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Principles of Cognitive Neuroscience > Neuroimaging > Flashcards

Neuroimaging Flashcards

Page 55 onwards

1
Q

What is the primary requirement for recording the MR signal?
a. Receiving coil tuned to a different RF frequency
b. Measure gravitational field decay
c. Apply a strong magnetic field
d. Receiving coil tuned to the same RF frequency as the exciter coil

A

d. Receiving coil tuned to the same RF frequency as the exciter coil

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2
Q

In T2 relaxation, what causes the decay of transverse magnetization?
a. Flipped nuclei realigning with the magnetic field
b. Loss of coherence in spinning
c. Disturbances in the magnetic field
d. Net magnetization precession

A

b. Loss of coherence in spinning

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3
Q

What is K-space in MRI?
a. A matrix storing raw data
b. Total magnetization vector
c. Resonance frequency
d. Gradient of magnetic field

A

a. A matrix storing raw data

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4
Q

How is spatial resolution achieved in MRI?
a. Using strong radiofrequency pulses
b. Applying a gradient of magnetic field
c. Increasing the number of nuclei
d. Decreasing the voxel size

A

b. Applying a gradient of magnetic field

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5
Q

What technique allows simultaneous imaging of multiple slices along the z-axis?
a. Echo Planar Imaging
b. Fourier Transform
c. MultiBand imaging
d. Slice selection

A

c. MultiBand imaging

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6
Q

Which MRI sequence is used to create images with different contrasts?
a. T1-weighted
b. T2-weighted
c. GRE
d. SWI

A

a. T1-weighted

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7
Q

How is T2* relaxation affected by inhomogeneities in the magnetic field?
a. It increases T2* relaxation
b. It decreases T2* relaxation
c. It has no effect on T2* relaxation
d. It reverses T2* relaxation

A

a. It increases T2* relaxation

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8
Q

What is the basis for functional MR imaging?
a. T1 relaxation
b. T2 relaxation
c. T2* relaxation
d. Spin coherence

A

c. T2* relaxation

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9
Q

What is the main determinant of image contrast in gradient echo sequences?
a. T1 relaxation
b. T2 relaxation
c. T2* relaxation
d. Spin coherence

A

c. T2* relaxation

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10
Q

What does EPI stand for in MRI?
a. Extended Pulse Imaging
b. Echo Planar Imaging
c. Enhanced Phase Inversion
d. Efficient Proton Interactions

A

b. Echo Planar Imaging

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11
Q

How does fMRI differ from EEG and MEG in terms of spatial and temporal resolution?
a. Higher spatial, higher temporal
b. Lower spatial, higher temporal
c. Higher spatial, lower temporal
d. Lower spatial, lower temporal

A

c. Higher spatial, lower temporal

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12
Q

What does BOLD contrast measure in fMRI?
a. Blood flow
b. Oxygen consumption
c. Oxygenation level
d. Blood volume

A

c. Oxygenation level

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13
Q

What is neurovascular coupling?

a. Connection between neurons and blood vessels
b. Relationship between local neural activity and changes in cerebral blood flow
c. Mechanism of blood clotting in the brain
d. Formation of new blood vessels in the nervous system

A

b. Relationship between local neural activity and changes in cerebral blood flow

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14
Q

Why does the brain require a constant supply of glucose and oxygen?
a. To maintain a high-energy state
b. To store energy
c. To produce ATP through anaerobic metabolism
d. To supply energy for intrinsic activity

A

d. To supply energy for intrinsic activity

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15
Q

What is the primary energy currency for cells in the human body?
a. Glucose
b. Oxygen
c. ATP
d. ADP

A

c. ATP

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16
Q

How is energy produced in the brain through ATP?
a. By breaking down glucose
b. By breaking down oxygen
c. By breaking down ADP
d. By breaking down water

A

a. By breaking down glucose

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17
Q

Which arteries form the Willis circle in the brain?
a. Anterior Cerebral Artery (ACA)
b. Middle Cerebral Artery (MCA)
c. Posterior Cerebral Artery (PCA)
d. All of the above

A

d. All of the above

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18
Q

What does the initial dip in HRF represent?
a. Decrease in blood flow
b. Increase in oxygen consumption
c. Increase in blood volume
d. Decrease in deoxyhemoglobin

A

b. Increase in oxygen consumption

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19
Q

According to the Balloon model, what happens during neuronal activation?
a. Blood flow into the venous system decreases
b. Venous system expands like a balloon
c. Blood volume decreases in active regions
d. Neuronal activity is suppressed

A

b. Venous system expands like a balloon

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20
Q

What is the controversial aspect of the Astrocyte-neuron lactate shuttle model?
a. It contradicts the principles of fMRI
b. It challenges the role of astrocytes in energy supply
c. It suggests lactate negatively affects neurons
d. It claims the BOLD response reflects astrocyte activation

A

d. It claims the BOLD response reflects astrocyte activation

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21
Q

How does the magnitude of the static field impact BOLD signal changes?
a. Higher field strength decreases signal changes
b. Lower field strength increases signal changes
c. Field strength has no impact on signal changes
d. Higher field strength increases signal changes

A

d. Higher field strength increases signal changes

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22
Q

What is the purpose of choosing a balanced TE in MRI sequences?
a. To increase T1 relaxation
b. To minimize T2 relaxation effects
c. To enhance T2* relaxation
d. To shorten TR

A

b. To minimize T2 relaxation effects

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23
Q

How does DTI visualize white matter tracts?
a. By measuring blood flow
b. By measuring water diffusion
c. By measuring glucose metabolism
d. By measuring neural activity

A

b. By measuring water diffusion

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24
Q

What does FA represent in DTI?
a. Fractional Anisotropy
b. Functional Activation
c. Fiber Accumulation
d. Fornix Assessment

A

a. Fractional Anisotropy

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25
Q

What is the main advantage of ASL in measuring cerebral blood flow?
a. It does not require exogenous contrast agents
b. It provides high spatial resolution
c. It has a shorter acquisition time
d. It measures both arterial and venous blood flow

A

a. It does not require exogenous contrast agents

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26
Q

How does ASL labeling occur in perfusion imaging?
a. It labels venous blood
b. It labels arterial blood
c. It labels both arterial and venous blood
d. It labels cerebrospinal fluid

A

b. It labels arterial blood

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27
Q

What is the main limitation of ASL perfusion imaging?
a. Limited spatial resolution
b. Long acquisition time
c. Sensitivity to motion artifacts
d. Need for contrast agents

A

a. Limited spatial resolution

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28
Q

How does MEG measure neural activity?
a. By measuring blood flow
b. By measuring magnetic fields generated by neural activity
c. By measuring glucose metabolism
d. By measuring water diffusion

A

b. By measuring magnetic fields generated by neural activity

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29
Q

What is the main advantage of MEG in terms of temporal resolution?
a. It provides high temporal resolution
b. It provides low temporal resolution
c. It is not sensitive to temporal changes
d. It has no impact on temporal resolution

A

a. It provides high temporal resolution

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30
Q

Which of the following is a common use of PET imaging in neuroscience?
a. Measuring blood flow
b. Assessing white matter integrity
c. Studying glucose metabolism
d. Examining structural abnormalities

A

c. Studying glucose metabolism

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31
Q

What is the basis for fNIRS technology?
a. Measurement of magnetic fields
b. Measurement of near-infrared light absorption
c. Measurement of glucose metabolism
d. Measurement of water diffusion

A

b. Measurement of near-infrared light absorption

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32
Q

What is the primary application of EEG in neuroscience?
a. Measuring blood flow
b. Assessing white matter integrity
c. Studying electrical brain activity
d. Examining structural abnormalities

A

c. Studying electrical brain activity

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33
Q

What is the primary advantage of MRI over CT in neuroimaging?

a) Higher spatial resolution
b) Lower cost
c) Less time-consuming
d) Better bone density visualization

A

a) Higher spatial resolution

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34
Q

What is the main advantage of fMRI over PET?

a) Provides structural information
b) Measures electrical activity directly
c) Offers higher temporal resolution
d) Utilizes radioactive tracers

A

c) Offers higher temporal resolution

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35
Q

What is the primary application of fNIRS in neuroscience research?

a) Detecting brain tumors
b) Measuring oxygen levels in the blood
c) Imaging neural activity in deep structures
d) Assessing bone density

A

c) Imaging neural activity in deep structures

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36
Q

How does the EPI sequence contribute to functional MRI (fMRI)?

a) Enhances structural details
b) Accelerates image acquisition
c) Reduces susceptibility artifacts
d) Increases temporal resolution

A

d) Increases temporal resolution

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37
Q

What does DTI primarily visualize in the brain?

a) Blood flow patterns
b) Structural connectivity of white matter
c) Neuronal firing rates
d) Glucose metabolism

A

b) Structural connectivity of white matter

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38
Q

What is the primary limitation of EEG in neuroimaging?

a) Low temporal resolution
b) Limited spatial coverage
c) High cost
d) Measures only structural details

A

b) Limited spatial coverage

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39
Q

How is fMRI affected by susceptibility artifacts?

a) Increased signal strength
b) Improved spatial resolution
c) Reduced image accuracy
d) Enhanced temporal resolution

A

c) Reduced image accuracy

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40
Q

What is a “session” in the context of fMRI?

A) Single acquisition of an image.
B) Continuous acquisition of images from a subject in one day.
C) Set of task conditions administered to a participant.
D) Acquisition of an image of the entire brain.

A

B) Continuous acquisition of images from a subject in one day.

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41
Q

Which factor contributes to spatial resolution in fMRI studies?

A) Matrix size.
B) Slice thickness.
C) Voxel size.
D) Field of view.

A

C) Voxel size.

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42
Q

What is a “voxel” in the context of fMRI?

A) Two-dimensional portion of the brain.
B) Volume element representing a numerical quantity.
C) Continuous acquisition of an image.
D) Set of task conditions administered to a participant.

A

B) Volume element representing a numerical quantity.

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43
Q

Why might one choose smaller voxels in functional imaging?

A) To reduce acquisition time.
B) To increase the partial volume effects.
C) To visualize transient changes in BOLD contrast.
D) To enhance the signal-to-noise ratio.

A

D) To enhance the signal-to-noise ratio.

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44
Q

What is the main drawback of high spatial resolution in fMRI?

A) Increased acquisition time.
B) Reduced signal-to-noise ratio.
C) Limited field of view.
D) Inability to detect weak effects.

A

A) Increased acquisition time.

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45
Q

How does fMRI temporal resolution vary for event-related designs with different TRs?

A) Higher TR results in higher risk of aliasing.
B) Lower TR allows better spatial coverage.
C) TR does not affect temporal resolution.
D) Shorter TR is suitable for block-designs.

A

D) Shorter TR is suitable for block-designs.

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46
Q

What does a high Contrast-to-Noise Ratio (CNR) indicate in fMRI?

A) Difficulty in distinguishing between tissues.
B) Low variability in noise measurement.
C) Easy differentiation between two tissues.
D) High absolute differences in tissue intensities.

A

C) Easy differentiation between two tissues.

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47
Q

How does the Signal-to-Noise Ratio (SNR) affect fMRI data quality?

A) High SNR increases noise.
B) Low SNR improves signal detection.
C) SNR is not relevant for fMRI.
D) High SNR is critical for visualizing differences.

A

D) High SNR is critical for visualizing differences.

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48
Q

Which technique helps correct for head motion artifacts in fMRI?

A) Prospective Motion Correction.
B) Filtering approaches.
C) Denoising using Principal Component Analysis.
D) Trial Averaging.

A

A) Prospective Motion Correction.

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49
Q

What is a potential solution for increasing (f)SNR with trial averaging?

A) Increasing the number of participants.
B) Reducing the number of trials per condition.
C) Averaging data across different runs.
D) Diminishing returns after a certain number of trials.

A

A) Increasing the number of participants.

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50
Q

What is the purpose of spatial smoothing in fMRI analysis?

A) To enhance spatial resolution.
B) To reduce noise and increase signal detection.
C) To decrease the field of view.
D) To eliminate motion artifacts.

A

B) To reduce noise and increase signal detection.

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51
Q

In the context of fMRI, what does the term “baseline” refer to?

A) The initial data acquisition.
B) A period of rest or inactivity.
C) The lowest point of the BOLD response.
D) The total duration of the scanning session.

A

B) A period of rest or inactivity.

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52
Q

What is the significance of the hemodynamic response function (HRF) in fMRI studies?

A) It represents the heartbeat’s influence on brain activity.
B) It characterizes the delay between stimulus and neural response.
C) It models the vascular changes associated with neural activity.
D) It determines the spatial extent of the BOLD signal.

A

C) It models the vascular changes associated with neural activity.

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53
Q

Why is statistical correction for multiple comparisons important in fMRI analyses?

A) To increase the likelihood of Type I errors.
B) To decrease the likelihood of Type I errors.
C) Multiple comparisons have no impact on fMRI results.
D) To exclude participants with multiple conditions.

A

B) To decrease the likelihood of Type I errors.

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54
Q

What is a potential challenge in interpreting fMRI results in group studies?

A) Increased statistical power.
B) Variability in individual brain anatomy and function.
C) Homogeneity of participant characteristics.
D) Lack of impact from head motion.

A

B) Variability in individual brain anatomy and function.

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55
Q

How can resting-state fMRI be utilized in studying brain connectivity?

A) By measuring neural responses to external stimuli.
B) By examining brain activity during sleep.
C) By assessing spontaneous fluctuations in the BOLD signal.
D) By focusing solely on task-based paradigms.

A

C) By assessing spontaneous fluctuations in the BOLD signal.

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56
Q

What is the primary limitation of fMRI in studying fast neural events?

A) Limited field of view.
B) Low temporal resolution.
C) Inability to visualize deep brain structures.
D) Dependence on exogenous contrast agents.

A

B) Low temporal resolution.

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57
Q

What role does the default mode network (DMN) play in fMRI research?

A) It is irrelevant to resting-state fMRI.
B) It is associated with brain activity during task performance.
C) It reflects brain activity during rest and self-referential thinking.
D) It is a methodological artifact in fMRI studies.

A

C) It reflects brain activity during rest and self-referential thinking.

58
Q

How can machine learning be applied in fMRI research?

A) To replace traditional statistical analyses.
B) To enhance spatial resolution.
C) To predict cognitive states or mental health conditions.
D) To eliminate the need for preprocessing steps.

A

C) To predict cognitive states or mental health conditions.

59
Q

1: What are the dimensions of fMRI data?
A. 2 dimensions (x, y)
B. 3 dimensions (x, y, z)
C. 4 dimensions (x, y, z, time)
D. 5 dimensions (x, y, z, time, intensity)

A

C. 4 dimensions (x, y, z, time)

60
Q

What is the main goal of the sample preprocessing sequence in fMRI data?
A. Increase temporal resolution
B. Increase spatial resolution
C. Increase functional SNR and prepare for statistical analysis
D. Reduce the number of dimensions

A

C. Increase functional SNR and prepare for statistical analysis

61
Q

What is the purpose of distortion correction in the preprocessing sequence?
A. Increase spatial resolution
B. Correct distortions due to the magnetic field
C. Remove low-frequency noise
D. Enhance the signal of interest

A

B. Correct distortions due to the magnetic field

62
Q

Which step involves setting the origin of images to an arbitrary 0 point in the middle of the anterior commissure?
A. Spatial smoothing
B. Head motion correction
C. Realignment
D. Spatial normalization

A

C. Realignment

63
Q

How is head motion corrected in fMRI data preprocessing?
A. Using distortion correction
B. Utilizing slice timing correction
C. Co-registration/realignment
D. Applying spatial smoothing

A

C. Co-registration/realignment

64
Q

What is the purpose of spatial smoothing in fMRI data preprocessing?
A. Increase spatial resolution
B. Reduce spatial variability between brains
C. Correct distortions
D. Enhance temporal resolution

A

B. Reduce spatial variability between brains

65
Q

What does the term “realignment” involve in fMRI preprocessing?
A. Correcting distortions due to the magnetic field
B. Adjusting the spatial orientation of images
C. Enhancing the signal of interest
D. Correcting slice timing errors

A

B. Adjusting the spatial orientation of images

66
Q

How is the computational demand reduced during the realignment process in fMRI data preprocessing?
A. By increasing the number of discarded data acquisitions
B. By using linear interpolation
C. By assuming differential scaling is not possible
D. By employing algorithms with heuristics in an iterative process

A

D. By employing algorithms with heuristics in an iterative process

67
Q

What is the purpose of slice timing correction in fMRI preprocessing?
A. Correct distortions in frequency space
B. Align anatomical and functional images
C. Adjust the temporal derivatives of the HRF model
D. Compensate for differences in slice acquisition times

A

D. Compensate for differences in slice acquisition times

68
Q

What is the goal of spatial normalization in fMRI preprocessing?
A. Increase spatial resolution
B. Align anatomical and functional images
C. Reduce spatial variability between brains
D. Correct distortions due to the magnetic field

A

C. Reduce spatial variability between brains

69
Q

How does spatial smoothing affect spatial resolution in fMRI data?
A. Increases spatial resolution
B. Has no effect on spatial resolution
C. Decreases spatial resolution
D. Enhances temporal resolution

A

C. Decreases spatial resolution

70
Q

Which correction method compensates for multiple comparisons and is less stringent than Bonferroni correction?
A. Bonferroni-Holms (Step-down)
B. False Discovery Rate (FDR)
C. Family-Wise Error Correction (FWE)
D. Permutation/resampling methods

A

B. False Discovery Rate (FDR)

71
Q

What is the primary advantage of using cluster-based analyses in fMRI?
A. Improved spatial resolution
B. Reduced spatial smoothing
C. Increased sensitivity to small effects
D. Enhanced detection of isolated voxels

A

C. Increased sensitivity to small effects

72
Q

What is the purpose of Small-Volume Correction (SVC) in fMRI analysis?
A. To correct for motion artifacts
B. To adjust for multiple comparisons in a specific region
C. To enhance spatial resolution
D. To minimize the impact of physiological confounds

A

B. To adjust for multiple comparisons in a specific region

73
Q

In a Fixed Effects (First Level) Analysis in fMRI, what does the analysis consider?
A. Both within-subject and between-subject variance
B. Only within-subject variance
C. Only between-subject variance
D. The effects of physiological confounds

A

B. Only within-subject variance

74
Q

What does a One Sample T-Test in fMRI analyze?
A. Main effects and interactions
B. Correlations between task-specific activations and other measures
C. Whether activations from a contrast are different from 0/chance
D. Simple main effects and sphericity problems

A

C. Whether activations from a contrast are different from 0/chance

75
Q

What is the role of an Independent Variable in experimental design?
A. It is the measured variable of interest
B. It is manipulated to generate changes in the measured response
C. It is the response magnitude in random effect analysis
D. It is a source of extraneous variability

A

B. It is manipulated to generate changes in the measured response

76
Q

What is the trade-off between internal and external validity in experimental design?
A. Increasing internal validity decreases external validity
B. Increasing external validity decreases internal validity
C. Both increase simultaneously
D. Both decrease simultaneously

A

B. Increasing external validity decreases internal validity

77
Q

What is the primary aim of the Subtraction design in fMRI experiments?

a) To maximize confounding variables
b) To compare two unrelated conditions
c) To identify brain structures involved in a specific process
d) To minimize the baseline problem through randomization

A

c) To identify brain structures involved in a specific process

78
Q

How does Conjunction differ from Subtraction in fMRI experimental design?

a) Conjunction compares unrelated conditions, while Subtraction isolates the same process.
b) Conjunction minimizes confounding variables, while Subtraction increases them.
c) Conjunction combines multiple conditions to find common activation, while Subtraction directly compares two conditions.
d) Conjunction assumes pure insertion, while Subtraction relies on factorial designs.

A

c) Conjunction combines multiple conditions to find common activation, while Subtraction directly compares two conditions.

79
Q

What is the main advantage of Parametric Designs in fMRI?

a) They minimize confounding variables.
b) They allow for flexible testing of relations between BOLD and stimulus parameters.
c) They rely on categorical variables only.
d) They simplify the experimental procedure.

A

b) They allow for flexible testing of relations between BOLD and stimulus parameters.

80
Q

In Psychophysiological Interactions (PPI), what does effective connectivity refer to?

a) The strength of the correlation between different contrasts.
b) The modulation of neural activity in specific regions.
c) The psychological context in which stimuli are presented.
d) The neurobiological plausibility of interpretations.

A

b) The modulation of neural activity in specific regions.

81
Q

What is a potential disadvantage of Block/Epoch designs in fMRI experiments?

a) They are less efficient for detecting effects than event-related designs.
b) They allow separation of responses to individual trials.
c) They are not suitable for tasks that cannot be blocked.
d) They are robust to uncertainty in timing.

A

c) They are not suitable for tasks that cannot be blocked.

82
Q

Question: Factorial Designs

a) Testing the significance of consistent effects across contrasts.
b) Allowing verification of the pure insertion assumption.
c) Modeling linear and non-linear interactions.
d) A parametric factorial design with a psychological context and a physiological source.

A

c) Modeling linear and non-linear interactions.
b) Allowing verification of the pure insertion assumption.

83
Q

fMRI-Adaptation Studies

a) Measurement relative to a maximum, non-adapted state.
b) Employed as indices of brain function.
c) Testing the significance of conjunctions.
d) Examining responses to a series of similar stimuli.

A

a) Measurement relative to a maximum, non-adapted state.
b) Employed as indices of brain function.

84
Q

Methodological Issues in fMRI Research

a) Inferring the occurrence of a process from the activation of a region.
b) Problem of multicollinearity in the design matrix.
c) Noisy and non-replicable results outside the scanner.
d) High number of statistical tests in univariate approaches.

A

a) Inferring the occurrence of a process from the activation of a region.
b) Problem of multicollinearity in the design matrix.
c) Noisy and non-replicable results outside the scanner.
d) High number of statistical tests in univariate approaches.

85
Q

NEUROMODULATION TECHNIQUES

A

Neuromodulation involves the alteration of nerve activity through the delivery of electrical or pharmaceutical agents directly to a target area. It is a broad term that encompasses various techniques, and here we will focus on neuromodulation techniques such as transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), and transcranial random noise stimulation (tRNS).

86
Q

TRANSCRANIAL DIRECT CURRENT STIMULATION (tDCS)

A

tDCS delivers a low electrical current through electrodes placed on the scalp. The current flows from the anode to the cathode, modulating the resting membrane potential of neurons. This technique is considered neuromodulatory rather than neurostimulatory since it doesn’t directly induce action potentials but rather alters the likelihood of neuronal firing.

87
Q

Effects of tDCS:

A

Anodal Stimulation: Generally associated with increased excitability and depolarization of neurons.
Cathodal Stimulation: Often linked to decreased excitability and hyperpolarization of neurons.

88
Q

Applications of tDCS:

A

Cognitive enhancement.
Treatment for various neuropsychiatric conditions.
Motor rehabilitation after stroke.
Pain management.

89
Q

TRANSCRANIAL ALTERNATING CURRENT STIMULATION (tACS)

A

tACS applies sinusoidal electrical currents to the scalp, modulating neuronal oscillations. The frequency of the applied current determines the type of neural entrainment, influencing the natural oscillatory activity of the brain.

90
Q

Frequency-specific Effects:

A

Alpha Frequency (8-12 Hz): Associated with attention and visual processing.
Theta Frequency (4-8 Hz): Involved in memory and cognitive control.
Gamma Frequency (>30 Hz): Linked to perceptual binding and higher cognitive functions.

91
Q

Applications of tACS:

A

Cognitive enhancement.
Investigation of brain oscillations.
Treatment for neurological and psychiatric disorders.

92
Q

TRANSCRANIAL RANDOM NOISE STIMULATION (tRNS)

A

tRNS delivers random electrical noise across a broad frequency spectrum. This technique is less frequency-specific compared to tACS and is thought to increase cortical excitability by introducing stochastic resonance.

93
Q

Applications of tRNS:

A

Cognitive enhancement.
Motor learning.
Treatment for neurological conditions

94
Q

COMPARISON OF TMS AND tDCS

Spatial Resolution:

A

TMS: More focal, allows targeting specific cortical regions.
tDCS: Less focal, modulates a broader area.

95
Q

COMPARISON OF TMS AND tDCS

Temporal Resolution:

A

TMS: Immediate and direct.
tDCS: Gradual and indirect.

96
Q

COMPARISON OF TMS AND tDCS

Mechanism:

A

TMS: Induces action potentials.
tDCS: Modulates resting membrane potential

97
Q

COMPARISON OF TMS AND tDCS
Applications:

A

TMS: research and clinical applications (Diagnosis, treatment, and therapy)
tDCS: Cognitive enhancement, neuropsychiatric treatment.

98
Q

Which factor is crucial for the percentage signal change obtained on BOLD activation?
a) Susceptibility differences
b) Image quality
c) Field strength
d) Signal dephasing effects

A

c) Field strength

99
Q

At higher field strengths, what has a greater signal dephasing effect?
a) Susceptibility differences
b) Image quality
c) Field strength
d) Signal change

A

a) Susceptibility differences

100
Q

What trade-off occurs with higher field strengths according to the text?
a) Signal dephasing effects
b) Image quality
c) Susceptibility differences
d) Percentage signal change

A

b) Image quality

101
Q

In MRI imaging, what is the term used to describe the interference caused by imperfect RF-pulse calibration?
A) Slice thickness
B) Cross-talk
C) Signal-to-noise ratio
D) Phase encoding

A

B) Cross-talk

102
Q

What consequence may arise from imperfect RF-pulse calibration in MRI imaging?
A) Motion artifacts
B) Partial volume effects
C) Image blurring
D) Signal loss

A

B) Partial volume effects

103
Q

Which of the following is a consequence of cross-talk in MRI imaging?
A) Image distortion
B) Reduced spatial resolution
C) Partial volume effects
D) Increased signal-to-noise ratio

A

C) Partial volume effects

104
Q

Which of the following strategies can help reduce partial volume effects in MRI imaging?
A) Decreasing slice thickness
B) Increasing imaging matrix sizes
C) Using longer duration RF-pulses
D) All of the above

A

D) All of the above

105
Q

What is a crucial requirement for making inferences about the relative timing of neuronal activity with fMRI?
A) Increasing the field of view
B) Manipulating various mental processes randomly
C) Systematically manipulating a mental process while holding all other conditions constant
D) Using shorter echo times

A

C) Systematically manipulating a mental process while holding all other conditions constant

106
Q

According to the linear system framework, what does the principle of scaling entail?
A) The output of a linear system is inversely proportional to the magnitude of its input
B) The output of a linear system is unrelated to the magnitude of its input
C) The output of a linear system is proportional to the magnitude of its input
D) The output of a linear system is exponential in relation to the magnitude of its input

A

C) The output of a linear system is proportional to the magnitude of its input

107
Q

According to the principles of the linear system framework, what does the principle of superimposition entail?
A) The total response to a set of impulses equals the subtraction of individual responses to the impulse
B) The total response to a set of impulses equals the division of individual responses to the impulse
C) The total response to a set of impulses equals the multiplication of individual responses to the impulse
D) The total response to a set of impulses equals the summation of individual responses to the impulse

A

D) The total response to a set of impulses equals the summation of individual responses to the impulse

108
Q

How can adaptation studies in fMRI help understand brain functions?
A) By measuring the refractory effects of stimuli
B) By manipulating stimuli to induce refractory effects
C) By exploiting refractory effects to infer how brain regions code for stimulus features
D) By analyzing the recovery time of brain regions after refractory effects

A

C) By exploiting refractory effects to infer how brain regions code for stimulus features

109
Q

In adaptation studies using fMRI, how can the presence or absence of adaptation in a brain region help researchers infer its function?
A) If adaptation is present, the region is involved in stimulus discrimination.
B) If adaptation is present, the region does not code for the changing feature.
C) If adaptation is absent, the region treats stimuli equally.
D) If adaptation is absent, the region codes for the manipulated stimulus feature.

A

B) If adaptation is present, the region does not code for the changing feature.
D) If adaptation is absent, the region codes for the manipulated stimulus feature.

110
Q

What does the left inferior frontal gyrus primarily code for, according to the given statement?
A) Single exemplars of an object
B) Physical appearance of an object
C) Semantic category of an object
D) Emotional response to an object

A

C) Semantic category of an object

111
Q

How is the raw signal-to-noise ratio (SNR) used to assess MRI scanner performance?
A) By comparing the signal intensity inside and outside the sample
B) By measuring the intensity of the noise within the scanner
C) By evaluating the contrast-to-noise ratio (CNR) of the images
D) By dividing the intensity of the signal within the sample by the intensity of the noise outside the sample

A

D) By dividing the intensity of the signal within the sample by the intensity of the noise outside the sample

112
Q

What does the contrast-to-noise ratio (CNR) in MRI imaging describe?
A) The intensity difference between two tissues
B) The intensity of noise within the scanner
C) The ratio of signal intensity to noise intensity within the sample
D) The ratio of signal intensity to noise intensity outside the sample

A

A) The intensity difference between two tissues

113
Q

How does the contrast-to-noise ratio (CNR) contribute to MRI imaging assessment?
A) By measuring the intensity of noise within the scanner
B) By quantifying the variability in tissue measurements
C) By describing the ease of detecting differences between tissues
D) By comparing the signal intensity inside and outside the sample

A

C) By describing the ease of detecting differences between tissues

114
Q

What does the functional signal-to-noise ratio (SNR) primarily describe in fMRI?
A) The intensity difference between two states of the brain
B) The intensity of noise within the scanner
C) The ratio between signal intensity and noise intensity within a voxel or cluster over time
D) The ratio between signal intensity and noise intensity across different voxels in space

A

C) The ratio between signal intensity and noise intensity within a voxel or cluster over time

115
Q

How does the functional signal-to-noise ratio (SNR) differ from the contrast-to-noise ratio (CNR) in fMRI imaging?
A) Functional SNR depends on intensity differences within a voxel or cluster over time, while CNR depends on the intensity difference between voxels across space.
B) Functional SNR measures the intensity of noise within the scanner, while CNR measures the variability in tissue measurements.
C) Functional SNR describes the ease of detecting differences between experimental conditions or fluctuations over time, while CNR describes the ease of detecting differences between tissues.
D) Functional SNR compares the signal intensity inside and outside the sample, while CNR compares the intensity difference between two tissues.

A

A) Functional SNR depends on intensity differences within a voxel or cluster over time, while CNR depends on the intensity difference between voxels across space.

116
Q

In MRI imaging, what causes aliasing artifacts?
A) Inadequate field of view
B) Insufficient sampling rate to resolve high frequencies
C) Magnetic field inhomogeneities
D) Motion artifacts during scanning

A

B) Insufficient sampling rate to resolve high frequencies

117
Q

Where does the majority of noise power occur in fMRI timeseries?
A) At high frequencies (f > 0.5 Hz)
B) At mid-range frequencies (0.1 Hz < f < 0.5 Hz)
C) At low frequencies (f < 0.05 Hz)
D) At all frequencies equally distributed across the spectrum

A

C) At low frequencies (f < 0.05 Hz)
-the exact cause remains unclear,altough it is probably some mixture of scanner drift, aliased cardiac and respiratory physiological noise

118
Q

In which part of the brain are field inhomogeneities most common in fMRI?
A) Occipital lobes
B) Temporal lobes
C) Frontal lobes
D) Parietal lobes

A

C) Frontal lobes
Field inhomogeneities in fMRI are most common in regions near air-tissue interfaces, such as the frontal lobes and the sinuses.

119
Q

In EPI sequences (typical of fMRI studies), susceptibility artifacts can be a problem for imaging the following
region:
a. inferior frontal pole
b. inferior medial frontal cortex
c. temporal lobe
d. occipital lobe
e. A and B

A

e. A and B

120
Q

What is a key feature of Siemens Prospective Acquisition CorrEction (PACE) in MRI imaging?
A) It corrects motion artifacts after data acquisition.
B) It requires acquiring raw data separately for motion correction.
C) It shifts slices in real-time to follow motion during data acquisition.
D) It is primarily used for retrospective motion correction.

A

C) It shifts slices in real-time to follow motion during data acquisition.

121
Q

What effect does mass motion have on the magnetic field in MRI imaging?
A) It stabilizes the magnetic field, reducing distortions.
B) It amplifies the magnetic field, improving image resolution.
C) It creates distortions in the magnetic field.
D) It has no effect on the magnetic field in MRI imaging.

A

C) It creates distortions in the magnetic field.

122
Q

Inter-subject Variability is a problem for?

A

Subject Averaging

123
Q

Which are solutions for addressing inter-subject variability in fMRI studies?
A) Standardizing the MRI acquisition parameters across all subjects
B) Implementing retrospective motion correction algorithms
C) Using individual subject’s modeled hemodynamic responses
D) using random effects analyses
E) C and D

A

E) C and D

124
Q

Which approach is best suited for isolating and removing structured noise in fMRI time series?
A) Filtering Approaches
B) Denoising using independent component analysis (ICA)
C) Denoising using principal component analysis (PCA)
D) Increasing the field strength

A

B) Denoising using independent component analysis (ICA)

125
Q

What characteristic distinguishes independent component analysis (ICA) from principal component analysis (PCA) in denoising fMRI time series?
A) ICA is superior for isolating and removing random noise, while PCA is best for structured noise.
B) PCA is best for isolating and removing physiological noise, while ICA excels at removing scanner noise.
C) ICA is optimal for removing structured noise, while PCA is superior for random noise removal.
D) PCA is most effective for removing motion artifacts, while ICA is better suited for correcting field inhomogeneities.

A

C) ICA is optimal for removing structured noise, while PCA is superior for random noise removal.

126
Q

What are the possible solutions to improve SNR?
a. filtering higher and lower frequency noise
b. denoising of time series by ICA or PCA
c. increasing field strength
d. all of the above

A

d. all of the above

127
Q

How can head motion artifacts be mitigated in fMRI studies?
A) By increasing the field of view during scanning
B) By using higher temporal resolution imaging sequences
C) By applying co-registration/realignment steps to correct for bulk head motion
D) By increasing the number of echo-planar imaging (EPI) volumes collected

A

C) By applying co-registration/realignment steps to correct for bulk head motion

128
Q

How can movement parameters be incorporated to address head motion artifacts in fMRI analysis?
A) By excluding subjects with excessive head motion from the study
B) By increasing the magnetic field strength of the MRI scanner
C) By including movement parameters as regressors of no-interest in the design matrix
D) By acquiring MRI scans during specific phases of the cardiac cycle

A

C) By including movement parameters as regressors of no-interest in the design matrix

129
Q

Despite the variation in noise over time, what is a robust and reliable method for determining brain activity?
A) Averaging the noisy data
B) Discarding noisy data points
C) Increasing the signal-to-noise ratio
D) Implementing retrospective motion correction algorithms

A

A) Averaging the noisy data

130
Q

How can mass motion artifacts, such as those caused by speech or hand actions, be mitigated in fMRI studies?
A) By acquiring data continuously at a high temporal resolution
B) By employing rapid event-related designs with short inter-trial intervals
C) By using sparse scanning or a slow event-related design with longer inter-trial intervals
D) By increasing the magnetic field strength of the MRI scanner

A

C) By using sparse scanning or a slow event-related design with longer inter-trial intervals

131
Q

Why is spatial normalization performed in fMRI studies?
A) To increase the signal-to-noise ratio
B) To reduce motion artifacts
C) To align results from different studies to a standard stereotaxic space
D) To improve the temporal resolution of the data

A

C) To align results from different studies to a standard stereotaxic space

132
Q

What are some advantages of spatial smoothing in fMRI data processing?
A) Increases the likelihood of detecting small, localized activations
B) Reduces effective number of comparisons
C) Enhances the spatial resolution of the images
D) Increases the signal-to-noise ratio (SNR)
E) Improves comparisons across subjects
F) A, B and C
G) B, D and E
H) All of the above

A

G) B, D and E

133
Q

What is one potential disadvantage of spatial smoothing in fMRI data processing?
A) It decreases the spatial resolution of the images.
B) It reduces the likelihood of detecting small, localized activations.
C) It simplifies the application of Gaussian Field Theory.
D) It reduces the effective number of comparisons.
E) A and B
F) all of the above

A

E) A and B

134
Q

What does the False Discovery Rate (FDR) control in fMRI data analysis?
A) The likelihood of any false positives
B) The likelihood of false negatives
C) The expected proportion of false positives among all suprathreshold voxels
D) The expected proportion of true positives among all suprathreshold voxels

A

D) The expected proportion of true positives among all suprathreshold voxels

135
Q

What makes False Discovery Rate (FDR) more sensitive compared to other methods of controlling false positives?
A) FDR adapts to the amount of signal in the data
B) FDR uses a stricter control over false positives
C) FDR controls the likelihood of any false positives
D) FDR controls the expected proportion of false positives among all suprathreshold voxels

A

A) FDR adapts to the amount of signal in the data

136
Q

In what scenario does False Discovery Rate (FDR) provide similar control over false positives as other methods?
A) When there is no signal in the brain
B) When there is high variability in the data
C) When there is significant motion artifact in the images
D) When there is low spatial resolution in the images

A

A) When there is no signal in the brain

137
Q

Which of the following is NOT an alternative approach for addressing multiple comparisons in fMRI studies?
A) Smoothing and Gaussian Field Theory (FWE)
B) False positive rate (FPR)
C) Cluster-based analyses (with or without permutations)
D) Region of interest (ROI) approaches

A

B) False positive rate (FPR)

138
Q

What does Small-Volume Correction (SVC) involve in fMRI analysis?
A) Applying a correction factor to adjust for small variations in scanner noise
B) Using a predefined region of interest (ROI) for analyzing voxel-wise data
C) Adjusting statistical thresholds based on the size of the entire brain volume
D) Performing image registration to align functional data with anatomical landmarks

A

B) Using a predefined region of interest (ROI) for analyzing voxel-wise data

139
Q

Which parameters influence the p-value associated with t and Z scores in fMRI analysis?
A) The choice of statistical test and the magnitude of the effect size
B) The degrees of freedom and the choice of correction method for multiple comparisons
C) The voxel size and the field of view of the MRI scanner
D) The level of significance chosen by the researcher and the choice of smoothing kernel size

A

B) The degrees of freedom and the choice of correction method for multiple comparisons

140
Q

How does the test of global null hypothesis differ from the test of conjunction null hypothesis in fMRI analysis?
A) The test of global null hypothesis assesses the significance of consistent effects across contrasts, while the test of conjunction null hypothesis assesses the significance of effects within each specified contrast.
B) The test of global null hypothesis assesses the significance of effects within each specified contrast, while the test of conjunction null hypothesis assesses the significance of consistent effects across contrasts.
C) The test of global null hypothesis assesses the significance of inconsistent effects across contrasts, while the test of conjunction null hypothesis assesses the significance of effects within each specified contrast.
D) The test of global null hypothesis assesses the significance of effects > threshold, while the test of conjunction null hypothesis assesses the significance of consistent effects across contrasts.

A

A) The test of global null hypothesis assesses the significance of consistent effects across contrasts, while the test of conjunction null hypothesis assesses the significance of effects within each specified contrast.

141
Q
A

Principles of Cognitive Neuroscience (13 decks)

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