What does an fMRI measure?

Functional magnetic resonance imaging (fMRI) measures the small changes in blood flow that occur with brain activity.

What specific parameter does an fMRI measure?

Functional magnetic resonance imaging or functional MRI (fMRI) measures brain activity by detecting changes associated with blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area of the brain is in use, blood flow to that region also increases.

What does standard fMRI measure most specifically?

Summary: fMRI is one of the most popular methods in cognitive neuroscience, and certainly the most headline grabbing. fMRI provides unparalleled access to the patterns of brain activity underlying human perception, memory and action; but like any method, there are important limitations.

What do fMRI and PET measure?

fMRI and PET measure haemodynamic changes induced by regional changes in neuronal activity. Electroencephalogram (EEG) and MEG measure the neuronal electrical or magnetic activity with a high temporal resolution (i.e., milliseconds) albeit with a poorer spatial resolution (i.e., a few millimeters to one centimeter).

How to calculate Sample sizes for fMRI studies?

• The manuscript presents a method to calculate sample sizes for fMRI experiments • The power analysis is based on the estimation of the mixture distribution of null and active peaks • The methodology is validated with simulated and real data. 1 Abstract

How to estimate statistical power in functional MRI?

Abstract Estimation of statistical power in functional MRI (fMRI) requires knowledge of the expected percent signal change between two conditions as well as estimates of the variability in percent signal change.

How are correlation coefficients calculated in fMRI data?

In this case the time series for one or more pixels in, say the visual cortex is extracted (Figure 6.8c), and correlation coefficients are calculated between this waveform and that of every other pixel in the image. Such an analysis detects only those regions in the brain which respond to the stimulus in the same way as the visual cortex.

What does the suffix 1 mean in fMRI data?

The suffix ‘1’ refers to the n1images acquired during the ‘on’ period of the task, and ‘2’ refers to the n2images acquired during the rest period. Figure 6.7c shows the statistical parametric map of t-scores for the sample data set.