Poster A30, Thursday, August 16, 10:15 am – 12:00 pm, Room 2000AB
Improving pre-operative mapping of language in clinical fMRI using assessment of grammar
Monika Polczynska1, Kevin Japardi1, Susan Curtiss1, Teena Moody1, Christopher Benjamin2, Andrew Cho1, Celia Vigil1, Taylor Kuhn1, Michael Jones1, Susan Bookheimer1;1University of California, Los Angeles, 2Yale University
Introduction: In spite of using pre- and intra-operative language mapping techniques, surgical interventions are still challenging, particularly in the language dominant hemisphere. When the risk to new language deficits is too high, patients are frequently not recommended to undergo surgery. Standard protocols for mapping language function seem to be relatively good at predicting location of language at a group level, however, at an individual level they remain sub-optimal. The standard tests typically evaluate lexico-semantic language aspects only. The tests do not properly reflect the complexity of language production or comprehension at a sentence level. In a group of patients with left hemisphere dominance for language (as indicated by the standard fMRI language tests and/or the Wada test) we examined which tests best activate language areas in the brain. Methods: Twenty-five (13 females) candidates for brain surgery participated in the study. Mean age of the participants was 38.8 years (± 11.7). There were nine patients with epilepsy and 16 patients with a brain tumor. Eighteen patients had lesions in the left hemisphere and seven – in the right hemisphere. We compared tests of grammar with standard language tests using pre-operative fMRI. In the grammar component we applied seven tasks from the CYCLE-N. The test is an adaptation of a well-validated clinical instrument for assessment of grammar, the CYCLE (Curtiss and Yamada 2004). The CYCLE-N examines grammar aspects that have been shown to be especially vulnerable to brain damage: relativized subject and object clauses, word order in active and passive sentences, past tense marking and wh-subject and object questions. The standard tests included three tasks: object naming, auditory responsive naming and visual responsive naming. We selected nine regions of interest (ROI) in each hemisphere: four anterior ROI (the anterior superior temporal gyrus, BA 44, 45 and 47) and five posterior ROI (the angular gyrus, anterior and posterior supramarginal gyrus, posterior superior temporal gyrus and posterior middle temporal gyrus). We compared fMRI activations in both protocols at the group level and in individual patients. All tumors were masked. Results: The CYCLE-N produced more activity in the left hemisphere (the angular gyrus, anterior/posterior superior temporal gyrus). The tests helped identify additional language areas that were not detected by the standard tests (e.g., the left posterior middle temporal gyrus). The standard tests elicited more volume of activation only in left BA 47. Ten subjects showed more volume of activation in the left hemisphere during the CYCLE-N and two subjects – during the standard tests. However, after we excluded individual cases with extensive tumors in the posterior ROI (we did not record any activity in masked tumor areas), we found that no patients had significantly more activity in the standard tests than the CYCLE-N. The CYCLE-N also generated considerable activations in the right hemisphere. Thus, the tests were superior at detecting contributions to language processing both in the right and left hemisphere. Conclusion: We suggest that the grammar tests may be a valuable addition to the standard language testing conducted pre-operatively.
Topic Area: Grammar: Syntax