A researcher wants to conduct an imaging study of perceptual

A researcher wants to conduct an imaging study of perceptual priming. She needs to compare the timing in which a brain area of interest responds to two different stimuli. Temporal resolution is more important than spatial resolution. Which of the following imaging methods would work best for her study?

sMRI (structural magnetic resonance imaging)

PET (positron emission tomography)

EEG (electroencephalography)

fMRI (functional magnetic resonance imaging)

Solution

EEG has several strong points as a tool for exploring brain activity. EEG\'s can detect changes within a millisecond timeframe, excellent considering an action potential takes approximately 0.5-130 milliseconds to propagate across a single neuron, depending on the type of neuron. Other methods of looking at brain activity, such as PET and fMRI have time resolution between seconds and minutes. EEG measures the brain\'s electrical activity directly, while other methods record changes in blood flow (e.g., SPECT, fMRI) or metabolic activity (e.g., PET), which are indirect markers of brain electrical activity. EEG can be used simultaneously with fMRI so that high-temporal-resolution data can be recorded at the same time as high-spatial-resolution data, however, since the data derived from each occurs over a different time course, the data sets do not necessarily represent the exact same brain activity. There are technical difficulties associated with combining these two modalities, including the need to remove the MRI gradient artifact present during MRI acquisition and the ballistocardiographic artifact (resulting from the pulsatile motion of blood and tissue) from the EEG. Furthermore, currents can be induced in moving EEG electrode wires due to the magnetic field of the MRI.