Differences between Alzheimer's disease and mild cognitive impairment using brain networks from magnetic resonance texture analysis.

Several studies have aimed at identifying biomarkers in the initial phases of Alzheimer's disease (AD). Conversely, texture features, such as those from gray-level co-occurrence matrices (GLCMs), have highlighted important information from several types of medical images. More recently, texture-based brain networks have been shown to provide useful information in characterizing healthy individuals. However, no studies have yet explored the use of this type of network in the context of AD. This work aimed to employ texture brain networks to investigate the distinction between groups of patients with amnestic mild cognitive impairment (aMCI) and mild dementia due to AD, and a group of healthy subjects. Magnetic resonance (MR) images from the three groups acquired at two instances were used. Images were segmented and GLCM texture parameters were calculated for each region. Structural brain networks were generated using regions as nodes and the similarity among texture parameters as links, and graph theory was used to compute five network measures. An ANCOVA was performed for each network measure to assess statistical differences between groups. The thalamus showed significant differences between aMCI and AD patients for four network measures for the right hemisphere and one network measure for the left hemisphere. There were also significant differences between controls and AD patients for the left hippocampus, right superior parietal lobule, and right thalamus-one network measure each. These findings represent changes in the texture of these regions which can be associated with the cortical volume and thickness atrophies reported in the literature for AD. The texture networks showed potential to differentiate between aMCI and AD patients, as well as between controls and AD patients, offering a new tool to help understand these conditions and eventually aid early intervention and personalized treatment, thereby improving patient outcomes and advancing AD research.

Resistance training effects on pubertal children with a risk of developing pediatric dynapenia.

PURPOSE: Many modern-day children are at risk of pediatric dynapenia (muscle weakness). We examined the effects of a 12-week resistance training (RT) program on neuromuscular function and body composition parameters in pubertal children with a risk of dynapenia. METHODS: Twelve children (13.4 ± 0.9 y) with dynapenia performed a progressive RT program consisting of knee extension and flexion, bench press, abdominal crunch, back extension, lateral pull-down, elbow flexion, and upright row (1-2 sets of 10-15 repetitions/exercise) twice/week for 12 weeks. Outcome measures included one-repetition maximum (1-RM) strength, maximal voluntary isometric contraction (MVIC) torque, rate of torque development (RTD), electromyographic (EMG) activity, muscle thickness (MT), muscle quality (MQ) assessed by echo intensity (MQEI) of the knee extensors and specific tension of MVIC torque to thigh fat-free mass (MQST), and total and regional body and bone composition assessed by dual-energy X-ray absorptiometry. Changes in the measures before and after the 12-week RT and associations among the measures were analyzed by linear mixed models. RESULTS: Significant (p < 0.05) increases in 1-RM (63.9 ± 4.5%), MVIC torque (16.3 ± 17.8%), MT (18.8 ± 5.5%) and MQ (MQEI: -25.9 ± 15.2%; MQST: 15.1 ± 18.8%;) were evident from pre- to post-training. Total fat-free mass (FFM) increased by 2.3 ± 3.2% from baseline (p = 0.01), but no changes (p > 0.05) in the other measures were observed. Significant (p < 0.05) associations between the changes in 1-RM and/or MVIC torque and the changes in quadriceps MT, MQEI, MQST and total body FFM were evident. CONCLUSIONS: The 12-week RT was effective for improving neuromuscular and body composition parameters, and thereby reversed the risk of pediatric dynapenia.

Axonal dysfunction is associated with interferon-γ levels in childhood-onset systemic lupus erythematosus: a multivoxel magnetic resonance spectroscopy study.

OBJECTIVE: Axonal/neuronal damage has been shown to be a pathological finding that precedes neuropsychiatric manifestations in SLE. The objective of this study was to determine the presence of axonal dysfunction in childhood-onset SLE patients (cSLE) and to determine clinical, immunological and treatment features associated with its occurrence. METHODS: We included 86 consecutive cSLE patients [median age 17 (range 5-28) years] and 71 controls [median age 18 (5-28) years]. We performed proton magnetic resonance spectroscopic imaging using point resolved spectroscopy sequence over the superior-posterior region of the corpus callosum and signals from N-acetylaspartate (NAA), choline-based (CHO), creatine-containing (Cr), myo-inositol (mI), glutamate, glutamine and lactate were measured and metabolites/Cr ratios were determined. Complete clinical, laboratory and neurological evaluations were performed in all subjects. Serum IL-4, IL-5, IL-6, IL-10, IL-12, IL-17, TNF-α and INF-γ cytokine levels, antiribosomal P protein antibodies (anti-P) and S100ß were measured by ELISA using commercial kits. Data were compared by non-parametric tests. RESULTS: NAA/Cr ratios (P = 0.035) and lactate/Cr ratios (P = 0.019) were significantly decreased in cSLE patients when compared with controls. In multivariate analysis, IFN-γ levels [odds ratio (OR) = 4.1; 95% CI: 2.01, 7.9] and depressive symptoms (OR = 1.9; 95% CI: 1.1, 3.2) were associated with NAA/Cr ratio. Increased CHO/Cr was associated with the presence of cognitive impairment (OR = 3.4; 95% CI: 2.034, 5.078; P < 0.001). mI/Cr ratio correlated with cumulative glucocorticoids dosage (r = 0.361, P = 0.014). CONCLUSION: NAA and CHO ratios may be useful as biomarkers in neuropsychiatric cSLE. Longitudinal studies are necessary to determine whether they predict structural damage.

Spinal cord diffusion tensor imaging in patients with sensory neuronopathy.

INTRODUCTION: We investigated whether MR diffusion tensor imaging (DTI) analysis of the cervical spinal cord could aid the (differential) diagnosis of sensory neuronopathies, an underdiagnosed group of diseases of the peripheral nervous system. METHODS: We obtained spinal cord DTI and T2WI at 3 T from 28 patients, 14 diabetic subjects with sensory-motor distal polyneuropathy, and 20 healthy controls. We quantified DTI-based parameters and looked at the hyperintense T2W signal at the spinal cord posterior columns. Fractional anisotropy and mean diffusivity values at C2-C3 and C3-C4 levels were compared between groups. We also compared average fractional anisotropy (mean of values at C2-C3 and C3-C4 levels). A receiver operating characteristic (ROC) curve was used to determine diagnostic accuracy of average fractional anisotropy, and we compared its sensitivity against the hyperintense signal in segregating patients from the other subjects. RESULTS: Mean age and disease duration were 52 ± 10 and 11.4 ± 9.3 years in the patient group. Eighteen subjects had idiopathic disease and 6 dysimmune etiology. Fractional anisotropy at C3-C4 level and average fractional anisotropy were significantly different between patients and healthy controls (p < 0.001 and <0.001) and between patients and diabetic subjects (p = 0.019 and 0.027). Average fractional anisotropy presented an area under the curve of 0.838. Moreover, it had higher sensitivity than visual detection of the hyperintense signal (0.86 vs. 0.54), particularly for patients with short disease duration. CONCLUSION: DTI-based analysis enables in vivo detection of posterior column damage in sensory neuronopathy patients and is a useful diagnostic test for this condition. It also helps the differential diagnosis between sensory neuronopathy and distal polyneuropathies.

RehabGesture: An Alternative Tool for Measuring Human Movement.

BACKGROUND: Systems for range of motion (ROM) measurement such as OptoTrak, Motion Capture, Motion Analysis, Vicon, and Visual 3D are so expensive that they become impracticable in public health systems and even in private rehabilitation clinics. Telerehabilitation is a branch within telemedicine intended to offer ways to increase motor and/or cognitive stimuli, aimed at faster and more effective recovery of given disabilities, and to measure kinematic data such as the improvement in ROM. MATERIALS AND METHODS: In the development of the RehabGesture tool, we used the gesture recognition sensor Kinect(®) (Microsoft, Redmond, WA) and the concepts of Natural User Interface and Open Natural Interaction. RESULTS: RehabGesture can measure and record the ROM during rehabilitation sessions while the user interacts with the virtual reality environment. The software allows the measurement of the ROM (in the coronal plane) from 0° extension to 145° flexion of the elbow joint, as well as from 0° adduction to 180° abduction of the glenohumeral (shoulder) joint, leaving the standing position. The proposed tool has application in the fields of training and physical evaluation of professional and amateur athletes in clubs and gyms and may have application in rehabilitation and physiotherapy clinics for patients with compromised motor abilities. CONCLUSIONS: RehabGesture represents a low-cost solution to measure the movement of the upper limbs, as well as to stimulate the process of teaching and learning in disciplines related to the study of human movement, such as kinesiology.

[Pneumonia caused byCorynebacterium pseudodiphtheriticum]. / Neumonía por Corynebacterium pseudodiphtheriticum.

Microorganisms of the genera Corynebacterium, specie pseudodiphtheriticum are a part of the indigenous microbiota of human skin and oropharinx. Nevertheless in recent decades these bacilli are emerging as opportunistic pathogens causing clinically significant infections in patients with previous compromise. We report the case of a 76 years old female patient, with a history of hypertension, hypothyroidism, type 2 diabetes and chronic renal failure, who presented pneumonia during their stay at the intensive care unit. The induced sputum revealed a representative sample with monomicrobial gram positive pleomorphic coryneform rods (Gram stain) and cultures demonstrated the presence of C. pseudodiphtheriticum as the only bacteria recovered. The pacient received an empirical third generation cephalosporin medication with a succesfull recovery.

(31)P-MRS using visual stimulation protocols with different durations in healthy young adult subjects.

Phosphorus magnetic resonance spectroscopy ((31)P-MRS) combined with visual stimulation in functional experiments allows the non-invasive dynamic study of brain energy metabolism. (31)P-MRS has been applied to several diseases and to healthy subjects, but works have shown variable findings and non-reproducible results, possibly caused by low numbers of subjects combined with different stimulation paradigms. In the present work, we used (31)P-MRS at 3 T with two different visual stimulation protocols with different block duration ("short" and "long") to evaluate metabolic changes under different workloads in 38 healthy subjects. We found a 15 % (short protocol-blocks of 1.5 min stimulation) and 3 % (long protocol-blocks of 5 min stimulation) increase in the inorganic phosphate (Pi) to α-adenosine triphosphate (α-ATP) ratio, and a 5 % (short protocol) and 2 % (long protocol) decrease in the nicotinamide adenine nucleotide (NADH + NAD(+)) to α-ATP ratio. The NADH + NAD(+) results are, to the best of our knowledge, the first functional magnetic resonance spectroscopy in vivo assessment of these compounds, but their interpretation is difficult since they cannot be separately quantified at 3 T. Our results show that longer stimulations produce smaller concentration changes in Pi/α-ATP and (NADH + NAD(+))/α-ATP ratios, which suggests a possible adaptation effect during longer stimulations that leads metabolic concentrations towards the initial equilibrium.

Hand differences in aiming task: A complementary spatial approach and analysis of dynamic brain networks with EEG.

Left and right-hand exhibit differences in the execution of movements. Particularly, it has been shown that manual goal-directed aiming is more accurate with the right hand than with the left, which has been explained through the shorter time spent by the right hand in the feedback phase (FB). This explanation makes sense for the temporal aspects of the task; however, there is a lack of explanations for the spatial aspects. The present study hypothesizes that the right hand is more associated with the FB, while the left hand is more strongly associated with the pre-programming phase (PP). In addition, the present study aims to investigate differences between hands in functional brain connectivity (FBC). We hypothesize an increase in FBC of the right hand compared to the left hand. Twenty-two participants performed 20 trials of the goal-directed aiming task with both hands. Overall, the results confirm the study's hypotheses. Although the right hand stopped far from the target at the PP, it exhibited a lower final position error than the left hand. These findings imply that during the FB, the right hand compensates for the higher error observed in the PP, using the visual feedback to approach the target more closely than the left hand. Conversely, the left hand displayed a lower error at the PP than the right. Also, the right hand displayed greater FBC within and between brain hemispheres. This heightened connectivity in the right hand might be associated with inhibitory mechanisms between hemispheres.

Enhanced Diagnostic Precision: Assessing Tumor Differentiation in Head and Neck Squamous Cell Carcinoma Using Multi-Slice Spiral CT Texture Analysis.

This study explores the efficacy of texture analysis by using preoperative multi-slice spiral computed tomography (MSCT) to non-invasively determine the grade of cellular differentiation in head and neck squamous cell carcinoma (HNSCC). In a retrospective study, MSCT scans of patients with HNSCC were analyzed and classified based on its histological grade as moderately differentiated, well-differentiated, or poorly differentiated. The location of the tumor was categorized as either in the bone or in soft tissues. Segmentation of the lesion areas was conducted, followed by texture analysis. Eleven GLCM parameters across five different distances were calculated. Median values and correlations of texture parameters were examined in relation to tumor differentiation grade by using Spearman's correlation coefficient and Kruskal-Wallis and Dunn tests. Forty-six patients were included, predominantly female (87%), with a mean age of 66.7 years. Texture analysis revealed significant parameter correlations with histopathological grades of tumor differentiation. The study identified no significant age correlation with tumor differentiation, which underscores the potential of texture analysis as an age-independent biomarker. The strong correlations between texture parameters and histopathological grades support the integration of this technique into the clinical decision-making process.

Texture analysis of magnetic resonance images of patients with juvenile myoclonic epilepsy.

BACKGROUND/PURPOSE: Juvenile myoclonic epilepsy (JME) is the most frequent subsyndrome of the idiopathic generalized epilepsies, and experimental investigations support that the thalamus is a key structure in the mechanisms of JME. Texture analysis (TA) is an image processing technique which can be used to characterize images such as MRI. OBJECTIVE: The goal of this work was to investigate the thalamus of patients with JME using TA, a quantitative neuroimaging technique. METHODS: Patients and controls were submitted to MRI investigation. Images were acquired in a 2-Tesla scanner. The T1 volumetric sequence was used for thalamic segmentation and extraction of texture parameters. Twenty-four patients with a diagnosis of JME and 20 healthy volunteers were investigated. RESULTS: Texture analysis revealed differences between the right thalamus of patients and controls. CONCLUSIONS: The present investigation supports the participation of the thalamus in the disease mechanisms of JME. Texture analysis may be a useful tool in the quantitative neuroimaging investigation of the epilepsies and can be important to understand JME.

Texture-based brain networks for characterization of healthy subjects from MRI.

Brain networks have been widely used to study the relationships between brain regions based on their dynamics using, e.g. fMRI or EEG, and to characterize their real physical connections using DTI. However, few studies have investigated brain networks derived from structural properties; and those have been based on cortical thickness or gray matter volume. The main objective of this work was to investigate the feasibility of obtaining useful information from brain networks derived from structural MRI, using texture features. We also wanted to verify if texture brain networks had any relation with established functional networks. T1-MR images were segmented using AAL and texture parameters from the gray-level co-occurrence matrix were computed for each region, for 760 subjects. Individual texture networks were used to evaluate the structural connections between regions of well-established functional networks; assess possible gender differences; investigate the dependence of texture network measures with age; and single out brain regions with different texture-network characteristics. Although around 70% of texture connections between regions belonging to the default mode, attention, and visual network were greater than the mean connection value, this effect was small (only between 7 and 15% of these connections were larger than one standard deviation), implying that texture-based morphology does not seem to subside function. This differs from cortical thickness-based morphology, which has been shown to relate to functional networks. Seventy-five out of 86 evaluated regions showed significant (ANCOVA, p < 0.05) differences between genders. Forty-four out of 86 regions showed significant (ANCOVA, p < 0.05) dependence with age; however, the R2 indicates that this is not a linear relation. Thalamus and putamen showed a very unique texture-wise structure compared to other analyzed regions. Texture networks were able to provide useful information regarding gender and age-related differences, as well as for singling out specific brain regions. We did not find a morphological texture-based subsidy for the evaluated functional brain networks. In the future, this approach will be extended to neurological patients to investigate the possibility of extracting biomarkers to help monitor disease evolution or treatment effectiveness.

Graph analysis of cortical reorganization after virtual reality-based rehabilitation following stroke: a pilot randomized study.

Introduction: Stroke is the leading cause of functional disability worldwide. With the increase of the global population, motor rehabilitation of stroke survivors is of ever-increasing importance. In the last decade, virtual reality (VR) technologies for rehabilitation have been extensively studied, to be used instead of or together with conventional treatments such as physiotherapy or occupational therapy. The aim of this work was to evaluate the GestureCollection VR-based rehabilitation tool in terms of the brain changes and clinical outcomes of the patients. Methods: Two groups of chronic patients underwent a rehabilitation treatment with (experimental) or without (control) complementation with GestureCollection. Functional magnetic resonance imaging exams and clinical assessments were performed before and after the treatment. A functional connectivity graph-based analysis was used to assess differences between the connections and in the network parameters strength and clustering coefficient. Results: Patients in both groups showed improvement in clinical scales, but there were more increases in functional connectivity in the experimental group than in the control group. Discussion: The experimental group presented changes in the connections between the frontoparietal and the somatomotor networks, associative cerebellum and basal ganglia, which are regions associated with reward-based motor learning. On the other hand, the control group also had results in the somatomotor network, in its ipsilateral connections with the thalamus and with the motor cerebellum, which are regions more related to a purely mechanical activity. Thus, the use of the GestureCollection system was successfully shown to promote neuroplasticity in several motor-related areas.

Effects of virtual reality-based motor rehabilitation: a systematic review of fMRI studies.

Background.The use of virtual reality (VR) as a rehabilitation tool has been shown to induce motor and cognitive improvements in different populations. Functional magnetic resonance imaging (fMRI) has been used to investigate neuroplasticity resulting from these treatments. We hypothesize that VR rehabilitation induces functional improvement and brain changes that can be detected by fMRI.Objective.To systematically review the effects of VR intervention on the cortical reorganization measured by fMRI and associated with functional improvement.Approach.We performed a systematic review of studies published between 2005 and 2021. Papers were retrieved from six databases using the following keywords: 'motor rehabilitation', 'fMRI' and 'virtual reality'. Case studies, pre-post studies, cross-sectional studies, and randomized controlled trials published were included. Manuscripts were assessed by The National Institutes of Health study quality assessment tools to determine their quality.Main results.Twenty-three articles met our eligibility criteria: 18 about VR rehabilitation in stroke and five on other clinical conditions (older adults, cerebral palsy, and Parkinson's disease). Changes in neural patterns of activation and reorganization were revealed in both the ipsilesional and the contralesional hemispheres. Results were located mainly in the primary motor cortex, sensorimotor cortex and supplementary motor area in post-stroke patients in the acute, subacute, and chronic rehabilitation phases, and were associated with functional improvement after VR intervention. Similar effects were observed in older adults and in patients with other neurological diseases with improved performance.Significance.Most stroke-related studies showed either restoration to normal or increase of activation patterns or relateralization at/to the ipsilesional hemisphere, with some also reporting a decrease in activity or extent of activation after VR therapy. In general, VR intervention demonstrated evidence of efficacy both in neurological rehabilitation and in performance improvement of older adults, accompanied by fMRI evidence of brain reorganization.

Magnetic resonance imaging texture analysis to differentiate ameloblastoma from odontogenic keratocyst.

The differentiation between ameloblastoma (AB) and odontogenic keratocyst (OKC) is essential for the formulation of the surgical plan, especially considering the biological behavior of these two pathological entities. Therefore, developing means to increase the accuracy of the diagnostic process is extremely important for a safe treatment. The aim of this study was to use magnetic resonance imaging (MRI) based on texture analysis (TA) as an aid in differentiating AB from OKC. This study comprised 18 patients; eight patients with AB and ten with OKC. All diagnoses were determined through incisional biopsy and later through histological examination of the surgical specimen. MRI was performed using a 3 T scanner with a neurovascular coil according to a specific protocol. All images were exported to segmentation software in which the volume of interest (VOI) was determined by a radiologist, who was blind to the histopathological results. Next, the textural parameters were computed by using the MATLAB software. Spearman's correlation coefficient was used to assess the correlation between texture parameters and the selected variables. Differences in TA parameters were compared between AB and OKC by using the Mann-Whitney test. Mann-Whitney test showed a statistically significant difference between AB and OKC for the parameters entropy (P = 0.033) and sum average (P = 0.033). MRI texture analysis has the potential to discriminate between AB and OKC as a noninvasive method. MRI texture analysis can be an additional tool to differentiate ameloblastoma from odontogenic keratocyst.

Motor imagery practice and feedback effects on functional connectivity.

- Objective: the use of motor imagery (MI) in motor rehabilitation protocols has been increasingly investigated as a potential technique for enhancing traditional treatments, yielding better clinical outcomes. However, since MI performance can be challenging, practice is usually required. This demands appropriate training, actively engaging the MI-related brain areas, consequently enabling the user to properly benefit from it. The role of feedback is central for MI practice. Yet, assessing which underlying neural changes are feedback-specific or purely due to MI practice is still a challenging effort, mainly due to the difficulty in isolating their contributions. In this work, we aimed to assess functional connectivity (FC) changes following MI practice that are either extrinsic or specific to feedback. APPROACH: to achieve this, we investigated FC, using graph theory, in electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) data, during MI performance and at resting-state (rs), respectively. Thirty healthy subjects were divided into three groups, receiving no feedback (control), "false" feedback (sham) or actual neurofeedback (active). Participants underwent 12 to 13 hands-MI EEG sessions and pre- and post-MI training fMRI exams. MAIN RESULTS: following MI practice, control participants presented significant increases in degree and in eigenvector centrality for occipital nodes at rs-fMRI scans, whereas sham-feedback produced similar effects, but to a lesser extent. Therefore, MI practice, by itself, seems to stimulate visual information processing mechanisms that become apparent during basal brain activity. Additionally, only the active group displayed decreases in inter-subject FC patterns, both during MI performance and at rs-fMRI. SIGNIFICANCE: hence, actual neurofeedback impacted FC by disrupting common inter-subject patterns, suggesting that subject-specific neural plasticity mechanisms become important. Future studies should consider this when designing experimental NFBT protocols and analyses.

EEG Signal Connectivity for Characterizing Interictal Activity in Patients With Mesial Temporal Lobe Epilepsy.

Over the last decade, several methods for analysis of epileptiform signals in electroencephalography (EEG) have been proposed. These methods mainly use EEG signal features in either the time or the frequency domain to separate regular, interictal, and ictal brain activity. The aim of this work was to evaluate the feasibility of using functional connectivity (FC) based feature extraction methods for the analysis of epileptiform discharges in EEG signals. These signals were obtained from EEG-fMRI sessions of 10 patients with mesial temporal lobe epilepsy (MTLE) with unilateral hippocampal atrophy. The connectivity functions investigated were motif synchronization, imaginary coherence, and magnitude squared coherence in the alpha, beta, and gamma bands of the EEG. EEG signals were sectioned into 1-s epochs and classified according to (using neurologist markers): activity far from interictal epileptiform discharges (IED), activity immediately before an IED and, finally, mid-IED activity. Connectivity matrices for each epoch for each FC function were built, and graph theory was used to obtain the following metrics: strength, cluster coefficient, betweenness centrality, eigenvector centrality (both local and global), and global efficiency. The statistical distributions of these metrics were compared among the three classes, using ANOVA, for each FC function. We found significant differences in all global (p < 0.001) and local (p < 0.00002) graph metrics of the far class compared with before and mid for motif synchronization on the beta band; local betweenness centrality also pointed to a degree of lateralization on the frontotemporal structures. This analysis demonstrates the potential of FC measures, computed using motif synchronization, for the characterization of epileptiform activity of MTLE patients. This methodology may be helpful in the analysis of EEG-fMRI data applied to epileptic foci localization. Nonetheless, the methods must be tested with a larger sample and with other epileptic phenotypes.

Dynamic changes in white and gray matter volume are associated with outcome of surgical treatment in temporal lobe epilepsy.

BACKGROUND: The reasons for surgical failure in 30% of patients with unilateral mesial temporal lobe epilepsy (MTLE) are still unclear. We investigated if different outcomes could be associated to different patterns of subtle gray matter atrophy (GMA) and white matter atrophy (WMA), and searched for postoperative magnetic resonance imaging (MRI) changes. METHODS: We studied 69 controls and 67 operated patients with refractory unilateral MTLE. Patients were grouped as seizure-free (SF) group (34 patients Engel's IA), worthwhile improvement group (23 patients, Engel's IB-IIA) and failure group (10 patients Engel's IIB-IV). We created a voxel-based morphometry/MATLAB code to mask the surgical lacuna, and performed t-test and paired t-test to evaluate preoperative and postoperative MRI scans. RESULTS: Failure group showed a widespread pattern of preoperative GMA. On SF and improvement groups we identified a more restricted pattern of GMA. The three groups presented a widespread, bilateral pattern of WMA. In contrast, postoperative analyses showed bilateral hemispheric recovery (a relative increase of WM concentration) on SF and improvement groups, but few changes on failure group. We also identified areas with relative postoperative increase of GM on both SF and improvement groups, more widespread on SF group. CONCLUSION: Areas of subtle GMA may be related to poorer surgical outcome. In addition, we demonstrated a postoperative relative increase of WM and GM concentration associated with seizure control. These changes may represent neuroplasticity related to improvement of brain function after seizure control. Further studies with a multimodal approach may help to predict surgical outcome and improve selection of patients for surgical treatment of MTLE.

Asymmetrical hippocampal connectivity in mesial temporal lobe epilepsy: evidence from resting state fMRI.

BACKGROUND: Mesial temporal lobe epilepsy (MTLE), the most common type of focal epilepsy in adults, is often caused by hippocampal sclerosis (HS). Patients with HS usually present memory dysfunction, which is material-specific according to the hemisphere involved and has been correlated to the degree of HS as measured by postoperative histopathology as well as by the degree of hippocampal atrophy on magnetic resonance imaging (MRI). Verbal memory is mostly affected by left-sided HS, whereas visuo-spatial memory is more affected by right HS. Some of these impairments may be related to abnormalities of the network in which individual hippocampus takes part. Functional connectivity can play an important role to understand how the hippocampi interact with other brain areas. It can be estimated via functional Magnetic Resonance Imaging (fMRI) resting state experiments by evaluating patterns of functional networks. In this study, we investigated the functional connectivity patterns of 9 control subjects, 9 patients with right MTLE and 9 patients with left MTLE. RESULTS: We detected differences in functional connectivity within and between hippocampi in patients with unilateral MTLE associated with ipsilateral HS by resting state fMRI. Functional connectivity resulted to be more impaired ipsilateral to the seizure focus in both patient groups when compared to control subjects. This effect was even more pronounced for the left MTLE group. CONCLUSIONS: The findings presented here suggest that left HS causes more reduction of functional connectivity than right HS in subjects with left hemisphere dominance for language.

Proton MRS may predict AED response in patients with TLE.

PURPOSE: To compare relative N-acetylaspartate (NAA) measurements in temporal lobe epilepsy (TLE) patients with good response to the first trial of antiepileptic drugs (AEDs) (an important prognostic factor) to TLE patients who failed the first AED monotherapy and required further AED trials with monotherapy or polytherapy. METHODS: We studied 25 consecutive TLE patients who responded to first AED (responders) and 21 who did not (failure-group), as well as 27 controls. Patients were seen regularly in our Epilepsy Service and underwent electroencephalography (EEG) investigation, high-resolution magnetic resonance imaging (MRI), and single-voxel proton MR spectroscopy. Voxels were tailored to the medial temporal region on each side and involved the anterior hippocampus. RESULTS: Analysis of variance (ANOVA) demonstrated significant variation of NAA/creatine (NAA/Cr) values in both hippocampi, ipsilateral and contralateral to the EEG focus (p < 0.001 and p = 0.021) across the groups. Pairwise post hoc comparisons showed reduced NAA/Cr in both hippocampi of failure-group compared to controls (p < 0.001) and compared to responders (p < 0.05), but not between the controls and responders. Individual analyses showed NAA/Cr ratios lower than 2 SDs (standard deviations) below the mean of controls in 9 of 21 patients (42.8%) in the failure-group (6 with unilateral and 3 with bilateral reduction) but in none of the responders. DISCUSSION: These results indicate that patients with TLE who respond well to the first AED have significantly less evidence of neuronal and axonal damage/dysfunction compared to those who are refractory to the first AED trial.

Channel capacity in brain-computer interfaces.

OBJECTIVE: Adapted from the concept of channel capacity, the information transfer rate (ITR) has been widely used to evaluate the performance of a brain-computer interface (BCI). However, its traditional formula considers the model of a discrete memoryless channel in which the transition matrix presents very particular symmetries. As an alternative to compute the ITR, this work indicates a more general closed-form expression-also based on that channel model, but with less restrictive assumptions-and, with the aid of a selection heuristic based on a wrapper algorithm, extends such formula to detect classes that deteriorate the operation of a BCI system. APPROACH: The benchmark is a steady-state visually evoked potential (SSVEP)-based BCI dataset with 40 frequencies/classes, in which two scenarios are tested: (1) our proposed formula is used and the classes are gradually evaluated in the order of the class labels provided with the dataset; and (2) the same formula is used but with the classes evaluated progressively by a wrapper algorithm. In both scenarios, the canonical correlation analysis (CCA) is the tool to detect SSVEPs. MAIN RESULTS: Before and after class selection using this alternative ITR, the average capacity among all subjects goes from 3.71 [Formula: see text] 1.68 to 4.79 [Formula: see text] 0.70 bits per symbol, with p -value <0.01, and, for a supposedly BCI-illiterate subject, her/his capacity goes from 1.53 to 3.90 bits per symbol. SIGNIFICANCE: Besides indicating a consistent formula to compute ITR, this work provides an efficient method to perform channel assessment in the context of a BCI experiment and argues that such method can be used to study BCI illiteracy.