Genetic and environmental influences on MRI scan quantity and quality

The current study provides an overview of quantity and quality of MRI data in a large developmental twin sample (N = 512, aged 7–9), and investigated to what extent scan quantity and quality were influenced by genetic and environmental factors. This was examined in a fixed scan protocol consisting of two functional MRI tasks, high resolution structural anatomy (3DT1) and connectivity (DTI) scans, and a resting state scan. Overall, scan quantity was high (88% of participants completed all runs), while scan quality decreased with increasing session length. Scanner related distress was negatively associated with scan quantity (i.e., completed runs), but not with scan quality (i.e., included runs). In line with previous studies, behavioral genetic analyses showed that genetics explained part of the variation in head motion, with heritability estimates of 29% for framewise displacement and 65% for absolute displacement. Additionally, our results revealed that subtle head motion (after exclusion of excessive head motion) showed lower heritability estimates (0–14%), indicating that findings of motion-corrected and quality-controlled MRI data may be less confounded by genetic factors. These findings provide insights in factors contributing to scan quality in children, an issue that is highly relevant for the field of developmental neuroscience.     

Identification of the sensorimotor cortex with functional MRI: frequency and actual contribution in a neurosurgical context.

BACKGROUND AND PURPOSE: We assessed the actual frequency of motor functional MRI (fMRI) in a neurosurgical environment and estimated the extent to which it aided surgeons' identifications of the sensorimotor cortex. METHODS: During five consecutive years, an fMRI protocol aimed at generating a selective activation of the hand cortical area was prescribed to 147 patients showing a centrally located space-occupying lesion, which represents 6.7% of all assisted surgical candidates showing an intracranial mass. Three senior neurosurgeons indicated the position of the sensorimotor cortex on two different anatomical displays, reporting confidence ratings for each decision. RESULTS: The sensorimotor cortex could not be identified in 16.5% of cases using conventional anatomical MRI, and in 15% of cases using 3-dimensional reconstructions. In an additional 12.5% of cases, the neurosurgeons were not confident when they correctly identified the sensorimotor cortex. The tumor distorting effect on central region anatomy significantly contributed to sensorimotor cortex misidentification. fMRI, by contrast, showed a selective activation indicating the position of the sensorimotor cortex in all but 4% of cases. CONCLUSIONS: In our neurosurgical environment, fMRI was prescribed to a selected group of surgical candidates showing a centrally located brain lesion. Compared to conventional anatomical imaging, fMRI does appear to improve the identification of sensorimotor cortex.     

Altered insular functional connectivity in isolated REM sleep behavior disorder: a data-driven functional MRI study

ObjectiveFunctional connectivity (FC) changes can occur prior to structural changes. This study aimed to evaluate data-driven whole-brain FC associated with isolated rapid eye movement sleep behavior disorder (iRBD) using multivariate pattern analysis (MVPA).MethodsThis was a cross-sectional study of 50 polysomnography-confirmed iRBD patients and 20 age- and sex-matched controls. We used MVPA implemented in the connectome-MVPA CONN toolbox to identify data-driven seed regions for post hoc seed-to-voxel connectivity analysis. The association between FC changes and clinical characteristics, including cognition, depression, autonomic function, and daytime sleepiness, was evaluated.ResultsMVPA revealed one significant cluster located in the left posterior insular cortex. Seed-to-voxel FC analysis using the cluster as a seed showed significantly reduced FC with two clusters located in the precuneus in iRBD patients compared to the controls. The degree of FC was associated with the Montreal Cognitive Assessment-Korean version scores (r = 0.317, p = 0.025).ConclusionThis study emphasizes the insula as an important neural correlate associated with iRBD that was associated with cognitive function.     

Imaging the rapidly developing brain: Current challenges for MRI studies in the first five years of life

Rapid and widespread changes in brain anatomy and physiology in the first five years of life present substantial challenges for developmental structural, functional, and diffusion MRI studies. One persistent challenge is that methods best suited to earlier developmental stages are suboptimal for later stages, which engenders a trade-off between using different, but age-appropriate, methods for different developmental stages or identical methods across stages. Both options have potential benefits, but also biases, as pipelines for each developmental stage can be matched on methods or the age-appropriateness of methods, but not both. This review describes the data acquisition, processing, and analysis challenges that introduce these potential biases and attempts to elucidate decisions and make recommendations that would optimize developmental comparisons.     

Accurate age classification of 6 and 12 month-old infants based on resting-state functional connectivity magnetic resonance imaging data

Human large-scale functional brain networks are hypothesized to undergo significant changes over development. Little is known about these functional architectural changes, particularly during the second half of the first year of life. We used multivariate pattern classification of resting-state functional connectivity magnetic resonance imaging (fcMRI) data obtained in an on-going, multi-site, longitudinal study of brain and behavioral development to explore whether fcMRI data contained information sufficient to classify infant age. Analyses carefully account for the effects of fcMRI motion artifact. Support vector machines (SVMs) classified 6 versus 12 month-old infants (128 datasets) above chance based on fcMRI data alone. Results demonstrate significant changes in measures of brain functional organization that coincide with a special period of dramatic change in infant motor, cognitive, and social development. Explorations of the most different correlations used for SVM lead to two different interpretations about functional connections that support 6 versus 12-month age categorization.     

Use of complex visual stimuli allows controlled recruitment of cortical networks in infants

ObjectiveTo characterize cortical networks activated by patterned visual stimuli in infants, and to evaluate their potential for assessment of visual processing and their associations with neurocognitive development.MethodsThree visual stimuli, orientation reversal (OR), global form (GF), and global motion (GM), were presented to cohort of five-month-old infants (N = 26). Eye tracker was used to guide the stimulation and to choose epochs for analysis. Visual responses were recorded with electroencephalography and analysed in source space using weighted phase lag index as the connectivity measure. The networks were quantified using several metrics that were compared between stimuli and correlated to cognitive outcomes.ResultsResponses to OR/GF/GM stimuli were observed in nearly all (96/100/100%) recordings. All stimuli recruited cortical networks that were partly condition-specific in their characteristics. The more complex GF and GM conditions recruited wider global networks than OR. Additionally, strength of the GF network showed positive association with later cognitive performance.ConclusionsNetwork analysis suggests that visual stimulation recruits large-scale cortical networks that extend far beyond the conventional visual streams and that differ between stimulation conditions.SignificanceThe method allows controlled recruitment of wide cortical networks, which holds promise for the early assessment of visual processing and its related higher-order cognitive processes.     

Anatomical and functional distribution of functional MRI language mapping

ObjectiveThe aim of the present study was to compare localization of the language cortex using electrical cortical stimulation (ECS) and functional magnetic resonance imaging (fMRI) to establish the relevance of fMRI language mapping.MethodsLanguage mapping with fMRI and functional ECS mapping were retrospectively compared in ten patients with refractory epilepsy who underwent fMRI language mapping and functional ECS mapping between June 2012 and April 2019. A shiritori task, a popular Japanese word chain game, was used for fMRI language mapping.ResultsBOLD signal activation was observed in the left inferior frontal gyrus (including the pars opecularis and the pars triangularis), and superior temporal gyrus, which is a language-related area, as well as in the left superior and middle frontal gyri, the intraparietal sulcus, and fusiform gyrus. These results were compared with ECS to elucidate the functional role of the activated areas during fMRI language tasks. These activated areas included language areas, negative motor areas, supplementary motor areas (SMAs), and non-functional areas.ConclusionThe activated areas of fMRI language mapping include language-related areas, the negative motor area, and SMAs. These findings suggest the involvement of language and higher order motor networks in verbal expression.     

Neural correlates of facial motion perception

Several neuroimaging studies have revealed that the superior temporal sulcus (STS) is highly implicated in the processing of facial motion. A limitation of these investigations, however, is that many of them utilize unnatural stimuli (e.g., morphed videos) or those which contain many confounding spatial cues. As a result, the underlying mechanisms may not be fully engaged during such perception. The aim of the current study was to build upon the existing literature by implementing highly detailed and accurate models of facial movement. Accordingly, neurologically healthy participants viewed simultaneous sequences of rigid and nonrigid motion that was retargeted onto a standard computer generated imagery face model. Their task was to discriminate between different facial motion videos in a two-alternative forced choice paradigm. Presentations varied between upright and inverted orientations. In corroboration with previous data, the perception of natural facial motion strongly activated a portion of the posterior STS. The analysis also revealed engagement of the lingual gyrus, fusiform gyrus, precentral gyrus, and cerebellum. These findings therefore suggest that the processing of dynamic facial information is supported by a network of visuomotor substrates.     

Functional MRI reveals left amygdala activation during emotion

The potential of functional magnetic resonance imaging (fMRI) for experimental studies of the brain and behavior is considerable given its superior time and spatial resolution, but few studies have attempted to validate them against established methods for measuring cerebral activation. In a previous study absolute regional cerebral blood flow was measured in 16 healthy individuals using quantitative H₂¹⁵O-PET during standardized happy and sad mood induction and during two non-emotional control conditions. During sad mood, blood flow increased in the left amygdala and these changes correlated with shifts towards a negative affect. In the present study blood oxygenation level dependent (BOLD) changes were measured with fMRI during the same experimentally controlled mood states and control tasks. Twelve right-handed normal subjects were examined with a T2*-weighted FLASH sequence. A significant increase in signal intensity was found during sad as well as happy mood induction in the left amygdala. This converging evidence supports the potential of fMRI for advancing the understanding of neural substrates for emotional experience in humans.     

Altered resting-state thalamo-occipital functional connectivity is associated with cognition in isolated rapid eye movement sleep behavior disorder

ObjectiveIsolated rapid eye movement sleep behavior disorder (iRBD) patients are at risk of cognitive impairments, however the underlying mechanism is still unclear. This study aimed to evaluate thalamo-cortical functional connectivity (FC) using resting-state functional magnetic resonance imaging (fMRI) and its correlation with cognitive dysfunction in patients with iRBD.MethodsA total 37 polysomnographies (PSGs) confirmed iRBD patients and 15 age-sex matched controls underwent resting-state fMRI and comprehensive neuropsychological assessment. Thalamo-cortical FC was evaluated by using seed-to voxel analysis and was compared between the iRBD and controls. Correlation between the average value of significant clusters and cognitive function scores in iRBD were calculated.ResultsCompared to the control subjects, patients with iRBD patients showed cognitive decline in word list recognition (p = 0.016), and constructional recall (p = 0.044). The FC analysis showed increased FC between the left thalamus and occipital regions including the right cuneal cortex, left fusiform gyrus and lingual gyrus (cluster level p < 0.05, corrected for false discovery rate). The averaged thalamo-fusiform FC value positively correlated with word list recognition after adjusting for age and sex (adjusted r = 0.347, p = 0.041).ConclusionThalamic resting state FC is altered in iRBD patients and is associated with the cognitive function. Enhancement of the thalamo-occipital FC may reflect a compensatory mechanism for cognitive impairment in iRBD.     

Microstructural and functional MRI studies of cognitive impairment in epilepsy

Cognitive impairment is the most common comorbidity in children with epilepsy, but its pathophysiology and predisposing conditions remain unknown. Clinical epilepsy characteristics are not conclusive in determining cognitive outcome. Because many children with epilepsy do not have macrostructural magnetic resonance imaging (MRI) abnormalities, the underlying substrate for cognitive impairment may be found at the microstructural or functional level. In the last two decades, new MRI techniques have been developed that have the potential to visualize microstructural or functional abnormalities associated with cognitive impairment. These include volumetric MRI, voxel‐based morphometry (VBM), diffusion tensor imaging (DTI), MR spectroscopy (MRS), and functional MRI (fMRI). All of these techniques have shed new light on various aspects associated with, or underlying, cognitive impairment, although their use in epilepsy has been limited and focused mostly on adults. Therefore, in this review, the use of all these different MRI techniques to unravel cognitive impairment in epilepsy is discussed both in adults and children with epilepsy. Volumetric MRI and VBM have revealed significant volume losses in the area of the seizure focus as well as in distant areas. DTI adds evidence of loss of integrity of connections from the seizure focus to distant areas as well as between distant areas. MRS and fMRI have shown impaired function both in the area of the seizure focus as well as in distant structures. For this review we have compiled and compared findings from the various techniques to conclude that cognitive impairment in epilepsy results from a network disorder in which the (micro)structures as well as the functionality can be disturbed.     

Correspondence between altered functional and structural connectivity in the contralesional sensorimotor cortex after unilateral stroke in rats: a combined resting-state functional MRI and manganese-enhanced MRI study

This study shows a significant correlation between functional connectivity, as measured with resting-state functional magnetic resonance imaging (MRI), and neuroanatomical connectivity, as measured with manganese-enhanced MRI, in rats at 10 weeks after unilateral stroke and in age-matched controls. Reduced interhemispheric functional connectivity between the contralesional primary motor cortex (M1) and ipsilesional sensorimotor cortical regions was accompanied by a decrease in transcallosal manganese transfer from contralesional M1 to the ipsilesional sensorimotor cortex after a large unilateral stroke. Increased intrahemispheric functional connectivity in the contralesional sensorimotor cortex was associated with locally enhanced neuroanatomical tracer uptake, which underlines the strong link between functional and structural reorganization of neuronal networks after stroke.     

Resting state functional networks in 1-to-3-year-old typically developing children

Brain functional networks undergo substantial development and refinement during the first years of life. Yet, the maturational pathways of functional network development remain poorly understood. Using resting-state fMRI data acquired during natural sleep from 24 typically developing toddlers, ages 1.5–3.5 years, we aimed to examine the large-scale resting-state functional networks and their relationship with age and developmental skills. Specifically, two network organization indices reflecting network connectivity and spatial variability were derived. Our results revealed that reduced spatial variability or increased network homogeneity in one of the default mode network components was associated with age, with older children displaying less spatially variable posterior DMN subcomponent, consistent with the notion of increased spatial and functional specialization. Further, greater network homogeneity in higher-order functional networks, including the posterior default mode, salience, and language networks, was associated with more advanced developmental skills measured with a standardized assessment of early learning, regardless of age. These results not only improve our understanding of brain functional network development during toddler years, but also inform the relationship between brain network organization and emerging cognitive and behavioral skills.     

Regional and global connectivity disturbances in focal epilepsy,related neurocognitive sequelae,and potential mechanistic underpinnings

Epilepsy is among the most common brain network disorders, and it is associated with substantial morbidity and increased mortality. Although focal epilepsy was traditionally considered a regional brain disorder, growing evidence has demonstrated widespread network alterations in this disorder that extend beyond the epileptogenic zone from which seizures originate. The goal of this review is to summarize recent investigations examining functional and structural connectivity alterations in focal epilepsy, including neuroimaging and electrophysiologic studies utilizing model‐based or data‐driven analytic methods. A significant subset of studies in both mesial temporal lobe epilepsy and focal neocortical epilepsy have demonstrated patterns of increased connectivity related to the epileptogenic zone, coupled with decreased connectivity in widespread distal networks. Connectivity patterns appear to be related to the duration and severity of disease, suggesting progressive connectivity reorganization in the setting of recurrent seizures over time. Global resting‐state connectivity disturbances in focal epilepsy have been linked to neurocognitive problems, including memory and language disturbances. Although it is possible that increased connectivity in a particular brain region may enhance the propensity for seizure generation, it is not clear if global reductions in connectivity represent the damaging consequences of recurrent seizures, or an adaptive mechanism to prevent seizure propagation away from the epileptogenic zone. Overall, studying the connectome in focal epilepsy is a critical endeavor that may lead to improved strategies for epileptogenic‐zone localization, surgical outcome prediction, and a better understanding of the neuropsychological implications of recurrent seizures.     

Distributed neural systems for temporal production: a functional MRI study

Using functional magnetic resonance imaging (fMRI), we investigated the neural substrates for computing time intervals. Five right-handed males were asked to judge if a digit probe belonged to a string of digits presented immediately before but to provide their response only after 1.5s had elapsed. This time estimation condition, compared with control working memory and motor tasks, was associated with increased activity in the middle occipital gyri, in the right inferior parietal lobe, and bilaterally in the prefrontal cortex. We argue that activity elicited in the occipital lobe provides duration information about visual stimuli that can be quantified at the level of the inferior parietal lobe. Comparison with time reference information depends on the bilateral prefrontal cortex.     

Neural plasticity in fathers of human infants

Fathering plays an important role in infants’ socioemotional and cognitive development. Previous studies have identified brain regions that are important for parenting behavior in human mothers. However, the neural basis of parenting in human fathers is largely unexplored. In the current longitudinal study, we investigated structural changes in fathers’ brains during the first 4 months postpartum using voxel-based morphometry analysis. Biological fathers (n = 16) with full-term, healthy infants were scanned at 2–4 weeks postpartum (time 1) and at 12–16 weeks postpartum (time 2). Fathers exhibited increase in gray matter (GM) volume in several neural regions involved in parental motivation, including the hypothalamus, amygdala, striatum, and lateral prefrontal cortex. On the other hand, fathers exhibited decreases in GM volume in the orbitofrontal cortex, posterior cingulate cortex, and insula. The findings provide evidence for neural plasticity in fathers’ brains. We also discuss the distinct patterns of associations among neural changes, postpartum mood symptoms, and parenting behaviors among fathers.     

Neuroimaging and functional examination in hydrocephalus: a comment

All the papers were of a high scientific standard, giving us clearly defined information that will be applicable in the diagnosis and further management of infantile hydrocephalus. Particularly interesting subjects were the comparison of CT and MRI in the evaluation of hydrocephalus and cine MRI, which allows evaluation of the CSF dynamic flows. CBF measurements with xenon CT/CBF imaging or transcranial Doppler examinations of CBF velocity are used much more for evaluation of the shunt indications for shunting and also for definition of the outcome of shunting procedures. Although measurements of physiological CSF parameters are important, studies on the pathophysiology of hydrocephalus should be focused on the changes in CBF in hydrocephalus patients. The key points and conclusions presented by each author are discussed and the prospects mentioned for the future in neuroimaging and functional examination in hydrocephalus.Presented at the Consensus Conference: Hydrocephalus '92 Assisi, Italy, 26–30 April 1992     

Human infants orient to biological motion rather than audiovisual synchrony

Both orienting to audiovisual synchrony and to biological motion are adaptive responses. The ability to integrate correlated information from multiple senses reduces processing load and underlies the perception of a multimodal and unified world. Perceiving biological motion facilitates filial attachment and detection of predators/prey. In the literature, these mechanisms are discussed in isolation. In this eye-tracking study, we tested their relative strengths in young human infants. We showed five-month-old infants point-light animation pairs of human motion, accompanied by a soundtrack. We found that audiovisual synchrony was a strong determinant of attention when it was embedded in biological motion (two upright animations). However, when biological motion was shown together with distorted biological motion (upright animation and inverted animation, respectively), infants looked at the upright animation and disregarded audiovisual synchrony. Thus, infants oriented to biological motion rather than multimodally unified physical events. These findings have important implications for understanding the developmental trajectory of brain specialization in early human infancy.     

A probabilistic atlas of the human motion complex built from large‐scale functional localizer data

Accurate motion perception is critical to dealing with the changing dynamics of our visual world. A cluster known as the human MT+ complex (hMT+) has been identified as a core region involved in motion perception. Several atlases defined based on cytoarchitecture, retinotopy, connectivity, and multimodal features include homologs of the hMT+. However, an hMT+ atlas defined directly based on this region's response for motion is still lacking. Here, we identified the hMT+ based on motion responses from functional magnetic resonance imaging (fMRI) localizer data in 509 participants and then built a probabilistic atlas of the hMT+. As a result, four main findings were revealed. First, the hMT+ showed large interindividual variability across participants. Second, the atlases stabilized when the number of participants used to build the atlas was more than 100. Third, the functional hMT+ showed good agreement with the hMT+ atlases built based on cytoarchitecture, retinotopy, and connectivity, suggesting a good structural–functional correspondence. Fourth, tests on multiple fMRI data sets acquired from independent participants, imaging parameters and paradigms revealed that the functional hMT+ showed higher sensitivity than all other atlases in ROI analysis except that connectivity and multimodal hMT+ atlases in the left hemisphere could infrequently attain comparable sensitivity to the functional atlas. Taken together, our findings reveal the benefit of using large‐scale functional localizer data to build a reliable and representative hMT+ atlas. Our atlas is freely available for download; it can be used to localize the hMT+ in individual participants when functional localizer data are not available.