A new article in Human Brain Mapping by Benjamin CF et al, Presurgical language fMRI: Mapping of six critical regions investigates how best to identify critical language related brain regions from clinical task-fMRI. The six regions identified by the authors were Broca’s area, Wernicke’s area, Exner’s area, Supplementary Speech area, Angular gyrus [editor note: also sometimes referred to as Geschwind’s area], and Basal Temporal language area [editor note: this may include the ventral visual word form area but as the authors note, the exact overlap is not determined].
A core principle of this paper is highlighting the difficulties in setting a specific uniform threshold for language area activation in clinical fMRI. The authors indicate that expert clinician-guided flexible thresholds were superior to fixed thresholded maps in several facets (external independent clinical rating of activation maps, identification of language regions, and correlation with Wada results).
The authors drive home a critical point in the practice of clinical fMRI: “This finding emphasizes the key role of the clinical question, that is, the subjective goal of the person analyzing data, in defining the results of clinical fMRI.” They also highlight the importance of an experienced clinician in generating optimally thresolded task-fMRI language maps.