures changes in magnetic fields on the
surface of the scalp that are produced by changes in underlying patterns of neural activity. Its major advantage
over fMRI is its ____ ______; it can record fast
changes in neural activity.
temporal resolution
_____ _____ ______ is a technique for affecting the activity in an area of the cortex by
creating a magnetic field under a coil positioned next to
the skull
Transcranial magnetic stimulation (TMS)
The electroencephalogram (EEG) is a measure of the gross
electrical activity of the brain. It is recorded through
large electrodes by a device called an electroencephalograph
(EEG machine), and the technique is called ______.
electroencephalography
For example, ____ _____ are regular, 8- to 12-per-second, high-amplitude waves that are associated with relaxed
wakefulness.
alpha waves
Psychophysiologists are often more interested in the
EEG waves that accompany certain psychological events
than they are in the background EEG signal. These accompanying EEG waves are generally referred to as ___ _____ _____.
event related potentials (ERPs)
One commonly studied type
of event-related potential is the ____ _____
potential the change in the cortical EEG signal that is
elicited by the momentary presentation of a sensory stimulus.
sensory evoked
A method used to reduce the noise of the background EEG is \_\_\_\_ \_\_\_\_\_. First, a subject s response to a stimulus, such as a click, is recorded many let s say 1,000 times.
signal averaging
The analysis of average evoked potentials (AEPs) focuses on the various waves in the averaged signal. Each
wave is characterized by its direction, positive or negative, and by its latency. For example, the ____ ____ illustrated in Figure 5.10 is the positive wave that occurs
about 300 milliseconds after a momentary stimulus that
has meaning for the subject (e.g., a stimulus to which
the subject must respond)
P300 wave
In contrast, the portions of an evoked
potential recorded in the first few milliseconds after a
stimulus are not influenced by the meaning of the stimulus for the subject. These small waves are called _____ _____ because, although they are recorded
from the scalp, they originate far away in the sensory nuclei of the brain stem.
farfield potentials
_______ is the usual procedure for measuring muscle tension. The resulting record is called an
______ (EMG). EMG activity is usually recorded
between two electrodes taped to the surface of the skin
over the muscle of interest.
Electromyographym, electromyogram
The electrophysiological technique for recording eye movements is called ______, and the resulting record
is called an ______
electrooculography, electrooculogram (EOG).
Emotional thoughts and experiences are associated with increases in the ability of the skin to conduct electricity. The
two most commonly employed indexes of electrodermal activity are the ___ ____ ____ (SCL) and the ___ ____ ____ (SCR). The SCL is a measure of the
background level of skin conductance that is associated
with a particular situation, whereas the SCR is a measure of
the transient changes in skin conductance that are associated with discrete experiences.
skin conductance level
skin
conductance response
The electrical signal that is associated
with each heartbeat can be recorded through electrodes
placed on the chest. The recording is called an ______ (abbreviated either ECG, for obvious reasons, or EKG, from the original German).
electrocardiogram
A chronic blood pressure of more than
140/90 mmHg is viewed as a serious health hazard and is
called _______.
hypertension
_________
refers to the various techniques for measuring changes in
the volume of blood in a particular part of the body
Plethysmography
The ____ _____ is used to locate brain structures
in much the same way that a geographic atlas is used to
locate geographic landmarks. There is, however, one important difference. In contrast to the surface of the earth,
which has only two dimensions, the brain has three.
stereotaxic atlas
Accordingly, the brain is represented in a stereotaxic atlas
by a series of individual maps, one per page, each representing the structure of a single, two-dimensional frontal
brain slice. In stereotaxic atlases, all distances are given in
millimeters from a designated reference point. In some
rat atlases, the reference point is _____ the point on
the top of the skull where two of the major sutures (seams
in the skull) intersect.
bregma
The ____ ______ has two parts: a head
holder, which firmly holds each subject s brain in the
prescribed position and orientation; and an electrode
holder, which holds the device to be inserted. A system
of precision gears allows the electrode
holder to be moved in three dimensions: anterior posterior, dorsal ventral,
and lateral medial.
stereotaxic instrument