Despite the success of functional imaging to map changes in brain activation patterns after stroke, spatiotemporal dynamics of cerebral reorganization in correlation with behavioral recovery remain incompletely characterized. Here, we applied resting-state functional magnetic resonance imaging (rs-fMRI) together with behavioral testing to longitudinally assess functional connectivity within neuronal networks, in relation to changes in associated function after unilateral stroke in rats. Our specific goals were (1) to identify temporal alterations in functional connectivity within the bilateral cortical sensorimotor system and (2) to elucidate the relationship between those alterations and changes in sensorimotor function. Our study revealed considerable loss of functional connectivity between ipsilesional and contralesional primary sensorimotor cortex regions, alongside significant sensorimotor function deficits in the first days after stroke. The interhemispheric functional connectivity restored in the following weeks, but remained significantly reduced up to 10 weeks after stroke in animals with lesions that comprised subcortical and cortical tissue, whereas transcallosal neuroanatomical connections were preserved. Intrahemispheric functional connectivity between primary somatosensory and motor cortex areas was preserved in the lesion border zone and moderately enhanced contralesionally. The temporal pattern of changes in functional connectivity between bilateral primary motor and somatosensory cortices correlated significantly with the evolution of sensorimotor function scores. Our study (1) demonstrates that poststroke loss and recovery of sensorimotor function is associated with acute deterioration and subsequent retrieval of interhemispheric functional connectivity within the sensorimotor system and (2) underscores the potential of rs-fMRI to assess spatiotemporal characteristics of functional brain reorganization that may underlie behavioral recovery after brain injury.

Background. People with epilepsy who became seizure-free while taking antiepileptic drugs (AEDs) may

Objective To investigate whether language used in science abstracts can skew towards the use of strikingly positive and negative words over time.Design Retrospective analysis of all scientific abstracts in PubMed between 1974 and 2014.Methods The yearly frequencies of positive, negative, and neutral words (25 preselected words in each category), plus 100 randomly selected words were normalised for the total number of abstracts. Subanalyses included pattern quantification of individual words, specificity for selected high impact journals, and comparison between author affiliations within or outside countries with English as the official majority language. Frequency patterns were compared with 4% of all books ever printed and digitised by use of Google Books Ngram Viewer. Main outcome measuresFrequencies of positive and negative words in abstracts compared with frequencies of words with a neutral and random connotation, expressed as relative change since 1980.Results The absolute frequency of positive words increased from 2.0% (1974-80) to 17.5% (2014), a relative increase of 880% over four decades. All 25 individual positive words contributed to the increase, particularly the words "robust," "novel," "innovative," and "unprecedented," which increased in relative frequency up to 15 000%. Comparable but less pronounced results were obtained when restricting the analysis to selected journals with high impact factors. Authors affiliated to an institute in a non-English speaking country used significantly more positive words. Negative word frequencies increased from 1.3% to 3.2% (2014), a relative increase of 257%. Over the same time period, no apparent increase was found in neutral or random word use, or in the frequency of positive word use in published books.Conclusions Our lexicographic analysis indicates that scientific abstracts are currently written with more positive and negative words, and provides an insight into the evolution of scientific writing. Apparently scientists look on the bright side of research results. But whether this perception fits reality should be questioned.

In the vertebrate nervous system, myelination of axons for rapid impulse propagation requires the synthesis of large amounts of lipids and proteins by oligodendrocytes and Schwann cells. Myelin membranes are thought to be cell-autonomously assembled by these axon-associated glial cells. Here, we report the surprising finding that in normal brain development, a substantial fraction of the lipids incorporated into central nervous system (CNS) myelin are contributed by astrocytes. The oligodendrocyte-specific inactivation of sterol regulatory element-binding protein (SREBP) cleavage-activating protein (SCAP), an essential coactivator of the transcription factor SREBP and thus of lipid biosynthesis, resulted in significantly retarded CNS myelination; however, myelin appeared normal at 3 months of age. Importantly, embryonic deletion of the same gene in astrocytes, or in astrocytes and oligodendrocytes, caused a persistent hypomyelination, as did deletion from astrocytes during postnatal development. Moreover, when astroglial lipid synthesis was inhibited, oligodendrocytes began incorporating circulating lipids into myelin membranes. Indeed, a lipid-enriched diet was sufficient to rescue hypomyelination in these conditional mouse mutants. We conclude that lipid synthesis by oligodendrocytes is heavily supplemented by astrocytes in vivo and that horizontal lipid flux is a major feature of normal brain development and myelination.

Remodeling of neuronal structures and networks is believed to significantly contribute to (partial) restoration of functions after stroke. However, it has been unclear to what extent the brain reorganizes and how this correlates with functional recovery in relation to stroke severity. We applied serial resting-state functional MRI and diffusion tensor imaging together with behavioral testing to relate longitudinal modifications in functional and structural connectivity of the sensorimotor neuronal network to changes in sensorimotor function after unilateral stroke in rats. We found that gradual improvement of functions is associated with wide-ranging changes in functional and structural connectivity within bilateral neuronal networks, particularly after large stroke. Both after medium and large stroke, brain reorganization eventually leads to (partial) normalization of neuronal signal synchronization within the affected sensorimotor cortical network (intraregional signal coherence), as well as between the affected and unaffected sensorimotor cortices (interhemispheric functional connectivity). Furthermore, the bilateral network configuration shifts from subacutely increased "small-worldness," possibly reflective of initial excessive neuronal clustering and wiring, toward a baseline small-world topology, optimal for global information transfer and local processing, at chronic stages. Cortical network remodeling was accompanied by recovery of initially disrupted structural integrity in corticospinal tract regions, which correlated positively with retrieval of sensorimotor functions. Our study demonstrates that the degree of functional recovery after stroke is associated with the extent of preservation or restoration of ipsilesional corticospinal tracts in combination with reinstatement of interhemispheric neuronal signal synchronization and normalization of smallworld cortical network organization.

SUMMARYPurpose: Diffusion tensor imaging (DTI) is used increasingly to study white matter integrity in people with temporal lobe epilepsy (TLE). Most studies report fractional anisotropy (FA) decrease and mean diffusivity (MD) increase in multiple white matter regions. The disturbance of white matter integrity varies across studies and between regions. We aimed to obtain a more consistent estimate of white matter diffusion characteristics and relate these to the distance from the seizure focus. Methods: Studies comparing diffusion characteristics of people with epilepsy with those of healthy controls were systematically reviewed and quantified using random and mixed effects meta analysis. In addition to the overall metaanalysis, pooled FA and MD differences were determined per hemisphere and white matter category separately. Key Findings: We included 13 cross-sectional studies. The pooled FA difference for all white matter was )0.026 (95% confidence interval [CI] )0.033 to )0.019) and MD difference was 0.028 · 10 )3 mm 2 /s (95% CI 0.015-0.04). FA was reduced significantly in people with TLE compared with healthy controls in both ipsilateral (mean difference )0.03) and contralateral white matter ()0.02). MD was significantly increased ipsilaterally and contralaterally. MD differed significantly between white matter connected to the affected temporal lobe and remote white matter. Significance: The meta-analysis provides a better estimation of the true diffusion characteristics. White matter structural integrity in TLE is disturbed more severely in the ipsilateral than in the contralateral hemisphere, and tracts closely connected with the affected temporal lobe are most disturbed. The exact underlying mechanisms remain to be elucidated.

FRs that persist before and after resection predict poor postsurgical outcome. These findings hold for different tailoring approaches. FRs can thus be used for tailoring epilepsy surgery with repeated intraoperative ECoG measurements. Ann Neurol 2017;81:664-676.

We have presented and evaluated REKINDLE, a linear and robust estimation framework for DKI. While REKINDLE has been developed for DKI, it is by design also applicable to DTI and other diffusion models that can be linearized.