Hemispheric Dominance for Task Dependent Frontal Lobe Function & Its Relationship to Language Lateralization and Handedness

Abstract The present study investigates a potential method to optimize effective functional localization strategies for both language regions and the dorsolateral prefrontal cortex (dlPFC) while in a scanner. This functional task combines elements of creative problem solving, executive decision making based on an internal rule set, and working memory. Retrospective analysis was performed on a total of 58 unique participants (40% female, Mage = 42.84 years, SDage = 16.51). Of these participants, 47 were classified as right-handed, 7 were classified as left-handed, and 4 were classified as “mixed-handed” or ambidextrous according to the Edinburgh Handedness Inventory. The imaging data was judged by two blinded investigators to assess language and dlPFC dominance while using the motor cortex activitation to confirm that participants engaged in the task. We show that 25% of right handed individuals seem to have a dominant dlPFC localized to the right hemisphere rather than the assumed left, and more than a quarter of left handers were dominant in their left hemisphere. Given the clinical relevance of dlPFC dominance, this task appears to be an evidence-based technique for determining appropriate dlPFC target for the purposes of neuromodulation (e.g. TMS).