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At least 1,243 records · Page 69Linked to original sources
PubMed1988

[Reorganization of the synaptic architectonics of the cerebral cortex in antigenic sensitization of the brain and in convulsive paroxysms].

In Krushinskiĭ-Molodkina rats sensibilized for 5 days with brain extract antigens (BEA) and/or subjected to repetitive seizures (S), the synaptic architectonics of the molecular layer was studied in the sensorimotor cortex preparations treated with phosphotungstic acid. Unlike the S effect, BEA-sensibilization and BEA+S action sharply reduced the number of interneuronal contacts, especially the symmetric ones, and the structure relations of the subsynaptic units system with the surrounding cytoskeleton with decrease in the number of very small, small and medium-size synapses. In any effects the major compensatory mechanism was the hypertrophy and splitting of the interneuronal contacts. Only S action resulted in the compensatory enhancement of the new synapses formation. Possible mechanisms of the "immune" lesion of the interneuronal contacts are discussed.

Acoustic Stimulation↗
PubMed1984

The electroencephalographic characteristics of the rhombencephalectomized cat.

The electroencephalographic responses in the rhombencephalectomized cat after the application of photic and epileptogenic agents resemble those phenomena in the normal animal. The spontaneous EEG of the motor region had fewer beta waves, a slower alpha but more delta components than the presection record. The response to photic stimulation in the occipital cortex was similar before and after the rhombencephalectomy, although the initial waves were slightly delayed. Epileptic activity upon topical application or intravenous administration of epileptogenic agents was demonstrated in the sensorimotor cortex.

Animals↗
PubMed2002

Degeneration of corticospinal and bulbospinal systems in the superoxide dismutase 1(G93A G1H) transgenic mouse model of familial amyotrophic lateral sclerosis.

In the superoxide dismutase 1 (SOD1)(G93A G1H) transgenic mouse, the primary pathology and disease signs are associated with the degeneration of motor neurons in the lumbar spinal cord. It is unclear if the descending motor pathways from the cortex and brainstem are also compromised. The retrograde tracer Fluorogold was inserted into the T(12) segment of the spinal cord and the number of labelled neurons counted in the sensorimotor cortex and brainstem of 60, 90 and 110 day-old mice. A small loss of corticospinal and bulbospinal projections was detected at 60 days. By 110 days, 53% of corticospinal, 41% of bulbospinal and 43% of rubrospinal neurons were lost. The progressive loss of corticospinal axons was confirmed using the stereological fractionator method. These findings suggest that the expression of the SOD1(G93A G1H) mutant protein results in a disease that resembles the late stages of human motor neuron disease. This involves not only the destruction of lower motor neurons in the spinal cord, but also additional loss of descending cortical and bulbar neurons.

Amyotrophic Lateral Sclerosis↗
PubMed1997

[Brain functional MRI using 3D-SPGR pulse sequence].

We reported the effects of motor cortex stimulation of normal volunteers using conventional MR imaging techniques on standard 1.5 T clinical scanner. The imaging technique was an optimized conventional 2D and 3D spoiled GRASS. In the 3D-SPGR measurement, a slab of 96 mm with 32 partition was evaluated in sagital direction. The motor cortex stimulation was achieved by touching each finger to thumb in a sequential, self-paced, and repetitive manner. During stimulation, areas of increased signal intensity were identified in the sensorimotor cortex with both 2D and 3D SPGR method. The 3D-SPGR method in sagital direction is rather insensitive to inflow effects, thus signal increases with 3D-SPGR method is mainly due to the blood oxygenation level dependent effects.

Brain↗
PubMed1998

Clinical applicability of functional magnetic resonance imaging and activation study with single photon emission computerized tomography for functional mapping.

The purpose of this study is to estimate the clinical applicability of functional magnetic resonance imaging (f-MRI) combined with the activation study using single photon emission computerized tomography (SPECT) with special reference to identification of primary sensorimotor area. Five healthy volunteers and 5 patients with brain tumors located around the sensorimotor cortex were studied by both f-MRI with gradient echo and SPECT with 99mTc-ethyl cysteinate dimer using split-dose and subtraction method. In f-MRI study, the significant activation of the sensorimotor area was observed in all subjects. Various concurrent activation regions such as supplementary motor (2 volunteers vs. 4 patients), premotor (1 vs. 2) and ipsilateral sensorimotor area (1 vs. 2) were also observed. In the cases with the activation of neighboring regions of sensorimotor area, it was difficult to identify the area in f-MRI. In SPECT study, the sensorimotor area was depicted as the most increased area in regional cerebral blood flow in eight cases, the characteristics of which were helpful to diagnose the area, while significant activation of the area with edema could not be detected in two patients. Consequently, the sensorimotor area was cross-validated with both the modalities. This study demonstrated that it would be valuable to use both techniques for the clinical assessment of the sensorimotor area.

Adult↗
PubMedDate not supplied

Assessment of local cerebral blood flow in neonates with N-isopropyl-P-[123I]iodoamphetamine and single photon emission computed tomography.

Local cerebral blood flow was measured in 10 high-risk infants with neonatal episodic neurological events at 41-44 post-conceptional weeks using N-isopropyl-p-[123I]iodoamphetamine (IMP) and single photon emission computed tomography (SPECT). In 5 of the 7 infants with normal neurological outcome, prominent cerebral perfusion was found in the basal ganglia, brainstem, cerebellum, parietal white matter, and sensory motor cortex. The frontal lobes showed poor relative perfusion. In 3 infants with severe neurological deficits, SPECT demonstrated severe hypoperfusion of all parts of the brain except the basal ganglia, brainstem and sensorimotor cortex. However, MRI revealed non-specific changes, such as poor myelination and ventricular dilatation. SPECT, when performed in the first weeks of life, can be useful and may be more sensitive than MRI in predicting the occurrence of major neurological handicaps. However, because of the relatively invasive character and high cost of SPECT, SPECT should not necessarily be performed in all high-risk neonates.

Amphetamines↗
PubMed2003

Mapping of spikes, slow waves, and motor tasks in a patient with malformation of cortical development using simultaneous EEG and fMRI.

We report on the simultaneous and continuous acquisition of EEG and functional MRI data in a patient with a left hemiparesis and focal epilepsy secondary to malformation of cortical development in the right hemisphere. EEG-triggered fMRI localization was previously demonstrated in this patient. In the experiments reported here, 322 spikes maximum at electrode C4 and 126 focal slow waves were identified offline. A hierarchy of models was explored in order to assess the relative contributions of each type of EEG event. Modeling the BOLD response to C4 spikes alone showed an area of activation within the large malformation, adjacent to the area of infolding cortex. However, also modeling slow-waves gave rise to a broader and stronger activation, suggesting that the generators overlap. Motor mapping of the right hand showed activation in the left sensorimotor cortex; left-hand tapping led to a more diffuse area of activation, displaced superiorly into the superior frontal gyrus, and a small area of activation within the lesion. In conclusion, continuous EEG-fMRI is useful to compare the functional mapping of epileptiform activity and eloquent cortices in individual patients.

Adult↗
PubMed2001

Gray matter T2 hypointensity is related to plaques and atrophy in the brains of multiple sclerosis patients.

Cortical and subcortical gray matter hypointensities on T2-weighted MR images (T2WI) occur commonly in MS brains and have been related to disease duration, clinical course, and the level of neurologic disability. These hypointensities have been reported to occur in the thalamus, basal ganglia, and rolandic cortex. We assessed whether T2 hypointensity is associated with the severity of white matter plaques and atrophy of MS brains. In 114 MS patients, hypointensity of the thalamus, putamen, caudate, and sensorimotor cortex was ordinally rated against age- and gender-matched normal controls on 1.5-T MRI fast spin-echo axial T2WI. Regional and global T2 hyperintense and T1 hypointense parenchymal lesion loads were ordinally rated. Enlargement of subarachnoid and ventricular spaces (atrophy) was ordinally rated vs. age- and gender-matched normal controls. T2 hypointensity was highly, positively correlated with many other MRI variables. Regression modeling showed that T2 hypointensity was related to total atrophy, total T2 lesion load, third ventricular enlargement, parietal atrophy, and to a lesser extent, frontal T1 lesions and cerebellar T2 lesions, but not related to gadolinium enhancement. Ordinal ratings of T2 lesions and central atrophy showed high correlations with quantitative computerized assessments. We conclude that gray matter hypointensity on T2WI may reflect pathologic iron deposition and brain degeneration in MS. This T2 hypointensity is associated with brain atrophy and other MR markers of tissue damage. Further study is warranted to determine if T2 hypointensity is predictive of disease course in MS and is a useful surrogate outcome measure in therapeutic trials.

Adolescent↗
PubMed1999

The origin of hypsarrhythmia and tonic spasms in West syndrome: evidence from a case of porencephaly and hydrocephalus with focal hypsarrhythmia.

We report on a 3-year-old girl with West syndrome and with focal hypsarrhythmia. The left hemisphere of the patient was virtually completely defective and continuous hypsarrhythmia was only seen in the residual right frontal cortex, where an interictal single photon emission computed tomography (SPECT) showed hyperperfusion. Despite a focal epileptic pattern, the tonic spasms were quite symmetrical. In our patient, spasms might not require the sensorimotor cortex, but the brainstem containing the descending pathways that control spinal reflexes and other infratentorial structures seem to be essential for the occurrence of spasms. This is in accordance with the result of an ictal SPECT that showed hyperperfusion of the brainstem and cerebellum. These findings suggest that hypsarrhythmia originates from cortical lesions, while subcortical structures may be primarily responsible for the tonic spasms in this patient.

Brain↗
PubMed2003

Neuromagnetic imaging of cortical oscillations accompanying tactile stimulation.

We applied a new method of imaging frequency-specific changes in brain activity in humans during a finger brushing task in order to measure changes in cortical rhythms during tactile stimulation. Neuromagnetic recordings were conducted in five subjects using a whole-head MEG system during tactile stimulation of the right index finger, with or without visual feedback, and while viewing another individual's index finger being stimulated. Volumetric images of changes in source power relative to pre-stimulus baseline levels were computed with 2 mm resolution over the entire brain using a minimum-variance beamforming algorithm (synthetic aperture magnetometry). Onset of tactile stimulation produced a brief (200-300 ms) suppression of mu band (8-15 Hz) and beta band (15-30 Hz) cortical activity in the primary somatosensory and primary motor cortex, respectively, followed by a bilateral increase in beta band activity ('beta rebound') in motor cortex. This pattern of suppression/rebound was absent when subjects observed finger brushing or brushing motions without receiving stimulation. In contrast, these conditions resulted in bilateral increases in beta band activity in sensorimotor areas and decreased power in the alpha (8-12 Hz) band in primary visual areas. These results show that spatially filtered MEG provides a useful method for directly imaging the temporal sequence of changes in cortical rhythms during transient tactile stimulation, and provide evidence that observation of tactile input to another individual's hand, or object motion itself, can influence independent rhythmic activity in visual and sensorimotor cortex.

Adult↗
PubMed2000

Motor imagery in normal subjects and in asymmetrical Parkinson's disease: a PET study.

OBJECTIVE: To investigate, using PET and H2(15)O, brain activation abnormalities of patients with PD during motor imagery. To determine whether motor imagery activation patterns depend on the hand used to complete the task. BACKGROUND: Previous work in PD has shown that bradykinesia is associated with slowness of motor imagery. METHODS: The PET study was performed in eight patients with PD with predominantly right-sided akinesia, and in eight age-matched control subjects, all right-handed. Regional cerebral blood flow was measured by PET and H2(15)O while subjects imagined a predetermined unimanual externally cued sequential movement with a joystick with either the left or the right hand, and during a rest condition. RESULTS: In normal subjects, the prefrontal cortex, supplementary motor area (SMA), superior parietal lobe, inferior frontal gyrus, and cerebellum were activated during motor imagery with either the left or the right hand. Contralateral primary motor cortex activation was noted only when the task was imagined with the right (dominant) hand, whereas activation of the dorsolateral prefrontal cortex was observed only during imagery with the left hand. In patients with PD, motor imagery with the right ("akinetic") hand was characterized by lack of activation of the contralateral primary sensorimotor cortex and the cerebellum, persistent activation of the SMA, and bilateral activation of the superior parietal cortex. Motor imagery with the left ("non-akinetic") hand was also abnormal, with lack of activation of the SMA compared with controls. CONCLUSIONS: In patients with PD with predominantly right-sided akinesia, brain activation during motor imagery is abnormal and may appear even with the less affected hand. In normal subjects, brain activation during motor imagery depends on the hand used in the imagined movement.

Adult↗
PubMedDate not supplied

[The correlation of the behavioral, bioelectrical and cytobiochemical characteristics of the effect of taftsin].

The complex neurophysiological, biochemical, and histochemical investigation carried out in dogs, cats, rabbits, and rats revealed the effects of taftsin (300 mcg/kg) at the macro- and microlevels within different periods (30 and 75 min) after its intraperitoneal injection. It was shown that after taftsin administration the configuration of evoked potentials was modified, especially, in the visual cortex and the nucleus accumbens. The absolute power of EEG spectra increased in a wide range of brain structures under consideration. Catecholaminergic activity was augmented and serotonin activity suppressed in the sensorimotor cortex and caudate nucleus, the indices of the protein metabolism reciprocally changed in the cortical and subcortical structures. Comparison of taftsin effects at different levels suggests that such effects are mainly caused by the interaction between the dopamine-containing brain structures. The consequence of taftsin administration can be probably interpreted as an intervention into the processes of visual perception.

Animals↗
PubMed1998

[Morphological changes in the central nervous system of animals depending on the dosage and time elapsed after exposure to low let radiation].

Analytical review of the morphological investigations of cerebral cortex neurons of various animals shortly after exposure to X- and gamma-radiation was made. Considered were data of qualitative and quantitative analyses of dystrophic changes in neurons of the sensorimotor cortex of the large cerebral hemispheres of rats immediately and a long period since X-irradiation. Results of the quantitative analysis of structural disorders in the central nervous system neurons suggest radiation-produced damages early after exposure of animals to relatively low doses. Higher incidence of irreversible changes in neurons of the experimental animals, as compared with intact controls, was stimulated by the doses of no more than 0.25 to 1.0 Gy. The relative number of structural disorders in neurons and percentage of irreversibly impaired cells rose proportionally to the dose growth and further delay of the time of investigation. Possible mechanisms of delayed disorders that led to a massive building-up of the number of dystrophic neurons following 3 to 4 months post irradiation of rats are discussed.

Animals↗
PubMed1995

Functional connectivity in the motor cortex of resting human brain using echo-planar MRI.

An MRI time course of 512 echo-planar images (EPI) in resting human brain obtained every 250 ms reveals fluctuations in signal intensity in each pixel that have a physiologic origin. Regions of the sensorimotor cortex that were activated secondary to hand movement were identified using functional MRI methodology (FMRI). Time courses of low frequency (< 0.1 Hz) fluctuations in resting brain were observed to have a high degree of temporal correlation (P < 10(-3)) within these regions and also with time courses in several other regions that can be associated with motor function. It is concluded that correlation of low frequency fluctuations, which may arise from fluctuations in blood oxygenation or flow, is a manifestation of functional connectivity of the brain.

Acoustic Stimulation↗
PubMed1996

EM colocalization of AMPA and NMDA receptor subunits at synapses in rat cerebral cortex.

Electrophysiology and light microscopy suggest that a single excitatory synapse may use both amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) and N-methyl-D-aspartate (NMDA) receptors. Using immunogold electron microscopy, we here provide direct evidence for colocalization at individual synapses in sensorimotor cortex of adult rats. Colocalization was most commonly observed on dendritic spines; subunits of the two classes of receptors seemed to be independently distributed within the synaptic active zone.

Animals↗
PubMed2006

Creutzfeldt-jakob disease involvement of rolandic cortex: a quantitative apparent diffusion coefficient evaluation.

BACKGROUND: Previous reports have suggested that abnormally reduced water diffusivity and T2 prolongation involving cerebral gray matter in patients with early sporadic Creutzfeldt-Jakob disease (sCJD) involves all areas of neocortex with similar frequency, except for primary sensorimotor cortex (Rolandic cortex) and visual cortex. Rolandic cortex often appears to be spared even in the presence of extensive surrounding neocortical signal intensity abnormality in adjacent frontal and parietal gray matter. A quantitative apparent diffusion coefficient (ADC) analysis was designed to investigate whether this unusual pattern results from pathophysiologic sparing of Rolandic cortex or from reduced conspicuity of signal intensity abnormality on MR imaging echo-planar diffusion-weighted images (epiDWI) related to unknown underlying features of Rolandic cortex. METHODS: ADC maps were derived from epiDWI of 6 patients with sCJD and 8 control patients. Bilateral regions of interest were manually selected in precentral gyri, superior frontal gyri, postcentral gyri, supramarginal gyri, thalamus, putamen, and caudate nuclei. ADC and relative ADC (rADC) values were calculated for each region of interest. RESULTS: Patients with CJD had significantly lower ADC values than control patients in all areas (P < or = 0.05). The trend toward decreased ADC values in the deep nuclei correlates well with previously published reports. rADC were not significantly different between CJD and control groups in any area (P > 0.25 in all cases). CONCLUSION: Quantitative ADC measurements in patients with early sCJD demonstrate a similar degree of reduced water diffusivity in the primary somatosensory cortex as in other neocortical areas, despite the normal appearance of these areas on visual inspection of epiDWI.

Aged↗
PubMed2004

Bilateral effects of spinal overhemisections on the development of the somatosensory system in rats.

Connections of the forepaw regions of somatosensory cortex (S1) were determined in rats reared to maturity after spinal cord overhemisections at cervical level C3 on postnatal day 3. Overhemisections cut all ascending and descending pathways and intervening gray on one side of the spinal cord and the pathways of the dorsal funiculus contralaterally. Bilateral lesions of the dorsal columns reduced the size of the brainstem nuclei by 41%, and the ventroposterior lateral subnucleus (VPL) of the thalamus by 20%. Bilateral lesions also prevented the emergence of the normal cytochrome oxidase barrel pattern in forepaw and hindpaw regions of S1. Injections of wheat germ agglutinin conjugated to horseradish peroxidase were placed in the forepaw region of granular S1 and surrounding dysgranular S1 contralateral to the hemisection. The VPL nucleus was densely labeled, whereas the adjoining ventroposterior medial subnucleus, VPM, representing the head, was unlabeled. Thus, there was no evidence of abnormal connections of VPM to forepaw cortex. Foci of transported label in the ipsilateral hemisphere appeared to be in normal locations and of normal extents, but connections in the opposite hemisphere were broadly and nearly uniformly distributed in sensorimotor cortex in a pattern similar to that in postnatal rats. Rats with incomplete lesions that spared the dorsal column pathway on the left side but not the right demonstrated surprisingly normal distributions of callosal connections in the nondeprived right hemisphere, even though the injected left hemisphere was deprived. Thus, the development of the normal pattern of callosal connections depends on dorsal column input and not on normal interhemsipheric interactions.

Afferent Pathways↗
PubMed1991

Impaired metabolic activation in Alzheimer's disease: a PET study during continuous visual recognition.

Regional cerebral metabolic rate of glucose (rCMRGl) was studied in 21 patients with probable Alzheimer's disease (AD) and nine age-matched normal controls by positron emission tomography (PET) of 2(18F)-fluoro-deoxy-D-glucose (FDG) at rest and during stimulation with a continuous visual recognition task. While global metabolism at rest was comparable in both groups, rCMRGl in the temporo-parietal junction area, the mid-temporal and the frontal cortex was typically decreased in the AD patients. The continuous visual recognition task adapted to the individual performance capacity increased the global metabolic rate in the controls by 21 +/- 18%, while in the AD patients the metabolic change (5.7 +/- 11.1%) during activation was significantly weaker (P = 0.023). Due to the tasks chosen the activation of rCMRGl in both groups was most prominent in the visual cortex and the temporo-parietal association areas, although the recognition task additionally involved widespread brain structures with varying rCMRGl. A significant correlation was found between rCMRGl in areas usually severely affected by AD pathology, e.g. the temporo-parietal cortex, and GDS scores, and became stronger during metabolic activation. Neither at rest nor during stimulation was there a relationship between the rCMRGl of structures usually less involved in AD, e.g. the sensorimotor cortex, and the severity of dementia as assessed by the global deterioration scale (GDS). From these results it can be concluded that metabolic rate at rest reflects the extent of morphologic damage, while PET studies during activation indicate the brain's reserve capacity to respond to functional tasks. Since metabolism in AD patients during activation is more severely impaired than at rest, PET studies during functional tests could help in the selection of patients with a potential to benefit from therapeutic intervention.

Alzheimer Disease↗