Detection of Hyperexcitability by Functional Magnetic Resonance Imaging after Experimental Traumatic Brain Injury.

Diagnosis of ongoing epileptogenesis and associated hyperexcitability after brain injury is a major challenge. Given that increased neuronal activity in the brain triggers a blood oxygenation level-dependent (BOLD) response in functional magnetic resonance imaging (fMRI), we hypothesized that fMRI could be used to identify the brain area(s) with hyperexcitability during post-injury epileptogenesis. We applied fMRI to detect onset and spread of BOLD activation after pentylenetetrazol (PTZ)-induced seizures (PTZ, 30 mg/kg, intraperitoneally) in 16 adult male rats at 2 months after lateral fluid percussion (FPI)-induced traumatic brain injury (TBI).

Nutritive sucking induces age-specific EEG-changes in 0-24 week-old infants.

Little is known how the brain of the newborn infant responds to the postnatal nutrition and care. No systematic studies exist in which the effects of nutritional and non-nutritional sucking on the brain activity of the infant were compared. We recorded the EEG activity of 40 infants at the ages of 0,6,12 and 24 weeks in four successive behavioral stages: while the infants were hungry and waiting for sucking, during non-nutritional and nutritional sucking, and during satiation after completed feeding.

Kubios HRV--heart rate variability analysis software.

Kubios HRV is an advanced and easy to use software for heart rate variability (HRV) analysis. The software supports several input data formats for electrocardiogram (ECG) data and beat-to-beat RR interval data. It includes an adaptive QRS detection algorithm and tools for artifact correction, trend removal and analysis sample selection.

Monitoring functional impairment and recovery after traumatic brain injury in rats by FMRI.

The present study was designed to test a hypothesis that functional magnetic resonance imaging (fMRI) can be used to monitor functional impairment and recovery after moderate experimental traumatic brain injury (TBI). Moderate TBI was induced by lateral fluid percussion injury in adult rats. The severity of brain damage and functional recovery in the primary somatosensory cortex (S1) was monitored for up to 56 days using fMRI, cerebral blood flow (CBF) by arterial spin labeling, local field potential measurements (LFP), behavioral assessment, and histology.

Simultaneous BOLD fMRI and local field potential measurements during kainic acid-induced seizures.

Purpose: To investigate how kainic acid-induced epileptiform activity is related to hemodynamic changes probed by blood oxygenation level-dependent functional magnetic resonance imaging (BOLD fMRI).

Methods: Epileptiform activity was induced with kainic acid (KA) (10 mg/kg, i.p.

Evoked local field potentials can explain temporal variation in blood oxygenation level-dependent responses in rat somatosensory cortex.

The aim of this study was to explain the temporal variations between subjects in the blood oxygenation level-dependent (BOLD) response. Somatosensory responses were elicited with the electrical forepaw stimulus at a frequency of 10 Hz in urethane-anesthetized rats, and functional magnetic resonance imaging (fMRI) with BOLD contrast and local field potential (LFP) measurements were performed simultaneously. BOLD fMRI activation was evaluated by two different models, one based on the stimulus paradigm (the block model) and the other on the simultaneously measured evoked LFP responses.

Simultaneous fMRI and local field potential measurements during epileptic seizures in medetomidine-sedated rats using raser pulse sequence.

Simultaneous electrophysiological and functional magnetic resonance imaging measurements of animal models of epilepsy are methodologically challenging, but essential to better understand abnormal brain activity and hemodynamics during seizures. In this study, functional magnetic resonance imaging of medetomidine-sedated rats was performed using novel rapid acquisition by sequential excitation and refocusing (RASER) fast imaging pulse sequence and simultaneous local field potential measurements during kainic acid-induced seizures. The image distortion caused by the hippocampal-measuring electrode was clearly seen in echo planar imaging images, whereas no artifact was seen in RASER images.

Distinct MRI pattern in lesional and perilesional area after traumatic brain injury in rat--11 months follow-up.

To understand the dynamics of progressive brain damage after lateral fluid-percussion induced traumatic brain injury (TBI) in rat, which is the most widely used animal model of closed head TBI in humans, MRI follow-up of 11 months was performed. The evolution of tissue damage was quantified using MRI contrast parameters T(2), T(1rho), diffusion (D(av)), and tissue atrophy in the focal cortical lesion and adjacent areas: the perifocal and contralateral cortex, and the ipsilateral and contralateral hippocampus. In the primary cortical lesion area, which undergoes remarkable irreversible pathologic changes, MRI alterations start at 3 h post-injury and continue to progress for up to 6 months.

Quantitative assessment of water pools by T 1 rho and T 2 rho MRI in acute cerebral ischemia of the rat.

The rotating frame longitudinal relaxation magnetic resonance imaging (MRI) contrast, T(1 rho), obtained with on-resonance continuous wave (CW) spin-lock field is a sensitive indicator of tissue changes associated with hyperacute stroke. Here, the rotating frame relaxation concept was extended by acquiring both T(1 rho) and transverse rotating frame (T(2 rho)) MRI data using both CW and adiabatic hyperbolic secant (HSn; n=1, 4, or 8) pulses in a rat stroke model of middle cerebral artery occlusion. The results show differences in the sensitivity of spin-lock T(1 rho) and T(2 rho) MRI to detect hyperacute ischemia.

Noise sensitivity of a principal component regression based RT interval variability estimation method.

Ventricular repolarization duration (VRD) is controlled by neural regulatory system same way as heart rate and, thus, also VRD varies in time. Traditionally, VRD variability is assessed by determining the time differences between successive R and T-waves, i.e.

Software for advanced HRV analysis.

A computer program for advanced heart rate variability (HRV) analysis is presented. The program calculates all the commonly used time- and frequency-domain measures of HRV as well as the nonlinear Poincaré plot. In frequency-domain analysis parametric and nonparametric spectrum estimates are calculated.