Microstructural differences in migraine: A diffusion-tensor imaging study.

BACKGROUND: Diffusion-tensor imaging can be applied to describe the microstructural integrity of the whole brain. As findings about microstructural alterations in migraine are inconsistent, we aimed to replicate the most frequent results and assess a relationship between migraine parameters and changes in microstructure. METHODS: Diffusion-weighted MRI data of 37 migraine patients and 40 controls were collected. Two indices of diffusion of water molecules, fractional anisotropy and mean diffusivity were used in a voxel-wise analysis. Group comparisons were carried out in SPM12 using age and sex as covariates. Statistically significant results survived family-wise error correction (pFWE < 0.05). Migraine intensity, frequency, and duration were self-reported and correlated with mean fractional anisotropy and mean diffusivity values across clusters. RESULTS: Migraine patients showed significantly lower fractional anisotropy in occipital regions, and significantly higher fractional anisotropy in thirteen clusters across the brain. Mean diffusivity of migraine patients was significantly decreased in the cerebellum and pons, but it was not increased in any area. Correlation between migraine duration and fractional anisotropy was significantly positive in the frontal cortex and significantly negative in the superior parietal lobule. CONCLUSION: We suggest that microstructural integrity of the migraine brain is impaired in visual areas and shows duration-related alterations in regions of the default mode network.

Fronto-thalamic structural and effective connectivity and delusions in schizophrenia: a combined DTI/DCM study.

BACKGROUND: Schizophrenia (SZ) is a complex disorder characterized by a range of behavioral and cognitive symptoms as well as structural and functional alterations in multiple cortical and subcortical structures. SZ is associated with reduced functional network connectivity involving core regions such as the anterior cingulate cortex (ACC) and the thalamus. However, little is known whether effective coupling, the directed influence of one structure over the other, is altered during rest in the ACC-thalamus network. METHODS: We collected resting-state fMRI and diffusion-weighted MRI data from 18 patients and 20 healthy controls. We analyzed fronto-thalamic effective connectivity using dynamic causal modeling for cross-spectral densities in a network consisting of the ACC and the left and right medio-dorsal thalamic regions. We studied structural connectivity using fractional anisotropy (FA). RESULTS: We found decreased coupling strength from the right thalamus to the ACC and from the right thalamus to the left thalamus, as well as increased inhibitory intrinsic connectivity in the right thalamus in patients relative to controls. ACC-to-left thalamus coupling strength correlated with the Positive and Negative Syndrome Scale (PANSS) total positive syndrome score and with delusion score. Whole-brain structural analysis revealed several tracts with reduced FA in patients, with a maximum decrease in white matter tracts containing fronto-thalamic and cingulo-thalamic fibers. CONCLUSIONS: We found altered effective and structural connectivity within the ACC-thalamus network in SZ. Our results indicate that ACC-thalamus network activity at rest is characterized by reduced thalamus-to-ACC coupling. We suggest that positive symptoms may arise as a consequence of compensatory measures to imbalanced fronto-thalamic coupling.

Anticipation and violated expectation of pain are influenced by trait rumination: An fMRI study.

Rumination - as a stable tendency to focus repetitively on feelings related to distress - represents a transdiagnostic risk factor. Theories suggest altered emotional information processing as the key mechanism of rumination. However, studies on the anticipation processes in relation to rumination are scarce, even though expectation in this process is demonstrated to influence the processing of emotional stimuli. In addition, no published study has investigated violated expectation in relation to rumination yet. In the present study we examined the neural correlates of pain anticipation and perception using a fear conditioning paradigm with pain as the unconditioned stimulus in healthy subjects (N = 30). Rumination was assessed with the 10-item Ruminative Response Scale (RRS). Widespread brain activation - extending to temporal, parietal, and occipital lobes along with activation in the cingulate cortex, insula, and putamen - showed a positive correlation with rumination, supporting our hypothesis that trait rumination influences anticipatory processes. Interestingly, with violated expectation (when an unexpected, non-painful stimulus follows a pain cue compared to when an expected, painful stimulus follows the same pain cue) a negative association between rumination and activation was found in the posterior cingulate cortex, which is responsible for change detection in the environment and subsequent behavioral modification. Our results suggest that rumination is associated with increased neural response to pain perception and pain anticipation, and may deteriorate the identification of an unexpected omission of aversive stimuli. Therefore, targeting rumination in cognitive behavioral therapy of chronic pain could have a beneficial effect.

Neurodevelopmental effect of intracranial hemorrhage observed in hypoxic ischemic brain injury in hypothermia-treated asphyxiated neonates - an MRI study.

BACKGROUND: Identification of early signs of hypoxic ischemic encephalopathy (HIE) with magnetic resonance imaging (MRI) has proven of prognostic significance. Yet, the importance of intracranial hemorrhage (ICH), being present concomitantly had not been investigated yet, despite the known influence of hypothermia on hemostasis. We aimed to determine whether presence of ICH on MRI alongside the signs of HIE have an impact on prognosis in neonates with the clinical diagnosis of HIE. METHODS: A retrospective study of consecutively sampled 108 asphyxiated term infants admitted to a tertiary neonatal intensive care unit (between 2007 and 2016), treated with whole body hypothermia and having brain MRI within 1 week of life was conducted. Presence or absence of HIE signs on MRI (basal ganglia-thalamus, watershed pattern and total brain injury) and on MR spectroscopy (lactate peak with decreased normal metabolites measured by Lac/NAA ratio) and/or of the five major types of ICH were recorded. Neurodevelopmental outcome was measured with Bayley Scales of Infant Development-II (BSID-II) test. Death or abnormal neurodevelopment (BSID-II score < 85) was defined as poor outcome in Chi-square test. Multivariate logistic regression analysis was performed on survivors. RESULTS: MRI and MR-spectroscopy (MRS) signs of HIE were present in 72% (n = 78). 36% (n = 39) of neonates had ICH, being mainly small in size. Chi-square test showed a relationship between neurodevelopmental outcome and initial MRI. Unadjusted logistic regression showed that neonates presenting MRI and MRS signs of HIE have 6.23 times higher odds for delayed mental development (OR = 6.2292; CI95% = [1.2642; 30.6934], p = 0.0246), than infants without imaging alterations; with no ICH effect on outcome. Adjustment for clinical and imaging parameters did not change the pattern of results, i.e. HIE remained an independent risk factor for delayed neurodevelopment (OR = 6.2496; CI95% = [1.2018; 32.4983], p = 0.0294), while ICH remained to have no significant effect. CONCLUSION: HIE related MRI abnormalities proved to be important prognostic factors of poor outcome in cooled asphyxiated infants when present, suggesting that early MRI with MRS is beneficial for prognostication. Interestingly, ICHs present in about one third of all cases had no significant effect on neurodevelopmental outcome, despite the known hemostasis altering effects of hypothermia.

Prognostic value of early, conventional proton magnetic resonance spectroscopy in cooled asphyxiated infants.

BACKGROUND: Neonatal hypoxic-ischemic encephalopathy (HIE) commonly leads to neurodevelopmental impairment, raising the need for prognostic tools which may guide future therapies in time. Prognostic value of proton MR spectroscopy (H-MRS) between 1 and 46 days of age has been extensively studied; however, the reproducibility and generalizability of these methods are controversial in a general clinical setting. Therefore, we investigated the prognostic performance of conventional H-MRS during first 96 postnatal hours in hypothermia-treated asphyxiated neonates. METHODS: Fifty-one consecutive hypothermia-treated HIE neonates were examined by H-MRS at three echo-times (TE = 35, 144, 288 ms) between 6 and 96 h of age, depending on clinical stability. Patients were divided into favorable (n = 35) and unfavorable (n = 16) outcome groups based on psychomotor and mental developmental index (PDI and MDI, Bayley Scales of Infant Development II) scores (≥ 70 versus < 70 or death, respectively), assessed at 18-26 months of age. Associations between 36 routinely measured metabolite ratios and outcome were studied. Age-dependency of metabolite ratios in whole patient population was assessed. Prognostic performance of metabolite ratios was evaluated by Receiver Operating Characteristics (ROC) analysis. RESULTS: Three metabolite ratios showed significant difference between outcome groups after correction for multiple testing (p < 0.0014): myo-inositol (mIns)/N-acetyl-aspartate (NAA) height, mIns/creatine (Cr) height, both at TE = 35 ms, and NAA/Cr height at TE = 144 ms. Assessment of age-dependency showed that all 3 metabolite ratios (mIns/NAA, NAA/Cr and mIns/Cr) stayed constant during first 96 postnatal hours, rendering them optimal for prediction. ROC analysis revealed that mIns/NAA gives better prediction for outcome than NAA/Cr and mIns/Cr with cut-off values 0.6798 0.6274 and 0.7798, respectively, (AUC 0.9084, 0.8396 and 0.8462, respectively, p < 0.00001); mIns/NAA had the highest specificity (95.24%) and sensitivity (84.62%) for predicting outcome of neonates with HIE any time during the first 96 postnatal hours. CONCLUSIONS: Our findings suggest that during first 96 h of age even conventional H-MRS could be a useful prognostic tool in predicting the outcome of asphyxiated neonates; mIns/NAA was found to be the best and age-independent predictor.

Novel structured MRI reporting system in neonatal hypoxic-ischemic encephalopathy - issues of development and first use experiences.

BACKGROUND AND PURPOSE: To develop an evidence-based, standardized structured reporting (SR) method for brain MRI examinations in neonatal hypoxic-ischemic encephalopathy (HIE) suitable both for clinical and research use. METHODS: SR template development was based on comprehensive review of the pertinent literature with the basic sections and subdivisions of the template defined according to MRI sequences (both conventional and diffusion-weighted, MR-spectroscopy (MRS), and T2*-weighted imaging), and the items targeted on age-related imaging patterns of HIE. In order to evaluate the usability of the proposed SR template we compared data obtained from the brain MR image analysis of 87 term and 19 preterm neonates with the literature. The enrolled 106 infants were born between 2013 and 2015, went through therapeutic hypothermia according to the TOBY criteria due to moderate to severe asphyxia and had at least one brain MRI examination within the first two weeks of life. Ethical approval was obtained for this retrospective study. Descriptive statistical analysis was also performed on data exported from the structured reporting system as feasibility test. RESULTS: The mean gestational age of the study population was 38.3±2.2 weeks; brain MRI was performed on 5.8±2.9 day of life, hence in 78% of our patients after the conclusion of therapeutic hypothermia. Our main imaging findings were concordant to the pertinent literature. Moreover, we identified a characteristic temporal evolution of diffusion changes. Interestingly 18% (n=19/106) of the clinically asphyxiated infants had isolated axial-extraaxial haemorrhage without any imaging sign of HIE. CONCLUSION: In this article our approach of reporting HIE cases with our novel SR template is described. The SR template was found suitable for reporting HIE cases, moreover it uncovered time and location dependent evolution of diffusion abnormalities (and pseudonormalization, as well), suggesting its usefulness in clinical research applications. The high number of isolated intracranial haemorrhages, and the changing diffusion pattern emphasizes the importance of early imaging in HIE.

ICN_Atlas: Automated description and quantification of functional MRI activation patterns in the framework of intrinsic connectivity networks.

Generally, the interpretation of functional MRI (fMRI) activation maps continues to rely on assessing their relationship to anatomical structures, mostly in a qualitative and often subjective way. Recently, the existence of persistent and stable brain networks of functional nature has been revealed; in particular these so-called intrinsic connectivity networks (ICNs) appear to link patterns of resting state and task-related state connectivity. These networks provide an opportunity of functionally-derived description and interpretation of fMRI maps, that may be especially important in cases where the maps are predominantly task-unrelated, such as studies of spontaneous brain activity e.g. in the case of seizure-related fMRI maps in epilepsy patients or sleep states. Here we present a new toolbox (ICN_Atlas) aimed at facilitating the interpretation of fMRI data in the context of ICN. More specifically, the new methodology was designed to describe fMRI maps in function-oriented, objective and quantitative way using a set of 15 metrics conceived to quantify the degree of 'engagement' of ICNs for any given fMRI-derived statistical map of interest. We demonstrate that the proposed framework provides a highly reliable quantification of fMRI activation maps using a publicly available longitudinal (test-retest) resting-state fMRI dataset. The utility of the ICN_Atlas is also illustrated on a parametric task-modulation fMRI dataset, and on a dataset of a patient who had repeated seizures during resting-state fMRI, confirmed on simultaneously recorded EEG. The proposed ICN_Atlas toolbox is freely available for download at http://icnatlas.com and at http://www.nitrc.org for researchers to use in their fMRI investigations.

Impaired mixed emotion processing in the right ventrolateral prefrontal cortex in schizophrenia: an fMRI study.

BACKGROUND: Schizophrenia has a negative effect on the activity of the temporal and prefrontal cortices in the processing of emotional facial expressions. However no previous research focused on the evaluation of mixed emotions in schizophrenia, albeit they are frequently expressed in everyday situations and negative emotions are frequently expressed by mixed facial expressions. METHODS: Altogether 37 subjects, 19 patients with schizophrenia and 18 healthy control subjects were enrolled in the study. The two study groups did not differ in age and education. The stimulus set consisted of 10 fearful (100%), 10 happy (100%), 10 mixed fear (70% fear and 30% happy) and 10 mixed happy facial expressions. During the fMRI acquisition pictures were presented in a randomized order and subjects had to categorize expressions by button press. RESULTS: A decreased activation was found in the patient group during fear, mixed fear and mixed happy processing in the right ventrolateral prefrontal cortex (VLPFC) and the right anterior insula (RAI) at voxel and cluster level after familywise error correction. No difference was found between study groups in activations to happy facial condition. Patients with schizophrenia did not show a differential activation between mixed happy and happy facial expression similar to controls in the right dorsolateral prefrontal cortex (DLPFC). CONCLUSIONS: Patients with schizophrenia showed decreased functioning in right prefrontal regions responsible for salience signaling and valence evaluation during emotion recognition. Our results indicate that fear and mixed happy/fear processing are impaired in schizophrenia, while happy facial expression processing is relatively intact.

Evoked effective connectivity of the human neocortex.

The role of cortical connectivity in brain function and pathology is increasingly being recognized. While in vivo magnetic resonance imaging studies have provided important insights into anatomical and functional connectivity, these methodologies are limited in their ability to detect electrophysiological activity and the causal relationships that underlie effective connectivity. Here, we describe results of cortico-cortical evoked potential (CCEP) mapping using single pulse electrical stimulation in 25 patients undergoing seizure monitoring with subdural electrode arrays. Mapping was performed by stimulating adjacent electrode pairs and recording CCEPs from the remainder of the electrode array. CCEPs reliably revealed functional networks and showed an inverse relationship to distance between sites. Coregistration to Brodmann areas (BA) permitted group analysis. Connections were frequently directional with 43% of early responses and 50% of late responses of connections reflecting relative dominance of incoming or outgoing connections. The most consistent connections were seen as outgoing from motor cortex, BA6-BA9, somatosensory (SS) cortex, anterior cingulate cortex, and Broca's area. Network topology revealed motor, SS, and premotor cortices along with BA9 and BA10 and language areas to serve as hubs for cortical connections. BA20 and BA39 demonstrated the most consistent dominance of outdegree connections, while BA5, BA7, auditory cortex, and anterior cingulum demonstrated relatively greater indegree. This multicenter, large-scale, directional study of local and long-range cortical connectivity using direct recordings from awake, humans will aid the interpretation of noninvasive functional connectome studies.

Investigating the need of triggering the acquisition for infant diffusion MRI: a quantitative study including bootstrap statistics.

Diffusion weighted magnetic resonance imaging is increasingly being used for neonatal and young pediatric subjects. Our purpose was to investigate a) whether cardiac triggering was needed to reduce variability of diffusion (tensor) imaging data, b) how pulsation artifacts affect the fitted diffusion tensor when triggering is not used and c) the feasibility of triggered data acquisition in neonates and young children. Data were collected from 11 infants and 7 adults. In seven infants and seven adults, diffusion encoding was applied solely along the z gradient direction with and without cardiac triggering. Non-parametric bootstrap statistical methods were applied to investigate the dependence of variance on triggering. One infant and all adults served as test-retest controls. From the remaining three infants diffusion tensor imaging data were acquired with and without triggering. Our findings that used the repeated measurements in a single diffusion-encoding direction indicated that without triggering the variability in the data was increased significantly both in infants and adults. When collecting diffusion tensor data in infants, this increased variability results in erroneous fractional anisotropy values and artifactual fiber direction estimates. Contrary to previous reports but supported by our findings involving adults, pulsation artifacts were present in a larger extent of the brain in the infant population. In conclusion, triggering is feasible in young subjects and is preferred when acquiring diffusion MRI data. In doing so, the amount of erroneous estimations due to image artifacts will be minimized, which in turn will lead to more specific and less ambiguous interpretations. Although fitting the pulse-monitoring device requires additional set-up time, the total imaging time is usually shorter than acquiring multiple data sets to compile a single, artifact-free set.

Brain Connectivity Correlates of Breathing and Cardiac Irregularities in SUDEP: A Resting-State fMRI Study.

Sudden unexpected death in epilepsy (SUDEP) is the leading cause of premature mortality among people with epilepsy. Evidence from witnessed and monitored SUDEP cases indicate seizure-induced cardiovascular and respiratory failures; yet, the underlying mechanisms remain obscure. SUDEP occurs often during the night and early morning hours, suggesting that sleep or circadian rhythm-induced changes in physiology contribute to the fatal event. Resting-state fMRI studies have found altered functional connectivity between brain structures involved in cardiorespiratory regulation in later SUDEP cases and in individuals at high-risk of SUDEP. However, those connectivity findings have not been related to changes in cardiovascular or respiratory patterns. Here, we compared fMRI patterns of brain connectivity associated with regular and irregular cardiorespiratory rhythms in SUDEP cases with those of living epilepsy patients of varying SUDEP risk, and healthy controls. We analysed resting-state fMRI data from 98 patients with epilepsy (9 who subsequently succumbed to SUDEP, 43 categorized as low SUDEP risk (no tonic-clonic seizures (TCS) in the year preceding the fMRI scan), and 46 as high SUDEP risk (>3 TCS in the year preceding the scan)) and 25 healthy controls. The global signal amplitude (GSA), defined as the moving standard deviation of the fMRI global signal, was used to identify periods with regular ('low state') and irregular ('high state') cardiorespiratory rhythms. Correlation maps were derived from seeds in twelve regions with a key role in autonomic or respiratory regulation, for the low and high states. Following principal component analysis, component weights were compared between the groups. We found widespread alterations in connectivity of precuneus/posterior cingulate cortex in epilepsy compared to controls, in the low state (regular cardiorespiratory activity). In the low state, and to a lesser degree in the high state, reduced anterior insula connectivity (mainly with anterior and posterior cingulate cortex) in epilepsy appeared, relative to healthy controls. For SUDEP cases, the insula connectivity differences were inversely related to the interval between the fMRI scan and death. The findings suggest that anterior insula connectivity measures may provide a biomarker of SUDEP risk. The neural correlates of autonomic brain structures associated with different cardiorespiratory rhythms may shed light on the mechanisms underlying terminal apnea observed in SUDEP.

Regular Practice of Autogenic Training Reduces Migraine Frequency and Is Associated With Brain Activity Changes in Response to Fearful Visual Stimuli.

Several factors can contribute to the development and chronification of migraines, including stress, which is undoubtedly a major trigger. Beyond pharmacotherapy, other treatment methods also exist, including behavioral techniques aiming at reducing patients' stress response. However, the exact brain mechanisms underlying the efficacy of such methods are poorly understood. Our pilot study examined whether the regular practice of autogenic training (AT) induces functional brain changes and if so, how it could be associated with the improvement of migraine parameters. By exploring neural changes through which AT exerts its effect, we can get closer to the pathomechanism of migraine. In particular, we investigated the effect of a headache-specific AT on brain activation using an implicit face emotion processing functional MRI (fMRI) task in female subjects with and without episodic migraine. Our focus was on migraine- and psychological stress-related brain regions. After a 16-week training course, migraineurs showed decreased activation in the migraine-associated dorsal pons to fearful compared with neutral visual stimuli. We also detected decreasing differences in supplementary motor area (SMA) activation to fearful stimuli, and in posterior insula activation to happy stimuli between healthy subjects and migraineurs. Furthermore, migraineurs reported significantly less migraine attacks. These brain activation changes suggest that AT may influence the activity of brain regions responsible for emotion perception, emotional and motor response integration, as well as cognitive control, while also being able to diminish the activation of regions that have an active role in migraine attacks. Improvements induced by the training and the underlying neurophysiological mechanisms are additional arguments in favor of evidence-based personalized behavioral therapies.

Inter-individual differences in pain anticipation and pain perception in migraine: Neural correlates of migraine frequency and cortisol-to-dehydroepiandrosterone sulfate (DHEA-S) ratio.

Previous studies targeting inter-individual differences in pain processing in migraine mainly focused on the perception of pain. Our main aim was to disentangle pain anticipation and perception using a classical fear conditioning task, and investigate how migraine frequency and pre-scan cortisol-to-dehydroepiandrosterone sulfate (DHEA-S) ratio as an index of neurobiological stress response would relate to neural activation in these two phases. Functional Magnetic Resonance Imaging (fMRI) data of 23 participants (18 females; mean age: 27.61± 5.36) with episodic migraine without aura were analysed. We found that migraine frequency was significantly associated with pain anticipation in brain regions comprising the midcingulate and caudate, whereas pre-scan cortisol-to DHEA-S ratio was related to pain perception in the pre-supplementary motor area (pre-SMA). Both results suggest exaggerated preparatory responses to pain or more general to stressors, which may contribute to the allostatic load caused by stressors and migraine attacks on the brain.

Spatiotemporal brain activation pattern following acute citalopram challenge is dose dependent and associated with neuroticism: A human phMRI study.

BACKGROUND: The initial effects of selective serotonin reuptake inhibitors (SSRIs) in the human living brain are poorly understood. We carried out a 3T resting state fMRI study with pharmacological challenge to determine the brain activation changes over time following different dosages of citalopram. METHODS: During the study, 7.5 mg i.v. citalopram was administered to 32 healthy subjects. In addition, 11.25 mg citalopram was administered to a subset of 9 subjects to investigate the dose-response. Associations with neuroticism (assessed by the NEO PI-R) of the emerging brain activation to citalopram was also investigated. RESULTS: Citalopram challenge evoked significant activation in brain regions that are part of the default mode network, the visual network and the sensorimotor network, extending to the thalamus, and midbrain. Most effects appeared to be dose-dependent and this was statistically significant in the middle cingulate gyrus. Individual citalopram-induced brain responses were positively correlated with neuroticism scores and its subscales in specific brain areas; anxiety subscale scores in thalamus and midbrain and self-consciousness scores in middle cingulate gyrus. There were no sex differences. LIMITATIONS: We investigated only healthy subjects and we used a relatively low sample size in the 11.25 mg citalopram analysis. DISCUSSION: Our results suggest that SSRIs acutely induce an increased arousal-like state of distributed cortical and subcortical systems that is mediated by enhanced serotonin neurotransmission according to levels of neuroticism and underpins trait sensitivity to environmental stimuli and stressors. Studies in depression are needed to determine how therapeutic effects eventually emerge. This article is part of the special issue entitled 'Serotonin Research: Crossing Scales and Boundaries'.

Type of featural attention differentially modulates hMT+ responses to illusory motion aftereffects.

Activity in the human motion complex (hMT(+)/V5) is related to the perception of motion, be it either real surface motion or an illusion of motion such as apparent motion (AM) or motion aftereffect (MAE). It is a long-lasting debate whether illusory motion-related activations in hMT(+) represent the motion itself or attention to it. We have asked whether hMT(+) responses to MAEs are present when shifts in arousal are suppressed and attention is focused on concurrent motion versus nonmotion features. Significant enhancement of hMT(+) activity was observed during MAEs when attention was focused either on concurrent spatial angle or color features. This observation was confirmed by direct comparison of adapting (MAE inducing) versus nonadapting conditions. In contrast, this effect was diminished when subjects had to report on concomitant speed changes of superimposed AM. The same finding was observed for concomitant orthogonal real motion (RM), suggesting that selective attention to concurrent illusory or real motion was interfering with the saliency of MAE signals in hMT(+). We conclude that MAE-related changes in the global activity of hMT(+) are present provided selective attention is not focused on an interfering feature such as concurrent motion. Accordingly, there is a genuine MAE-related motion signal in hMT(+) that is neither explained by shifts in arousal nor by selective attention.

Learning to filter out visual distractors.

When learning to master a visual task in a cluttered natural environment, it is important to optimize the processing of task-relevant information and to efficiently filter out distractors. However, the mechanisms that suppress task-irrelevant information are not well understood. Here we show that training leads to a selective increase in motion coherence detection thresholds for task-irrelevant motion directions that interfered with the processing of task-relevant directions during training. Furthermore, using functional magnetic resonance imaging we found that training attenuated neural responses associated with the task-irrelevant direction compared with the task-relevant direction in the visual cortical areas involved in processing of visual motion. The strongest suppression of functional magnetic resonance imaging responses to task-irrelevant motion information was observed in human area MT+. These findings reveal that perceptual learning leads to the suppression and efficient filtering of task-irrelevant visual information.

Personalized microstructural evaluation using a Mahalanobis-distance based outlier detection strategy on epilepsy patients' DTI data - Theory, simulations and example cases.

Quantitative MRI methods have recently gained extensive interest and are seeing substantial developments; however, their application in single patient vs control group comparisons is often limited by inherent statistical difficulties. One such application is detecting malformations of cortical development (MCDs) behind drug resistant epilepsies, a task that, especially when based solely on conventional MR images, may represent a serious challenge. We aimed to develop a novel straightforward voxel-wise evaluation method based on the Mahalanobis-distance, combining quantitative MRI data into a multidimensional parameter space and detecting lesion voxels as outliers. Simulations with standard multivariate Gaussian distribution and resampled DTI-eigenvalue data of 45 healthy control subjects determined the optimal critical value, cluster size threshold, and the expectable lesion detection performance through ROC-analyses. To reduce the effect of false positives emanating from registration artefacts and gyrification differences, an automatic classification method was applied, fine-tuned using a leave-one-out strategy based on diffusion and T1-weighted data of the controls. DWI processing, including thorough corrections and robust tensor fitting was performed with ExploreDTI, spatial coregistration was achieved with the DARTEL tools of SPM12. Additional to simulations, clusters of outlying diffusion profile, concordant with neuroradiological evaluation and independent calculations with the MAP07 toolbox were identified in 12 cases of a 13 patient example population with various types of MCDs. The multidimensional approach proved sufficiently sensitive in pinpointing regions of abnormal tissue microstructure using DTI data both in simulations and in the heterogeneous example population. Inherent limitations posed by registration artefacts, age-related differences, and the different or mixed pathologies limit the generalization of specificity estimation. Nevertheless, the proposed statistical method may aid the everyday examination of individual subjects, ever so more upon extending the framework with quantitative information from other modalities, e.g. susceptibility mapping, relaxometry, or perfusion.

What can DTI tell about early cognitive impairment? - Differentiation between MCI subtypes and healthy controls by diffusion tensor imaging.

Mild cognitive impairment (MCI) gained a lot of interest recently, especially that the conversion rate to Alzheimer Disease (AD) in the amnestic subtype (aMCI) is higher than in the non-amnestic subtype (naMCI). We aimed to determine whether and how diffusion-weighted MRI (DWI) using the diffusion tensor model (DTI) can differentiate MCI subtypes from healthy subjects. High resolution 3D T1W and DWI images of patients (aMCI, n = 18; naMCI, n = 20; according to Petersen criteria) and controls (n = 27) were acquired at 3T and processed using ExploreDTI and SPM. Voxel-wise and region of interest (ROI) analyses of fractional anisotropy (FA) and mean diffusivity (MD) were performed with ANCOVA; MD was higher in aMCI compared to controls or naMCI in several grey and white matter (GM, WM) regions (especially in the temporal pole and the inferior temporal lobes), while FA was lower in WM ROI-s (e.g. left Cingulum). Moreover, significant correlations were identified between verbal fluency, visual and verbal memory performance and DTI metrics. Logistic regression showed that measuring FA of the crus of fornix along GM volumetry improves the discrimination of aMCI from naMCI. Additional information from DWI/DTI aids preclinical detection of AD and may help detecting early non-Alzheimer type dementia, too.

Trait Rumination Influences Neural Correlates of the Anticipation but Not the Consumption Phase of Reward Processing.

Cumulative evidence suggests that trait rumination can be defined as an abstract information processing mode, which leads people to constantly anticipate the likely impact of present events on future events and experiences. A previous study with remitted depressed patients suggested that enhanced rumination tendencies distort brain mechanisms of anticipatory processes associated with reward and loss cues. In the present study, we explored the impact of trait rumination on neural activity during reward and loss anticipation among never-depressed people. We analyzed the data of 37 healthy controls, who performed the monetary incentive delay (MID) task which was designed for the simultaneous measurement of the anticipation (motivational) and consumption (hedonic) phase of reward processing, during functional magnetic resonance imaging (fMRI). Our results show that rumination-after controlling for age, gender, and current mood-significantly influenced neural responses to reward (win) cues compared to loss cues. Blood-oxygenation-level-dependent (BOLD) activity in the left inferior frontal gyrus (IFG) triangularis, left anterior insula, and left rolandic operculum was positively related to Ruminative Response Scale (RRS) scores. We did not detect any significant rumination-related activations associated with win-neutral or loss-neutral cues and with reward or loss consumption. Our results highlight the influence of trait rumination on reward anticipation in a non-depressed sample. They also suggest that for never-depressed ruminators rewarding cues are more salient than loss cues. BOLD response during reward consumption did not relate to rumination, suggesting that rumination mainly relates to processing of the motivational (wanting) aspect of reward rather than the hedonic (liking) aspect, at least in the absence of pathological mood.