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At least 73 records · Page 4Linked to original sources

PubMed2002

Modulation of the lexical-semantic network by auditory semantic priming: an event-related functional MRI study.

The current event-related fMRI study specifies the neuroanatomical correlates of semantic priming and differences in semantic relation types using an auditory primed lexical decision task (LDT). Word pairs consisted of different relation types, associations (key-chain), pure categorical relations (cow-dog), and unrelated words (table-window), as well as word-pseudoword (way-tinne) and pseudoword-pseudoword (ahurn-döva) pairs. The factor lexical status, i.e., the processing of words compared to pseudowords, was associated with activation in the middle temporal gyri and the left striatum. The factor relatedness, i.e., the contrast between unrelated and related target words, was associated with increased activation of the left inferior frontal gyrus, the deep frontal operculum bilaterally, and the middle frontal gyri. A direct contrast between the two semantic relation types indicated that the processing of purely categorical compared to associative information recruits the right precuneus, the isthmus gyrus cinguli, and the cuneus, suggesting more effortful processing of the former information type. The present data show that the factors lexical status, semantic relatedness, and type of semantic relation in a primed LDT modulate the hemodynamic response in cerebral areas that subserve auditory word recognition and subsequent lexical-semantic processing.

Adult↗

PubMed1989

Electric brain potentials evoked by pictures of faces and non-faces: a search for "face-specific" EEG-potentials.

In three different experimental series, electroencephalographic responses evoked by changes in pictorial patterns were recorded in 29 adult human subjects (19 females, 10 males). Quantitative data evaluation for the evoked responses from electrodes T5, T6, Cz, Pz (10-20 system) was performed. The stimuli were projected to a 4 x 6 degree binocularly viewed field. The patterns changed within 6 ms every 2.5-4.5 s according to a random program. Paradigm (1): Identical line drawings of a face, a tree and a chair were used, either black on white (P-stimuli) or white on black (N-stimuli); in each set altogether 160 slides appeared in semi-random order. At Cz and Pz a prototypical EEG-response evoked by face stimuli was found exhibiting 3 prominent peaks, very similar for P-stimuli and N-stimuli. A P150 maximum was especially pronounced in the responses to face stimuli but absent in the evoked potentials aroused by chair or tree stimuli. The difference curves (face-chair, face-tree, chair-tree) supported the hypothesis of "face-responsive" components in these responses. Paradigm (2): 4 x 6 degree slides (black and white photographs) of 54 different human faces, 53 different vases and 53 different pairs of shoes were projected as in paradigm (1), but instruction to the subjects on a supposed post-test memory task raised their attention during the recordings. "Face-responsive" components (an early N 140-160, P 210-240, N 300) were more marked in female than in male subjects, and again most pronounced at electrode Cz. Paradigm (3): When a recognition task was included in paradigm (2)--9 out of 192 items were memorized 20 minutes before the recording session--essentially the same evoked potentials were obtained as in (2), but an additional late positive wave (450-600 ms) appeared in the responses to all stimuli. We assume that the "face-specific" components--a designation which is used cautiously considering the limited number of non-face stimuli--do not originate in the temporo-occipital cortical face region, but in limbic structures (amygdala, hippocampus) deep in the temporal lobe or in the gyrus cinguli. In the present study no significant hemispheric differences (T5, T6) in the evoked responses were found (all stimulus categories), but such differences are known to appear with highly schematic face stimuli.

Adult↗

PubMed1984

Distribution of NT-IR perikarya in the brain of the guinea pig with special reference to cardiovascular centers in the medulla oblongata.

The occurrence and distribution of neurotensin-immunoreactive (NT-IR) perikarya was studied in the central nervous system of the guinea pig using a newly raised antibody (KN 1). Numerous NT-IR perikarya were found in the nuclei amygdaloidei, nuclei septi interventriculare, hypothalamus, nucleus parafascicularis thalami, substantia grisea centralis mesencephali, ventral medulla oblongata, nucleus solitarius and spinal cord. The distribution of NT-IR perikarya was similar to that previously described in the rat and monkey. In the gyrus cinguli, hippocampus and nucleus olfactorius, though, no NT-IR neurons were detected in this investigation. Additional immunoreactive perikarya, however, were observed in areas of the ventral medulla oblongata, namely in the nucleus paragigantocellularis, nucleus retrofacialis and nucleus raphe obscurus. The relevance of the NT-IR perikarya within the ventral medulla oblongata is discussed with respect to other neuropeptides, which are found in this area, and to cardiovascular regulation.

Animals↗

PubMed1989

Adult-type citrullinemia.

An autopsy case of adult-type citrullinemia in a 42-year-old male is reported. The patient neuropathologically presented mixed cerebral changes consisting of the pseudoulegyric and ischemic types of hepatocerebral disease. In common with previously reported cases of the pseudoulegyric type, the nature and localization of the cerebral changes in this case were characteristic, in that neuronal loss occurred most severely and symmetrically in the mediobasal part of the frontal and occipital lobes, gyrus cinguli, claustrum, insula and temporal lobe, and that the watershed area of the cerebral cortex, basal ganglia and Purkinje cells were only slightly affected. The importance of hypercitrullinemia was stressed in the pathogenesis of the cerebral changes evident in adult-type citrullinemia.

Adult↗

PubMed1983

An unusual case of Pick's disease.

A man aged 64, with a history of chronic trichloroethylene intoxication, presented early headache, impairment of memory, and "stehende Redensarten", later on mental deterioration with muteness and oral tendency. He died of bronchopneumonia. The brain was studied by light and electron microscopy. Numerous inflated cells, intraneuronal argentophil Pick bodies and central chromatolysis of neurons were found throughout the cerebral cortex. Widespread diffuse fibrillary gliosis was the finding bearing a striking resemblance to "progressive subcortical gliosis". Severe loss of nerve cells was observed in the temporal lobe (except the posterior of T 1) and moderate or mild loss in the gyrus rectus, insula, gyrus cinguli, and partial areas of the frontal, parietal, and occipital lobes. By electron microscopy, the argentophil Pick bodies consisted of a conglomeration of randomly arranged short 100-150 A filaments, ribosomes, vesicles, mitochondria, and scanty paired helical filaments. The present case was considered to represent a rare case of Pick's disease of the temporo-fronto-parieto-occipital type or panencephalic type.

Brain↗

PubMed2000

Reduction of the synaptic protein rab3a in the thalamus and connecting brain regions in post-mortem schizophrenic brains.

Although the psychotic symptoms in schizophrenia can be alleviated by treatment with dopaminergic receptor antagonists, the etiology and underlying neurochemical pathology remains obscure. Both neuropathological and magnetic resonance imaging studies have found evidence for neuronal loss and atrophy in the thalamus in schizophrenia, implicating this key structure for gating information to cortical areas in the pathophysiology. Recent studies have also found evidence of synaptic loss in the thalamus in schizophrenia. To further examine possible synaptic disturbances, we studied the synaptic related protein rab3a as a marker for synaptic density, using both quantitative Western blotting and immunohistochemistry. The material consisted of brains from 22 schizophrenic patients (mean age 79.3 years), and 24 control subjects (74.8 years). Reduced rab3a protein levels were found in the left thalamus in schizophrenia (0.47 +/- 0.17 vs. 1.00 +/- 0.18; p < 0.0001), while a less marked decrease was found also in the right thalamus (0.75 +/- 0.13 vs. 1.00 +/- 0.09; p < 0.0001). Immunohistochemistry, performed on two schizophrenic and two control brains, revealed that rab3a immunoreactivity was most reduced in the left anterior and mediodorsal thalamic nuclei. Therefore, we extended the study to brain regions connected these thalamic nuclei. Reduced rab3a protein levels were found schizophrenia also in the frontal cortex, hippocampus, gyrus cinguli, and parietal cortex, while no significant differences were found in the temporal cortex, or in cerebellum. The reduction in rab3a was not found to be secondary to confounding factors such as age-differences, post-mortem delay time, generalized brain atrophy, or antipsychotic medication. Therefore, the reduction of rab3a probably reflects synaptic disturbances, possibly synaptic loss, in the limbic system and neocortical areas, in schizophrenia. This part of the brain is known to be involved in behavioral and emotional control, and thus to be crucial for higher mental functions, suggesting that synaptic disturbances in the limbic system may be of importance in the development of psychotic symptoms in schizophrenia.

Adult↗

PubMed1994

Iron, copper, zinc, magnesium, and calcium in postmortem brain tissue from schizophrenic patients.

The regional distribution of iron, copper, zinc, magnesium, and calcium in postmortem brain of schizophrenic patients was compared with that of matched controls. In none of the brain regions investigated (caudate nucleus, hippocampus, amygdala, cortex, corpus mamillare, gyrus cinguli, and hypothalamus) were significant differences observed between these two groups. In the total group, region-specific differences were found for iron, copper, zinc, and calcium, but not for magnesium. Gender differences were observed only for zinc. There was no correlation between a neuroleptic-free period before death and the content of any of the metals investigated, except for a positive correlation between copper in the hippocampus and a neuroleptic-free period. The results of the present study suggest that there are no profound differences in the content of iron, copper, zinc, magnesium, and calcium in postmortem brains between controls and schizophrenic patients.

Adult↗

PubMed1979

Petit mal and grand mal seizures produced by toluene or benzene intoxication in the cat.

Motor incoordination, euphoria and hallucinations are symptoms reported for humans voluntarily intoxicated by industrial solvents. An epileptic-like consciousness impairment has also been noted. The present paper describes a technique used for the experimental study of solvent intoxication in which toluene and benzene can be applied directly into the trachea of freely moving cats with chronically implanted electrodes. This technique permits the control of solvent dose and time of exposure. Results showed a 3 Hz spike-wave activity in the gyrus cinguli recording with both toluene or benzene intoxication. Furthermore, benzene inhalation produced generalized tonic-clonic seizures. These effects were dose-related. However, a sensitization period was essential for the development of such alterations, and effects showed a tendency to shortening through chronic exposures. These alterations were correlated with behavioral disturbances such as nodding, twitching and apparent hallucinations. Results are discussed regarding the sensitization period, the optimal peak of effects, and the period of tolerance development relevant to an earlier found amygdalar activation that could be correlated with other methods inducing experimental seizures, such as repetitive stimulation of the brain (kindling).

Amygdala↗

PubMed1991

The neocortico to mesio-basal limbic propagation of focal epileptic activity during the spike-wave complex.

In order to localize epileptogenic electrophysiological sources, a multichannel MEG system was used in 3 patients with partial epilepsy during presurgical evaluation. MEG and EEG (including scalp, sphenoidal and intracranial foramen ovale electrodes) were recorded simultaneously during a period of intensive video-EEG monitoring in order to observe single spontaneous spikes. In addition to MRI, SPECT and PET investigations were performed. Electrical activity subsequent to the activity of the epileptic focus could be localized by the MEG after noise reduction using a temporal correlation technique. Simultaneous registration of the magnetic field and the electrical field showed that the source of the primary focal epileptic activity (first period during the total spike wave complex where a dipolar magnetic field pattern is found) is localized in neocortical lateral regions, whereas another focal epileptic activity in a later phase of propagation occurs in temporal mesial regions. In 1 patient (case 1) the primary focal epileptic activity was localized in the surrounding neocortical tissue of an angioma and the middle and inferior temporal gyrus. The second phase of propagation is localized in temporo-basal-mesial regions, including para- and hippocampal structures. The latest center of activity occurred in posterior parts of the gyrus cinguli. In 2 other patients, the primary focal epileptogenic activity was localized at the insula and also spread into temporal basal mesial regions. A multi-modal approach to research of focal epilepsy, combining metabolic, electrical potential, magnetoencephalographic and morphological data, recorded by non-invasive techniques, offers new perspectives for the detection of involved brain regions. The 3-D and time-resolved localization of focal epileptic activity, correlated with the individual anatomy of the human brain, may improve the determination of neuronal populations involved in the individual epileptogenic process, especially in the interaction between temporal or extratemporal neocortex and limbic system.

Adult↗

PubMed1996

Monoaminergic neurotransmitters, their precursors and metabolites in brains of Alzheimer patients.

The catecholamines dopamine (DA), noradrenaline (NA) and adrenaline (A), their aminoacid precursors tyrosine (Tyr), L-3,4-dihydroxyphenylalanine (L-DOPA), two of their metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and 4-hydroxy-3-methoxy phenyl glycol (MHPG), serotonin (5-HT) and its precursor tryptophan (Trp), were measured by high pressure liquid chromatography (HPLC) with electrochemical detection in seven regions (globus pallidus, putamen, nucleus amygdalae, nucleus caudatus, substantia nigra, gyrus cinguli and raphe) of postmortem brains from eight histologically verified cases with Alzheimer's disease (AD) and six histologically normal controls. Concentrations of L-DOPA, DA, DOPAC, NA and 5-HT were significantly reduced, while Tyr and MHPG concentrations were significantly increased in AD versus control patients. The concentrations of Trp and A in AD patients were not significantly different from controls. Furthermore, for most brain regions examined, significant negative correlations between Tyr and DA as well as between NA and MHPG levels were found. These data confirm and extend findings of monoaminergic systems disturbances in AD, emphasize the significance of dopaminergic deficit for AD and suggest that in pharmacotherapy of AD, attempts to restore deficits of the transmitter systems should be directed to the monoaminergic, in particular the dopaminergic system.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2005

Fatal familial insomnia: a model disease in sleep physiopathology.

Fatal Familial Insomnia (FFI) is characterized by loss of sleep, oneiric stupor with autonomic/motor hyperactivity and somato-motor abnormalities (pyramidal signs, myoclonus, dysarthria/dysphagia, ataxia). Positon emission tomography (PET) disclosed thalamic hypometabolism and milder involvement of the cortex; neuropathology severe neuronal loss in the thalamic nuclei variably affecting the caudate, gyrus cinguli and fronto-temporal cortices. Genetic analysis disclosed a mutation in the PRNP gene and FFI was transmitted to experimental animals, thus classifying FFI within the prion diseases. Rare Sporadic Fatal Insomnia (SFI) cases occur without PRNP mutation but with features similar to FFI. FFI represents a model disease for the study of sleep-wake regulation: (I) the profound thalamic hypometabolism/atrophy associated with lack of sleep spindles and delta sleep implicate the thalamus in the origin of slow wave sleep (SWS); (II) loss of SWS is associated with marked autonomic and motor hyperactivity; termed 'agrypnia excitata', this association has been proposed as a useful clinical concept representative of thalamo-limbic dysfunction; (III) lack of SWS occurs with substantial preservation of stage 1 NREM sleep, implying that the latter has mechanisms different from SWS and unaffected by thalamic atrophy; accordingly, conflating stage 1 NREM with SWS into NREM sleep is inappropriate.

Adult↗

PubMed1980

Microanalysis of lipids in discrete brain areas of the rabbit following intramuscular administration of steroid contraceptive.

The effects of 60- and 90-day administration of a pill containing 0.05 mg ethinylestradiol and 0.5 mg norgestrel on the regional lipid levels of female albino rabbit brains have been investigated. Decreased levels of total lipids, phospholipids, cholesterol, free fatty acids and esterified fatty acids were observed in hypothalamus, hippocampus, amygadaloid nucleus, midline nuclei of thalamus and gyrus cinguli. However, the levels of esterified fatty acids only in the amygdaloid nucleus and that of cholesterol in hypothalamus were significantly increased.

Animals↗

PubMed1982

Karyometric studies and quantitation of the DNA content in nerve and oligodendroglial cells after intraperitoneal administration of Vincristine.

Karyometric and cytophotometric investigations were conducted on nuclei of nerve cells of the Gyrus cinguli and on oligodendroglial nuclei of the corpus callosum following a 12-fold intraperitoneal injection of Vincristine into Wistar rats. The results of our investigations have shown a distinctly decreased content of DNA in neuronal nuclei of experimental rats along with a slightly increased content of DNA in glial cells. It is assumed that intraperitoneal administration of Vincristine does not inhibit the replication of DNA by oligodendroglial cells and that the observed reduction of DNA in neurocytes is the result of a disturbed turnover of DNA that is due to some damage of cytoplasmatic structures (rough endoplasmatic reticulum and microtubules) induced by the applied cytostatic compound.

Animals↗

PubMed1986

Karyometric, cytophotometric and histoenzymatic studies on neuroglia of rats treated with 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU/lomoustine).

CCNU is a cytostatic drug, a nitrosourea derivative, used--among others--in therapy of tumors of the central nervous system. Even if the drug is regarded safe for central and peripheral nervous systems, a possibility of harmful effects of CCNU on the central nervous system should be examined caused by the affinity of all nitrosourea derivatives to lipids. This has prompted us to study the drug effect on neuroglia cells in corpus callosum and gyrus cinguli. The drug was administered to rats by the intragastric route in four doses--one dose a week. Three doses of 2.5 mg each were followed by one dose of 5 mg. Some brains were isolated for the studies, and paraffin sections were prepared for karyometric as well as cytophotometric studies and for section staining according to Nissl and Klüver-Barrer techniques 8 days after the last dosage. Brains of other experimental rats served for preparing cryostat sections for demonstration of phosphatase and esterase activities. The studies, conducted after CCNU administration, documented a significant decrease in size of oligodendroglia nuclei and an increase in size of astroglia nuclei. DNA content of neuroglia nuclei was markedly decreased. Histoenzymatic changes in experimental animals were not very pronounced and included a slight increase in TPPase and nonspecific esterase activities as well as a decrease in ATPase activity. Despite the changes in neuroglia cells no damage to corpus callosum myelin sheaths was observed.

Adenosine Triphosphatases↗

PubMed1986

A Golgi study of the polymicrogyric cortex in Aicardi syndrome.

The neuropathological examination of the brain of a 4-month-old girl with Aicardi syndrome (infantile spasms, chorioretinal lacunae, psychomotor retardation, agenesis of the corpus callosum and vertebral anomalies) showed agenesis of the corpus callosum, agenesis of the anterior commissure and abnormal orientation of the hippocampal formation, in addition to periventricular cerebral nodules and extensive non-laminated cortical polymicrogyria of the fronto-parietal regions and gyrus cinguli of both hemispheres. A non-communicating medial supracollicular cyst, racemose cysts of the choroid plexus, underdevelopment of the inferior cerebellar vermis tonsils were also observed. The study of the polymicrogyric cortex with the Golgi method revealed an abnormal orientation of neurons; but the different varieties of cells were located at the depth corresponding to that were they are normally found. The Golgy study of the periventricular nodules disclosed the presence of different types of cortex-like neurons. On the basis of these data it may be suggested that polymicrogyria is not a migratory disturbance, but rather the result of a partial necrosis of the cortical mantle occurring before the 5th month of foetal life.

Agenesis of Corpus Callosum↗

PubMed2000

Increased frequency of the alpha-1-antichymotrypsin T allele in cerebral amyloid angiopathy.

Cerebral amyloid angiopathy (CAA) is a process of unknown etiology characterized by amyloid deposition in the wall of small cerebral and meningeal blood vessels. CAA is also a feature of Alzheimer's disease (AD) and of a subgroup of elderly people. Alpha-1-Antichymotrypsin (ACT) is a serum glycoprotein frequently associated with vascular and senile plaque amyloid. The ACT gene is known to have a bi-allele polymorphism that causes a simple amino acid substitution. In an attempt to clarify the possible role of ACT polymorphism in AD and in cases of CAA, the ACT genotype was investigated in AD, CAA, and intellectually intact controls. Representative brain areas (cerebral cortex, hippocampus, putamen, white matter, and gyrus cinguli) from all cases were studied using classical histologic staining techniques (hematoxylin-eosin (HE), Mallory's thrichromic or alkaline congo red stain), and immunohistochemistry for tau and beta-amyloid proteins. There was a significantly increased T allele and TT genotype frequency in the CAA group, but not in the AD group, suggesting a role for the ACT genotype in the development of vascular lesions. The presence of the apolipoprotein E4 allele (ApoE4) did not correlate with the ACT-A allele, as previously reported, and appeared to be independent of the risk for developing AD.

Aged↗

PubMed1998

The striatum in a putative cerebral network activated by verbal awareness in normals and in ADHD children.

The aim of the present study was to evaluate the striatum's involvement in verbal awareness (semantic processing and supra-modal attention) in normals and children with attention deficit hyperactivity disorder (ADHD). Our previous finding of striatal hypoperfusion in ADHD at rest, supports our prediction that the striatum will also show reduced activation in response to tasks requiring verbal awareness. Regional cerebral blood flow (rCBF) was studied with the Xenon133 SPECT method in 12 boys with ADHD and six normal controls. The experimental controls included: (1) White Noise, (2) Passive Listening to a series of animal names, and (3) Detection of Targets ("dangerous animals") from the same series of animal names. The conditions were selected to isolate the semantic processing (Passive Listening - White Noise) and supra-modal attention components (Detection of Targets - Passive Listening of verbal awareness). ADHD children had decreased rCBF in the right striatum when compared to normals (mean difference from grand mean of each subject 8.06 ml/100 g/min vs 14.16 ml/100 g/min, p < 0.05). Factor analysis of the rCBF data revealed high factor I loadings for the frontal and striatal regions, which, in conjunction with the nature of the experimental conditions supported the inference that factor I mediated verbal awareness. Factor scores, which summarized the activity of all of the regions of interest (ROI's) on factor I, were differentially affected by the language component of the experimental tasks. Function scores were derived from factor I for the anterior cingulum and infero-frontal regions to evaluate their respective involvement in supra-modal attention and semantic processing. Function scores were also developed for the striatum, because of its central location and potential role in ADHD. The anterior cingulum was activated by supra-modal attention. The infero-frontal and the striatal regions were both activated by the language demands of the tasks. However, the striatum demonstrated reduced function scores (p < 0.05) in ADHD for all tasks. Our finding that the anterior gyrus cinguli were activated by supramodal attention and that the infero-frontal and striatal regions were activated by semantic processing supports the involvement of these ROI's in verbal awareness. Furthermore, the depressed functional contribution of the striatum to verbal awareness in ADHD children is consistent with and helps to explain their reduced cognitive control over behaviour and mental function.

Journal Article↗

PubMed2002

Cognitive function and fMRI in patients with multiple sclerosis: evidence for compensatory cortical activation during an attention task.

Mild cognitive impairment has frequently been reported for patients in the early stages of multiple sclerosis. The aim of the present study was to measure whether altered cortical activation during a sustained attention task occurs along with limited extent of neuropsychological problems. Expanded brain activation of multiple sclerosis patients with normal motor function compared with healthy controls during a finger tapping paradigm has previously been reported. Compensatory brain activation in patients with multiple sclerosis compared with normal controls may also be observed when the subjects are performing cognitive functions. In 21 patients with clinically definite relapsing-remitting multiple sclerosis, a psychometric assessment was performed using the Wechsler Memory Scale (WMS) and the Multiple Sclerosis Functional Composite Score (MSFC). In addition, functional MRI was performed during a Paced Visual Serial Addition Task (PVSAT), a visual analogue of the Paced Auditory Serial Addition Task (PASAT). All patients were within 3 years of diagnosis and were not suffering from a relapse at the time of investigation. The multiple sclerosis patients were compared with a control group of 21 healthy volunteers matched for handedness, age, years of education and sex. With regard to psychometric results, the WMS general memory score showed statistically significant differences between patients and controls. We did not find differences for either the MSFC or the PASAT scores. A group analysis of the functional imaging data during the PVSAT revealed different activation patterns for patients compared with control subjects. In healthy volunteers, the main activation was found in the frontal part of the right gyrus cinguli (Brodmann area 32). In patients, the main activation was detected at the right hemispheric frontal cortex (Brodmann areas 6, 8 and 9). In addition, the left hemispheric Brodmann area 39 was activated. We interpret the different patterns of activation, accompanied with intact performance in a sustained attention task of our multiple sclerosis sample compared with healthy controls, as the consequence of compensatory mechanisms. This is an expression of neuronal plasticity during early stages of a chronic disease.

Adolescent↗