Language lateralization in temporal lobe epilepsy: A behavioral screening tool for surgical planning.

OBJECTIVE: Temporal lobe epilepsy can disturb eloquent areas, affecting language. We applied a visually-mediated task to measure lateralization of language recognition in drug-resistant temporal lobe epilepsy. METHOD: Patients with left (n = 26), right (n = 28) temporal lobe epilepsy and controls (n = 30) were administered the translingual lexical decision task. We performed repeated measures analyses of variance, with the visual half-field as an intrasubject factor and the group as an intersubject factor. RESULTS: A main effect of visual half-field was found, showing the right visual field (left hemisphere) advantage for both accuracy and response time. A main effect of the group was found in accuracy, showing that both epilepsy groups performed less accurately than controls, and left temporal lobe epilepsy performed less accurately than right temporal lobe epilepsy. Also, the group-by-visual half-field interaction was significant. Post hoc t tests indicated the controls and right temporal lobe epilepsy performed better in the right visual field than in the left visual field, whereas no visual half-field effect was found in left temporal lobe epilepsy. For response times, the interaction was also significant. Post hoc t tests showed a significant right visual-field advantage for controls (two-tailed) and for the right temporal lobe epilepsy (one-tailed). Right visual-field advantage was absent in left temporal lobe epilepsy. CONCLUSIONS: The translingual lexical decision task can efficiently distinguish between left and right temporal lobe epilepsy. Compared to right temporal lobe epilepsy and controls, language lateralization is diminished in left temporal lobe epilepsy. The potential use of the translingual lexical decision task as an effective noninvasive presurgical language lateralization screening tool is highlighted. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Hemispheric asymmetries in cortical grey matter of gyri and sulci in modern human populations from South America.

Structural asymmetries of brain regions associated with lateralised functions have been extensively studied. However, there are fewer morphometric analyses of asymmetries of the gyri and sulci of the entire cortex. The current study assessed cortical asymmetries in a sample of healthy adults (N = 175) from an admixed population from South America. Grey matter volume and surface area of 66 gyri and sulci were quantified on T1 magnetic resonance images. The departure from zero of the differences between left and right hemispheres (L-R), a measure of directional asymmetry (DA), the variance of L-R, and an index of fluctuating asymmetry (FA) were evaluated for each region. Significant departures from perfect symmetry were found for most cortical gyri and sulci. Regions showed leftward asymmetry at the population level in the frontal lobe and superior lateral parts of the parietal lobe. Rightward asymmetry was found in the inferior parietal, occipital, frontopolar, and orbital regions, and the cingulate (anterior, middle, and posterior-ventral). Despite this general pattern, several sulci showed the opposite DA compared to the neighbouring gyri, which remarks the need to consider the neurobiological differences in gyral and sulcal development in the study of structural asymmetries. The results also confirm the absence of DA in most parts of the inferior frontal gyrus and the precentral region. This study contributes with data on populations underrepresented in the databases used in neurosciences. Among its findings, there is agreement with previous results obtained in populations of different ancestry and some discrepancies in the middle frontal and medial parietal regions. A significant DA not reported previously was found for the volume of long and short insular gyri and the central sulcus of the insula, frontomarginal, transverse frontopolar, paracentral, and middle and posterior parts of the cingulate gyrus and sulcus, gyrus rectus, occipital pole, and olfactory sulcus, as well as for the volume and area of the transverse collateral sulcus and suborbital sulcus. Also, several parcels displayed significant variability in the left-right differences, which can be partially attributable to developmental instability, a source of FA. Moreover, a few gyri and sulci displayed ideal FA with non-significant departures from perfect symmetry, such as subcentral and posterior cingulate gyri and sulci, inferior frontal and fusiform gyri, and the calcarine, transverse collateral, precentral, and orbital sulci. Overall, these results show that asymmetries are ubiquitous in the cerebral cortex.

Brain mapping of emotional prosody in patients with drug-resistant temporal epilepsy: An indicator of plasticity.

INTRODUCTION: Emotional prosody, a suprasegmental component of language, is predominantly processed by right temporo-frontal areas of the cerebral cortex. In temporal lobe epilepsy (TLE), brain disturbances affecting prosody processing frequently occur. This research assesses compensatory brain mechanisms of prosody processing in refractory TLE using fMRI. METHODS: Patients with focal unilateral epilepsy, right (RTLE) (N = 19), left (LTLE) (N = 19), and healthy controls (CTRL) (N = 20) were evaluated during a prosody decoding fMRI task. The stimuli consisted in spoken numbers with different tones of voice (joy, fear, anger, neutral and silent trials). Participants were instructed to label the emotion with a keypad. "Joy" was removed from the analysis due to a high degree of variability. A lateralization index (LI) was used to see individual differences in the interhemispheric activations of each participant. RESULTS: Behaviorally, The LTLE and RTLE groups did not differ significantly from each other neither from CTRL. In Negative Emotions versus Baseline contrast, the whole sample analysis showed extensive activations in bilateral superior temporal gyrus, bilateral precentral and post-central gyrus, right putamen, and left cerebellar vermis. Compared to the LTLE and CTRL, RTLE activated similar areas, but to a lesser extent. The LI analysis revealed significant differences in hemispheric laterality of the temporal lobe and the parietal lobe between RTLE compared to LTLE and CTRL, being the RTLE group lateralized towards the left, unlike the other two groups. DISCUSSION: The LI indicated that, since the CTRL and the LTLE groups recruited putative prosodic regions, the RTLE lateralized prosody processing towards the left, recruiting contralateral nodes, homotopic to the putative areas of the prosody. Considering that the groups did not differ in prosody task performance, the findings suggest that, in the RTLE group, alternative brain nodes were recruited for the task, demonstrating plasticity.

Emotional salience enhances intelligibility in adverse acoustic conditions.

INTRODUCTION: Emotion facilitates word recognition under adverse acoustic conditions. We use an auditory emotional paradigm to evaluate the ability to distinguish words from irrelevant random stimuli, elucidating its neural correlates. Secondarily, we evaluate the impact of schizotypy traits on this capacity. METHODS: 25 participants, undertook an fMRI task, indicating whether they recognized words, through a response box. 20 audio files of emotionally negative words and 20 neutral words were presented. Word intelligibility was manipulated merging the audio files with white noise at varying signal-to-noise ratios (SNR), resulting in 3 levels (high, medium, and low). We measured schizotypy with the O-LIFE scale. RESULTS: A 2x3 factorial ANOVA was performed with emotion (neutral or negative) and intelligibility (high, medium, and low) as factors. There was an interaction between emotion and intelligibility [F(2,44) = 23.89,p<0.001]. Post hoc t-test demonstrated that, in medium and low intelligibility, negative words were more recognized than neutral ones. Negative words minus neutral, activated the right anterior cingulate cortex (rACC), right dorsolateral prefrontal cortex (rDLPFC), and right orbitofrontal cortex (rOFC). Low compared to high intelligibility, activated the left medial temporal gyrus (lMTG), left supramarginal gyrus (lSMG), and left angular gyrus (lAG). Medium compared with high intelligibility, activated the left temporal pole (lTP) and the lMTG. There were correlations between schizotypy and rACC, lMTG, and rOFC activations. DISCUSSION: Negative emotional salience improves intelligibility, possibly by recruiting selective attention. Less intelligible stimuli activated temporo-parietal regions related to speech processing in adverse acoustic conditions, while emotionally negative stimuli activated areas associated with emotional processing (rACC and rOFC) and selective attention (rDLPFC). High schizotypy correlated with greater responses in rACC, lMTG, and rOFC, during low intelligibility. Irrelevant emotionally salient stimuli would capture automatic attention activating rACC and rOFC, enhancing speech comprehension through additional recruitment of lMTG, which could derive in false word recognition.