Directed functional connectivity of the default-mode-network of young and older healthy subjects.

Alterations in the default mode network (DMN) are associated with aging. We assessed age-dependent changes of DMN interactions and correlations with a battery of neuropsychological tests, to understand the differences of DMN directed connectivity between young and older subjects. Using a novel multivariate analysis method on resting-state functional MRI data from fifty young and thirty-one healthy older subjects, we calculated intra- and inter-DMN 4-nodes directed pathways.

Directed functional connectivity of the sensorimotor system in young and older individuals.

Introduction: Studies in the sensorimotor system of older versus young individuals have shown alterations in functional connectivity and organization. Our objective was to explore the implications of these differences in terms of local organizations, and to identify processes that correlate with neuropsychological parameters.

Methods: Using a novel multivariate analysis method on resting-state functional MRI data obtained from 50 young and 31 older healthy individuals, we identified directed 4-node functional pathways within the sensorimotor system and examined their correlations with neuropsychological assessments.

Aberrant Intrinsic Brain Network Functional Connectivity During a Face-Matching Task in Women Diagnosed With Premenstrual Dysphoric Disorder.

Background: Premenstrual dysphoric disorder (PMDD) is characterized by affective, cognitive, and physical symptoms, suggesting alterations at the brain network level. Women with PMDD demonstrate aberrant discrimination of facial emotions during the luteal phase of the menstrual cycle and altered reactivity to emotional stimuli. However, previous studies assessing emotional task-related brain reactivity using region-of-interest or whole-brain analysis have reported conflicting findings.

Emotional states as distinct configurations of functional brain networks.

The conceptualization of emotional states as patterns of interactions between large-scale brain networks has recently gained support. Yet, few studies have directly examined the brain's network structure during emotional experiences. Here, we investigated the brain's functional network organization during experiences of sadness, amusement, and neutral states elicited by movies, in addition to a resting-state.

Asymmetry of the insula-sensorimotor circuit in Parkinson's disease.

Patients with Parkinson's disease (PD) experience motor and non-motor symptoms, suggesting alterations of the motor and/or limbic system or more probably of their communications. We hypothesized that the communication between the insula (part of the limbic system) and sensorimotor cortex in PD is altered and hemispheric asymmetric. Furthermore, that this asymmetry relates to non-motor symptoms, and specifically, that apathy-related asymmetry is unique to PD.

Altered sensorimotor fMRI directed connectivity in Parkinson's disease patients.

Dopamine depletion in the axons of Parkinson's disease (PD) patients precedes depletion in cell bodies thus proposing that macroscopic connectivity can be used to understand disease mechanism. A novel multivariate functional connectivity analysis, based on high order coherence among four fMRI BOLD signals was applied on resting-state fMRI data of controls and PD patients (OFF and ON medication states) and unidirectional multiple-region pathways in the sensorimotor system were identified. Pathways were classified as "preserved" (unaffected by the disease), "damaged" (not observed in patients) and "corrected" (observed in controls and in PD-ON state).

Childhood Trauma and Premenstrual Symptoms: The Role of Emotion Regulation.

Background: Women with Premenstrual Dysphoric Disorder (PMDD) are more likely to have a history of childhood trauma, and may experience more severe premenstrual symptomatology. However, the pathway in which childhood trauma affects the prevalence and severity of premenstrual symptoms remains largely unclear.

Objective: To determine whether childhood trauma is associated with increased premenstrual symptoms, and if so, whether emotional dysregulation mediates or moderates this relationship.

Trait-related changes in brain network topology in premenstrual dysphoric disorder.

The female predominance in the prevalence of depression is partially accounted by reactivity to hormonal fluctuations. Premenstrual dysphoric disorder (PMDD) is a reproductive subtype of depression characterized by cyclic emotional and somatic symptoms that recur before menstruation. Despite the growing understanding that most psychiatric disorders arise from dysfunctions in distributed brain circuits, the brain's functional connectome and its network properties of segregation and integration were not investigated in PMDD.

Impact of dopamine and cognitive impairment on neural reactivity to facial emotion in Parkinson's disease.

Emotional and cognitive impairments in Parkinson's disease (PD) are prevalent, hamper interpersonal relations and reduce quality of life. It is however unclear to what extent these domains interplay in PD-related deficits and how they are influenced by dopaminergic availability. This study examined the effect of cognitive impairment and dopaminergic medication on neural and behavioral mechanisms of facial emotion recognition in PD patients.

Bidirectional signal exchanges and their mechanisms during joint attention interaction - A hyperscanning fMRI study.

Social interactions are essential to our daily life. We tested the hypothesis that social interactions during joint attention (JA) require bidirectional communication, each with a different mechanism. We used a novel multivariate functional connectivity analysis, which enables obtaining directed pathways between four regions at each time-frequency point, with hyper-scanning MRI data of real-time JA interaction.

Characterizing directed functional pathways in the visual system by multivariate nonlinear coherence of fMRI data.

A multivariate measure of directed functional connectivity is used with resting-state fMRI data of 40 healthy subjects to identify directed pathways of signal progression in the human visual system. The method utilizes 4-nodes networks of mutual interacted BOLD signals to obtains their temporal hierarchy and functional connectivity. Patterns of signal progression were defined at frequency windows by appealing to a hierarchy based upon phase differences, and their significance was assessed by permutation testing.

Sex differences during emotion processing are dependent on the menstrual cycle phase.

Sex differences in the neural processing of emotion are of special interest considering that mood and anxiety disorders predominant in females. However, these sex-related differences were typically studied without considering the hormonal status of female subjects, although emotion processing in the brain was shown to differ between phases of the menstrual cycle. In this functional MRI study, we demonstrated the influence of the menstrual cycle phase on sex differences in brain activity and functional connectivity during negative and positive emotions, using two different paradigms: emotion perception and emotion experience.

Separate neural representations of depression, anxiety and apathy in Parkinson's disease.

Depression, anxiety and apathy are distinct neuropsychiatric symptoms that highly overlap in Parkinson's disease (PD). It remains unknown whether each symptom is uniquely associated with a functional network dysfunction. Here, we examined whether individual differences in each neuropsychiatric symptom predict functional connectivity patterns in PD patients while controlling for all other symptoms and motor function.

Frequency-phase analysis of resting-state functional MRI.

We describe an analysis method that characterizes the correlation between coupled time-series functions by their frequencies and phases. It provides a unified framework for simultaneous assessment of frequency and latency of a coupled time-series. The analysis is demonstrated on resting-state functional MRI data of 34 healthy subjects.

Multiple-region directed functional connectivity based on phase delays.

Network analysis is increasingly advancing the field of neuroimaging. Neural networks are generally constructed from pairwise interactions with an assumption of linear relations between them. Here, a high-order statistical framework to calculate directed functional connectivity among multiple regions, using wavelet analysis and spectral coherence has been presented.

Emotional regulation difficulties and premenstrual symptoms among Israeli students.

Premenstrual dysphoric disorder (PMDD) is a severe form of premenstrual syndrome (PMS) reported to affect 3-8 % of women of reproductive age and resulting in marked emotional and occupational impairment. Despite its prevalence, the etiology of PMDD is largely unknown, and patients remain mostly undiagnosed and poorly treated. It has been suggested that PMDD is a manifestation of underlying depressive disorder which is associated with the inability to regulate emotions in an adaptive manner.

Alterations in the expression of a neurodevelopmental gene exert long-lasting effects on cognitive-emotional phenotypes and functional brain networks: translational evidence from the stress-resilient Ahi1 knockout mouse.

Many psychiatric disorders are highly heritable and may represent the clinical outcome of early aberrations in the formation of neural networks. The placement of brain connectivity as an 'intermediate phenotype' renders it an attractive target for exploring its interaction with genomics and behavior. Given the complexity of genetic make up and phenotypic heterogeneity in humans, translational studies are indicated.

Reduced connectivity and inter-hemispheric symmetry of the sensory system in a rat model of vulnerability to developing depression.

Defining the markers corresponding to a high risk of developing depression in humans would have major clinical significance; however, few studies have been conducted since they are not only complex but also require homogeneous groups. This study compared congenital learned helpless (cLH) rats, selectively bred for high stress sensitivity and learned helplessness (LH) behavior, to congenital non-learned helpless (cNLH) rats that were bred for resistance to uncontrollable stress. Naïve cLH rats show some depression-like behavior but full LH behavior need additional stress, making this model ideal for studying vulnerability to depression.

Understanding alterations in serotonin connectivity in a rat model of depression within the monoamine-deficiency and the hippocampal-neurogenesis frameworks.

The monoamine-deficiency and the hippocampal-neurogenesis hypotheses of depression propose that alterations in the serotonin system and of hippocampal functionality are critical in the pathogenesis of depression. We measured the alterations in the connectivity level of the raphe nucleus in the chronic mild stress (CMS) rat model of depression using the manganese enhanced MRI method (MEMRI). Manganese ions were injected into the median raphe and their anterograde intracellular propagation was followed.

Maximizing negative correlations in resting-state functional connectivity MRI by time-lag.

This paper aims to better understand the physiological meaning of negative correlations in resting state functional connectivity MRI (r-fcMRI). The correlations between anatomy-based brain regions of 18 healthy humans were calculated and analyzed with and without a correction for global signal and with and without spatial smoothing. In addition, correlations between anatomy-based brain regions of 18 naïve anesthetized rats were calculated and compared to the human data.

Functional connectivity in prenatally stressed rats with and without maternal treatment with ladostigil, a brain-selective monoamine oxidase inhibitor.

Stress during pregnancy in humans is known to be a risk factor for neuropsychiatric disorders in the offspring. Prenatal stress in rats caused depressive-like behavior that was restored to that of controls by maternal treatment with ladostigil (8.5 mg/kg per day), a brain-selective monoamine oxidase (MAO) inhibitor that prevented increased anxiety-like behavior in stressed mothers.

Neural mechanisms underlying stress resilience in Ahi1 knockout mice: relevance to neuropsychiatric disorders.

The Abelson helper integration site 1 (AHI1) gene has a pivotal role in brain development. Studies by our group and others have demonstrated association of AHI1 with schizophrenia and autism. To elucidate the mechanism whereby alteration in AHI1 expression may be implicated in the pathogenesis of neuropsychiatric disorders, we studied Ahi1 heterozygous knockout (Ahi1(+/-)) mice.