Brain Connectivity Changes in Postconcussion Syndrome as the Neural Substrate of a Heterogeneous Syndrome.

Postconcussion syndrome (PCS) or persistent symptoms of concussion refers to a constellation of symptoms that persist for weeks and months after a concussion. To better capture the heterogeneity of the symptoms of patients with PCS, we aimed to separate patients into clinical subtypes based on brain connectivity changes. Subject-specific structural and functional connectomes were created based on diffusion weighted and resting state functional magnetic resonance imaging, respectively.

Cerebrovascular reactivity changes in acute concussion: a controlled cohort study.

Background: Evidence suggests that cerebrovascular reactivity (CVR) increases within the first week after the incidence of concussion, indicating a disruption of normal autoregulation. We sought to extend these findings by investigating the effects of acute concussion on the speed of CVR response and by visualizing global and regional impairments in individual patients with acute concussion.

Methods: Twelve patients aged 18-40 years who experienced concussion less than a week before this prospective study were included.

The Effect of CO on Resting-State Functional Connectivity: Isocapnia vs. Poikilocapnia.

The normal variability in breath size and frequency results in breath-to-breath variability of end-tidal PCO (PCO), the measured variable, and arterial partial pressure of carbon dioxide (PaCO), the independent variable affecting cerebral blood flow (CBF). This study examines the effect of variability in PaCO on the pattern of resting-state functional MRI (rs-fMRI) connectivity. A region of interest (ROI)-to-ROI and Seed-to-Voxel first-level bivariate correlation, hemodynamic response function (hrf)-weighted analysis for measuring rs-fMRI connectivity was performed during two resting-state conditions: (a) normal breathing associated with breath-to-breath variation in PaCO (poikilocapnia), and (b) normal breathing with breath-to-breath variability of PCO dampened using sequential rebreathing (isocapnia).

The value of a shorter-delay arterial spin labeling protocol for detecting cerebrovascular impairment.

Background: The aim of this study was to determine the relationship between blood oxygen level dependent (BOLD) cerebrovascular reactivity (CVR) and cerebral blood flow (CBF) obtained from arterial spin labeling (ASL) using different post labeling delays (PLD).

Methods: Forty-two patients with steno-occlusive diseases and impaired CVR were divided into two groups, one scanned with a 1.5-second (1.

Sex-specific differences in resting-state functional connectivity of large-scale networks in postconcussion syndrome.

Concussions are associated with a range of cognitive, neuropsychological and behavioral sequelae that, at times, persist beyond typical recovery times and are referred to as postconcussion syndrome (PCS). There is growing support that concussion can disrupt network-based connectivity post-injury. To date, a significant knowledge gap remains regarding the sex-specific impact of concussion on resting state functional connectivity (rs-FC).

Neuroimaging the emotional modulation of urge inhibition in Tourette Syndrome.

Tourette Syndrome (TS) is a neuropsychiatric condition characterized by tics that are typically preceded by uncomfortable urges that build until the tic is performed. Both tics and their associated urges are commonly exacerbated during states of heightened emotion. However, the neural substrates that are responsible for the development of urges have not been fully elucidated, particularly with regards to the influence of emotion.

Accelerated ethanol elimination via the lungs.

Ethanol poisoning is endemic the world over. Morbidity and mortality depend on blood ethanol levels which in turn depend on the balance between its rates of absorption and clearance. Clearance of ethanol is mostly at a constant rate via enzymatic metabolism.

A Promising Subject-Level Classification Model for Acute Concussion Based on Cerebrovascular Reactivity Metrics.

Concussion imaging research has primarily focused on neuronal disruption with lesser emphasis directed toward vascular dysfunction. However, blood flow metrics may be more sensitive than measures of neuronal integrity. Vascular dysfunction can be assessed by measuring cerebrovascular reactivity (CVR)-the change in cerebral blood flow per unit change in vasodilatory stimulus.

Cerebrovascular Reactivity Assays Collateral Function in Carotid Stenosis.

In patients with carotid artery stenosis (CAS), the risk of stroke, its severity, and response to revascularization are strongly related to the availability of collateral blood flow. Unfortunately, there is poor agreement between observers in assessing collateral flow using flow-based imaging. We used changes in blood-oxygen-level-dependent (BOLD) MRI as a surrogate of changes in regional cerebral blood flow in response to a hypercapnic stimulus [i.

The functional connectivity profile of tics and obsessive-compulsive symptoms in Tourette Syndrome.

Tourette Syndrome (TS) is characterized by the presence of tics and sensory phenomena, such as premonitory urges, and is often accompanied by significant obsessive-compulsive symptoms (OCS). The goal of this exploratory study was to determine the association between functional connectivity and the different symptom domains of TS, as little is currently known about how they differ. Resting-state functional magnetic resonance imaging was performed in 39 patients with TS and 20 matched healthy controls.

Examining the functional activity of different obsessive-compulsive symptom dimensions in Tourette syndrome.

Objectives: Tourette syndrome (TS) is commonly comorbid with obsessive-compulsive disorder (OCD) and many phenomenological similarities exist between tics and obsessive-compulsive symptoms (OCS). Therefore, due to the clinical importance of comorbid OCD, the goal of this study was to investigate the neural substrates of OCS in TS using functional magnetic resonance imaging.

Methods: Forty patients with TS and 20 healthy controls underwent functional magnetic resonance imaging while viewing blocks of OCS-provoking pictures relating to washing, checking and symmetry symptoms, as well as generally disgusting and neutral scenes.

Slowed Temporal and Parietal Cerebrovascular Response in Patients with Alzheimer's Disease.

Background: Recent investigations now suggest that cerebrovascular reactivity (CVR) is impaired in Alzheimer's disease (AD) and may underpin part of the disease's neurovascular component. However, our understanding of the relationship between the magnitude of CVR, the speed of cerebrovascular response, and the progression of AD is still limited. This is especially true in patients with mild cognitive impairment (MCI), which is recognized as an intermediate stage between normal aging and dementia.

The efficiency of the brain connectome is associated with cerebrovascular reactivity in persons with white matter hyperintensities.

The purpose of this study was to determine the relationship between the organization of the brain connectome and cerebrovascular reactivity (CVR) in persons with white matter hyperintensities. Diffusion tensor and CVR mapping 3T MRI scans were acquired in 31 participants with white matter hyperintensities. In each participant, the connectome was assessed by reconstructing all white matter tracts with tractography and segmenting the whole brain into multiple regions.

Cerebrovascular Resistance in Healthy Aging and Mild Cognitive Impairment.

Measures of cerebrovascular reactivity (CVR) are used to judge the health of the brain vasculature. In this study, we report the use of several different analyses of blood oxygen dependent (BOLD) fMRI responses to CO to provide a number of metrics of CVR based on the sigmoidal resistance response to CO. To assess possible differences in these metrics with age, we compiled atlases reflecting voxel-wise means and standard deviations for four different age ranges and for a group of patients with mild cognitive impairment (MCI) and compared them.

3-Tesla MRI of deep brain stimulation patients: safety assessment of coils and pulse sequences.

Objective: Physicians are more frequently encountering patients who are treated with deep brain stimulation (DBS), yet many MRI centers do not routinely perform MRI in this population. This warrants a safety assessment to improve DBS patients' accessibility to MRI, thereby improving their care while simultaneously providing a new tool for neuromodulation research.

Methods: A phantom simulating a patient with a DBS neuromodulation device (DBS lead model 3387 and IPG Activa PC model 37601) was constructed and used.

Correction: Monitoring for myelopathic progression with multiparametric quantitative MRI.

[This corrects the article DOI: 10.1371/journal.pone.

Neuropathic pain and pain interference are linked to alpha-band slowing and reduced beta-band magnetoencephalography activity within the dynamic pain connectome in patients with multiple sclerosis.

Chronic pain is a common occurrence in multiple sclerosis (MS) that severely affects quality of life, but the underlying brain mechanisms related to these symptoms are unknown. Previous electroencephalography studies have demonstrated a role of alpha-band and beta-band power in pain processing. However, how and where these brain signals change in MS-related chronic pain is unknown.

Impact of white matter hyperintensities on surrounding white matter tracts.

Purpose: It is unclear how white matter hyperintensities disrupt surrounding white matter tracts. The aim of this tractography study was to determine the spatial relationship between diffusion characteristics along white matter tracts and the distance from white matter hyperintensities.

Methods: Diffusion tensor 3-T MRI scans were acquired in 29 participants with white matter hyperintensities.

The aging brain and cerebrovascular reactivity.

Cerebrovascular reactivity (CVR) is a measure of vascular response to a vasoactive stimulus, and can be used to assess the health of the brain vasculature. In this current study we used different analyses of BOLD fMRI responses to CO to provide a number of metrics including ramp and step CVR, speed of response and transfer function analysis (TFA). 51 healthy control volunteers between the ages of 18-85 (26 males) were recruited and scanned at 3T field strength.

Cerebrovascular Resistance: The Basis of Cerebrovascular Reactivity.

The cerebral vascular network regulates blood flow distribution by adjusting vessel diameters, and consequently resistance to flow, in response to metabolic demands (neurovascular coupling) and changes in perfusion pressure (autoregulation). Deliberate changes in carbon dioxide (CO) partial pressure may be used to challenge this regulation and assess its performance since CO also acts to change vessel diameter. Cerebrovascular reactivity (CVR), the ratio of cerebral blood flow (CBF) response to CO stimulus is currently used as a performance metric.

Long-term changes in cerebrovascular reactivity following EC-IC bypass for intracranial steno-occlusive disease.

The purpose of this retrospective observational study is to investigate the long-term changes in cerebrovascular reactivity (CVR) as a measure of cerebral hemodynamics in patients with intracranial steno-occlusive disease (IC-SOD) after they have undergone an Extracranial-intracranial (EC-IC) bypass. Twenty-six patients suffering from IC-SOD were selected from our CVR database. Nineteen patients underwent unilateral and 7 underwent bilateral revascularization.

The Neural Correlates of Self-Regulatory Fatigability During Inhibitory Control of Eye Blinking.

The capacity to regulate urges is an important human characteristic associated with a range of social and health outcomes. Self-regulatory capacity has been postulated to have a limited reserve, which when depleted leads to failure. The authors aimed to investigate the neural correlates of self-regulatory fatigability.

Importance of Collateralization in Patients With Large Artery Intracranial Occlusive Disease: Long-Term Longitudinal Assessment of Cerebral Hemodynamic Function.

Patients with large artery intracranial occlusive disease (LAICOD) are at risk for both acute ischemia and chronic hypoperfusion. Collateral circulation plays an important role in prognosis, and imaging plays an essential role in diagnosis, treatment planning, and prognosis of patients with LAICOD. In addition to standard structural imaging, assessment of cerebral hemodynamic function is important to determine the adequacy of collateral supply.

Is Rest Really Rest? Resting-State Functional Connectivity During Rest and Motor Task Paradigms.

Numerous studies have identified several large-scale networks within the brain of healthy individuals, some of which have been attributed to ongoing mental activity during the wakeful resting state. While engaged during specific resting-state functional magnetic resonance imaging (fMRI) paradigms, it remains unclear as to whether traditional block-design simple movement fMRI experiments significantly influence these mode networks or other areas. Using blood-oxygen level-dependent fMRI, we characterized the pattern of functional connectivity in healthy subjects during a resting-state paradigm and compared this with the same resting-state analysis performed on motor task data residual time courses after regressing out the task paradigm.

Monitoring for myelopathic progression with multiparametric quantitative MRI.

Background: Patients with mild degenerative cervical myelopathy (DCM) are often managed non-operatively, and surgery is recommended if neurological progression occurs. However, detection of progression is often subjective. Quantitative MRI (qMRI) directly measures spinal cord (SC) tissue changes, detecting axonal injury, demyelination, and atrophy.