Selective blockade of rat brain T-type calcium channels provides insights on neurophysiological basis of arousal dependent resting state functional magnetic resonance imaging signals.

A number of studies point to slow (0.1-2 Hz) brain rhythms as the basis for the resting-state functional magnetic resonance imaging (rsfMRI) signal. Slow waves exist in the absence of stimulation, propagate across the cortex, and are strongly modulated by vigilance similar to large portions of the rsfMRI signal.

Reduced Interference and Serial Dependency Effects for Naming in Older but Not Younger Adults after 1 Hz rTMS of Right Pars Triangularis.

1 Hz repetitive transcranial magnetic stimulation (rTMS) was used to decrease excitability of right pars triangularis (R PTr) to determine whether increased R PTr activity during picture naming in older adults hampers word finding. We hypothesized that decreasing R PTr excitability would reduce interference with word finding, facilitating faster picture naming. 15 older and 16 younger adults received two rTMS sessions.

Examining fMRI time-series entropy as a marker for brain E/I balance with pharmacological neuromodulation in a non-human primate translational model.

Recently, there has been a lot of interest in the neuroimaging community in exploring fMRI time-series measures of local neuronal activity and excitation/inhibition (E/I) balance in the brain. In this preliminary study we probed the sensitivity of widely used sample entropy (SE) measure at multiple scales to controlled alteration of the brain's E/I balance in non-human primates (NHPs) with a well-characterized sub-anesthetic ketamine infusion fMRI model. We found that SE failed to detect the expected changes in E/I balance induced by ketamine.

Effects of ketamine treatment on cocaine-induced reinstatement and disruption of functional connectivity in unanesthetized rhesus monkeys.

Rationale: Substance use disorders are characterized by a loss of executive control over reward-based decision-making, and disruption of fronto-striatal connectivity has been implicated in this process. Sub-anesthetic ketamine has recently been shown to bolster fronto-striatal connectivity in drug-naïve subjects.

Objectives: The influence of ketamine treatment was examined on the disruptive effects of cocaine on functional connectivity (FC) and on cocaine-seeking behavior in female rhesus monkeys.

Exploring brain mechanisms underlying Gulf War Illness with group ICA based analysis of fMRI resting state networks.

Around 200,000 veterans (up to 32% of those deployed) of the 1991 Gulf War (GW) suffer from GW illness (GWI), which is characterized by multiple deficits in cognitive, affective, sensory and nociception domains. In this study we employed resting state fMRI (rsfMRI) to map impairments in brain function in GWI with advanced network analysis. RsfMRI data was obtained from 60 GWI veterans and 30 age-matched military controls.

Donepezil effects on hippocampal and prefrontal functional connectivity in Alzheimer's disease: preliminary report.

We used functional connectivity magnetic resonance imaging (fcMRI) to investigate changes in interhemispheric brain connectivity in 11 patients with mild Alzheimer's disease (AD) following eight weeks of treatment with the cholinesterase inhibitor donepezil. We examined functional connectivity between four homologous temporal, frontal, and occipital regions. These regions were selected to represent sites of AD neuropathology, sites of donepezil-related brain activation change in prior studies, and sites that are minimally affected by the pathologic changes of AD.

Optical head tracking for functional magnetic resonance imaging using structured light.

An accurate motion-tracking technique is needed to compensate for subject motion during functional magnetic resonance imaging (fMRI) procedures. Here, a novel approach to motion metrology is discussed. A structured light pattern specifically coded for digital signal processing is positioned onto a fiduciary of the patient.

Validation of non-rigid registration between functional and anatomical magnetic resonance brain images.

This paper presents a set of validation procedures for nonrigid registration of functional EPI to anatomical MRI brain images. Although various registration techniques have been developed and validated for high-resolution anatomical MRI images, due to a lack of quantitative and qualitative validation procedures, the use of nonrigid registration between functional EPI and anatomical MRI images has not yet been deployed in neuroimaging studies. In this paper, the performance of a robust formulation of a nonrigid registration technique is evaluated in a quantitative manner based on simulated data and is further evaluated in a quantitative and qualitative manner based on in vivo data as compared to the commonly used rigid and affine registration techniques in the neuroimaging software packages.

Functional MRI of language in aphasia: a review of the literature and the methodological challenges.

Animal analogue studies show that damaged adult brains reorganize to accommodate compromised functions. In the human arena, functional magnetic resonance imaging (fMRI) and other functional neuroimaging techniques have been used to study reorganization of language substrates in aphasia. The resulting controversy regarding whether the right or the left hemisphere supports language recovery and treatment progress must be reframed.

Neural substrates of syntactic mapping treatment: an fMRI study of two cases.

Two patients (G01, J02) with chronic nonfluent aphasia and sentence production deficits received syntactic mapping treatment to improve sentence production. The patients had dramatically different outcomes in that improved syntax production generalized to nontreatment tasks for G01, but not for JO2. To learn how treatment influenced the neural substrates for syntax production, both patients underwent pre- and posttreatment functional magnetic resonance imaging (fMRI) of sentence generation.

A pneumatic vibrotactile stimulation device for fMRI.

Mapping the functional response of the somatosensory cortex is useful both for characterizing normal brain activity and for determining the functional integrity of damaged cortex compromised by stroke or other neurological insults. A variety of stimulators have been used to produce somatosensory cortex activation in functional brain imaging, including brushes and swabs operated manually, pneumatically and mechanically powered mechanical vibrators, air puffs, and vibrating ceramic piezoelectric wafers and benders. A closed-system, pneumatically driven rubber diaphragm is reported that overcomes many of the limitations of existing vibrotactile devices and produces robust sensory cortex activation in an fMRI experiment.

Functional magnetic resonance imaging before and after aphasia therapy: shifts in hemodynamic time to peak during an overt language task.

Background And Purpose: Comparing the temporal characteristics of hemodynamic responses in activated cortical regions of aphasic patients before and after therapy would provide insight into the relationship between improved task performance and changes in blood oxygenation level-dependent (BOLD) functional MRI (fMRI) signal. This study investigated differences in the time to peak (TTP) of hemodynamic responses in activated regions of interest (ROIs), before and after therapy, and related them to changes in task performance.

Methods: Three aphasic patients and 3 controls overtly generated a single exemplar in response to a category.

Central representation of visceral and cutaneous hypersensitivity in the irritable bowel syndrome.

We have previously shown that irritable bowel syndrome (IBS) patients have both visceral and cutaneous hyperalgesia. The neural mechanisms of these forms of hyperalgesia were further characterized by comparing cortical processing of both rectal distension (35, 55mmHg) and cutaneous heat nociceptive stimuli (foot immersion in 45 and 47 degrees C water bath) in IBS patients and in a group of healthy age/sex-matched controls. Our approach relied on functional magnetic resonance imaging neuroimaging analyses in which brain activation in age/sex-matched control subjects was subtracted from that found in IBS patients.