imaging {languageR}

fMRI Filtered Signal and Priming Scores for Brain-Damaged Patients

Description

Filtered fMRI signal at the most significant voxel and average priming scores for brain-damaged patients, in a study addressing the extent to which phonological and semantic processes recruit the same brain areas.

Usage

data(imaging)

Format

A data frame with 35 observations on the following 3 variables.

Condition

a factor with levels irregulars (the morphological condition involving priming using inflected forms of irregular English verbs, e.g., 'began'-'begin') and semantics (priming with semantically related words such as 'card' and 'paper').

BehavioralScore

a numeric vector for the average priming scores.

FilteredSignal

a numeric vector for the intensity of the filtered fMRI signal at the most significant voxel.

Details

Location of data points reconstructed from the pixel map of Figure 2b of Tyler et al. 2005.

Source

Tyler, L.K., Marslen-Wilson, W.D. and Stamatakis, E.A. (2005) Differentiating lexical form, meaning, and structure in the neural language system, PNAS, 102, 8375-8380.

Examples

## Not run: 
data(imaging)

imaging.lm = lm(FilteredSignal~BehavioralScore*Condition, data=imaging)
summary(imaging.lm)

plot(imaging$BehavioralScore, imaging$FilteredSignal, type = "n", 
  xlim = c(-30, 40), ylim = c(0, 80))
semantics = imaging[imaging$Condition == "semantics",]
irregulars = imaging[imaging$Condition == "irregulars",]
points(semantics$BehavioralScore, semantics$FilteredSignal, col = "black")
points(irregulars$BehavioralScore, irregulars$FilteredSignal, col = "darkgrey")
abline(lm(FilteredSignal ~ BehavioralScore, data = semantics), col = 'black')
abline(lm(FilteredSignal ~ BehavioralScore, data = irregulars), 
  col = 'darkgrey')

# model criticism

plot(imaging.lm)
outliers = c(1, 19) # given Cook's distance, or perhaps only
outliers = 1        # the outlier in the semantics subset
imaging.lm = lm(FilteredSignal ~ BehavioralScore * Condition, 
  data = imaging[-outliers, ])
summary(imaging.lm)



## End(Not run)