Figure 7.

fMRI working memory tasks and correlation with other measures. In the top panel the Stroop is used to assess executive function levels through measurements of processing speed, simple and complex reaction time, speed-accuracy trade off, and inhibition and selective attention. Participants are required to indicate the color of a word flashed on a screen. The words, “red,” “blue,” or “green,” are displayed in either the corresponding color (congruent trials, e.g. “red” is written in the color red) or a conflicting color (incongruent trials, e.g. “blue” is written in the color green). Longer reaction time to give an answer was associated with low myoinositol. The Comprehensive Trail-Making Test (CTMT is a measure of set-shifting, working memory, divided attention, and cognitive flexibility. Trails 4 and 5 (Part B) require the examinee to connect a series of numbers and letters in a specific sequence as quickly as possible without crossing lines. Numbers are presented as Arabic numerals (e.g. 1, 8) or spelled out in English (i.e. three). This easily administered set of tasks is remarkably sensitive to neuropsychological deficits of many types. CTMT trials 1–3 require only simple sequencing skills. Trials 4 and 5, in contrast, require a higher level of “set shifting” or cognitive flexibility analysis.