The role of inferior parietal and inferior frontal cortex in working memory.

Verbal working memory involves two major components: a phonological store that holds auditory-verbal information very briefly and an articulatory rehearsal process that allows that information to be refreshed and thus held longer in short-term memory (A. Baddeley, 1996, 2000; A. Baddeley & G. Hitch, 1974). In the current study, the authors tested two groups of patients who were chosen on the basis of their relatively focal lesions in the inferior parietal (IP) cortex or inferior frontal (IF) cortex. Patients were tested on a series of tasks that have been previously shown to tap phonological storage (span, auditory rhyming, and repetition) and articulatory rehearsal (visual rhyming and a 2-back task). As predicted, IP patients were disproportionately impaired on the span, rhyming, and repetition tasks and thus demonstrated a phonological storage deficit. IF patients, however, did not show impairment on these storage tasks but did exhibit impairment on the visual rhyming task, which requires articulatory rehearsal. These findings lend further support to the working memory model and provide evidence of the roles of IP and IF cortex in separable working memory processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Morphology of poststreptococcal glomerulonephritis in adults

The authors followed the evolution of morphologic changes in adult patients with poststreptococcal glomerulonephritis (PSGN). In all the patients the kidney biopsies repeated in the period of 2 to 5 years after the acute phase, showed certain histopathologic changes as follows: increased number of mesangial cells, increase of mesangial matrix with scattered axiation and lobulation, segmental thickening of Bowman's capsule, interstitial fibrosis along with preservation of capillary lumen and absence of changes in major blood vessels. According to severity of histopathologic changes, the patients were classified into 4 groups: moderate severe changes--2 patients, mild--15 patients, small--12 and minimal changes were seen in 5 patients. It was proved that after acute stage of PSGN, in which morphologic appearance was more or less typical but not pathognomonic as well, increased number of secretory active mesangial cells was kept, which lead to gradual increasing of mesangial matrix and in slowly evolutive process by the model of glomerulosclerosis lead to irreversible damage of glomerules and interstitial fibrosis.     

Relations between source amnesia and frontal lobe functioning in older adults.

A study is reported in which the relations among normal aging, source amnesia, and frontal lobe functioning were explored. Twenty-four older adults (aged 60–84 years) were tested on their ability to remember where they had acquired new factual information; they were also given the Wisconsin Card Sorting Test (WCST), a test of verbal fluency, and other psychometric tests. The degree of source amnesia in this normal sample correlated with age, verbal fluency, and some measures from the WCST. Source amnesia was not related to Performance IQ, however, or to a measure of fact recall. The implications for the relations among aging, memory, and frontal lobe functions are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experience-induced neurogenesis in the senescent dentate gyrus

We demonstrate here that under physiological conditions neurogenesis continues to occur in the dentate gyrus of senescent mice and can be stimulated by living in an enriched environment. Neurogenesis was investigated by confocal microscopy of three-channel immunofluorescent staining for the proliferation marker bromodeoxyuridine (BrdU) and neuronal and glial markers. Quantification was performed with unbiased stereological counting techniques. Neurogenesis decreased with increasing age. Stimulation of adult and aged mice by switching from standard housing to an enriched environment with opportunities for social interaction, exploration, and physical activity for 68 d resulted in an increased survival of labeled cells. Phenotypic analysis revealed that, in enriched living animals, relatively more cells differentiated into neurons, resulting in a threefold net increase of BrdU-labeled neurons in 20-month-old mice (105 vs 32 cells) and a more than twofold increase in 8-month-old mice (684 vs 285 cells) compared with littermates living under standard laboratory conditions. Corresponding absolute numbers of BrdU-positive astrocytes and BrdU-positive cells that did not show colabeling for neuronal or glial markers were not influenced. The effect on the relative distribution of phenotypes can be interpreted as a survival-promoting effect that is selective for neurons. Proliferation of progenitor cells appeared unaffected by environmental stimulation.     

Dendritic atrophy in the dentate gyrus of the senescent rat

Quantitative electron microscopic analysis of the supragranular zone of the dentate gyrus molecular layer has shown that the number, volume fraction and surface area of dendritic shaft profiles are significantly decreased in senescent rats, relative to young adults. These modifications of dendritic morphology, which are not associated with age-related changes in dimensions of the molecular layer or in numbers of granule cells, may result from a decrease in the number and/or length of dendrites. In either case, the decreases in the number, volume fraction and surface area of dendritic shaft profiles found in the dentate gyrus of senescent rats signify an age-related atrophy of dendrites. Comparison of changes in the number and volume fraction of dendritic shaft profiles has demonstrated that age-related dendritic atrophy involves predominantly dendritic branches.     

Cognitive support at encoding attenuates age differences in recollective experience among adults of lower frontal lobe function.

Free recall and recollective experience were investigated in relation to low and high cognitive support at encoding and to neuropsychological measures of frontal lobe function (FLF) in 105 healthy adults divided into 3 age groups (young, young-old, old). Statistically significant main effects suggested free recall was inferior with increasing age and lower FLF. For recollective experience however, a significant interaction between age and FLF was modified by the provision of cognitive support at encoding. Recognition measures classified as familiar did not vary according to age, neuropsychological function, or encoding condition. The results suggest that the neural systems of the prefrontal cortex underlie age differences in recollective experience and that cognitive support modifies the influence of those systems in old age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual differences in P3 scalp distribution in older adults, and their relationship to frontal lobe function

There is evidence that frontal lobe function may diminish in normal aging. The P3 component of the event-related brain potential (ERP) elicited by target events in an oddball paradigm becomes more frontally oriented in elderly subjects. It was hypothesized that the extent to which the P3 distribution is frontally oriented in old subjects may index less efficient frontal lobe function. In this study, bootstrapping methods were used to establish the reliability of the locations of maxima of surface brain activity obtained with ERP recordings from young and old subjects. The results indicated that brain activity maxima are reliable for a given individual. However, among the elderly only, there were also clear individual differences in the distribution of the P3 component elicited by target stimuli in an oddball paradigm. On the basis of these differences, the old subjects were divided into two groups. In line with predictions, those elderly subjects who showed frontal-maximal P3 scalp distributions had lower performance on standardized neuropsychological tests of frontal lobe function than those elderly subjects who showed posterior-maximal scalp topographies.     

Foreign body in the frontal sinus

The authors describe the case of the foreign body in frontal sinus left there after prior surgery. The case was treated surgically with good results.     

Development of the frontal sinuses

Variability studies on frontal sinuses, covering the age range from childhood to adulthood have been neglected in literature up to now. On a total of 215 children and youths from 3-17 years (117 boys and 98 girls), the growth rate of the frontal sinuses had been examined. The difference between males and females proved to be quite interesting. The frontal sinuses of girls increase evenly in size during the years, whereby from 1-5 years the development runs parallel with boys and girls. From 8-12 years the growth rate of male frontal sinuses is very low, causing a retardation of growth on boys in comparison to girls. After that period, however, a substantial acceleration of the growth rate takes place, so, that at the age from 14-15 years the frontal sinuses of the males have surpassed the female ones referring to size. At the age of 18 years the forming of frontal sinuses can be considered as finished.     

Extracellular recordings in the colchicine-lesioned rat dentate gyrus following transplants of fetal dentate gyrus and CA1 hippocampal subfield tissue

Grafts of fetal dentate gyrus (DG) and CA1 hippocampal subfield tissue were extruded into the dentate gyri of adult male Sprague-Dawley rats, 7-10 days after lesioning the granule cells with colchicine (0.06 microliter of 7 mg/ml solution at each of 5 sites/hippocampus). Graft area-host and host-graft area connectivities were investigated 4-6 months post-transplantation by recoding extracellular evoked response in hippocampal slice preparations. Following stimulation of the host mid-molecular layer, evoked field potential responses, showing considerable variation, were recorded in both types of graft. Evoked responses in the lesioned DG without grafts were recorded in very few slices. Stimulation of the area of DG tissue grafts occasionally evoked responses in the host CA3/CA4 and there was no evidence for CA1 graft area-CA3/CA4 connectivity; stimulation of DG and CA1 graft areas occasionally evoked responses in the host CA1. Responses in the area of both DG and CA1 grafts supported short-term potentiation following stimulation of the host mid-molecular layer but only DG graft areas supported long-term potentiation of the population spike amplitude. In the area of both types of transplant a tonic bicuculline-sensitive inhibition was present and paired-pulse stimulation paradigms provided some evidence for inhibition. It is possible that responses recorded within the area of grafted tissue to stimulation of the host are attributable to host-graft connectivity and similarly, responses recorded in the host to stimulation of the area of the graft may be attributable to graft-host connectivity. Only DG graft areas received host inputs which were capable of sustaining a long-term potentiation and establishing efferent contacts with the host CA3/CA4 subfield, suggesting that these would be more likely than CA1 grafts to reinstate normal functional circuitry.     

Hypertrophy of astroglial processes in the dentate gyrus of the senescent rat

Quantitative electron microscopic analysis of the supragranular zone of the dentate gyrus molecular layer has shown that the number and volume fraction of profiles of astroglial processes are significantly increased in senescent rat relative to young adults. These ultrastructural modifications, which are not associated with significant age-related changes in the number of astrocytes or in the width of the molecular layer, may result from a formation of new astroglial processes and/or elongation of existing ones. In either case, the increase in the number and volume fraction of astroglial process profiles is an indicator of age-related astroglial hypertrophy. Hypertrophy of astroglial procecesses, which seems to develop with advanced age as a response to partial deafferentation of neurons, may compensate for a decrease in the dendritic volume fraction, thereby preventing changes in the dimensions of the dentate gyrus molecular layer in senescence.     

Oncocytoma of the inferior turbinate

According to the World Health Organization more than 60% of European countries have achieved the goal of no more than 3 DMFT at the age of 12 years. The others, including the newly independent Baltic states, still have high caries levels. Data from recent studies show that mean caries prevalence among 12-year-olds in Latvia, Lithuania, and Estonia was 5.8, 4.9, and 4.6, respectively. Absence of caries was recorded in 5% of Latvian and Estonian and 12% of Lithuanian 12-year-olds. Fifteen-year-old Latvians and Lithuanians averaged 8.1 and 7.0 DMFT, which, owing to the absence of radiographic examination, may be a substantial underestimation of real caries levels. The possible adverse effects of the privatization of dental care and the benefits of increased access to fluoride dentifrice in these countries have not yet been evaluated. The extremely poor oral hygiene seen in epidemiologic surveys indicates that fluoride dentifrices may not be widely used. The caries levels in the Baltic states resemble those commonly encountered a couple of decades ago in the Nordic countries. Data from two follow-up studies in Iceland show 66% and 52% decline in caries prevalence for 12- and 15-year-old children, respectively, over a period of 7 years. However, the caries experience of the 15-year-olds in the latter study was similar to that of 12-year-olds 10 years earlier, both in mean caries score (DMFS 11.3 and 12.1) and frequency distribution. Nor has the proportion of occlusal and approximal DF values changed in spite of frequent use of fissure sealants. While caries has become mainly a pit and fissure phenomenon in 12-year-olds, 44.3% of Swedish 19-year-olds reportedly have approximal lesions, and, when enamel lesions are recorded, approximal caries dominates the DFS scores. Analyses of trends in Nordic countries show that, despite a substantial decline in caries prevalence, vigilance is required to prevent a delayed caries development in the future adult population.     

Functional connectivity of the angular gyrus in normal reading and dyslexia

The classic neurologic model for reading, based on studies of patients with acquired alexia, hypothesizes functional linkages between the angular gyrus in the left hemisphere and visual association areas in the occipital and temporal lobes. The angular gyrus also is thought to have functional links with posterior language areas (e.g., Wernicke's area), because it is presumed to be involved in mapping visually presented inputs onto linguistic representations. Using positron emission tomography , we demonstrate in normal men that regional cerebral blood flow in the left angular gyrus shows strong within-task, across-subjects correlations (i.e., functional connectivity) with regional cerebral blood flow in extrastriate occipital and temporal lobe regions during single word reading. In contrast, the left angular gyrus is functionally disconnected from these regions in men with persistent developmental dyslexia, suggesting that the anatomical disconnection of the left angular gyrus from other brain regions that are part of the "normal" brain reading network in many cases of acquired alexia is mirrored by its functional disconnection in developmental dyslexia.     

Pentylenetetrazol causes polysynaptic responses to appear in the dentate gyrus

In a particular brain region specific changes in inhibition or excitation may be the basis of seizure initiation. Alternatively, changes in the balance of excitation and inhibition in the circuit, which may be detectable as polysynaptic responses may be more important indicators of epileptogenesis. That the appearance of polysynaptic responses precedes the initiation and, therefore, may be necessary for the onset of epileptiform activity in the hippocampal-parahippocampal circuit was tested using the chemical convulsant pentylenetetrazol. Excitation and paired-pulse inhibition were measured in CA1 and the dentate gyrus of the urethane-anaesthetized rat before and after administration of pentylenetetrazol. In addition, three polysynaptic responses were monitored. In both CA1 and the dentate gyrus, pentylenetetrazol, 100 mg/kg, caused a trend towards increased excitability and caused a relatively mild loss of inhibition. Two polysynaptic responses appeared in the dentate gyrus after the administration of pentylenetratrazol, both apparently mediated through the entorhinal cortex. A polysynaptic response of the CA1 pyramidal neurons to contralateral angular bundle stimulation was not observed. These experiments demonstrate that pentylenetetrazol will facilitate only the appearance of polysynaptic responses mediated through the entorhinal cortex. These results support the hypothesis that pentylenetetrazol has a specific action within the entorhinal cortex that may facilitate the synchronization and spread of epileptiform activity. These results are also consistent with the hypothesis that the appearance of polysynaptic responses may be necessary for the onset of epileptogenesis in the hippocampal-parahippocampal circuit.     

Genetic influence on neurogenesis in the dentate gyrus of adult mice

To address genetic influences on hippocampal neurogenesis in adult mice, we compared C57BL/6, BALB/c, CD1(ICR), and 129Sv/J mice to examine proliferation, survival, and differentiation of newborn cells in the dentate gyrus. Proliferation was highest in C57BL/6; the survival rate of newborn cells was highest in CD1. In all strains approximately 60% of surviving newborn cells had a neuronal phenotype, but 129/SvJ produced more astrocytes. Over 6 days C57BL/6 produced 0.36% of their total granule cell number of 239,000 as new neurons, BALB/c 0.30% of 242,000, CD1 (ICR) 0.32% of 351,000, and 129/SvJ 0.16% of 280,000. These results show that different aspects of adult hippocampal neurogenesis are differentially influenced by the genetic background.     

Long-term potentiation and dual-component quantal signaling in the dentate gyrus

Long-term potentiation (LTP) of excitatory transmission is an important candidate cellular mechanism for the storage of memories in the mammalian brain. The subcellular phenomena that underlie the persistent increase in synaptic strength, however, are incompletely understood. A potentially powerful method to detect a presynaptic increase in glutamate release is to examine the effect of LTP induction on the rate at which the use-dependent blocker MK-801 attenuates successive N-methyl-D-aspartic acid (NMDA) receptor-mediated synaptic signals. This method, however, has given apparently contradictory results when applied in hippocampal CA1. The inconsistency could be explained if NMDA receptors were opened by glutamate not only released from local presynaptic terminals, but also diffusing from synapses on neighboring cells where LTP was not induced. Here we examine the effect of pairing-induced LTP on the MK-801 blocking rate in two afferent inputs to dentate granule cells. LTP in the medial perforant path is associated with a significant increase in the MK-801 blocking rate, implying a presynaptic increase in glutamate release probability. An enhanced MK-801 blocking rate is not seen, however, in the lateral perforant path. This result still could be compatible with a presynaptic contribution to LTP in the lateral perforant path if intersynaptic cross-talk occurred. In support of this hypothesis, we show that NMDA receptors consistently sense more quanta of glutamate than do alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors. In the medial perforant path, in contrast, there is no significant difference in the number of quanta mediated by the two receptors. These results support a presynaptic contribution to LTP and imply that differences in intersynaptic cross-talk can complicate the interpretation of experiments designed to detect changes in transmitter release.     

Differential fMRI responses in the left posterior superior temporal gyrus and left supramarginal gyrus to habituation and change detection in syllables and tones

Enteroscopy does not yet carry the conviction that physicians are used to with gastroscopy and colonoscopy. The examination is never complete. The distance of small bowel examined in any individual examination is unknown. Although some therapeutic maneuvers are possible, the further the endoscope is into the small bowel the more difficult it becomes to pass and control the instruments. There is more room for improvement in enteroscopy than in almost any other area of gastrointestinal endoscopy. Nonetheless, there have been real gains for patients with difficult gastrointestinal bleeding and small bowel pathology with advances in diagnostic and therapeutic ability with enteroscopes achieved by a combination of relatively minor technologic changes and some clinical enthusiasm.     

Leiomyosarcoma of the inferior vena cava

BACKGROUND: The inferior vena cava is an uncommon location for leiomyosarcoma, a malignant tumor which develops from the smooth muscle tissue of the media. CASE REPORT: A 76-year-old woman was hospitalized for swelling of the lower limbs. Ultrasonography, computed tomography of the abdomen and magnetic resonance imaging showed tumoral invasion of the inferior vena cava extending to the atrium. Histology examination of a tumoral fragment obtained by transjugular catheterism affirmed the diagnosis of leiomyosarcoma. DISCUSSION: Prognosis of leiomyosarcoma of the inferior vena cava is very poor. No medical or surgical treatment has given satisfactory results. Two factors would explain the poor prognosis: the tumoral localization and the low degree of tumoral differentiation. Clinical presentation and imaging findings suggest the diagnosis which must be confirmed by pathology examination of a tumoral biopsy specimen.