Left White Matter Research Articles

The persistent crucial role of the left hemisphere for language in left-handers with a left low grade glioma: a stimulation mapping study

Left-handers have a more bilateral language representation than right-handers. Therefore, in left-handers with a low-grade glioma (LGG) in the left hemisphere (LH), one could hypothesize that the right hemisphere (RH) might allow language compensation, at least partly, with no or only a minor persistent role of the LH in speech. However, although LGG induces language reorganization in right-handed patients, little is known in left-handers. Here, we report the first series of left-handers who underwent awake surgery for a left LGG using intraoperative mapping, in order to investigate whether there was still an involvement of LH in language. Ten consecutive left-handed patients were operated for a left LGG (three frontal, four paralimbic, one parietal, one temporal, one parieto-temporal tumor) using an awake procedure with intraoperative electrical language mapping. Intraoperative language disorders were elicited in all cases but one by electrostimulation in the LH. Cortical language sites were detected in nine cases. Subcortical stimulation also demonstrated the crucial role of left white matter pathways in language, including the inferior occipital-frontal fascicle, arcuate fascicle, lateral segment of the superior longitudinal fascicle and fibers from the ventral premotor cortex. Moreover, stimulation of deep gray nuclei generated language disturbances in four patients. These nine patients experienced transient postoperative language worsening, supporting the persistent critical role of LH in speech. In only one patient, no language deficit was evoked intraoperatively and postoperatively. The ten patients returned to a normal life. Total or subtotal resection was achieved in all cases but one. Our results suggest that, even though the RH may participate in language compensation, the LH in left-handers still plays a crucial role, despite a left slow-growing LGG. Thus, we propose to routinely consider awake surgery for left LGG removal in left-handers patients, to optimize the extent of resection while preserving language.

Correlations of ADHD symptoms with neurometabolites measured by 1H magnetic resonance spectroscopy.

Despite the number of studies on neurometabolite changes in ADHD (Attention deficit/hyperactivity disorder), there is lack of evidence on neurometabolite associations with ADHD symptoms. We aimed to find the correlations of neurometabolites with ADHD symptoms. Twenty ADHD children were examined by means of 1H-MRS. The spectra were taken from dorsolateral prefrontal cortex (DLPFC) and white matter behind DLPFC, bilaterally. Neurometabolites were correlated with ADHD-RS-IV (ADHD-Rating Scales IV), CPRS (Conners Parent rating Scale) and DPREMB (Daily Parent Rating of Evening and Morning Behavior) scores. NAA/Cr (N-acetylaspartate/creatine) in the right DLPFC positively correlated with CPRS subscale IV learning problems and negatively correlated in the left white matter with DPREMB morning behavior subscale and ADHD-RS-IV score. Glx/Cr (glutamate + glutamine/creatine) positively correlated in the right white matter with ADHD-RS-IV and negatively correlated in the left white matter with DPREMB morning behavior subscale score. Cho/Cr (choline/creatine) in the left white matter negatively correlated with DPREMB morning behavior subscale and ADHD-RS-IV score. ADHD symptoms could result from different activities of the left- and right-hemisphere prefrontal circuits. In consequence to impulses to novel task searching the increased right prefrontal circuit activity could be mediated by different motivational control (Fig. 9, Ref. 73).

Central Nervous System Venulitis Presenting as Migraine

To describe a case of pediatric central nervous system (CNS) venulitis. Primary angiitis of the CNS is a rare but increasingly well-recognized cause of morbidity in children. It primarily involves the arteries and arterioles of the CNS, with only 1 published case of a pediatric patient found to have isolated CNS venulitis on brain biopsy. A 17-year-old female with a 4-year history of migraines presented with increasingly frequent migraines and right-sided hemiplegia. Infectious, hematologic, and rheumatologic work-ups were negative. Brain magnetic resonance imaging showed multiple rim-enhancing lesions consistent with calcifications affecting the deep left white matter. On brain biopsy, there was evidence of an inflammatory process involving small veins and venules. The patient displayed clinical improvement with a course of high-dose steroids and 6 monthly cyclophosphamide infusions followed by maintenance therapy with mycophenolate mofetil. We describe a case of pediatric CNS venulitis presenting with migraine.

White matter lateralization and interhemispheric coherence to auditory modulations in normal reading and dyslexic adults

Neural activation of slow acoustic variations that are important for syllable identification is more lateralized to the right hemisphere than activation of fast acoustic changes that are important for phoneme identification. It has been suggested that this complementary function at different hemispheres is rooted in a different degree of white matter myelination in the left versus right hemisphere.The present study will investigate this structure–function relationship with Diffusion Tensor Imaging (DTI) and Auditory Steady-State Responses (ASSR), respectively. With DTI we examined white matter lateralization in the cortical auditory and language regions (i.e. posterior region of the superior temporal gyrus and the arcuate fasciculus) and white matter integrity in the splenium of the corpus callosum. With ASSR we examined interhemispheric coherence to slow, syllabic-rate (i.e. 4Hz) and fast, phonemic-rate (i.e. 20Hz) modulations. These structural and functional techniques were applied in a group of normal reading adults and a group of dyslexic adults for whom previously reduced functional interhemispheric connectivity at 20Hz has been reported (Poelmans et al. (2012). Ear and Hearing, 33, 134–143). This sample was chosen since it is hypothesized that in dyslexic readers insufficient hemispheric asymmetry in myelination might relate to their auditory and phonological problems.Results demonstrate reduced white matter lateralization in the posterior superior temporal gyrus and the arcuate fasciculus in the dyslexic readers. Additionally, white matter lateralization in the posterior superior temporal gyrus and white matter integrity in the splenium of the corpus callosum related to interhemispheric coherence to phonemic-rate modulations (i.e. 20Hz). Interestingly, this correlation pattern was opposite in normal versus dyslexic readers. These results might imply that less pronounced left white matter dominance in dyslexic adults might relate to their problems to process phonemic-rate acoustic information and to integrate them into the phonological system.

Clinicoradiological changes of brain NK/T cell lymphoma manifesting pure akinesia: a case report

BackgroundPure akinesia (PA) is a distinct form of parkinsonism characterized by freezing phenomena. Little is known about brain tumor-associated PA. We highlight the clinicoradiological changes in a patient with PA and central nervous system (CNS) metastases of natural killer/T-cell lymphoma (NKTL).Case presentationA 68-year-old man with stage IVB extranodal NKTL developed a gait disturbance. Neurological examination of his gait revealed freezing, start hesitation, short step, forward flexion posture, festination and postural instability. Mild facial hypomimia and micrographia were observed. There was no rigidity or tremor in any of the four extremities. Brain magnetic resonance imaging (MRI) displayed T2-hyperintense lesions in the dorsal brainstem, cerebellum and periventricular white matter. Diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC) revealed hyperintensity in these regions. Cerebrospinal fluid cytology revealed CD56-positive cells on immunohistochemical staining. The patient's neurological deficits did not respond to L-dopa treatment and intrathecal administration of methotrexate (MTX). Two weeks later, he displayed confusion and generalized convulsions. T2-hyperintense lesions spread to the basal ganglia and the infratentorial regions. Gadolinium enhancement was observed in the cerebellum and frontal subcortex. DWI and the ADC revealed diffusion-restricted lesions in the middle cerebellar peduncles, left internal capsules and cerebral white matter. MTX pulse therapy and intrathecal administration of cytosine arabinoside and MTX were performed. Two months later, his ambulatory state was normalized. Brain MRI also revealed marked alleviation of the infratentorial and supratentorial lesions.ConclusionsThe clinicoradiological profile of our patient suggested that dorsal ponto-mesencephalic lesions could contribute to the pathogenesis of PA. Physicians should pay more attention to striking CNS seeding of metastatic NKTL. MTX pulse therapy had an excellent effect in improving serious symptoms and brain lesions in our patient.

Amblyopic dyslexia: A little investigated reading disorder

We present a case of a little investigated reading disorder we call ‘amblyopic dyslexia’. The reading impairment in this patient resulted from a left extrastriate and white matter lesion causing a scotomatic area of partial deficit within the right visual field. The visual deficit was consistent with cerebral amblyopia, that is, reduced form, colour, and light sensitivity without a complete loss of vision. The patient's reading deficit was characterized by accurate single letter naming and almost accurate but effortful single word reading, with no letter-by-letter strategy. The criteria for distinguishing amblyopic dyslexia from other reading disorders and the most appropriate treatment are discussed.

Can PET/CT imaging advance our understanding of the neurobiology of schizophrenia?

Schizophrenia is a severe psychiatric disorder affecting approximately 1% of the population worldwide. The disorder is ranked among the top 10 causes of disability worldwide. New drugs and therapeutic interventions are therefore warranted to reduce symptomatology, delay onset, or potentially cure this devastating disorder. This would greatly help individuals in the early stages of schizophrenia. Although schizophrenia has a strong genetic basis (80%), owing to the nature of the neurobiological and genetic heterogeneity of the disorder, its a etiology has remained elusive. Schizophrenia is characterized by psychotic symptoms, emotional disturbances, and cognitive dysfunction. These symptoms may be the result of dopamine dysregulation in individuals with schizophrenia [1]. Advances in anatomical and functional imaging have provided useful insights into the neurobiological mechanisms of schizophrenia, enabling brain function to be studied at a molecular level. Recent imaging investigations using computed tomography (CT) and magnetic resonance imaging (MRI) have reported grey matter reduction and ventricular enlargement in schizophrenia [2], and functional MRI studies have reported abnormalities in the frontotemporal and frontoparietal function regions. Diffusion tensor imaging is used to provide an insight into white matter tract integrity and regional cerebral connectivity. Recent studies show abnormalities in frontoparietal and left cerebellar white matter tract integrity in schizophrenia [3]. Positron emission tomography (PET) is an effective functional imaging technique that uses radioactive tracers to help identify regions associated with brain function. It has been used to detect levels of dopaminergic activity in individuals with major psychiatric disorders. The most consistent findings from adult-onset schizophrenia studies are differences in dopaminergic content in the prefrontal cortex (PFC), anterior cingulate gyrus, and hippocampus between normal controls and patients with schizophrenia. Several PET tracers have been used to identify brain

Gray, White Matter Concentration Changes and Their Correlation with Heterotopic Neurons in Temporal Lobe Epilepsy

ObjectiveTo identify changes in gray and white matter concentrations (GMC, WMC), and their relation to heterotopic neuron numbers in mesial temporal lobe epilepsy (mTLE).Materials and MethodsThe gray matter or white matter concentrations of 16 left and 15 right mTLE patients who achieved an excellent surgical outcome were compared with those of 24 healthy volunteers for the left group and with 23 healthy volunteers for the right group, by optimized voxel-based morphometry using unmodulated and modulated images. A histologic count of heterotopic neurons was obtained in the white matter of the anterior temporal lobe originating from the patients' surgical specimens. In addition, the number of heterotopic neurons were tested to determine if there was a correlation with the GMC or WMC.ResultsThe GMCs of the left and right mTLE groups were reduced in the ipsilateral hippocampi, bilateral thalami, precentral gyri, and in the cerebellum. The WMCs were reduced in the ipsilateral white matter of the anterior temporal lobe, bilateral parahippocampal gyri, and internal capsules, but increased in the pons and bilateral precentral gyri. The heterotopic neuron counts in the left mTLE group showed a positive correlation (r = 0.819, p < 0.0001) with GMCs and a negative correlation (r = -0.839, p < 0.0001) with WMCs in the white matter of the anterior temporal lobe. ConclusionThe present study shows the abnormalities of the cortico-thalamo-hippocampal network including a gray matter volume reduction in the anterior frontal lobes and an abnormality of brain tissue concentration in the pontine area. Furthermore, heterotopic neuron numbers were significantly correlated with GMC or WMC in the left white matter of anterior temporal lobe.

Concordant anatomical and functional connectivity changes in developmental stuttering

Stuttering is based on a maldevelopment of speech-relevant brain regions and is associated later in life with left perisylvian grey and white matter anomalies and right-hemispheric functional compensation attempt. We hypothesized that in adult stutterers left-hemispheric structural anomalies alter the functional connectivity of the speech production network which prompts stutterers to use right-hemispheric strategies to reduce symptoms. To study anatomical and functional connectivity during overt reading, we performed a structural (DTI) and functional (EPI) study on 13 male adult stutterers and 13 male matched fluent control subjects. Anatomical connectivity was assessed by comparing values of fractional anisotropy using TBSS for FSL and functional connectivity was studied by comparing psychophysiological interactions for overt>covert reading in SPM. Anatomical connectivity changes were restricted to the left hemisphere: We confirmed (Sommer et al., Lancet 2002) an FA reduction below the somatomotor representation of articulation and found pathologically enhanced FA values in fibre tracts below the left inferior frontal gyrus, anterior insula and in the anterior segment of the arcuate fasciculus. The increases and decreases of anatomical connectivity were accompanied by similar changes in functional connectivity of the corresponding brain regions: Functional connectivity during overt>covert reading was reduced between the articulatory motor cortex and the superior temporal gyrus while it was enhanced between the inferior frontal and the supramarginal gyrus compared to fluent controls. We interpret the concordant alterations in functional connectivity in adult stutterers as a consequence of pathological anatomical connectivity on the basis of a left perisylvian maldevelopment in early childhood. Thus, linking comparative analyses of anatomical and functional connectivity helps understanding how structural pathology translates into dysfunction.

White matter microstructures underlying mathematical abilities in children

The role of gray matter function and structure in mathematical cognition has been well researched. Comparatively little is known about white matter microstructures associated with mathematical abilities. Diffusion tensor imaging data from 13 children (7-9 years) and two measures of their mathematical competence were collected. Relationships between children's mathematical competence and fractional anisotropy were found in two left hemisphere white matter regions. Although the superior corona radiata was found to be associated with both numerical operations and mathematical reasoning, the inferior longitudinal fasciculus was correlated with numerical operations specifically. These findings suggest a role for microstructure in left white matter tracts for the development of mathematical skills. Moreover, the findings point to the involvement of different white matter tracts for numerical operations and mathematical reasoning.

Voxel-based morphometry study on brain structure in children with high-functioning autism

Earlier studies have suggested abnormal brain volumes in autism, but inconsistencies exist. Using voxel-based morphometry, we compared global and regional brain volumes in 17 high-functioning autistic children with 15 matched controls. We identified significant reduction in left white matter volume and white/gray matter ratio in autism. Regional brain volume reductions were detected for right anterior cingulate, left superior parietal lobule white matter volumes, and right parahippocampal gyrus gray matter volume, whereas enlargements in bilateral supramarginal gyrus, right postcentral gyrus, right medial frontal gyrus, and right posterior lobe of cerebellum gray matter in autism. Our findings showed global and regional brain volumes abnormality in high-functioning autism.

Brain anatomy differences in childhood stuttering

Stuttering is a developmental speech disorder that occurs in 5% of children with spontaneous remission in approximately 70% of cases. Previous imaging studies in adults with persistent stuttering found left white matter deficiencies and reversed right–left asymmetries compared to fluent controls. We hypothesized that similar differences might be present indicating brain development differences in children at risk of stuttering. Optimized voxel-based morphometry compared gray matter volume (GMV) and diffusion tensor imaging measured fractional anisotropy (FA) in white matter tracts in 3 groups: children with persistent stuttering, children recovered from stuttering, and fluent peers. Both the persistent stuttering and recovered groups had reduced GMV from normal in speech-relevant regions: the left inferior frontal gyrus and bilateral temporal regions. Reduced FA was found in the left white matter tracts underlying the motor regions for face and larynx in the persistent stuttering group. Contrary to previous findings in adults who stutter, no increases were found in the right hemisphere speech regions in stuttering or recovered children and no differences in right–left asymmetries. Instead, a risk for childhood stuttering was associated with deficiencies in left gray matter volume while reduced white matter integrity in the left hemisphere speech system was associated with persistent stuttering. Anatomical increases in right hemisphere structures previously found in adults who stutter may have resulted from a lifetime of stuttering. These findings point to the importance of considering the role of neuroplasticity during development when studying persistent forms of developmental disorders in adults.

Sex differences in the relationship between white matter microstructure and impulsivity in adolescents

Rapid maturational brain changes occur during adolescence--a time associated with risk-taking behaviors and improvements in cognition. The present study examined the relationship between white matter (WM) microstructure, impulsive behavior and response inhibition in female and male adolescents. Twenty-one healthy adolescents underwent diffusion tensor imaging using a 3.0-T magnetic resonance imaging system. Impulse control was assessed using the Bar-On Emotional Quotient Inventory, Youth Version. Response inhibition was assessed using the Stroop Color-Word Interference Test. Fractional anisotropy (FA), a measure of WM coherence, and trace, a measure of overall diffusivity, were determined from voxels manually placed in the midline and in the left and right forward-projecting arms of the genu and the splenium of the corpus callosum. Sex-specific differences were observed for the relationship between FA and impulsive behavior in the right anterior callosum for males and in the splenium for females. Males, compared to females, displayed significantly higher FA in the left WM region. Although trace was not associated with impulse control, trace in the genu (for females) and splenium (males and females) was associated with Stroop performance. Regional differences in trace also were evident, with lower values in the splenium observed than in all other regions. Although the latter significantly improved with age, no sex differences in impulse control or in Stroop performance were detected. The present findings provide supporting evidence for sex-related differences in the development of WM microstructure during adolescence. These data further suggest a neurobiological mechanism underlying some of the emotional and cognitive changes commonly observed in males versus females during the adolescent period.

Effects of X-monosomy and X-linked imprinting on superior temporal gyrus morphology in Turner syndrome

Background Turner syndrome (TS) results from complete or partial monosomy X. The cognitive phenotype of TS involves preservation of verbal skills with visuospatial functioning deficits. The superior temporal gyrus (STG), which is involved in language capacities, has not been investigated in TS. Methods The STG was measured in 30 female subjects (mean age = 14.73 ± 6.41; range = 7.56–33.30) with TS and 30 age-matched control subjects (mean age = 14.63 ± 5.90; range = 6.35–32.65) using volumetric magnetic resonance imaging analyses. Results Right STG, including both gray and white matter volumes, was significantly larger in TS compared with control subjects. Overall left STG volume was not significantly different between groups, although left white matter volume was increased in the TS subjects. The TS subgroup with a maternally derived X chromosome (Xm) demonstrated more aberrant STG volumes compared with subjects with a paternally (Xp) derived X and control subjects. The difference in STG volumes between Xm and control subjects involved both white and gray matter. The Xm subjects differed from Xp subjects only in terms of gray matter. Conclusions These findings suggest that X-monosomy and X-linked imprinting negatively affect STG development, possibly by disrupting neural pruning mechanisms.

Analysis of asymmetry in 2D and 1D projections of left and right cerebral hemisphere grey and white matter

Analysis of asymmetry in 2D and 1D projections of left and right cerebral hemisphere grey and white matter

Gerstmann Syndrome in Systemic Lupus Erythematosus: Neuropsychological, Neuroimaging and Spectroscopic Findings

Gerstmann syndrome (GS) comprises four interlaced neuropsychological symptoms including finger agnosia, right-left confusion, agraphia, and acalculia. While GS is commonly associated with focal lesions to the region of the left angular gyrus, it has also been associated with numerous diffuse etiologies including atrophy, alcoholism, carbon monoxide poisoning, lead intoxication and anaphylactic shock. Thus, a vigorous debate has emerged as to whether GS represents a syndrome arising from general brain decline or a distinct and localizing lesion. We report a right-handed patient who developed neuropsychological dysfunction secondary to systemic lupus erythematosus (SLE). Neuropsychological evaluation found the patient to exhibit symptoms consistent with the GS tetrad, as well as general cognitive decline. Magnetic resonance imaging revealed a distinct focal lesion of the left parieto-occipital white matter underlying the angular gyrus as well as diffuse atrophy. 1 H-magnetic resonance spectroscopy revealed substantial metabolic derangement in a voxel placed within the visible lesion, although substantial metabolic derangement was observed in regions remote from the focal pathology. Thus, GS in this first case in SLE would appear to comprise a focal neurological tetrad of disorders within a more general pattern of cognitive decline and metabolic derangement.

Reduced regional cerebral blood flow in non-psychotic violent offenders

The present study was designed to replicate previously reported findings of abnormal frontal and/or temporal cerebral blood flow in violent offenders and to control for the influence of major mental disorder (MMD), substance abuse, and current medication. HMPAO-SPECT-CBF and MRI scans from pretrial forensic psychiatric investigations of 21 subjects convicted of impulsive violent crimes were retrospectively re-evaluated. In 16/21 subjects, visual assessment of SPECT scans showed some hypoperfusion in the temporal and/or frontal lobes. MRI showed no corresponding structural damage. Quantified regional cerebral blood flow (rCBF) in defined regions of interest was compared between index cases and 11 healthy control subjects. Index subjects had significant reductions in the right angular gyrus and the right medial temporal gyrus, bilaterally in the hippocampus, and in the left white frontal matter, but they had significantly increased rCBF in the parietal association cortex bilaterally. The aberrations were as frequent and severe among the subjects without MMD, substance abuse, and current medication ( n=7) as in the entire group of index subjects.

A rodent model of infusion brain edema: Methodology and pathophysiological effects of saline and protein infusions

To evaluate the potency of putative secondary mediators of brain edema and their possible contribution to edema related brain dysfunction an infusion model of brain edema was developed in rats. 100 ul of fluid (saline, 20% nonautologous protein) was infused over one hour into the left forebrain white matter through a stereotaxically placed (+1.2 mm ant to bregma, 3 mm lateral and 2.9 mm depth) 25 G needle. Brain tissue hydraulic resistance (Rt), regional cerebral blood flow (rCBF), cortical somatosensory evoked potentials (SEPs) and intracranial pressure (ICP) (intraventricular needle) were monitored during the infusion and rCBF CO2 reactivity (hydrogen clearance), local brain water content (microgravimetry), BBB integrity (Evans Blue 2%) and brain histology (H & E. Solochrome-cyanin) were evaluated after the infusion. Saline infusates caused no physiological dysfunction despite ipsilateral expansion and vacuolation of the subcortical white matter, separation of axonal bundles and a significant decrease (p = 3.8 x 10(-5] in local subcortical tissue specific gravity. Cortical histology and specific gravity adjacent to the infusion locus were normal. Rt significantly decreased (p = 6.5 x 10(-4] during the infusion but there were only minor increases in ICP. Findings with 20% protein infusates were similar despite a focal 65% decrement in the rCBF CO2 reactivity adjacent to the infusion site. This study has shown that a simple and inexpensive model of infusion brain edema can be created in the rat and that it provides a useful model for assessing the physiological effects of mediator compounds in the infusate. Potential applications and methodological improvements for this model are discussed.

Language disturbances following vascular lesions restricted to the left basal ganglia, thalamus, and white matter.

Language disturbances following vascular lesions restricted to the left basal ganglia, thalamus, and white matter.

Language disturbances following vascular lesions restricted to the left basal ganglia, thalamus, and white matter.

Language disturbances following vascular lesions restricted to the left basal ganglia, thalamus, and white matter.