Language lateralization in left-handed and ambidextrous people

Szaflarski, Jerzy P.; Binder, Jeffrey R.; Possing, Edward T.; McKiernan, K.A.; Ward, B. Douglas; Hammeke, Thomas A.

doi:10.1212/wnl.59.2.238

Cited by 477 publications

(410 citation statements)

References 37 publications

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“…Thus, in the large majority of left-handers, language functions are left-lateralized, just as they are in righthanders. Nevertheless, left-handers show a greater diversity in language lateralization than right-handers: more left-handers show bilateral language function or have reversed lateralization [72][73][74] . In the majority of language-lateralization studies, 'language' is treated as a unitary cognitive function, and most investigations used speech-production tasks (such as a verb-generation task) to quantify levels of 'language'-related activation in frontal parts of the two hemispheres.…”

Section: Cerebral Lateralizationmentioning

confidence: 96%

On the other hand: including left-handers in cognitive neuroscience and neurogenetics

et al. 2014

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Left-handers are often excluded from study cohorts in neuroscience and neurogenetics in order to reduce variance in the data. However, recent investigations have shown that the inclusion or targeted recruitment of left-handers can be informative in studies on a range of topics, such as cerebral lateralization and the genetic underpinning of asymmetrical brain development. Left-handed individuals represent a substantial portion of the human population and therefore left-handedness falls within the normal range of human diversity; thus, it is important to account for this variation in our understanding of brain functioning. We call for neuroscientists and neurogeneticists to recognize the potential of studying this often-discarded group of research subjects

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Section: Cerebral Lateralizationmentioning

confidence: 96%

On the other hand: including left-handers in cognitive neuroscience and neurogenetics

et al. 2014

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“…In all other cases, they responded with button press "2." This task is known to activate numerous brain areas involved in language processing, including the prefrontal cortex of the inferior, middle, and superior frontal gyri, posterior cingulated gyrus and retrosplenial cortex, anterior/ superior temporal sulcus and middle temporal gyrus, posterior/inferior temporal gyrus, fusiform and anterior parahippocampal gyri, anterior hippocampus, angular gyrus, and posterior cerebellum [44]. The total duration of this task is 7 minutes 15 seconds.…”

Section: Semantic Decision/tone Decision Task (Sdtd)-thismentioning

confidence: 99%

Comprehensive presurgical functional MRI language evaluation in adult patients with epilepsy

Szaflarski

Holland

Jacola

et al. 2008

Epilepsy & Behavior

112

137

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Functional magnetic resonance imaging (fMRI) has the potential to replace the intracarotid amobarbital procedure (IAP) in presurgical evaluation of patients with epilepsy patients. In this study, we compared fMRI verb generation (VG) and semantic decision/tone decision (SDTD) tasks and the IAP in their ability to localize language functions in patients with epilepsy undergoing presurgical evaluation. We enrolled 50 healthy controls to establish normal language activation patterns for VG and SDTD tasks at 3 or 4 T, and to design language regions of interest (ROIs) that were later applied to 38 patients with epilepsy (28 of 38 also underwent the IAP). We calculated laterality indices (LIs) for each task for each subject based on the ROIs, and we used general linear modeling to analyze the fMRI data. All healthy and epileptic subjects activated language areas with both fMRI tasks. We found significant correlations in language lateralization between the fMRI tasks (r = 0.495, P ≤ 0.001) and between VG and IAP (r = 0.652, P < 0.001) and SDTD and IAP (r = 0.735, P < 0.001). The differences in LIs between SDTD and VG tasks were small and not affected by age, gender, epilepsy status, handedness, or performance. SDTD and VG tasks combined explained approximately 58.4% in the variability of the IAP/language. In the general linear modeling, only the SDTD task significantly contributed to the determination of language lateralization in patients with epilepsy undergoing presurgical evaluation. Results indicate a moderate convergent validity between both fMRI language tasks and between IAP and fMRI tasks. The results of this study indicate that either of these fMRI tasks can be used for language lateralization in patients with epilepsy undergoing presurgical evaluation, but that the SDTD task is likely to provide more information regarding language lateralization than the VG task.

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“…Similarly, Szaflarski et al [70] assessed degree of lateralization in healthy adults by measuring the extent of fMRI (BOLD) activation on a language task in lateral, medial, frontal, and temporal regions of interest. A lateralization index (LI), obtained by computing the ratio of voxels activated in the left and right hemispheres, correlated with participants' handedness quotients as assessed via the Edinburgh Inventory [60].…”

Section: Handedness and Hemispheric Asymmetry For Languagementioning

confidence: 99%

Handedness, hemispheric asymmetries, and joke comprehension

Coulson

Lovett

2004

Cognitive Brain Research

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To address the impact of differences in language lateralization on joke comprehension, event-related brain potentials (ERPs) were recorded as 16 left-and 16 right-handed adults read one-line jokes and non-funny control stimuli (''A replacement player hit a home run with my girl/ball,''). In right-handers, jokes elicited a late positivity 500 -900 ms post-stimulus onset that was largest over right hemisphere (RH) centro-parietal electrode sites, and a slow sustained negativity over anterior left lateral sites. In left-handers, jokes elicited a late positivity 500 -900 ms post-onset that was larger and more broadly distributed than in the right-handers' ERPs. In right-handed women, the late positivity was larger over RH electrode sites. In left-handed women, the late positivity was bilaterally symmetric. The highly asymmetric slow sustained negativity over left anterior electrode sites was absent from left-handers' ERPs to jokes. Differences may reflect more efficient inter-hemispheric communication in the left-handers, as they are reputed to have relatively larger corpus callosal areas than right-handers. Results support the portrait of more bilateral language representation among left-handers, and suggest language lateralization affects highlevel language comprehension tasks such as joke comprehension. D 2004 Elsevier B.V. All rights reserved.Theme: Neural basis of behavior Topic: Cognition

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Language lateralization in left-handed and ambidextrous people

Cited by 477 publications

References 37 publications

On the other hand: including left-handers in cognitive neuroscience and neurogenetics

On the other hand: including left-handers in cognitive neuroscience and neurogenetics

Comprehensive presurgical functional MRI language evaluation in adult patients with epilepsy

Handedness, hemispheric asymmetries, and joke comprehension

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