Right-hemispheric brain activation correlates to language performance

Abstract

Language function in the right-hemispheric homologues of Broca"s and Wernicke"s areas does not only correlate with left-handedness or pathology, but occurs naturally in righthanded healthy subjects as well. In the current study, two non-invasive methods of assessing language lateralization are correlated with behavioral results in order to link hemispheric dominance to language ability in healthy subjects.Functional Magnetic Resonance Imaging (fMRI) together with a sentence-completion paradigm was used to determine region-specific lateralization indices in the left-and rightsided Broca"s and Wernicke"s areas, the frontal temporal lobe, the anterior cingulate cortex and the parietal lobe. In addition, dichotic listening results were used to determine overall language lateralization and to strengthen conclusions by correlating with fMRI indices.Results showed that fMRI lateralization in the superior parietal, the posterior temporal, and the anterior cingulate cortices correlated to dichotic listening. A decreased right ear advantage (REA), which indicates less left-hemispheric dominance in language, correlated with higher performance in most administered language tasks, including reading, language ability, fluency, and non-word discrimination. Furthermore, right hemispheric involvement in the posterior temporal lobe and the homologue of Broca"s area suggests better performance in behavioral language tasks. This strongly indicates a supportive role of the right-hemispheric counterparts of Broca"s and Wernicke"s areas in language performance.

Right-hemispheric cortical contributions to language ability in healthy adults

“…That is to say, results in this whole-brain, subregion-specific study are in line with previous findings based on laterality indices in gross regions (Van Ettinger-Veenstra et al, 2010). Our findings of more right-hemispheric activation in the IFG, DLPFC, and the temporal lobe for higher language ability clearly indicate that cognitively demanding linguistic tasks are positively modulated in the right hemisphere.…”

“…In a previous attempt to characterize the correspondence of individual performance on a wide range of language ability tasks to brain activation, we performed a laterality study investigating differences between left-and right-hemispheric regions of interest (ROIs) (Van Ettinger-Veenstra et al, 2010). We calculated the laterality indices (LI) in ROIs of fourteen of the subjects that were included in the present study while they performed the SENCO task.…”

“…FMRI acquisition parameters and the sentence completion paradigm (SENCO) measuring reading comprehension are described in (Van Ettinger-Veenstra et al, 2010). For this study, we did not differentiate between the sentence reading and sentence completion moment but analyzed the activation related to 8 subsequent incomplete sentences and the pause in which the sentence was completed as one block.…”

Clinical fMRI of language function in aphasic patients: Reading paradigm successful, while word generation paradigm fails

“…Sentence reading: The sentence-reading paradigm consisted of 4 blocks of 8 incomplete sentences, which should be completed using a single noun (13,18). The sentences contained 3-10 words fitted into one single row.…”

“…These paradigms have been used in previous studies by us aiming to assess the correlation between brain activity and language performance (13). In healthy subjects, word generation results in activation in frontal language areas, predominantly in the left inferior frontal gyrus (Broca's area) (14,15).…”