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PubMedDate not supplied

[Summarized extracellular postsynaptic potential of a single axon, an EEG quantum in the rabbit neocortex].

The possibility to record an EEG quantum following negative spikes with small amplitude was studied in the rabbit's neocortex. In about half of the averagings of the focal post-spike ECoGs recorded with a low-resistance microelectrode the spike was followed by a microsignal of synaptic form. The small amplitude and the negative sign of the spike's main phase pointed to a true extracellular leading off of biopotentials. A relatively small ratio between the amplitudes of the spikes and the post-spike signals shows that the latter are not afterpotentials of the spikes. They do not reflect discrete PSPs of single synapses, because they were recorded with relatively thick microelectrodes. The latency of the post-spike signals corresponded to their monosynaptic nature. Hence, the recorded signals are the EEG quanta. Their recording is a relatively simple procedure.

Animals↗
PubMed1990

[A case of Binswanger disease with numerous diffuse plaques in the neocortex].

A case of Binswanger disease with numerous diffuse plaques in the neocortex was reported. This male patient had a previous history of hypertension and myocardial infarction. From the age of 60, he developed dysarthria, bradykinesia, marche à petit pas and falling down. Neurological examination at his first admission disclosed muscular rigidity and increased jaw and deep tendon reflexes, but dementia was not found. Brain CT showed moderate brain atrophy and EEG consisted of slow wave dysrhythmia. He was diagnosed of Parkinsonism and treatment started without effects. During his second admission for the treatment of myocardial infarction, at the age of 64, delirium developed. Progressive dementia began and finally he was confined to bed. From the age of 69, spontaneous speech became almost lost. Contracture of the extremities, increased deep tendon reflexes and force grasping were noted. Brain CT showed symmetrical low attenuation in the frontal and parietal white matter with moderate dilatation of the lateral ventricles. At the age of 70, he died of general prostration about ten years after the initial symptoms. Neuropathological findings: Macroscopic findings: The brain weighed 1300 g. Atherosclerotic changes of the large arteries at the base of the brain were moderate. Coronal sections of the brain showed moderate enlargement of the lateral ventricles with multiple small lacunes in the basal ganglia. Microscopic findings: Bilateral diffuse demyelination of the white matter with sparing of the U-fibers was noted. Holzer stain revealed fibrillary gliosis in the left parietal and occipital white matter. Marked adventitial fibrosis of the deep white matter arteries and terminal stages of hyalinosis of the perforating arteries were found. Basal ganglia showed status lacunaris. Bilateral pyramidal tracts were atrophic secondly.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

The thalamic projection to the sensory neocortex of the porpoise, Phocoena phocoena.

Retrograde tracers were injected in various parts of the neocortex of the porpoise (Phocoena phocoena). Labelled thalamic neurons were plotted in three-dimensional reconstructions. The lateral geniculate nucleus projects to the visually excitable part of the lateral gyrus. Ventral parts of the medial geniculate nucleus project to the auditory area of the suprasylvian gyrus, while dorsal medial geniculate projects to the 'secondary' auditory area of the ectosylvian gyrus and to the temporal operculum. The ventrobasal and ventropostero-inferior complex projects to cortex anterior to the suprasylvian auditory area, corresponding to somatosensory function. The main projection of the inferior pulvinar is to the suprasylvian gyrus, that of the medial pulvinar to the ectosylvian gyrus, and of the lateral pulvinar to the border of the lateral and suprasylvian gyri. The lateral and posterior complexes project to perisylvian cortex. Throughout the thalamus there is a rough topographic organisation. Lateral to medial through the thalamus represents progression from medial to lateral over the cortex from lateral gyrus to perisylvian cortex. Anterior in cortex is represented by anteroventral in thalamus, and posterior in cortex by posterodorsal in thalamus.

Animals↗
PubMed1990

Laminar organization and age-related loss of cholinergic receptors in temporal neocortex of rhesus monkey.

Using in vitro receptor autoradiography, the distributions of cholinergic muscarinic [3H-N-methyl scopolamine (NMS), 3H-pirenzepine (PZ), and 3H-oxotremorine-M (OXO-M)] and nicotinic [3H-acetylcholine (ACh)] receptors were mapped in the temporal cortices of rhesus monkeys (Macaca mulatta) ranging from 2-22 years of age. Although high-affinity 3H-PZ, low-affinity 3H-NMS binding (M1 sites) and high-affinity 3H-OXO-M, high-affinity 3H-NMS binding (M2 sites) occurred across all layers of the temporal neocortex, the laminar distribution of M1 and M2 receptor binding sites was different. M1 muscarinic receptor binding was concentrated in layers II and III, whereas M2 muscarinic receptor binding was greatest in layers IV and V. The concentration of both muscarinic (M1 and M2) and nicotinic receptor binding sites declined with increasing age, and decrements were uniform across all cortical layers. This investigation provides evidence for a decrease in cholinergic receptor binding with age in temporal cortices of rhesus monkeys. Moreover, these changes appear to precede previously reported age-associated memory deficits and neuropathological changes that occur in this species.

Aging↗
PubMed1989

[Possibilities of restoring the glial population of the neocortex after protein-energy insufficiency].

The aim of the work was to estimate reversibility degree, as well as possibilities of correction of the disturbances in formation of glial population in mouse neocortex, that occur under effect of insufficient nutrition. The work was performed on SBA mice. The protein-energetic insufficiency was produced by means of feeding to the animals a synthetic starch-casein diet with a twice reduced (in comparison with the control) content of the nutritional substances (5% of protein). The scheme of the experiment: the I group--mice undernourished from the 10th up to the 40th day, from the 40th up to the 70th day of life they were given normal feeding; in the II group to the normal diet during the period of food rehabilitation carnitine was added in the dose 0.5 mg/g of the body mass. 70-day-old mouse kept at the full-bodied diet served as the control. Quantitative and qualitative analyse of the glial population composition was performed in semithin araldit slices of the parietal cerebral cortex. During the period of food rehabilitation oligodendrocytes fully restore their amount, however, amount of mature oligodendrocytes is lower than normal. After rehabilitation the part of the perineuronal glia by 19%, and after rehabilitation with carnitine--by 36% higher than in the cerebral cortex of the control animals.

Animals↗
PubMed1989

Immuno- and histochemical evidence for changed neurotransmission in basal forebrain, hippocampal formation and neocortex of aged rats.

The distribution of choline acetyltransferase- and gamma-aminobutyric acid-immunoreactivity as well as acetylcholinesterase-, gamma-aminobutyrci acid-transaminase- and monoaminooxidase-positive structures in the basal forebrain, hippocampal formation and neocortex of young adult and aged rats was compared. The changes in the staining and density of the immuno- and histochemical positive nerve cells and fibers observed provide evidence for the involvement of different transmitters in normal ageing.

Aging↗
PubMed1989

[Transplantation of the embryonic neocortex into the brain in rats: angioarchitecture of the graft 5 months after surgery].

In five adult rats into a bilateral, two-week old cavity in the sensorimotor cortex a homologous embryonic neocortex was implanted which was removed on the 14th day of gestation. The angioarchitecture was studied after a whole body injection of Indian ink into the host circulation. The regional capillarization in the transplant corresponded to construction principles of the graft. The neuron agglomerations which were arranged in a nodal pattern displayed the same capillary density as surrounding cerebral tissue. In the glial septa and in portions of the glial scar the capillary density was substantially lower. In zone I. representing a complete fusion of the neuropil between graft and recipient there was an inapparent and continuous transition of the capillary network. Also in the area of the glial scar (zone II) and the gliomeningeal scar (zone III) vascular connection was established.

Animals↗
PubMed1989

[The nature of factors inactivating postural asymmetry factor at the initial stages of compensatory reconstruction in animals with unilateral lesions of the motor neocortex].

The disappearance of posture asymmetry factor activity in the CSF after three weeks of unilateral removals of the neocortex motor region is caused by inactivation factors (IF), which are thermolabile proteins with m.v. about 80 kD and 150 kD. One of IF (150 kD) interacted with protein A which shows its immunoglobulin++ nature.

Animals↗
PubMed1989

[Spatial organization and interneuronal relations in various areas of the neocortex in Cetacea].

The data on pyramidal neurons joining in the parietal and temporal areas of the dolphin neocortex by means of apical dendrites fasciculi are presented. The fasciculi also contain dendrites of spindle-like and stellate cells. The vertical fasciculi of the dendrites unite neurons of the layer V and of the sublayer III2. In the sublayer III1, after dichotonic division of the apical dendrites, fasciculi of the second order are formed, to them the dendrites of the pyramidal neurons of the sublayer III1 and the layer II join. Several forms of the interneuronal contacts have been revealed: axo-dendritic, axo-spinous and dendro-dendritic. Synaptic complexes of the converged and divergent types have been shown. A suggestion is made on formation of larger neuronal modules++, having common afferent entrance and demonstrating selectivity to the stimulus properties.

Animals↗
PubMed1989

Methylazoxymethanol acetate (MAM ac) effects on the ontogenesis of the mouse neocortex.

Methylazoxymethanol acetate (MAM ac) injected prenatally affects development of neocortex in mice. Treatment at 13 days of gestation results in cortical hypoplasia that affects all the cortical layers except the first. Treatment at 15 days of gestation causes a statistically significant reduction in cell density in the superficial layers, while the deepest layers show no significant differences compared to the controls. Treatment at 17 days of gestation causes an alterated arrangement of the cortical layers, not easily separable since MAM ac in limiting perhaps glial cell proliferation, modifies the subsequent migration mechanisms. Fetal MAM exposure prevents proliferation of the various cortical laminae and there aren't subsequent compensatory phenomena.

Alkylating Agents↗
PubMed1987

[Role of endogenous neurohumoral factors in mechanisms of the pathogenesis and compensation of unilateral movement disorders after serial removal of the motor neocortex].

The role of neurohumoral factors in the mechanisms of restoring the lost motor functions after two successive unilateral removals of the neocortex motor region, was studied. The dynamics of the restoring correlated with the posture asymmetry factor (PAF) activity in the CSF. PAF activity was reduced during the restoring by an inactivation factor (FI). Periods of restoration after the 2nd extirpation and inactivation of PAF were shorter than after the 1st one. The existence of the FI before the 2nd extirpation may account for this phenomenon.

Adaptation, Physiological↗
PubMed1985

Evidence for a presynaptic adenylate cyclase system facilitating [3H]norepinephrine release from rat brain neocortex slices and synaptosomes.

The effects of drugs known to enhance intracellular cyclic AMP levels on depolarization-induced [3H]norepinephrine release from superfused rat neocortical slices and synaptosomes were investigated. The adenylate cyclase activator forskolin, the membrane-permeating cyclic AMP analogues 8-bromo-cyclic AMP and dibutyryl cyclic AMP, as well as the phosphodiesterase inhibitors isobutylmethylxanthine and 4-(3-cyclopentyloxy-4-methoxyphenyl)-2-pyrolidone (ZK 62771) enhanced the electrically evoked release of [3H]norepinephrine from superfused rat brain neocortex slices. 8-Bromo-cyclic GMP was without effect on the electrically evoked release. When [3H]norepinephrine release was enhanced by prolonging the electrical pulse duration from 2 msec to 10 msec, the relative inhibitory effect of the Ca2+ channel blocker Cd2+ and the relative facilitatory effect of the K+ channel blocker 4-aminopyridine remained unaffected. In striking contrast, the relative facilitatory effects of forskolin and 8-bromo-cyclic AMP were strongly reduced, whereas the effect of ZK 62771 was almost doubled. When veratrine-induced release of [3H]norepinephrine from cortex synaptosomes was examined, the facilitatory effects of forskolin, 8-bromo-cyclic AMP, and ZK 62771 were even more pronounced than in brain slices. The data strongly support the hypothesis that a presynaptic adenylate cyclase system plays a facilitatory role in the stimulus-secretion coupling process in central noradrenergic nerve terminals.

Adenylyl Cyclases↗
PubMed1985

[Effect of hypoxia on the structure of the presynaptic grid of the interneuronal contacts of the rat neocortex].

Hypoxic effect (a 6 minute asphyxia) on the presynaptic grid structure and on the amount of synapses in the neocortex has been studied in white rats using the method of selective staining of synapses with phosphoric tungsten acid. Neurofilamentous formations of the presynaptic grid appeared to be most labile structures. Dense projections of the presynaptic grid are most sensitive to hypoxia: their height, distinctness of the frame, and the intensity degree of phosphoric tungsten acid staining decrease. The content of intermediate form contacts with low indistict dense projections increases with the increase in the number of light type changed synapses. The principle organization of the presynaptic grid does not change in the posthypoxic period: hexagonal division of dense projections and places of vesicular attachment are kept. The hypertrophy of the presynaptic grid is also kept during that process.

Animals↗
PubMedDate not supplied

[Role of the median forebrain bundle in organizing the electrical activity of the neocortex].

Bilateral coagulation of the forebrain medial bundle in the lateral hypothalamus enhances the formation of spontaneous spindles and facilitates the recruiting response in the neocortex. This combines with a defect of desynchronizing influences of the posterior hypothalamus and the concurrent dominance of synchronizing effects of the preoptic area (PA). PA stimulation enhances the slow wave and spindle activity in the ECoG of the intact brain. After disruption of PA connections with the bulbar synchronizing apparatus the stimulation effect is manifested only in enhanced spindle activity. It is assumed that in addition to hypnogenic influences which PA shares with the parasolitary apparatus, it maintains a definite level of cortical reactivity after the onset of sleep. Elimination of the orbito-frontal cortex, as well as PA coagulation, does not prevent the appearance of spindles in the ECoG of the preparation with an intersected medial bundle, only limiting them to some extent.

Animals↗
PubMed1988

[Electrophysiologic research on the afferent connections of embryonic neocortex allografts inserted into the projection zones of the cortex in adult rats].

Grafts of the rat fetal neocortex (the 17th-18th day of gestation) were placed into the cavity made by aspiration in the primary visual or somatosensory cortex of adult rats. Electrophysiological studies performed 3-3.5 months later showed that approximately in 50% of animals the neurons of the transplants responded to sensory stimuli of modality specific for cortical regions replaced by the transplant. These responses were elicited from local receptive fields that in some animals revealed topographic organization. Neuronal responses of transplants were elicited by local electrical stimulation of thalamic nucleus projecting to the cortical site of grafting, as by stimulation of contralateral homotopic cortical areas. Latency and temporal patterns of neuronal responses were similar to normal ones. Thus it may be concluded that afferent inputs to the cortical transplants retrace normal cortical inputs. The possible mechanisms of re-innervation of the grafts are discussed.

Afferent Pathways↗
PubMedDate not supplied

[Temporal structure of the spike trains of neuronal pairs in the neocortex during calm wakefulness in rabbits].

For revealing the conjugation of impulse activity of simultaneously recorded neurones in the visual and sensorimotor areas of rabbits neocortex, histograms were built of cross- and autocorrelation (CCH and ACH) of their discharges sequences. From successions of discharges of the visual cortex neurones, forming pairs of cells acting in correlation, spikes were singled out conjugated with neuronal discharges in the sensorimotor area, and their ACHs were built. In 77% of cases a resemblance was observed of temporal structure of conjugated discharges and real spike sequences, in 23%--there was no such resemblance. Analysis of conjugated discharges ACHs showed that they appeared predominantly periodically (87% of cases). The number of fragments with periodic discharges frequency within delta-frequency range from 3 to 4 Hz prevailed.

Action Potentials↗
PubMedDate not supplied

[Temperature changes in the neocortex, posterior hypothalamus and neck muscles in the wakefulness-sleep cycle of white rats].

In chronic experiments on male relatively unrestrained rats, simultaneous studies have been made on the behaviour during wake-sleep cycle and on changes in the temperature of the neocortex, posterior hypothalamus and neck muscles. Interaction of two mechanisms at the hypothalamic level is discussed, namely the development of various stages of the wake-sleep cycle and thermoregulation. Special attention is paid to the phase of rapid sleep, when the transition of an animal from homoiothermic to heterothermic conditions presumably takes place.

Animals↗