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PSYCH 377 > Lecture 3: Imaging the Brain > Flashcards

Lecture 3: Imaging the Brain Flashcards

1
Q

Electroencephalograms (EEGs)

A

a graph that records electrical activity through the skull or from the brain and represents graded potential of many neurons

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2
Q

Polygraph

A

an apparatus for simultaneously recording blood pressure, pulse, and respiration, as well as variations in electrical resistance of the skin

popularly known as a lie detector

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3
Q

Generator

A

the part of a neuron that produces a signal in response to changing inputs

also called a signal generator

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4
Q

Volume Conducted

A

a descriptor for electrical potential recorded in tissue at some distance from its source

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5
Q

Beta Rhythm

A

a fast brain-wave activity pattern associated with an alert state, or waking, EEG

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6
Q

Delta Waves

A

a slow brain-wave activity pattern associated with deep sleep

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7
Q

Parietal Seizure

A

abnormal electrical discharges restricted to only one or a few brain regions

also called a focal seizure

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8
Q

Generalized Seizures

A

a bilaterally symmetrical seizure without focal onset that can be characterized by loss of consciousness and by stereotyped motor activity

typified by three stages; tonic, clonic, and postictal depression

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9
Q

Electrocorticography

A

a procedure for transcranial EEG recording during surgery, in which electrodes are placed directly onto the brain surface, providing a more direct way of identifying the source of epileptic seizure

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10
Q

Coherence Theory

A

the proposal that, rather than brain activity consisting of a number of conscious “states”, a continuum of states exists, from high coherence (the brain is idling) to low coherence (the brain is actively processing information)

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11
Q

Event-Related Potentials

A

a complex electroencephalographic waveform related in time to a specific sensory event

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12
Q

Readiness Potentials

A

an event-related potential that occurs just before a movement

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13
Q

Magnetoencephalogram (MEG)

A

magnetic potentials recorded from detectors placed outside the skull

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14
Q

Deep Brain Stimulation

A

neurosurgery in which electrodes implanted in the brain stimulate a targeted area with a low-voltage electrical current to facilitate behavior

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15
Q

Akinesia

A

absence or poverty of movement

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16
Q

Transcranial Magnetic Stimulation (TMS)

A

a noninvasive procedure in which a magnetic coil is placed over the skull to stimulate the underlying brain

can be used either to induce behavior or to disrupt ongoing behavior

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17
Q

Conventional Radiography

A

an X-ray procedure

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18
Q

Pneumoencephalography

A

an invasive X-ray technique in which cerebrospinal fluid is replaced by air introduced through a lumbar procedure

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19
Q

Angiography

A

radiographic imaging of blood vessels filled with a contrast medium

20
Q

Computed Tomography (CT Scan)

A

an X-ray technique that produces a static, three-dimensional image of the brain in cross section

21
Q

Voxel

A

an area from which a measurement is taken, thus defining the resolution of brain-imaging method

22
Q

Positron Emission Tomography (PET)

A

an imaging technique that detects changes in blood flow by measuring changes in the uptake of compounds such as oxygen or glucose

used to analyze the metabolic activity of neurons

23
Q

Magnetic Resonance Imaging (MRI)

A

a technique that produces a static, three-dimensional brain image by passing a strong magnetic field through the brain, followed by a radio wave, an then measuring the radiation emitted from hydrogen atoms

24
Q

Precession

A

a comparatively slow gyration of the rotation axis of a spinning body about another line intersecting it, describing a cone shape

25
Q

Teslas

A

a unit for measuring the strength of a magnetic field

26
Q

Magnetic Resonance Spectroscopy (MRS)

A

a modification of MRI to identify changes in specific markers of neuronal function, including all macromolecules (DNA, RNA, most proteins, and phospholipids); cell membranes; organelles (such as mitochondria); and glial cells, not imaged by magnetic resonance imaging

27
Q

Diffusion Tenor Imaging (DTI)

A

a magnetic resonance imaging method that, by detecting the directional movements of water molecules, can image fiber pathways in the brain, DTI tractography maps the brain’s pathways and connectivity

28
Q

Functional Magnetic Resonance Imaging (fMRI)

A

magnetic resonance imaging in which changes in elements such as iron or oxygen are measured during the performance of a specific behavior

used to measure cerebral blood flow during rest or behavior

29
Q

BOLD Contrast

A

an acronym for blood oxygen level-dependent contrast, a measure used in fMRI that provides an index of the brain’s relative activity level

30
Q

Resting State fMRI (rs-fMRI)

A

a functional magnetic resonance imaging method that measures changes in elements such as iron or oxygen when the individual is resting (not engaged in a specific task)

31
Q

Motifs

A

recurring elements formed in waves of cortical activity, indicating functional connectivity (inherent functional relationships) among cortical systems

32
Q

Optical Tomography

A

a noninvasive, dynamic imaging technique (such as functional near-infrared spectrography [fNIRS]) in which the image of an object is constructed by measuring the intensity of light transmitted through it

33
Q

Default Mode Network (DMN)

A

linked brain regions active in participants who are resting rather than engaged in specific cognitive tasks and also active during such directed tasks as thinking about one’s past (autobiographical memory), thinking about the future, or when the mind is wandering

34
Q

What is an electroencephalography (EEG)?

A

electrical potential: scalp recorded (summation), first described by Berger (1929)

quantified in two domains:
time: measured by frequency (Hz) and voltage
frequency: frequency and power (Fourier transform)

event-related potentials: time locked activity, neurotransmitter binding

components:
exogenous: outside the body (loud noise, bright light)
endogenous: inside the body (thinking about dinner, having anxiety)

35
Q

What is the electrode placement for EEG?

A

10-20 system (size of people’s head varies)

measure distance from nose to back of the head, electrodes are placed within 10/20% of that distance

10 or 20% of midline distance from nasion to inion

Pz = parietal zero
O1 = occipital left
T4 = temporal right

36
Q

What do the letters and numbers on an EEG mean?

A

large first letter: where on the head it is

odd #: left

even #: right

magnitude of #: how far away it is from the midline

37
Q

What is the comparison between EEG and behavior?

A

ERP can elucidate specific cognitive processes underlying overt behavior

online measure in absence of overt behavior
e.g., automatic processes; below awareness threshold
also correct responses versus errors

small amplitude of ERP necessitate greater number of trials than RT experiments

38
Q

What are some advantages of EEG?

A

non-invasive

temporal resolution

cost (very cheap)

39
Q

What are Computerized Axial Tomography (CAT) Scans?

A

taking X-rays at different points on the brain

40
Q

What are the different ways of image acquisition for a CAT scan?

A

no one slice gets you a whole image of the brain (need many slices)

resolution is only as good as the slices you have

ascending: start at 1

descending: start at 11

interleaved: collect slice 1, 3, 5, 9, 11 then 2, 4, 6… (reduces imaging time)

41
Q

What is the static field in an MRI?

A

constant magnetic field (e.g. 0.5 Tesla - 7 Tesla)

alignment (all hydrogen atoms/tissue line up perfectly)

42
Q

What is the radio frequency field pulse sequence in an MRI?

A

transmitter coil: perturbation of static field - hydrogen atoms - excitation -resonance

receiver coil - reception (realignment) - image acquisition

43
Q

What is the gradient field in an MRI?

A

spatial information

44
Q

What is the difference between anatomical versus functional imaging?

A

CAT & MRI study what the brain looks like

functional imaging studies how the brain works

45
Q

What is the Positron Emission Tomography (PET)?

A

radioactive tracers (isotope): oxygen, glucose

positron (charged particle): released, collides with electron

annihilation: releases energy

photo cells

reverse triangulate where the photon was released

46
Q

What are the differences between MRI vs. fMRI?

A

MRI: high resolution, one image

fMRI: low resolution, many images (every 2 seconds for 5 minutes)

PSYCH 377 (14 decks)

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