Corrigendum: The Lateralization of Speech-Brain Coupling Is Differentially Modulated by Intrinsic Auditory and Top-Down Mechanisms.

[This corrects the article DOI: 10.3389/fnint.2019.00028.].

The Lateralization of Speech-Brain Coupling Is Differentially Modulated by Intrinsic Auditory and Top-Down Mechanisms.

The lateralization of neuronal processing underpinning hearing, speech, language, and music is widely studied, vigorously debated, and still not understood in a satisfactory manner. One set of hypotheses focuses on the temporal structure of perceptual experience and links auditory cortex asymmetries to underlying differences in neural populations with differential temporal sensitivity (e.g., ideas advanced by Zatorre et al. (2002) and Poeppel (2003). The Asymmetric Sampling in Time theory (AST) (Poeppel, 2003), builds on cytoarchitectonic differences between auditory cortices and predicts that modulation frequencies within the range of, roughly, the syllable rate, are more accurately tracked by the right hemisphere. To date, this conjecture is reasonably well supported, since - while there is some heterogeneity in the reported findings - the predicted asymmetrical entrainment has been observed in various experimental protocols. Here, we show that under specific processing demands, the rightward dominance disappears. We propose an enriched and modified version of the asymmetric sampling hypothesis in the context of speech. Recent work (Rimmele et al., 2018b) proposes two different mechanisms to underlie the auditory tracking of the speech envelope: one derived from the intrinsic oscillatory properties of auditory regions; the other induced by top-down signals coming from other non-auditory regions of the brain. We propose that under non-speech listening conditions, the intrinsic auditory mechanism dominates and thus, in line with AST, entrainment is rightward lateralized, as is widely observed. However, (i) depending on individual brain structural/functional differences, and/or (ii) in the context of specific speech listening conditions, the relative weight of the top-down mechanism can increase. In this scenario, the typically observed auditory sampling asymmetry (and its rightward dominance) diminishes or vanishes.

Brain functional connectivity in lung cancer population: an exploratory study.

The present study aimed to explore the functional connectivity differences in Resting State Networks (RSNs) induced by cancer and chemotherapy in Lung Cancer (LC) patients using an Independent Component Analysis (ICA). Three matched groups of 15 LC patients following Chemotherapy (C+), 15 LC patients before Chemotherapy (C-) and 15 Healthy Controls (HC) were included. Analysis was performed using ICA and a multivariate pattern analysis (MVPA) to classify groups based on profiles of functional connectivity. We found significant differences in four of the RSN identified: Default Mode Network (DMN), Predominantly Left and Right Anterior Temporal Network, and Cerebellum Network. Whereas DMN showed decreased connectivity, the other RSNs exhibited increased connectivity in both LC groups compared to HC and in C+ in comparison to C-. MVPA discriminated significantly and accurately between all groups. Our study showed that disrupted functional connectivity associated with cancer and chemotherapy-induced cognitive deficits is not only related to DMN decreased connectivity abnormalities but also to an increased connectivity of other RSNs, suggesting a potential compensatory mechanism. Graphical abstract.

Seizure-susceptible brain regions in glioblastoma: identification of patients at risk.

BACKGROUND AND PURPOSE: The main aim of this study was to identify which patients with glioblastoma multiforme (GBM) have a higher risk of presenting seizures during follow-up. METHODS: Patients with newly diagnosed GBM were reviewed (n = 306) and classified as patients with (Group 1) and without (Group 2) seizures at onset. Group 2 was split into patients with seizures during follow-up (Group 2A) and patients who never had seizures (Group 2B). The anatomical location of GBM was identified and compared by voxel-based lesion symptom mapping (discovery set). Seizure-susceptible brain regions obtained were assessed visually and automatically in external GBM validation series (n = 85). RESULTS: In patients with GBM who had no seizures at onset, an increased risk of presenting seizures during follow-up was identified in the superior frontal and inferior occipital lobe, as well as in inferoposterior regions of the temporal lobe. Conversely, those patients with GBM located in medial and inferoanterior temporal areas had a significantly lower risk of suffering from seizures during follow-up. Additionally, the seizure-susceptible brain region maps obtained classified patients in the validation set with high positive and negative predictive values. CONCLUSIONS: Tumor location is a useful marker to identify patients with GBM who are at risk of suffering from seizures during follow-up. These results may help to support the use of antiepileptic prophylaxis in a selected GBM population and to improve stratification in antiepileptic clinical trials.

Music supported therapy promotes motor plasticity in individuals with chronic stroke.

Novel rehabilitation interventions have improved motor recovery by induction of neural plasticity in individuals with stroke. Of these, Music-supported therapy (MST) is based on music training designed to restore motor deficits. Music training requires multimodal processing, involving the integration and co-operation of visual, motor, auditory, affective and cognitive systems. The main objective of this study was to assess, in a group of 20 individuals suffering from chronic stroke, the motor, cognitive, emotional and neuroplastic effects of MST. Using functional magnetic resonance imaging (fMRI) we observed a clear restitution of both activity and connectivity among auditory-motor regions of the affected hemisphere. Importantly, no differences were observed in this functional network in a healthy control group, ruling out possible confounds such as repeated imaging testing. Moreover, this increase in activity and connectivity between auditory and motor regions was accompanied by a functional improvement of the paretic hand. The present results confirm MST as a viable intervention to improve motor function in chronic stroke individuals.

Task-load manipulation in the Symbol Digit Modalities Test: an alternative measure of information processing speed.

OBJECTIVE: To evaluate the utility of an oral fMRI-adapted version of the Symbol Digit Modalities Test (SDMT) to assess information processing speed (IPS) using three different interstimulus intervals (ISI). METHODS: Nineteen right-handed healthy controls performed the adapted version of the SDMT, consisting of a block design that had a total of 6 control/activation block pairs with 3 different ISIs (1.5, 2 and 2.5s) presented in two different runs: in ascending and descending orders. The brain activation patterns during different ISIs were assessed by effective functional connectivity analysis based on independent component analysis. RESULTS: As expected, all conditions yielded activations in the fronto-parietal networks (FPNs) related to attention processes. Shorter ISIs (1.5 and 2s) not only yielded greater patterns of connectivity within fronto-parietal and occipital regions such as the FPN and fronto-occipital network (FON), but also recruited more functional networks overall. Task performance at the shortest ISI was negatively correlated with connectivity at the FPN and activity of the pre-supplementary motor area extending to the cingulate gyrus. CONCLUSION: Increasing IPS demands due to shorter ISIs resulted in an increased level and number of functional networks required, increased connectivity within the FPN and FON, and enhancement of the prefrontal cortex. IPS does not arise from activity of a single b area but from affective information transfer among distant cortical regions of the frontal and parietal cortices. This adapted version of the SDMT may be useful for studying alterations of IPS in clinical and nonclinical populations.

Analysis of automated methods for spatial normalization of lesioned brains.

Normalization of brain images is a crucial step in MRI data analysis, especially when dealing with abnormal brains. Although cost function masking (CFM) appears to successfully solve this problem and seems to be necessary for patients with chronic stroke lesions, this procedure is very time consuming. The present study sought to find viable, fully automated alternatives to cost function masking, such as Automatic Lesion Identification (ALI) and Diffeomorphic Anatomical Registration using Exponentiated Lie algebra (DARTEL). It also sought to quantitatively assess, for the first time, Symmetrical Normalization (SyN) with constrained cost function masking. The second aim of this study was to investigate the normalization process in a group of drug-resistant epileptic patients with large resected regions (temporal lobe and amygdala) and in a group of stroke patients. A dataset of 500 artificially generated lesions was created using ten patients with brain-resected regions (temporal lobectomy), ten stroke patients and twenty five-healthy subjects. The results indicated that although a fully automated method such as DARTEL using New Segment with an extra prior (the mean of the white matter and cerebro-spinal fluid) obtained the most accurate normalization in both patient groups, it produced a shrinkage in lesion volume when compared to Unified Segmentation with CFM. Taken together, these findings suggest that further research is needed in order to improve automatic normalization processes in brains with large lesions and to completely abandon manual, time consuming normalization methods.

[The contribution of magnetic resonance spectroscopy to the classification of high grade gliomas. The predictive value of macromolecules]. / Contribución de la espectroscopía de Resonancia Magnética a la clasificación del glioma de alto grado. Valor predictivo de las macromoléculas.

INTRODUCTION: 1H MRS allows the study of metabolite concentration changes in intracranial tumours, relating them, more or less successfully, to the histological type and grade of the tumour. OBJECTIVE: To analyse the patterns which are useful for classifying the grades of cerebral gliomas by means of various ratios obtained using 1H MRS with two echo times (ET), with and without water suppression, paying special attention to the macromolecules. PATIENTS AND METHODS: We studied 8 gliomas (1 grade II, 2 grade III and 5 grade IV) with single volume 1H MRS at ET 31 ms (8/8) and 136 ms (7/8). The intensities of the metabolites, including macromolecules (MMA, 0.9 ppm; MMB, 1.3 ppm), were normalised to water signal intensity for ET 31, to Cr at ET 31 and 136 ms and NAA/Cho for both ET and the ratio MMA/MMB at ET 31. RESULTS: There were significant differences between the three grades on the ratios MMA/MMB (p= 0.000) with descent of the MMA/MMB coefficient as the grade increases, and NNA/Cho at ET 136 (p= 0.018). We found an inverse relationship between the quantity in mI and the increase in grade. No macromolecules were found at ET 136 in any of the tumours of grade II or III. CONCLUSIONS: The spectra of gliomas with ET 31 showed macromolecules around 0.9 and 1.3 ppm with different relative ratios for each tumour grade. The ET 136 spectra informs about the content of NNA and Cho. Apart from the increase in MMB (0.9 ppm), with short ET the higher grades showed lower content of mI. The study of gliomas using 1H MRS with ET 31 and 136 ms contributes to the diagnosis of the grade of tumour.

Contribución de la espectroscopía de resonancia magnética a la clasificación del glioma de alto grado.Valor predictivo de las macromoléculas / The contribution of magnetic resonance spectroscopy to the classification of high grade gliomas. The predictive value of macromolecules

Introducción. La 1H ERM permite estudiar los cambios en las concentraciones de metabolitos en los tumores intracraneales, relacionándolos con éxito variable con el tipo histológico y el grado tumoral. Objetivo. Analizar los patrones útiles en la gradación de gliomas cerebrales mediante diversos cocientes obtenidos con 1H ERM a dos tiempos de eco (TE), con y sin supresión del agua, con especial interés en la aportación de las macromoléculas. Pacientes y métodos. Se estudiaron ocho gliomas (1grado II, 2 grado III y 5 grado IV) con 1H ERM de volumen único a TE 31 ms (8/8) y 136 ms (7/8). Las intensidades de diversos metabolitos, incluyendo macromoléculas (MMA, 0,9 ppm; MMB, 1,3 ppm), se normalizaron al H2O para TE 31, a Cr para TE 31 y 136 ms y NAA/Co para ambos TE y la relación MMA/MMB para TE 31. Resultados. Existen diferencias significativas para los tres grados en los cocientes MMA/MMB (p=0,000), con un descenso del cociente MMA/MMB al aumentar el grado, y NAA/Co a TE 136 (p=0,018). Se observó una relación inversa entre la cantidad de mio-inositol (mI) y el aumento de grado, pero no se detectaron macromoléculas a TE 136 en ninguno de los tumores de grado II o III. Conclusiones. En los espectros de gliomas a TE 31 aparecen macromoléculas a 0,9 y 1,3 ppm con proporción relativa distinta para cada uno de los grados. Los espectros a TE medio informan del contenido de NAA y Co. Además del aumento de MMB (0,9 ppm), a TE corto, los grados más altos presentan una disminución del contenido de mI. El estudio de gliomas mediante 1H ERM con TE corto y medio contribuye al diagnóstico del grado tumoral (AU)