Physical activity and the brain myelin content in humans

New imaging sequences and biophysical models allow adopting magnetic resonance imaging (MRI) for in vivo myelin mapping in humans. Understanding myelination and remyelination processes in the brain is fundamental from the perspective of proper design of physical exercise and rehabilitation schemes that aim to slow down demyelination in the aging population and to induce remyelination in patients with neurodegenerative diseases. Therefore, in this review we strive to provide a state-of-the art summary of the existing MRI studies in humans focused on the effects of physical activity on myelination/remyelination. We present and discuss four cross-sectional and four longitudinal studies and one case report. Physical activity and an active lifestyle have a beneficial effect on the myelin content in humans. Myelin expansion can be induced in humans throughout the entire lifespan by intensive aerobic exercise. Additional research is needed to determine (1) what exercise intensity (and cognitive novelty, which is embedded in the exercise scheme) is the most beneficial for patients with neurodegenerative diseases, (2) the relationship between cardiorespiratory fitness and myelination, and (3) how exercise-induced myelination affect cognitive abilities.

Diagnostic value of diffusion tensor imaging in patients with clinical signs of cervical spondylotic myelopathy

AIM OF THE STUDY

The aim of this study was to assess the diagnostic value of diffusion tensor imaging (DTI) in patients with symptoms of cervical myelopathy. Detailed goals included determining the diagnostic effectiveness of quantitative parameters, i.e. fractional anisotropy (FA) and apparent diffusion coefficient (ADC), in the diagnosis of cervical myelopathy, and the correlation between these parameters and clinical symptoms.

CLINICAL RATIONALE FOR THE STUDY

The demonstration of an ischaemic focus in the spinal cord by standard magnetic resonance imaging (MRI) methods is associated with already accomplished spinal cord damage, and of course limited treatment options. Therefore, finding a new examination protocol that allows early diagnosis of myelopathic focus, before the onset of full neurological symptoms, has become a priority in the diagnosis and treatment of spine diseases. Such an examination increases the chances of correctly qualifying the patient for conservative vs. surgical treatment.

MATERIAL AND METHODS

Between 2013 and 2017, 128 adults with clinical signs of cervical myelopathy were examined, and were divided into four symptomatic subgroups. A control group consisted of 37 healthy volunteers. DTI values were measured at the level of C2/C3, and at the most severe stenosis of the spine.

RESULTS

In patients with cervical spondylotic myelopathy (CSM), the ADC values were significantly higher (p < 0.001), and FA values were significantly lower (p < 0.001), than in healthy volunteers at the stenotic level. There were significant differences in DTI parameters between the clinical subgroups (p < 0.001).

CONCLUSIONS AND CLINICAL IMPLICATIONS

Changes in DTI parameters indicate a microstructural disorder of the core which is not visible in a structural MRI. FA and ADC values measured at the level of the most severe stenosis of the spinal canal allow the differentiation of patients with myelopathy of varying degrees of clinical severity. Extending standard MRI to include assessment of FA and ADC may be helpful in deciding treatment modalities (conservative vs. surgical) for patients with visible canal stenosis without full neurological symptoms. This may be useful in selecting patients for urgent rehabilitative treatment. This study is a starting point for further research, i.e. an evaluation of the extent of FA and ADC lesion withdrawal after surgical treatment.

Cannabis-Associated Psychotic-like Experiences Are Mediated by Developmental Changes in the Parahippocampal Gyrus

OBJECTIVE

Cannabis consumption during adolescence has been reported as a risk factor for psychotic-like experiences (PLEs) and schizophrenia. However, brain developmental processes associated with cannabis-related PLEs are still poorly described.

METHOD

A total of 706 adolescents from the general population who were recruited by the IMAGEN consortium had structural magnetic resonance imaging scans at both 14 and 19 years of age. We used deformation-based morphometry to map voxelwise brain changes between the two time points, using the pairwise algorithm in SPM12b. We used an a priori region-of-interest approach focusing on the hippocampus/parahippocampus to perform voxelwise linear regressions. Lifetime cannabis consumption was assessed using the European School Survey Project on Alcohol and other Drugs (ESPAD), and PLEs were assessed with the Comprehensive Assessment Psychotic-like experiences (CAPE) tool. We first tested whether hippocampus/parahippocampus development was associated with PLEs. Then we formulated and tested an a priori simple mediation model in which uncus development mediates the association between lifetime cannabis consumption and PLEs.

RESULTS

We found that PLEs were associated with reduced expansion within a specific region of the right hippocampus/parahippocampus formation, the uncus (p = .002 at the cluster level, p = .018 at the peak level). The partial simple mediation model revealed a significant total effect from lifetime cannabis consumption to PLEs (b = 0.069, 95% CI = 0.04-0.1, p =2 × 10^-16), as well as a small yet significant, indirect effect of right uncus development (0.004; 95% CI = 0.0004-0.01, p = .026).

CONCLUSION

We show here that the uncus development is involved in the cerebral basis of PLEs in a population-based sample of healthy adolescents.

Neural Correlates of Failed Inhibitory Control as an Early Marker of Disordered Eating in Adolescents

BACKGROUND

Binge eating and other forms of disordered eating behavior (DEB) are associated with failed inhibitory control. This study investigated the neural correlates of failed inhibitory control as a potential biomarker for DEB.

METHODS

The study used prospective longitudinal data from the European IMAGEN study adolescent cohort. Participants completed baseline assessments (questionnaires and a brain scan [functional magnetic resonance imaging]) at 14 years of age and a follow-up assessment (questionnaires) at 16 years of age. Self-reported binge eating and/or purging were used to indicate presence of DEB. Neural correlates of failed inhibition were assessed using the stop signal task. Participants were categorized as healthy control subjects (reported no DEB at both time points), maintainers (reported DEB at both time points), recoverers (reported DEB at baseline only), and developers (reported DEB at follow-up only). Forty-three individuals per group with complete scanning data were matched on gender, age, puberty, and intelligence (N = 172).

RESULTS

At baseline, despite similar task performance, incorrectly responding to stop signals (failed inhibitory control) was associated with greater recruitment of the medial prefrontal cortex and anterior cingulate cortex in the developers compared with healthy control subjects and recoverers.

CONCLUSIONS

Greater recruitment of the medial prefrontal and anterior cingulate regions during failed inhibition accords with abnormal evaluation of errors contributing to DEB development. As this precedes symptom onset and is evident despite normal task performance, neural responses during failed inhibition may be a useful biomarker of vulnerability for DEB. This study highlights the potential value of prospective neuroimaging studies for identifying markers of illness before the emergence of behavior changes.

Reduction of cerebellar grey matter in Crus I and II in schizophrenia

Structural deficiencies within the cerebellum have been associated with schizophrenia. Whereas several region-of-interest-based studies have shown deviations in cerebellar volume, meta-analyses on conventional whole-brain voxel-based morphometry (VBM) studies do not implicate abnormalities in the cerebellum. Since this discrepancy could be due to methodological problems of VBM, we used a cerebellum-optimized VBM procedure. We acquired high-resolution MRI scans from 29 schizophrenia patients and 45 healthy controls and used a VBM approach utilizing the Spatially Unbiased Infratentorial toolbox (Diedrichsen in Neuroimage 33:127-138, 2006). Relative to healthy controls, schizophrenia patients showed reductions of grey matter volume in the left cerebellum Crus I/II that were correlated with thought disorder (p < 0.05; one-sided) and performance in the Trail-making test B (p < 0.01). No cerebellar group differences were detected employing conventional whole-brain VBM. The results derived from the cerebellum analysis provide evidence for distinct grey matter deficits in schizophrenia located in Crus I/II. The association of this area with thought disorder and Trail-making performance supports the previously suggested role of the cerebellum in coordination of mental processes including disordered thought in schizophrenia. The failure of conventional VBM to detect such effects suggests that previous studies might have underestimated the importance of cerebellar structural deficits in schizophrenia.

Common structural correlates of trait impulsiveness and perceptual reasoning in adolescence

BACKGROUND

Trait impulsiveness is a potential factor that predicts both substance use and certain psychiatric disorders. This study investigates whether there are common structural cerebral correlates of trait impulsiveness and cognitive functioning in a large sample of healthy adolescents from the IMAGEN project.

METHODS

Clusters of gray matter (GM) volume associated with trait impulsiveness, Cloningers' revised temperament, and character inventory impulsiveness (TCI-R-I) were identified in a whole brain analysis using optimized voxel-based morphometry in 115 healthy 14-year-olds. The clusters were tested for correlations with performance on the nonverbal tests (Block Design, BD; Matrix Reasoning, MT) of the Wechsler Scale of Intelligence for Children IV reflecting perceptual reasoning.

RESULTS

Cloningers' impulsiveness (TCI-R-I) score was significantly inversely associated with GM volume in left orbitofrontal cortex (OFC). Frontal clusters found were positively correlated with performance in perceptual reasoning tasks (Bonferroni corrected). No significant correlations between TCI-R-I and perceptual reasoning were observed.

CONCLUSIONS

The neural correlate of trait impulsiveness in the OFC matches an area where brain function has previously been related to inhibitory control. Additionally, orbitofrontal GM volume was associated with scores for perceptual reasoning. The data show for the first time structural correlates of both cognitive functioning and impulsiveness in healthy adolescent subjects.

Brain grey matter deficits in smokers: focus on the cerebellum

Structural cerebral deficiencies in smokers have been well characterized by morphometric investigations focussing on cortical and subcortical structures. Although the role of the cerebellum is increasingly noted in mental and addiction disorders, no reports exist regarding cerebellar alterations in smokers employing a methodology specifically designed to assess the cerebellar morphology. We acquired high-resolution MRI scans from 33 heavy smokers and 22 never-smokers and used a voxel-based morphometry (VBM) approach utilizing the Spatially Unbiased Infratentorial (SUIT) toolbox (Diedrichsen 2006) to provide an optimized and fine-grained exploration of cerebellar structural alterations associated with smoking. Relative to never-smokers, smokers showed significant reductions of grey matter volume in the right cerebellum Crus I. The grey matter volume in Crus I correlated negatively with the amount of nicotine dependence as assessed by means of the Fagerström scale. Since Crus I has been identified as the cognitive division of the cerebellum, the structural deficit may in part mediate cognitive deficits previously reported in smokers. Of note, the dependence-related magnitude of the volume deficit may support the notion that the cerebellum is substantially involved in core mechanisms of drug dependence.

Cortical thickness correlates with impulsiveness in healthy adults

BACKGROUND

Impulsiveness is a central domain of human personality and of relevance for the development of substance use and certain psychiatric disorders. This study investigates whether there are overlapping as well as distinct structural cerebral correlates of attentional, motor and nonplanning impulsiveness in healthy adults.

METHODS

High-resolution magnetic resonance scans were acquired in 32 healthy adults to model the gray-white and gray-cerebrospinal fluid borders for each individual cortex and to compute the distance of these surfaces as a measure of cortical thickness (CT). Associations between CT and the dimensions of impulsiveness (Barratt-Impulsiveness-Scale 11, BIS) were identified in entire cortex analyses.

RESULTS

We observed a significant negative correlation between left middle frontal gyrus (MFG) CT and the attention BIS score (FDR p<.05), motor, nonplanning and total BIS score (each p<0.001 uncorrected). In addition, CT of the orbitofrontal (OFC) and superior frontal gyrus (SFG) were inversely correlated (p<0.001 uncorrected) with BIS total and motor score. Among other negative associations only one positive correlation (right inferior temporal with nonplanning score, p<0.001 uncorrected) was found.

CONCLUSIONS

The MFG is crucial for top-down control, executive and attentional processes. The MFG together with the OFC and SFG appears to be part of brain structures, which have previously been shown to mediate behavioral inhibition, well-planned action and attention, which are core facets of impulsiveness as measured with the Barratt-Impulsiveness-Scale.

[Gamma-hydroxybutyrat (GHB)-dependence and -withdrawal in the case of previous alcohol dependence]

OBJECTIVE

gamma-Hydroxybutyrat (GHB) is used medically for narcolepsy and as a narcotic. It is also a rare illegal drug. In this case report the development of a GHB-dependency against the background of a primary alcohol dependency is described.

METHODS

Based on established alcohol withdrawal scales (AWSS by Wetterling, CIWA) and neuropsychological testing procedures (CGI, GAF, SKID-II, PISQ, analog-scale for Craving), the initial situation, the development of psychopathological findings, and the course of detoxification were shown.

RESULTS/CONCLUSION

The combined detoxication of GHB and alcohol was successfully finished by a reduction schedule of diazepam. Withdrawal-assessment scales for alcohol were helpful, but show limitations for GHB-withdrawal symptoms. The patient suffers, according to ICD-10, from a multiple drug dependence (alcohol, GHB, abstinence from amphetamines). Symptoms of insomnia, major depression, and generalized anxiety disorder can be associated with the use of GHB.

Time-efficient localization of the human secondary somatosensory cortex by functional magnetic resonance imaging

Standardized, robust and time-efficient localization of the human secondary somatosensory cortex (S2) is a challenge in clinical blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI). A fully automated tactile stimulation was optimized in seven right-handed volunteers at 1.5 T for minimum scan time, high BOLD signals and robust localization of S2 by systematically varying the applied block-design. All volunteers had six different fMRI measurements of five stimulation-baseline-cycles (sbc) each with equal block duration that was changed between the measurements from 6 s to 30 s. Additional data sets of 4, 3 and 2 cycles were generated post hoc resulting in a total of 168 data sets that were evaluated individually for BOLD-signal intensity (dS%), correlation to the hemodynamic reference function (r) and Euclidean coordinates (x, y, z). Using different block-designs the S2 activation was highly variable regarding the localization rate (lr), the hemispheric symmetry and the BOLD-signals. The protocol with 3 cycles, a block duration (dp) of 15 s and a total scan time (dt) of 105 s most robustly localized S2 (contralateral: lr=71.4%, r=0.65, dS=1.01%; ipsilateral: lr=100%, r=0.6, dS=1.14%) whereas the most time-efficient protocol to localize SI (sbc=5, dp=6 s, dt=66 s) provided no robust localization of S2. Compared to other published fMRI protocols a scan time reduction up to 86% was achieved.

Fully automated localization of the human primary somatosensory cortex in one minute by functional magnetic resonance imaging

A clinical functional magnetic resonance imaging (fMRI) protocol based on a fully automated tactile stimulation was optimized in 10 right-handed volunteers at 1.5 T for minimum scan time, high BOLD-signals and robust localization of the primary somatosensory cortex (S1) by systematically varying the applied block design. All volunteers had six different fMRI measurements of 5 stimulation/baseline cycles each with equal block duration that was changed between the measurements from 6 to 30 s. Data sets of 4, 3 and 2 cycles were generated post hoc resulting in a total of 240 data sets that were evaluated individually for BOLD-signal intensity (dS%), correlation to the hemodynamic reference function (r) and Euclidean coordinates (x, y, z). The protocol with 5 cycles, a block duration of 6 s and a total scan time of 66 s provided the best BOLD-signal characteristics (dS% = 1.15, r = 0.78). Compared to the mean scan time of other clinical fMRI protocols (174 s) a reduction of 62% was achieved.

Prevalence and forms of congenital anomalies in twins born in Pomeranian District during the period from 1.07.1997 to 31.12.1998. Polish Register of Congenital Anomalies

The authors have analysed the frequency and structure of congenital anomalies in children born in the Pomeranian district in the period from 01.07.1997 to 31.12.1998. Among a total of 28.361 births in that area, 748 (2.64%) were affected by congenital anomalies. Among 28.361 births, 620 (2.18%) were from multiple pregnancies. 23 (3.71%) among births from multiple pregnancies were affected by congenital malformations. The prevalence rate of inborn anomalies in births from multiple pregnancy in our area were higher (3.71%) in comparison to births from singleton pregnancy (2.61%). It implies that children born from multiple pregnancy are at higher risk of developing congenital anomalies.

Differential effects of sphingomyelinase and cell-permeable ceramide analogs on proliferation of Swiss 3T3 fibroblasts

Metabolites of sphingomyelin, ceramide and sphingosine, have previously been implicated in cell growth regulation. Here we show that cell-permeable ceramide analogs and treatment with sphingomyelinase, which hydrolyzes sphingomyelin located on the outer leaflet of the bilayer, increase the progression of quiescent Swiss 3T3 fibroblasts through the S phase of the cell cycle leading to an increase in cell division. Although both potentiate the mitogenic effects of several growth factors [14], sphingomyelinase treatment antagonized the mitogenic effect of the tumor promoter, 12-O-tetradecanoylphorbol 13-acetate (TPA), while ceramide analogs had no effect, and sphingosine, a further metabolite of ceramide, potentiated the mitogenic effect of TPA. Concomitantly, sphingomyelinase, but not ceramide analogs, blunted the rapid increase in membrane-associated protein kinase C (PKC) activity induced by TPA without affecting the translocation of PKC alpha, delta, epsilon or zeta isoforms. Moreover, in contrast to sphingosine which activates phospholipase D (PLD) leading to an increase in phosphatidic acid levels, sphingomyelinase, but not ceramide analogs, reduced TPA-stimulated PLD activity. Our results suggest that the signaling pathways utilized by sphingomyelinase differ from those of cell-permeable ceramide analogs, and both act differently than sphingosine. The differential effects of exogenous short-chain ceramide analogs and sphingomyelinase call for caution in using these analogs as tools to study the role of ceramide in diverse cellular functions.

Pleiotropic glucose repression-resistant mutation in Saccharomyces carlesbergensis

We describe the characterization of a mutation of the locus GLR1. This mutation allowed for (i) the glucose repression-insensitive synthesis ot the enzymes maltase, galactokinase, alpha-galactosidase, reduced nicotinamide adenine dinucleotide-cytochrome c reductase, and cytochrome c oxidase and (ii) growth on maltose in the presence of the gratuitous glucose repressor D-glucosamine. The glucosamine resistance cosegregated with the glucose-insensitive synthesis of the enzymes listed above. In addition, crosses between the glucosamine-resistant mutant and isogenic sensitive strains gave only tetrads containing two resistant and two sensitive spores. Thus, a single pleiotropic mutation is responsible for both phenotypes. We call the locus GLR1, for glucose regulation, and the glucose repression-insensitive mutation glr1-1.