Determination of language hemispheric dominance (HD) in patients undergoing evaluation for epilepsy surgery has traditionally relied on the sodium amobarbital (Wada) test. The emergence of non-invasive methods for determining language laterality has increasingly shown to be a viable alternative. In this study, we assessed the efficacy of transcranial magnetic stimulation (TMS) and magnetoencephalography (MEG), compared to the Wada test, in determining language HD in a sample of 12 patients. TMS-induced speech errors were classified as speech arrest, semantic, or performance errors, and the HD was based on the total number of errors in each hemisphere with equal weighting of all errors (classic) and with a higher weighting of speech arrests and semantic errors (weighted). Using MEG, HD for language was based on the spatial extent of long-latency activity sources localized to receptive language regions. Based on the classic and weighted language laterality index (LI) in 12 patients, TMS was concordant with the Wada in 58.33% and 66.67% of patients, respectively. In eight patients, MEG language mapping was deemed conclusive, with a concordance rate of 75% with the Wada test. Our results indicate that TMS and MEG have moderate and strong agreement, respectively, with the Wada test, suggesting they could be used as non-invasive substitutes.

People with substance use disorders (SUDs) usually experience emotion dysregulation, which may be a consequence of or a risk factor for the development and maintenance of substance misuse. Despite growing evidence on emotion dysregulation among people with SUDs, relatively few studies have explored emotion dysregulation in heroin use disorder (HUD) patients.
Using event-related potentials (ERP), we compared the emotion regulation ability of 33 HUD patients and 30 healthy controls according to their average electroencephalogram amplitudes of the late positive potential (LPP) component in 400-1000 ms and 1000-2000 ms time windows, while viewing neutral and unpleasant emotional pictures, and using emotion regulation strategies (expressive suppression, cognitive reappraisal, and a combination) while viewing unpleasant pictures. We recorded their mood states and how successfully they used emotion regulation strategies in each block using 7-point scales.
Relative to healthy controls, the LPP amplitudes of HUD patients were significantly lower when viewing emotional stimuli (pearlyLPP < 0.05) and using emotion regulation strategies (all p < 0.05). The left hemisphere was more active in healthy controls (pearlyLPP < 0.05, plateLPP < 0.01); there were no differences in scalp position activation among HUD patients.
Compared to healthy controls, HUD patients\' emotional arousal and emotion regulation ability were impaired, as reflected by the LPP component. Their abnormal scalp activation pattern may imply abnormal brain activity. Future research could explore this with electroencephalogram source analysis techniques, functional magnetic resonance imaging, or other technologies. Intervention effects for emotion dysregulation in HUD treatment are also worth exploring.

A previous study we reported in this journal suggested that left and right-handers may differ in their patterns of lateralization for different language tasks (Woodhead et al. 2019 R. Soc. Open Sci. 6, 181801. (doi:10.1098/rsos.181801)). However, it had too few left-handers (N = 7) to reach firm conclusions. For this update paper, further participants were added to the sample to create separate groups of left- (N = 31) and right-handers (N = 43). Two hypotheses were tested: (1) that lateralization would be weaker at the group level in left-than right-handers; and (2) that left-handers would show weaker covariance in lateralization between tasks, supporting a two-factor model. All participants performed the same protocol as in our previous paper: lateralization was measured using functional transcranial Doppler sonography during six different language tasks, on two separate testing sessions. The results supported hypothesis 1, with significant differences in laterality between groups for four out of six tasks. For hypothesis 2, structural equation modelling showed that there was stronger evidence for a two-factor model in left than right-handers; furthermore, examination of the factor loadings suggested that the pattern of laterality across tasks may also differ between handedness groups. These results expand on what is known about the differences in laterality between left- and right-handers.

OBJECTIVE: The present study aims to investigate the relationship between transcallosal interhemispheric connectivity (IC) and hemispheric language lateralization by using a novel approach including repetitive navigated transcranial magnetic stimulation (rTMS), hemispheric dominance ratio (HDR) calculation, and rTMS-based diffusion tensor imaging fiber tracking (DTI FT).
METHODS: 31 patients with left-sided perisylvian brain lesions underwent diffusion tensor imaging (DTI) and rTMS language mapping. Cortical language-positive rTMS spots were used to calculate HDRs (HDR: quotient of the left-sided divided by right-sided naming error rates for corresponding left- and right-sided cortical regions) and to create regions of interest (ROIs) for DTI FT. Then, fibers connecting the rTMS-based ROIs of both hemispheres were tracked, and the correlation of IC to HDRs was calculated via Spearman\'s rank correlation coefficient (rs).
RESULTS: Fibers connecting rTMS-based ROIs of both hemispheres were detected in 12 patients (38.7%). Within the patients in which IC was detected, the mean number of subcortical IC fibers ± standard deviation (SD) was 138.0 ± 346.5 (median: 7.5; range: 1-1,217 fibers). Regarding rs for the correlation of HDRs and fiber numbers of patients that showed IC, only moderate correlation was revealed.
CONCLUSIONS: Our approach might be beneficial and technically feasible for further investigation of the relationship between IC and language lateralization. However, only moderate correlation was revealed in the present study.