fMRI Task: Verbal Responsive Naming
Visual responsive naming tasks involve patients reading a short, written description of an object, and thinking of the object name. This is a text-based, visual analog of auditory naming tasks. This task is completed in a "block design," where patients read a series of sentences describing different objects (often around 3 seconds per sentence) in a block (often around 24 seconds). These are alternated with blocks of a control task (of the same duration). Control conditions used are variable, and may constitute a crosshair, or a black screen; non-words; or images of the same sentences scrambled into visual white noise. These control tasks will result in different patterns of activation in the final images, because they activate different brain regions. For instance, using the same sentences scrambled will engage visual cortex only; using strings of letters will activate visual cortex as well as areas involved in processing word forms.
There are numerous examples from the fMRI literature (below), and agreement with Wada results as part of a panel of tasks was previously estimated at approximately 75-84%. Using a specific analysis approach with Object Naming and Auditory Responsive naming tasks we found overall 85% correspondence with Wada lateralization (Benjamin et al., 2017). The version of the task used in that paper is available free of charge for download here.
Gaillard et al. 2001. Cortical localization of reading in normal children: an fMRI language study. Neurology 57:47.
Gaillard et al. 2002. Language dominance in partial epilepsy patients identified with an fMRI reading task. Neurology 59:256.
Gaillard et al. 2004. fMRI language task panel improves determination of language dominance. Neurology 63:1403.
Benjamin et al., 2017. Presurgical language fMRI: Mapping of six critical regions. Human Brain Mapping: In press.