Brain Imaging Quiz: MRI, fMRI, EEG, PET and CT
Updated
CT and MRI reveal brain structure; fMRI and PET show brain activity; EEG and MEG measure electromagnetic signals with millisecond timing. Each method has trade-offs in spatial and temporal resolution, invasiveness, and cost.
This quiz tests your knowledge of the main brain imaging techniques: CT, MRI, fMRI, PET, EEG, and MEG. It is designed for students, neuroscience enthusiasts, and anyone curious about how we peer into the living brain. Each question covers how a technique works, what it measures, or its strengths and limitations.
Before starting, remember the core trade-off: structural techniques show anatomy, functional techniques show activity. CT and MRI are structural; fMRI and PET are functional; EEG and MEG record electromagnetic signals with high temporal resolution. Understanding these differences will help you answer correctly.
The questions
Which brain imaging technique uses X-rays to produce cross-sectional images of the head?
Which technique provides the highest spatial resolution for visualizing brain anatomy?
Functional MRI (fMRI) most directly measures changes in what?
Which technique is best for tracking brain activity with millisecond precision during a cognitive task?
Which imaging method requires injecting a radioactive tracer to visualize brain function?
Magnetoencephalography (MEG) detects which physical signal from the brain?
What is a major limitation of fMRI for studying rapid neural processes (e.g., within 100 ms)?
A patient arrives with a suspected acute stroke. Which technique is typically used first to quickly rule out a brain hemorrhage?
Which technique can measure the density of a specific neurotransmitter receptor (e.g., dopamine D2) in the living human brain?
During increased neural activity, what typically happens to the BOLD signal measured by fMRI?
Which technique is best for mapping the precise spatial pattern of brain activation (e.g., within a few millimeters) during a cognitive task?
Compared to EEG, MEG has a relative advantage in what aspect?
A researcher wants to study the sequence of brain events during a decision that occurs within 200 ms. Which technique is most appropriate?
Which technique is commonly used to map functional connectivity between brain regions in the resting state?
Which imaging technique could measure dopamine release in the nucleus accumbens during reward anticipation?
0 of 15 answered · 0 correct
Cheat sheet: key terms
| CT scan | Uses X-rays to create cross-sectional images; fast and good for bone and acute bleeding. |
|---|---|
| MRI | Uses strong magnetic fields and radio waves; high soft-tissue contrast, no ionizing radiation. |
| fMRI | Measures blood oxygenation (BOLD signal) to infer neural activity; good spatial, slow temporal resolution. |
| PET | Uses radioactive tracers to image metabolism, receptors, or neurotransmitters; molecular specificity but low resolution. |
| EEG | Records electrical potentials from the scalp; millisecond temporal resolution but poor spatial localization. |
| MEG | Detects magnetic fields from neural currents; high temporal and better spatial than EEG, but expensive. |
| BOLD signal | Blood-oxygen-level-dependent contrast; the basis of fMRI, reflecting changes in oxygenated blood flow. |
Answers explained
Show all 15 answers
- Which brain imaging technique uses X-rays to produce cross-sectional images of the head? Computed tomography (CT). CT scanners rotate an X-ray source around the head to create tomographic slices; the other techniques do not use X-rays.
- Which technique provides the highest spatial resolution for visualizing brain anatomy? Magnetic resonance imaging (MRI). MRI can resolve structures under a millimeter, whereas EEG has poor spatial localization and PET typically has lower resolution than MRI.
- Functional MRI (fMRI) most directly measures changes in what? Blood oxygenation level. fMRI detects the blood-oxygen-level-dependent (BOLD) signal, which reflects changes in oxygenated blood flow related to neural activity.
- Which technique is best for tracking brain activity with millisecond precision during a cognitive task? Electroencephalography (EEG). EEG records electrical activity directly from the scalp with high temporal resolution; fMRI and PET have slow hemodynamic or metabolic responses.
- Which imaging method requires injecting a radioactive tracer to visualize brain function? Positron emission tomography (PET). PET uses radiolabeled compounds that emit positrons; MRI, MEG, and CT do not involve radioactive tracers.
- Magnetoencephalography (MEG) detects which physical signal from the brain? Magnetic fields produced by neural currents. MEG measures the tiny magnetic fields generated by synchronized postsynaptic currents; EEG measures electrical potentials, MRI uses radio waves, CT uses X-rays.
- What is a major limitation of fMRI for studying rapid neural processes (e.g., within 100 ms)? Its signal is delayed by the slow hemodynamic response. The BOLD response peaks several seconds after neural activity, limiting temporal resolution; fMRI actually has good spatial resolution and no ionizing radiation.
- A patient arrives with a suspected acute stroke. Which technique is typically used first to quickly rule out a brain hemorrhage? Computed tomography (CT). CT is fast and highly sensitive to acute bleeding, making it the standard initial imaging for stroke; MRI takes longer and is less immediately available.
- Which technique can measure the density of a specific neurotransmitter receptor (e.g., dopamine D2) in the living human brain? Positron emission tomography (PET). PET uses radioligands that bind selectively to receptors; fMRI, MEG, and EEG do not provide molecular information about receptor density.
- During increased neural activity, what typically happens to the BOLD signal measured by fMRI? It increases due to local increases in oxygenated blood flow. Neural activity triggers vasodilation that overcompensates for oxygen consumption, leading to a net increase in oxygenated hemoglobin and BOLD signal.
- Which technique is best for mapping the precise spatial pattern of brain activation (e.g., within a few millimeters) during a cognitive task? Functional MRI (fMRI). fMRI offers millimeter-scale spatial resolution and whole-brain coverage; EEG and MEG have poor spatial localization, while PET has lower spatial resolution.
- Compared to EEG, MEG has a relative advantage in what aspect? Less distortion of signals by the skull, allowing better source localization. Magnetic fields pass through the skull with minimal distortion, whereas EEG potentials are smeared by varying tissue conductivities; both have similar temporal resolution.
- A researcher wants to study the sequence of brain events during a decision that occurs within 200 ms. Which technique is most appropriate? Electroencephalography (EEG). EEG (or MEG) provides millisecond temporal resolution needed to capture rapid neural dynamics; fMRI and PET are too slow.
- Which technique is commonly used to map functional connectivity between brain regions in the resting state? Functional MRI (fMRI). Resting-state fMRI measures correlated spontaneous BOLD fluctuations between regions; EEG is used but less standard for whole-brain connectivity, PET and CT are not typically used.
- Which imaging technique could measure dopamine release in the nucleus accumbens during reward anticipation? Positron emission tomography (PET). PET with radioligands like raclopride can detect displacement by endogenous dopamine; fMRI only reflects hemodynamic changes.
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