Cavum septum pellucidum in schizophrenia: a magnetic resonance imaging study

A research concerning the contents of Zn, Cu, Cd was carried out in 33 samples of human milk. The woman were inhabitants of Poznań (urban industrial area). The following concentrations of the metals were found: Zn 8.20 +/- 2.76 mg/l (colostrum 9.67, transitional 7.48 mg/l), Cu 0.54 +/- 0.16 mg/l (colostrum 0.47, transitional 0.60 mg/l), Cd 0.62 +/- 0.28 micrograms/l. The obtained results were considered regarding the woman's age, the day of puerperium on which the samples was taken, the number of deliveries and smoking factor. A negative correlation between the concentration of Zn and the day of puerperium was stated (p < 0.05). The contents of Zn and Cu doesn't exceed the accepted quantities in dairy products for babies. The contents of Cd in milk was the source of 1/6 PTWI given by FAO/WHO for adults. However it can present the danger to their health. The results of research point out the necessity for undertaking preventive measures and continuing the research on a larger scale.     

Generic brain activation mapping in functional magnetic resonance imaging: a nonparametric approach

We report a novel method to identify brain regions generically activated by periodic experimental design in functional magnetic resonance imaging data. This involves: 1) registering each of N individual functional magnetic resonance imaging datasets in a standard space; 2) computing the median standardised power of response to the experimental design; 3) testing median standardised power at each voxel against its nonparametrically ascertained distribution under the null hypothesis of no experimental effect; and 4) constructing a generic brain activation map. The method is validated by analysis of 6 null images, acquired under conditions when the null hypothesis was known to be true; 8 images acquired during periodic auditory-verbal stimulation; and 6 images acquired during periodic performance of a covert verbal fluency task.     

Functional neuroimaging of working memory in schizophrenia: Task performance as a moderating variable.

Functional neuroimaging studies in schizophrenia have demonstrated abnormal activation of dorsolateral prefrontal cortex (DLPFC) during working memory (WM) performance. However, findings of increased and decreased activity have been reported. The authors used meta-analysis to investigate whether diverging results arise as a function of differential WM task performance between patients and control participants. Results indicate that the magnitude of the group difference in WM performance is a moderator of DLPFC activation differences, and concepts such as hypo- or hyperfrontality do not universally characterize WM findings in schizophrenia. Thus, the variability in the WM activation findings between participants with schizophrenia and control participants reflects the specific conditions under which WM functions are evaluated, not just the WM construct per se. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Functional magnetic resonance imaging in macaque cortex

The ability to use fMRI in a monkey model would bridge the gap between the fMRI demonstration of cerebral activation in humans and the cumulative wealth of monkey data on the functional organization of the brain from single electrode mapping, radioisotope and histology studies. We report a new technique for fMRI in an awake co-operative rhesus macaque (Macaca mulatta) in a conventional clinical 1.5T MR scanner and present the first fMRI images from a macaque. Good resolution, signal-to-noise ratio and BOLD response (2.6-4.6%) have been achieved using the manufacturer's standard volume knee coil. T1 values of macaque gray and white matter (1490 ms, 1010 ms respectively) are higher than human brain, whereas T2 values are lower (55 ms, 48 ms respectively). An MR-compatible design for restraining the monkey is also described, along with a suitable EPI sequence for BOLD images, optimized for monkey T2, with voxel sizes from 29 to 61 microl, and MPRAGE sequence for anatomical studies with 0.8 mm isotropic resolution, optimized for monkey T1.     

Functional radiology of the liver: magnetic resonance imaging

Magnetic Resonance (MR) images sensitive to the flowing blood are defined as images of MR angiography. Proton movement within a magnetic field modifies both the intensity and the phase of Nuclear Magnetic Resonance (NMR) signal; two techniques of MR angiography are thus distinguished: (TOF) the "time of flight" (intensity) and the "phase-contrast" (phase) technique. In the time of flight MR angiography the blood may appear as hypointense or hyperintense compared to stationary tissues. Blood hypointensity in vessels is due to the flow void phenomenon while hyperintensity is due to the phenomenon of flow-related enhancement. In phase contrast MR angiography, protons moving within a magnetic field modify their phase directly proportional to the displacement velocity and gradient intensity. Moreover, MRI allows noninvasive measurement of blood flow. Flow velocity is measured with TOF sequences or phase-contrast sequences. In TOF sequences quantitative measurement is performed with the bolus tracking procedure. In contrast-phase sequences the velocity is measured based on the extent of signal phase modification induced by the proton displacement velocity. The recent use of liver-specific contrast media supplies information on parenchymal liver function.     

Functional magnetic resonance imaging shows localized brain activation during serial transcranial stimulation in man

Area and depth penetration of transcranial stimulation methods such as transcranial electrical stimulation (TES) are poorly defined. We investigated the feasibility of a simultaneous TES and fMRI measurement. The aim was to compare the signal intensity changes measured using BOLD fMRI during sequential finger movement with the signal response during artificial transcranial stimulation. Tes induced contralateral finger contractions and in T2* weighted images a transient signal increase was observed in the area underlying the electrodes. Compared with the signal obtained during sequential finger movements, the area activated by TES was more localized, signal amplitude, was smaller and there was no post-stimulus undershoot. These data indicate that TES induces a local blood flow increase associated with a drop in the concentration of deoxyhaemoglobin.     

Functional cerebral imaging in psychiatry: a new approach in research

The data on cerebral physiology accumulated over the last decade, and also the ideas of cognitive psychology affect the way studies of mental disorders are modelized through the cerebral functional imaging techniques. Present aspects of these relations are considered and highlighted by recent results of this type of research. The contribution of these techniques for a better understanding of the cerebral neuro-transmission and of the mechanism of action of psychotropic drugs is also reported.     

Quantitative brain magnetic resonance imaging in attention-deficit hyperactivity disorder

BACKGROUND: Anatomic magnetic resonance imaging (MRI) studies of attention-deficit hyperactivity disorder (ADHD) have been limited by small samples or measurement of single brain regions. Since the neuropsychological deficits in ADHD implicate a network linking basal ganglia and frontal regions, 12 subcortical and cortical regions and their symmetries were measured to determine if these structures best distinguished ADHD. METHODS: Anatomic brain MRIs for 57 boys with ADHD and 55 healthy matched controls, aged 5 to 18 years, were obtained using a 1.5-T scanner with contiguous 2-mm sections. Volumetric measures of the cerebrum, caudate nucleus, putamen, globus pallidus, amygdala, hippocampus, temporal lobe, cerebellum; a measure of prefrontal cortex; and related right-left asymmetries were examined along with midsagittal area measures of the cerebellum and corpus callosum. Interrater reliabilities were .82 or greater for all MRI measures. RESULTS: Subjects with ADHD had a 4.7% smaller total cerebral volume (P = .02). Analysis of covariance for total cerebral volume demonstrated a significant loss of normal right > left asymmetry in the caudate (P = .006), smaller right globus pallidus (P = .005), smaller right anterior frontal region (P = .02), smaller cerebellum (P = .05), and reversal of normal lateral ventricular asymmetry (P = .03) in the ADHD group. The normal age-related decrease in caudate volume was not seen, and increases in lateral ventricular volumes were significantly diminished in ADHD. CONCLUSION: This first comprehensive morphometric analysis is consistent with hypothesized dysfunction of right-sided prefrontal-striatal systems in ADHD.     

Functional magnetic resonance imaging: the basics of blood-oxygen-level dependent (BOLD) imaging

In isolated pea (Pisum sativum L.) mitochondria incorporation of 35S-methionine into newly synthesised proteins was influenced by the presence of site-specific inhibitors of the respiratory electron-transport chain. These effects were not produced by changes in the rate of respiratory electron transport itself nor by changes in ATP concentration. Protein synthesis was inhibited by inhibitors of ubiquinone reduction but not by inhibitors of ubiquinol oxidation. By the use of additional inhibitors at specific sites of the respiratory chain, different oxidation-reduction states were obtained for the different complexes in the electron-transport chain. It was found that electron transport through succinate:ubiquinone oxidoreductase (respiratory complex II) was specifically required for protein synthesis, even when all the other conditions for protein synthesis were satisfied. We suggest that a subunit of complex II, or a component closely associated with complex II, is involved in a regulatory system that couples electron transport to protein synthesis.     

Cerebral hypoxia during cardiopulmonary bypass: a magnetic resonance imaging study

BACKGROUND: Neurocognitive deficits after open heart operations have been correlated to jugular venous oxygen desaturation on rewarming from hypothermic cardiopulmonary bypass (CPB). Using a porcine model, we looked for evidence of cerebral hypoxia by magnetic resonance imaging during CPB. Brain oxygenation was assessed by T2*-weighted imaging, based on the blood oxygenation level-dependent effect (decreased T2*-weighted signal intensity with increased tissue concentrations of deoxyhemoglobin). METHODS: Pigs were placed on normothermic CPB, then cooled to 28 degrees C for 2 hours of hypothermic CPB, then rewarmed to baseline temperature. T2*-weighted, imaging was undertaken before CPB, during normothermic CPB, at 30-minute intervals during hypothermic CPB, after rewarming, and then 15 minutes after death. Imaging was with a Bruker 7.0 Tesla, 40-cm bore magnetic resonance scanner with actively shielded gradient coils. Regions of interest from the magnetic resonance images were analyzed to identify parenchymal hypoxia and correlated with jugular venous oxygen saturation. Post-hoc fuzzy clustering analysis was used to examine spatially distributed regions of interest whose pixels followed similar time courses. Attention was paid to pixels showing decreased T2* signal intensity over time. RESULTS: T2* signal intensity decreased with rewarming and in five of seven experiments correlated with the decrease in jugular venous oxygen saturation. T2* imaging with fuzzy clustering analysis revealed two diffusely distributed pixel groups during CPB. One large group of pixels (50% +/- 13% of total pixel count) showed increased T2* signal intensity (well-oxygenated tissue) during hypothermia, with decreased intensity on rewarming. Changes in a second group of pixels (34% +/- 8% of total pixel count) showed a progressive decrease in T2* signal intensity, independent of temperature, suggestive of increased brain hypoxia during CPB. CONCLUSIONS: Decreased T2* signal intensity in a diffuse spatial distribution indicates that a large proportion of cerebral parenchyma is hypoxic (evidenced by an increased proportion of tissue deoxyhemoglobin) during CPB in this porcine model. Neuronal damage secondary to parenchymal hypoxia may explain the postoperative neuropsychological dysfunction after cardiac operations.     

Functional magnetic resonance imaging of motor cortex: hemispheric asymmetry and handedness

A hemispheric asymmetry in the functional activation of the human motor cortex during contralateral (C) and ipsilateral (I) finger movements, especially in right-handed subjects, was documented with nuclear magnetic resonance imaging at high field strength (4 tesla). Whereas the right motor cortex was activated mostly during contralateral finger movements in both right-handed (C/I mean area of activation = 36.8) and left-handed (C/I = 29.9) subjects, the left motor cortex was activated substantially during ipsilateral movements in left-handed subjects (C/I = 5.4) and even more so in right-handed subjects (C/I = 1.3).     

Mapping of semantic, phonological, and orthographic verbal working memory in normal adults with functional magnetic resonance imaging.

Twelve neurologically normal participants (4 men and 8 women) performed semantic, phonological, and orthographic working memory tasks and a control task during functional magnetic resonance imaging. Divergent regions of the posterior left hemisphere used for decoding and storage of information emerged in each working memory versus control task comparison. These regions were consistent with previous literature on processing mechanisms for semantic, phonological, and orthographic information. Further, working memory versus control task differences extended into the left frontal lobe, including premotor cortex, and even into subcortical structures. Findings were consistent with R. C. Martin and C. Romani's (1994) contention that different forms of verbal working memory exist and further suggest that a reconceptualization of premotor cortex functions is needed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Functional magnetic resonance imaging of primary visual processing using a 1.0 Tesla scanner

Recent advances in functional magnetic resonance imaging (fMRI) at > or = 1.5 T magnetic field strength and with high speed single-shot echo planar imaging techniques have made it possible to monitor local changes in cerebral blood volume, cerebral blood flow, and blood oxygenation level in response to sensory stimulation, simple motor activity, and possibly also to more complex cognitive processing. However, fMRI has also been accomplished on conventional MR scanners of medium field strength (approximately 1.0 T) using special pulse sequences and appropriate methods for image analysis. We present results from six subjects on photic stimulation using a standard 1.0 T MR scanner together with special software for off-line image analysis. Continuous serial T2-weighted imaging were performed for 6 minutes in the plane of the calcarine fissure. There were 3 repetitions of 1 minute resting state of darkness (OFF) and 1 minute activated state (ON) with 8 Hz flicker stimulation. To directly map these functional images to the underlying anatomy we also acquired a high resolution T1-weighted image from the same axial slice. The results demonstrated that stimulus-related signals can be obtained from primary visual cortex with a conventional 1.0 T MR scanner. Further methodological improvements are discussed and related to present and future possibilities for the use of fMRI within psychophysiology.     

Resource utilization in traumatic brain injury: the role of magnetic resonance imaging

A number of potential matrix candidates were investigated with regard to the importance of the pH in the matrix-assisted laser desorption/ionization mass spectrometry (MALDI/MS) analysis of non-covalently bound protein complexes. The matrices examined were 2,5-dihydroxybenzoic acid (DHB), 4-hydroxy-alpha-cyanocinnamic acid (HCCA), 2-aminonicotinic acid (ANA), 4-nitroaniline (NA), 2-amino-4-methyl-5-nitropyridine (AMNP) and 3-hydroxypicolinic acid (HPA). In solution these matrix compounds permitted the preparation of MALDI samples at pH in the range 2-7. Among the matrices tested, complex formation, by specific non-covalent interactions, could only be observed when HPA (pH 3.8) was used as the matrix for the MALDI analysis. Under these conditions, specific non-covalent complex formation of recombinant streptavidin and glutathione-S-transferases were observed but not for human hemoglobin. The MALDI spectra obtained with the neutral compounds ANA (pH 4.4), NA (pH 6.4) and AMNP (pH 7.1) as matrices contain only peaks of the subunit with no signal of the non-covalent bound complexes present. Considering the results obtained in this study with basic and acidified matrix materials, there does not appear to be a strong correlation between the pH of the matrix solution and the utility of a matrix for the analysis of non-covalently bound complexes.     

A study of injected dose for brain mapping on the ECAT HR+: activation maps for a parametric verbal working memory task

The success of the 15O-water PET technique to localize statistically significant changes in regional cerebral blood flow is dependent on factors such as the activity level injected and the magnitude of the flow change. Undetectable changes may occur if insufficient activity is injected leading to high levels of statistical noise or the task performed results in only small changes in blood flow. To explore the relationship between injected activity and statistical significance, we performed a series of studies with the ECAT EXACT HR+, a high resolution PET tomograph. A parametric verbal working memory task (the N-back task) was selected to examine the relationship between regional cerebral blood flow and working memory load across a range of injected doses of 15O-water. At each activity level the volunteers were required to perform four different levels of the N-back task, a task in which a letter displayed on a monitor is matched with the letter displayed N letters previously. With increasing N, this task places increased load on working memory. For this study, 5, 10, and 15 mCi of 15O-water were injected into nine normal volunteers. The complete sequence of four tasks (N = 0, 1, 2, and 3) at three activity levels was repeated twice, for a total of 24 injections of 15O-water. We show that the peak count rate performance for the HR+ is approached at injected activity levels of 15O-water around 15 mCi. For this particular choice of N-back task, robust activation maps can nevertheless be obtained with as little as 5 mCi injected dose.