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PubMed1988

Cytoterminology of cortical components of ciliates: somatic and oral kinetids.

The terminology of cortical structures in ciliated protists is determined partly by the organizational perspective from which these organisms are viewed. A general descriptive terminology is to be preferred to a particular and specialized one since the latter approach will lead to inflation in the number of terms. For the components of the ciliate kinetid, postciliary (microtubular) ribbons, transverse (microtubular) ribbons, nematodesma and kinetodesmal fibril are preferred terms. One, two and more than two kinetosome kinetids are referred to as mono-, di- and polykinetids, whether in somatic or oral regions of the cortex. In the oral region, adoral, circumoral, and paroral are the preferred descriptive adjectives, modified by the name of the taxonomic category in which the structures are found.

Animals↗

PubMed1982

Cingulate damage attenuates conditioned bradycardia.

New Zealand albino rabbits received either sham, midline cortical, lateral cortical, or combined medial-lateral cortical lesions, and were subjected to differential pavlovian conditioning in which tones of different frequencies served as the conditioning stimulus and a brief paraorbital electric shock train served as the unconditioned stimulus. Heart rate conditioned responses were recorded.d Damage to medial but not lateral neocortex abolished the heart rate conditioned response. These data suggest that midline cortical structures may modulate higher level processing of stimulus information.

Animals↗

PubMed1986

Somatostatin binding sites in human leptomeninx.

Specific binding sites for somatostatin (SRIF) have been visualized in the human leptomeninx by means of autoradiographical techniques using the stable SRIF octapeptide analog 125I-204-090 as radioligand. The binding sites are specific for SRIF since only biologically active SRIF analogs compete with the radioligand. The density of the binding sites is comparable to that of the adjacent cortical structure. The presence of SRIF binding sites in the human leptomeninx, together with the recent demonstration of SRIF binding sites in human meningiomas, strongly suggest that this peptide may play a role in the physiology of the leptomeninx.

Arachnoid↗

PubMed1988

The rat accessory optic system: effects of cortical lesions on the directional selectivity of units within the medial terminal nucleus.

Single units within the medial terminal nucleus of the accessory optic system were recorded and examined for their responses to a moving pattern, in both intact and decorticated urethane-anesthetized rats. The preferred directions of motion in control rats were mainly upward with a temporal component and downward with a nasal component. The responses to upward motion were almost absent after cortical ablation, with most units now preferring temporal or downward-nasal directions. These data suggest that cortical structures modulate the directional selectivity of accessory optic neurons in the rat.

Action Potentials↗

PubMed1992

Delayed increase of extracellular arginine, the nitric oxide precursor, following electrical white matter stimulation in rat cerebellar slices.

Amino acid levels were measured in perfusates from biplanar slices of rat cerebellum installed in a Krebs-filled three-compartment chamber. The two lateral compartments housed the white matter and a section containing parallel fibres respectively. The central compartment housed cortical structures, including the Purkinje cell and granule cell bodies. This arrangement allows selective electrical stimulation of the parallel fibre or mossy fibre pathways, recording of the evoked responses to such stimulation and collection of the perfusion medium passing through the central chamber for amino acid analysis using high-pressure liquid chromatography (HPLC). Both, 2-Hz and 5-Hz stimulation of white matter caused a delayed increase in arginine levels in the perfusate. Since L-arginine is the physiological precursor of nitric oxide, a neuronal messenger in the brain, the data suggest that physiological stimuli can result in the release of this precursor, possibly to supply the nitric oxide synthase.

Afferent Pathways↗

PubMed1982

Systemic injection of kainic acid: effect on neurotransmitter markers in piriform cortex, amygdaloid complex and hippocampus and protection by cortical lesioning and anticonvulsants.

Systemic injection of kainic acid (12 mg/kg) in rats induces a well established pattern of neuronal lesions in different brain regions. These lesions are accompanied by changes in neurotransmitter markers. In the piriform cortex and amygdaloid complex, the kainic acid lesion was accompanied by a reduction in the high affinity uptake of glutamate and in the activities of glutamate decarboxylase and choline acetyltransferase, whereas in the hippocampus there was a reduction in the high affinity uptake of glutamate and in glutamate decarboxylase activity. Hemidecortication, hemitransection, a caudal knife cut in the cortex, or treatment with diazepam, all protected against the effects of kainic acid in the piriform cortex and amygdaloid complex but not in the hippocampus. Diphenylhydantoin had no effect on the neurotoxicity of kainic acid. The results indicate that the neurotoxic effects of kainic acid in the piriform cortex and amygdala are dependent on an intact cortical structure, probably due to a dependence on specific excitatory circuitry. The neurons involved may be glutamergic/aspartergic.

Afferent Pathways↗

PubMed1990

Organization of radial glia and related cells in the developing murine CNS. An analysis based upon a new monoclonal antibody marker.

A monoclonal antibody, RC1, has been generated which provides a selective and sensitive immunohistochemical marker of radial glial cells and related cell forms during development of the mouse CNS. Beginning on embryonic day E10, immunocytochemistry performed on cryostat sections stains throughout the CNS a subpopulation of cells in the ventricular zone with radial processes that terminate with endfeet at the pial surface. These processes become fasciculated and attain maximal densities by E12-14 in the spinal cord and lower brainstem and by E14-16 in the midbrain, cerebellum and forebrain. Fasciculation is especially prominent for a subclass of these cells at the midline of the brainstem and spinal cord. As nuclear and cortical structures develop, the trajectories of the radial fiber fascicles undergo systematic and region-specific distortions in their initially simple linear configuration, in the process maintaining a consistent spatial registration of germinal ventricular zones with distal sites of assembly of post-migratory neurons. In the late fetal period, radial glial progressively disappear and scattered immature astrocytes bearing multiple fine processes appear in most regions of the CNS. In the spinal cord, a transitional unipolar radial form is identified in the emerging ventral and lateral funiculi between E13 and E17. In the cerebellum, precursors to the unipolar Bergmann glial cell are identified by E15, and in the retina, precursors of the bipolar Müller cell are identified by E16. Postnatally, RC1-stained radial glia become sparse, and after one week, immunoreactive cells include only ependymal cells, hypothalamic tanycytes, Bergmann glia, Müller cells, a unipolar radial form in the dentate gyrus, and a subpopulation of white matter astrocytes. These results suggest that radial cells of astroglial lineage comprise a diverse set of cell classes which subserve multiple functions in the developing and adult brain.

Animals↗

PubMed1995

Functional mapping of the late stages of status epilepticus in the lithium-pilocarpine model in rat: a 14C-2-deoxyglucose study.

Pilocarpine administration to lithium chloride-pretreated rats results initially in discrete convulsive seizures, each behaviorally and electroencephalographically terminated, which then progress to convulsive activity with waxing-and-waning behavioral and electrographic severity; finally, a continuous convulsive state ensues, associated electrographically with continuous fast spiking. This stage does not last indefinitely but is followed by a dramatic electrographic change to periodic epileptiform discharges. The purpose of the present study was to determine with the 14C-2-deoxyglucose functional mapping technique what changes occur in the seizure anatomic substrate during and after this transition, in order to enable inferences about underlying mechanisms. Behavior associated with early and late continuous fast spiking consisted of head twitching; corresponding deoxyglucose autoradiographs displayed seizure-induced intense glucose utilization in most forebrain areas; extranigral brainstem was normal. At 2-3 h of status, fast spiking became interrupted by flat periods; periodic complexes soon dominated the electroencephalogram. Behaviorally, convulsive severity increased. Despite this dramatic electrographic evolution, little change in generalized forebrain metabolic hyperactivation occurred, except that the zona incerta/pretectal/superior colliculus complex displayed markedly increased activity. Deoxyglucose studies in late stages of periodic epileptiform discharges established a sequence of further changes. In late periodic discharges with clonic jerks, at 4 h after status entry, generalized forebrain hyperactivation still prevailed, but to a lesser degree than in early periodic discharges with clonic jerks. At a still later stage, late periodic discharges, subtle convulsive, autoradiographs revealed constriction of the seizure-activated anatomic substrate: hyperactivation was lost in most of neocortex and thalamus, and in caudal olfactory structures, cortical amygdala, and entorhinal areas, but retained in deep occipital cortex and many limbic areas. In the last stage, late periodic discharges, electrical, not associated with convulsive behavior, autoradiographs revealed residual activation in only Ammon's horn; in contrast, much of the forebrain displayed below-normal glucose utilization. These results demonstrate that in the later stages of status epilepticus, the transition from fast spiking to periodic complexes is not associated with a reduction in the seizure anatomic substrate. The electrographic entity of periodic epileptiform discharges is not anatomically or behaviorally homogeneous, but proceeds through successive stages characterized initially by a reduction of glucose utilization within generalized seizure-activated forebrain, then a contraction of the seizure anatomic substrate. Possible mechanisms underlying the transition to periodic complexes are discussed.

Animals↗

PubMed1987

Acute effects of tobacco on human brain stem evoked potentials.

Reports of tobacco-induced electrocortical activation have frequently indicated that this effect is mediated via nicotine's action on sub-cortical structures. This study focused on human brain stem involvement by examining the acute effects of tobacco smoking on brain stem auditory potentials (BSAEPs). Twelve regular smokers were tested on two separate sessions involving sham or real smoking. On each session, BSAEPs were recorded during a baseline period and immediately after smoking. BSAEPs, recorded from Cz, were elicited by presentation of 1,000 monaural, rare fraction click stimuli. Latency and amplitudes of peak components I, III and V were assessed and analysed. No significant effects were observed for latency measures or for amplitudes of peaks I and III. A significant effect was observed for peak V with tobacco resulting in larger amplitudes relative to sham smoking. Peak V reflects activity from upper pontine-lower midbrain sites and this tobacco-peak V finding is discussed in relation to arousal and information processing theories of smoking.

Adult↗

PubMed1994

Lack of evidence for serotonergic effect on the cellular development of the olfactory bulb in the postnatal rat.

Serotonin has been postulated to influence several developmental parameters. The potential role of serotonin in the development of the rat olfactory bulb, a simple cortical structure, was determined following selective depletion of serotonin to the olfactory bulb of neonate rats. In the neonate, 5,7-dHT was injected into the anterior olfactory nucleus to selectively destroy serotonergic axons leading to the bulb. Following survival of 5 days to 3 months, the rats were sacrificed and analyzed by immunocytochemical markers, Nissl stain, Golgi impregnation, and image analysis. The serotonin depletions had no significant effect on the cytoarchitecture of the bulb or on neuronal or glial cell growth. In addition, the depletions did not affect neuronal migration or differentiation (overall length of dendrites, branch points, or dendritic spines) of cell populations in the bulb. These findings suggest that serotonin does not, by itself, affect the overall development of cellular elements in the bulb, although this study does not rule out the possibility that serotonin may affect other parameters of development.

5,7-Dihydroxytryptamine↗

PubMed1996

Delayed visual maturation in infants: a disorder of figure-ground separation?

Delayed visual maturation (DVM) is characterised by visual unresponsiveness in early infancy, which subsequently improves spontaneously to normal levels. We studied the optokinetic response and recorded pattern reversal VEPs in six infants with DVM (aged 2-4 months) when they were at the stage of complete visual unresponsiveness. Although no saccades or visual tracking with the eyes or head could be elicited to visual objects, a normal full-field rapid buildup OKN response occurred when viewing biocularly or during monocular stimulation in the temporo-nasal direction of the viewing eye. Almost no monocular OKN could be elicited in the naso-temporal direction, which was significantly poorer than normal age-matched infants. No OKN quick phases were missed, and there were no other signs of "ocular motor apraxia." VEPs were normal in amplitude and latency for age. It appears, therefore, that infants with DVM are delayed in orienting to local regions of the visual field, but can respond to full-field motion. The presence of normal OKN quick-phases and slow-phases suggests normal brain stem function, and the presence of normal pattern VEPs suggests a normal retino-geniculo-striate pathway. These oculomotor and electrophysiological findings suggest delayed development of extra-striate cortical structures, possibly involving either an abnormality in figure-ground segregation or in attentional pathways.

Attention↗

PubMed1995

The European Spine Phantom--a tool for standardization and quality control in spinal bone mineral measurements by DXA and QCT.

The lack of standardization in bone mineral measurements of the lumbar spine and other skeletal sites is generally recognized as an important and unresolved issue. We report and discuss efforts at standardization and cross-calibration of DXA and QCT equipment. We have designed and tested a geometrically defined, semi-anthropomorphic phantom, the European Spine Phantom (ESP). It contains a spine insert consisting of three vertebrae of increasing bone mineral densities and thicknesses of cortical structures; the respective parameters are given in tabular form for the final phantom design. Results for cross-calibration with the ESP compare well with patient results. Measurements on the first 30 phantoms confirmed that the ESP can be manufactured with a variation of about 1%. We conclude that the ESP is suitable for daily quality assurance, cross-calibration of instruments and universal standardization. The ESP was used to establish standardized BMD (sBMD) units for DXA equipment going into effect in late 1995. Its acceptance by manufacturers as a calibration standard for DXA and QCT measurements appears imminent.

Absorptiometry, Photon↗

PubMed1993

Developmental changes of aminopeptidase activity in the cortex of the cat brain.

Aminopeptidase activity has been proposed as a candidate regulator of the degradation of several neuroactive peptides. In this paper, possible changes in Lys-, Arg-, Asp- and Tyr-aminopeptidase activities in the cat brain neocortex (frontal, parietal, area 17 and areas 18 and 19 as a whole) were examined during two of the first stages of the critical developmental period (15 and 30 days postbirth). Aminopeptidase activities were studied by measuring the rate of hydrolysis of the artificial substrates Lys-, Arg-, Asp- and Tyr-2-naphthylamides (fluorimetrically detected in triplicate). Lys- and Arg-aminopeptidase activities do not show significant changes between the first the second stage in any of the cortical regions assayed. On the contrary, in all the cortical structures, activity with Tyr-2-naphthylamide shows significant increase with age. In contrast, the activity of Asp-aminopeptidase shows significant decreases on the 30th day (except in area 17). It is suggested that these activities play a part in the neurochemical changes that take place during cat brain maturation.

Aminopeptidases↗

PubMedDate not supplied

Assessment of olfactory deficits in detoxified alcoholics.

Olfactory functioning was evaluated in 37 male detoxified alcoholics and in 21 age-matched nonalcoholic controls using the University of Pennsylvania Smell Identification Test (UPSIT). Of the original subjects, 23 alcoholics and 14 controls returned for reevaluation 3-4 months following initial testing. The results showed that alcoholics had significantly lower UPSIT scores than did the controls, both at baseline and follow-up testing. Thirty-two percent of the alcoholics' UPSIT scores, in comparison to five percent of the controls' scores, fell into the clinically impaired range. Although current smoking patterns correlated significantly with UPSIT indices, comparisons limited to nonsmokers still indicated that the alcoholics were significantly impaired on this olfactory task. Correlational analyses indicated that olfactory performance was unrelated to alcoholics' scores on visuoconceptual and language tasks. Correlations with MR-derived indices of CSF volume showed a highly significant relationship between UPSIT scores and cortical sulcal volumes. Additionally, alcoholics (N = 15) who remained abstinent had significantly higher scores at follow-up than those who were not abstinent (N = 8). These findings demonstrate that alcoholism is associated with basic olfactory impairments which are only partially reversible with abstinence and that cortical structures play an important role in this sensory loss.

Adult↗

PubMed1996

Dynamic Plasticity Influences the Emergence of Function in a Simple Cortical Array.

In computational experiments with a simplified cortical array we investigated the factors that give rise to the functional organization of the cerebral cortex during brain development. We show that a dynamical spatial modulation of plasticity in the substrate (i.e., a "wave of plasticity") induces higher functional development in the later-developing parts of the cortical array. This result suggests an account of the role that changes in developmental timing may have in the development of different cortical structures. Copyri

Journal Article↗

PubMed1994

Neurobiology of attention and automaticity.

Research in the field of attention and automaticity examines the nature of processing information with and without attention. Behavioral results show automatic processing is a continuous effect that is task specific and is affected by top-down influences. Neurobiological data show that differential attentional processing occurs in a distributed network, where initial performance is more strongly influenced by more anterior cortical structures. Recent models of attentional and autonomic processing directly incorporate physiological constraints and predict practice effects as a result of a variety of competing mechanisms.

Attention↗

PubMed2004

Targeted mutation of CCK(2) receptor gene antagonises behavioural changes induced by social isolation in female, but not in male mice.

Neuropeptide cholecystokinin (CCK) regulates the adaptation of rodents in the novel environment. In the present study we analysed the behavioural changes induced by the individual housing in mice, lacking CCK(2) receptors. The wild-type (+/+) and homozygous (-/-) CCK(2) receptor deficient mice of both gender were used throughout the study. The weight gain during the 21-day isolation period and changes in the locomotor activity following the social separation were measured. The elevated plus-maze and resident/intruder tests were also performed to test alterations in the emotional behaviour. Social isolation induced locomotor hyperactivity, reduced weight gain and increased aggressiveness in the wild-type (+/+) and homozygous (-/-) male mice. In the wild-type (+/+) female mice the significant reduction of exploratory activity in the plus-maze was evident. By contrast, in female mice, lacking CCK(2) receptors, the exploration of the plus-maze was not significantly affected by the individual housing. This finding demonstrates that the social isolation does not cause anxiety-like state in the CCK(2) receptor deficient mice. Moreover, the targeted invalidation of CCK(2) receptors increased in male mice the affinity of dopamine D(2) receptors in the sub-cortical structures, whereas in female mice the increased affinity of 5-hydroxytryptamine(2) (5-HT(2)) receptors in the frontal cortex was established. The increased affinity of 5-HT(2) receptors is probably the compensatory change to the lack of CCK(2) receptors in female mice and probably reflects the reduced sensitivity of these animals to the anxiogenic manipulations. In conclusion, targeted mutation of CCK(2) receptors selectively antagonised the behavioural changes induced by the individual housing in females, but not in male mice.

Aggression↗

PubMed2004

Occurrence of limb movement during sleep in rats with spinal cord injury.

Several studies have shown the occurrence of Periodic Leg Movement (PLM) in spinal cord injury patients. The aim of this study was to identify the occurrence of limb movements during sleep in spinal cord injury rats and the possible involvement of the spinal cord in causing these movements. The animals were allocated to spinal cord injury (SCI) and SHAM groups. The two groups were submitted to surgery and electrodes inserted to analyze sleep patterns (electroencephalogram-ECoG) and muscular activity patterns (eletromyogram-EMG). After baseline sleep recording (24 h), the spinal cord injury surgery (level T9) was performed on the SCI group rats and sleep was recorded for seven consecutive days. After spinal cord injury, 10 of the 11 rats began to present limb movements during sleep, while the SHAM group showed no limb movements during the 8-day sleep-recording period. In relation to sleep efficiency, the SCI group presented alterations during the first few days after spinal cord injury but returned to normal values at the end of the 7-day experimental period. The data suggest that spinal cord injury rats may be used as models to study PLM in paraplegic patients, and that these movements may be generated in the spinal cord itself, without the involvement of the cortical structures.

Animals↗