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White matter hyperintensities (WMH), a common feature of cerebral small vessel disease, affect a wide range of cognitive dysfunctions, including spatial neglect. The latter is a disorder of spatial attention and exploration typically after right hemisphere brain damage. To explore the impact of WMH on neglect‐related structural disconnections, the present study investigated the indirectly quantified structural disconnectome induced by either stroke lesion alone, WMH alone, or their combination. Furthermore, we compared different measures of structural disconnection—voxel‐wise, pairwise, tract‐wise, and parcel‐wise—to identify neural correlates and predict acute neglect severity. We observed that WMH‐derived disconnections alone were not associated with neglect behavior. However, when combined with disconnections derived from individual stroke lesions, pre‐stroke WMH contributed to post‐stroke neglect severity by affecting right frontal and subcortical substrates, like the middle frontal gyrus, basal ganglia, thalamus, and the fronto‐pontine tract. Predictive modeling demonstrated that voxel‐wise disconnection data outperformed other measures of structural disconnection, explaining 42% of the total variance; interestingly, the best model used predictors of stroke‐based disconnections only. We conclude that prestroke alterations in the white matter microstructure due to WMH contribute to poststroke deficits in spatial attention, likely by impairing the integrity of human attention networks. Comprehensive analyses were carried out to examine the impact of white matter hyperintensities on structural disconnections related to post‐stroke deficits in spatial attention. Findings indicate that disruptions of right fronto‐subcortical pathways are strongly associated with spatial attention deficits when white matter hyperintensities are involved.

ObjectiveFrontotemporal dementia (FTD) is typically associated with changes in behaviour, language and movement. However, recent studies have shown that patients can also develop an abnormal response to pain, either heightened or diminished. We aimed to investigate this symptom in mutation carriers within the Genetic FTD Initiative (GENFI).MethodsAbnormal responsiveness to pain was measured in 462 GENFI participants: 281 mutation carriers and 181 mutation-negative controls. Changes in responsiveness to pain were scored as absent (0), questionable or very mild (0.5), mild (1), moderate (2) or severe (3). Mutation carriers were classified into C9orf72 (104), GRN (128) and MAPT (49) groups, and into presymptomatic and symptomatic stages. An ordinal logistic regression model was used to compare groups, adjusting for age and sex. Voxel-based morphometry was performed to identify neuroanatomical correlates of abnormal pain perception.ResultsAltered responsiveness to pain was present to a significantly greater extent in symptomatic C9orf72 expansion carriers than in controls: mean score 0.40 (SD 0.71) vs 0.00 (0.04), reported in 29% vs 1%. No significant differences were seen between the other symptomatic groups and controls, or any of the presymptomatic mutation carriers and controls. Neural correlates of altered pain perception in C9orf72 expansion carriers were the bilateral thalamus and striatum as well as a predominantly right-sided network of regions involving the orbitofrontal cortex, inferomedial temporal lobe and cerebellum.ConclusionChanges in pain perception are a feature of C9orf72 expansion carriers, likely representing a disruption in somatosensory, homeostatic and semantic processing, underpinned by atrophy in a thalamo-cortico-striatal network.

Spatial neglect is commonly attributed to lesions of a predominantly right-hemispheric cortical network. Although spatial neglect was also repeatedly observed after lesions to the basal ganglia and the thalamus, many anatomical network models omit these structures. We investigated if disruption of functional or structural connectivity can explain spatial neglect in subcortical stroke. We retrospectively investigated data of first-ever, acute stroke patients with right-sided lesions of the basal ganglia ( n  = 27) or the thalamus ( n  = 16). Based on lesion location, we estimated (i) functional connectivity via lesion-network mapping with normative resting state fMRI data, (ii) structural white matter disconnection using a white matter atlas and (iii) tract-wise disconnection of association fibres based on normative tractography data to investigate the association of spatial neglect and disconnection measures. Apart from very small clusters of functional disconnection observed in inferior/middle frontal regions in lesion-network symptom mapping for basal ganglia lesions, our analyses found no evidence of functional or structural subcortico-cortical disconnection. Instead, the multivariate consideration of lesion load to several association fibres predicted the occurrence of spatial neglect ( p  = 0.0048; AUC = 0.76), which were the superior longitudinal fasciculus, inferior occipitofrontal fasciculus, superior occipitofrontal fasciculus, and the uncinate fasciculus. Disconnection of long (cortico-cortical) association fibres can explain spatial neglect in subcortical stroke. Like the competing theory of remote cortical hypoperfusion, our finding does not support a genuine role for subcortical grey matter structures in spatial neglect.

ObjectivesWe aimed to investigate changes in regional cerebral blood flow (rCBF) using arterial spin labelling (ASL) in patients with visual snow syndrome (VSS), in order to understand more about the underlying neurobiology of the condition, which remains mostly unknown.MethodsWe performed an MRI study in which whole-brain maps of rCBF were obtained using pseudo-continuous ASL. Twenty-four patients with VSS and an equal number of gender and age-matched healthy volunteers took part in the study. All subjects were examined with both a visual paradigm consisting of a visual-snow like stimulus, simulating key features of the snow, and a blank screen at rest, randomly presented.ResultsPatients with VSS had higher rCBF than controls over an extensive brain network, including the bilateral cuneus, precuneus, supplementary motor cortex, premotor cortex and posterior cingulate cortex, as well as the left primary auditory cortex, fusiform gyrus and cerebellum. These areas were largely analogous comparing patients either at rest, or when looking at a ‘snow-like’ visual stimulus. This widespread, similar pattern of perfusion differences in either condition suggests a neurophysiological signature of visual snow. Furthermore, right insula rCBF was increased in VSS subjects compared with controls during visual stimulation, reflecting a greater task-related change and suggesting a difference in interoceptive processing with constant perception of altered visual input.ConclusionThe data suggest VSS patients have marked differences in brain processing of visual stimuli, validating its neurobiological basis.

Background Stroke is the second leading cause of disability worldwide. Stroke results in focal neurological deficit and often leads to auditory problems due to its impact on the auditory pathway. Altered connections in the auditory pathway, caused by stroke, can result in hearing difficulties ranging from impaired sound detection to altered auditory perception. A better understanding of how stroke affects these early sound processing mechanisms will provide valuable insights into stroke recovery and rehabilitation options. Methods We recruited forty consecutive adult patients with stroke (30 males, 10 females) due to ischemic or intracerebral hemorrhage > 3 and up to 12 months after stroke (subacute stage). Brain MRIs were performed on all patients, and we calculated a central auditory nervous system stroke severity index (CANS SSI) according to number of CANS areas involved and an extended CANS definition of auditory responsive areas. All patients underwent cognitive screening assessment, basic audiological assessments, and a hierarchical central auditory processing assessment battery with the Queen Square Tests of Auditory Cognition (early perceptual processing, apperceptive processing, semantic Processing) and Gaps in Noise tests. Results When comparing patients with auditory responsive cortical lesions and with versus without Heschl’s gyrus involvement (primary auditory cortex), patients with Heschl’s gyrus involvement exhibited worse early perceptual scores. The CANS SSI showed a significant negative correlation with early perceptual test scores. Conclusion This study demonstrates a correlation between stroke severity, characterized by a higher number of lesions involving auditory areas in patients with subacute stroke, and worse early perceptual scores. Heschl’s gyrus involvement is associated with poorer early perceptual score.

The 22q11.2 deletion is one of the most common copy number variants in humans. Carriers of the deletion have a markedly increased risk for neurodevelopmental brain disorders, including schizophrenia, autism spectrum disorders, and attention deficit hyperactivity disorder. The high risk of psychiatric disorders associated with 22q11.2 deletion syndrome offers a unique possibility to identify the functional abnormalities that precede the emergence of psychosis. Carriers of a 22q11.2 deletion show a broad range of sensory processing and cognitive abnormalities similar as in schizophrenia, such as auditory and visual sensory processing, response inhibition, working memory, social cognition, reward processing and arithmetic processing. All these processes have a significant negative impact on daily life if impaired and have been studied extensively in schizophrenia using task-based functional neuroimaging. Here, we review task-related functional brain mapping studies that have used electroencephalography or functional magnetic resonance imaging to identify functional alterations in carriers with 22q11.2 deletion syndrome within the above mentioned cognitive and sensory domains. We discuss how the identification of functional changes at the brain system level can advance the general understanding of which neurobiological alterations set the frame for the emergence of neurodevelopmental disorders in the human brain. The task-based functional neuroimaging literature shows conflicting results in many domains. Nevertheless, consistent similarities between 22q11.2 deletion syndrome and schizophrenia have been found for sensory processing, social cognition and working memory. We discuss these functional brain alterations in terms of potential biomarkers of increased risk for psychosis in the general population. •22q11.2DS can provide insights into the emergence of neurodevelopmental disorders.•Functional brain alterations in 22q11.2DS resemble anomalies in schizophrenia.•Activity in frontal areas are generally decreased in 22q11.2DS.

Hemispatial neglect is thought to result from disruption of interhemispheric equilibrium. Right hemisphere lesions deactivate the right frontoparietal network and hyperactivate the left via release from interhemispheric inhibition. Support for this putative mechanism comes from neuropsychological evidence as well as transcranial magnetic stimulation (TMS) studies in healthy subjects, in whom right posterior parietal cortex (PPC) inhibition causes neglect-like, rightward, visuospatial bias. Concurrent TMS and fMRI after right PPC TMS show task-dependent changes but may fail to identify effects of stimulation in areas not directly activated by the specific task, complicating interpretations. We used resting-state functional connectivity (RSFC) after inhibitory TMS over the right PPC to examine changes in the networks underlying visuospatial attention and used diffusion-weighted imaging to measure the structural properties of relevant white matter pathways. In a crossover experiment in healthy individuals, we delivered continuous theta burst TMS to the right PPC and vertex as control condition. We hypothesized that PPC inhibitory stimulation would result in a rightward visuospatial bias, decrease frontoparietal RSFC, and increase the PPC RSFC with the attentional network in the left hemisphere. We also expected that individual differences in fractional anisotropy (FA) of the frontoparietal network and the callosal pathway between the PPCs would account for variability of the TMS-induced RSFC changes. As hypothesized, TMS over the right PPC caused a rightward shift in line bisection judgment and increased RSFC between the right PPC and the left superior temporal gyrus. This effect was inversely related to FA in the posterior corpus callosum. Local inhibition of the right PPC reshapes connectivity in the attentional network and depends significantly on interhemispheric connections.

Amblyopia is a relatively common (incidence 3%) developmental disorder in which there is loss of vision as a consequence of a disruption to normal visual development. Although the deficit is monocular and known to be of cortical origin, the nature of the processing deficit is controversial. Human behavioral studies have identified two main deficits — a loss of contrast sensitivity and perceived spatial distortions. Here we use a multifocal fMRI approach to ascertain, in a group of anisometropic amblyopes, whether these two deficits have a single common cause or whether they are the result of two underlying independent cortical disorders. We found that fMRI magnitudes were attenuated in amblyopic eye stimulation, and that there was poor fidelity for co-localization of the activity clusters between the amblyopic and fellow-fixing eye stimulation. These effects varied across eccentricities and correlate with the degree of amblyopia but not with one another, suggesting two independent cortical deficits: a reduced responsiveness as well as reduced fidelity of spatial representation. These deficits are independent of eccentricity within the central field and consistent across early cortical visual areas. •A multi-focal fMRI analysis was used to map the deficits of the amblyopic brain.•The diseased brain had deficits in response magnitude.•The diseased brain had deficits in response localization.•These two cortical deficits are independent in amblyopia.

Deeper understanding of Subtle Visual Dysfunctions (VisDys) in the early stage of mental illness and their neurobiological underpinnings, as reflected by microstructural brain texture features, could advance our understanding of the underlying disease perceptual mechanisms that mediate susceptibility to psychosis. In this study, we aim a) to investigate the utility of brain texture features for the prediction of VisDys in recent onset psychosis (ROP) and clinical high-risk syndromes for psychosis (CHR-P), respectively, b) to test prediction models established in ROP and CHR-P in an independent validation sample with recent onset depression (ROD) diagnoses and c) to test for symptom expression related brain features associated with VisDys. sMRI were acquired in a training sample including 128 ROP (67 patients with VisDys), 134 CHR-P (71 patients with VisDys). Independent validation sets included 46 ROP (19 with VisDys), 124 CHR-P (68 patients with VisDys) and a sample of 256 ROD (50 patients with VisDys). Both classification schemas in ROP and CHR-P presented balanced accuracy >77% and >64% in the independent validation samples of ROP, CHR-P, and ROD, respectively. Statistically significant associations were identified with scores from the Positive and Negative Symptom Scale, psychosocial functioning, and the Scale of Negative Symptoms.

The occipital lobe contains a substantial part of the neural machinery involved in visual perception. Mutations in the LAMC3 gene have recently been shown to cause complex bilateral occipital cortical gyration abnormalities. However, to what extent these structural changes impact visual behavior is not known. We recorded responses for two screening test batteries targeting visual function (Leuven - Perceptual Organization Screening Test, Cortical Vision Screening Test) and measured eye fixation performance in a visual attention experiment from a patient with homozygous LAMC3 gene mutation. Using voxel-based morphometry (VBM) we quantitatively assessed the extent of structural changes brought on by the genetic mutation by comparing mean cortical curvature, cortical thickness, and gray matter volume in 34 cortical areas between patient and an age-, sex-, and education-matched control group. Anatomical connectivity between these cortical areas was investigated by a structural covariance analysis. Visual screening-, and behavioral results revealed that the patient's impairments were predominantly in visuo-spatial attention. Consistent with this, VBM and structural connectivity results revealed significant structural changes in cortical regions subserving attentional functions. We conclude that the LAMC3 gene mutation affects cortical areas beyond the occipital lobe and primarily those visual functions that involve heavily distributed networks – such as visuo-spatial attention. •LAMC3 gene mutation links to cortical structural changes beyond the occipital lobe.•LAMC3 gene mutation links to deficits in visual attention.•Structural changes primarily in cortical areas subserving visual attention.•Spared object and face recognition despite compromised cortical architecture.