RAS Pavlov Institute of Physiology

Saint Petersburg, Russia

RAS Pavlov Institute of Physiology

Saint Petersburg, Russia
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Dick O.E.,RAS Pavlov Institute of Physiology
Neurocomputing | Year: 2017

The task is to estimate quantitative features in involuntary oscillations of shaking (tremor) of fingers accompanied the performance of the motor task by healthy subjects, patients with Parkinson’ disease and individuals with the essential tremor. For solving the task the tremor patterns are examined by the wavelet-transform modulus maxima method and the recurrence quantification analysis. The physiological tremor is characterized by the minimal energy of the wavelet spectrum, the maximal degree of multifractality, the minimal degree of determinism and the maximal recurrence time density entropy, reflecting the greatest uncertainty of the period value. During the essential tremor the significant enhancement of the wavelet spectrum energy and the decrease of the dynamical complexity of involuntary oscillations are observed. It is evident as the fall in the multifractality degree, the growth of determinism in recurrence plots, the decrease of the recurrence time density entropy and the emergence of unstable periodic orbits in involuntary oscillations. For the parkinsonian tremor all the trends are enhanced that lead to more definite dynamics of patterns. Therefore, our results demonstrate that the dynamical complexity of patterns of involuntary oscillations decreases in larger degree for Parkinson’ disease, than for patients with the syndrome of the essential tremor, that is, it declines with increasing the severity degree of motor disorders. The results obtained for the first time can be applied for evaluating the degree of deviation of the motor function from the healthy one. © 2017

Zolotarev V.A.,RAS Pavlov Institute of Physiology
Current Pharmaceutical Design | Year: 2014

In the stomach, pre-absorptive perception of food constituents is of particular importance in maintaining secretion and motility that matches the quantity and quality of nutrients. Products of food protein hydrolysis, free amino acids and short peptides, are the most potent chemical stimulants of the gastric phase of digestion. They are recognized by a variety of extracellular receptors belonging to the G-protein-coupled receptor superfamily, which are expressed by gastric mucosal exocrine and endocrine cells. Enteroendocrine G and D cells are likely the first level of integration of amino-acid-induced signals influencing a balance of endocrine activation and inhibition of gastric functions. This review focuses mainly on the physiological significance of dietary L-glutamate (Glu) in control of the gastric phase of digestion. The Glu signaling system in the stomach is linked to activation of the vagal afferents. In contrast to other natural amino acids, luminal Glu activates a paracrine cascade led by nitric oxide and followed by serotonin (5-HT), interacting in turn with 5- HT3 receptors on the afferent endings in the sub-mucosal layer. Glu, the only amino acid regularly ingested in a free form, enhances secretory and gastroprokinetic responses to protein- and amino-acid-rich diets but has no effect when applied alone or with carbohydrates. Possible mechanisms are discussed. © 2014 Bentham Science Publishers.

Galeeva A.,RAS Pavlov Institute of Physiology
Vitamins and hormones | Year: 2010

Corticosteroid hormones are important intrinsic factors that not only mediate the response to stress but also largely contribute to the main physiological processes. The biological actions of these steroids involve, first of all, the activation of specific receptors, namely mineralocorticoid (MR) and glucocorticoid (GR) receptors. These two receptor types govern a flexible and well-balanced mechanism that leads to the often opposing changes in the cell. The hippocampus is the central part of the extrahypothalamic feedback loop in the control of the hypothalamic-pituitary-adrenal (HPA) axis activity. The coexpression of both MR and GR in the hippocampus serves a coordinated response to corticosteroids in the hippocampal neurons, thereby mediating the neuronal excitability, stress response, and behavioral adaptation. Each receptor type reveals distinct ontogenetic pattern over the postnatal period. This review addresses the issues relating to postnatal development of the HPA axis and especially the hippocampal expression of the GR proteins in intact and prenatally stressed rats. Copyright 2010 Elsevier Inc. All rights reserved.

Ivanov K.P.,RAS Pavlov Institute of Physiology
Respiratory Physiology and Neurobiology | Year: 2013

Human lungs weighing ca 600. g permit the passage of 5-6. l of blood per minute. The blood capacity of the human lungs is about 0.5. l. Consequently, each 0.5. l of blood is during 5. s. The questions arise of how such a large mass of blood passes through such a small mass of lungs and what the reasons are for such a high rate of blood oxygenation. Since the structure of lungs in mammals is almost the same, we tried to solve these issues studying the rats, in which 20-22. ml of blood pass through the lungs of 1.5-2.0. g mass. A great blood flow appeared to be associated with a large diameter of the lung arterioles and a high rate of the blood flow in them. The high rate of oxygenation is accounted for by a special structure of alveoli and special conditions of the blood flow, which create ideal conditions for oxygen diffusion. © 2013 Elsevier B.V.

The present study provides evidence for anti-ictogenic activity of the mystixin 7 (MTX) mini-peptide in the pentylenetetrazole model of seizure. MTX was effective in inhibiting/suppressing ictal- and interictal-like activities over a long period of time (during 60-80. min). The peptide's anti-ictogenic effects were concentration- and time-dependent. An enzymatic treatment of MTX was accompanied by a decrease of the frequency pattern of epileptiform discharges, but their total blockade did not occurred. These findings indicate that the MTX mini-peptide has pronounced anti-ictogenic properties. © 2014 Elsevier B.V.

Danilova M.V.,RAS Pavlov Institute of Physiology
Journal of vision | Year: 2010

Are boundaries between color categories associated with enhanced discrimination? In the present experiments, chromatic thresholds were obtained for discriminations along lines orthogonal to the yellow-blue axis of color space. The targets were parafoveal and thresholds were measured with a spatial two-alternative forced choice. In interleaved experimental runs, we also obtained empirical estimates of the subjective yellow-blue line by asking observers to categorize colors as reddish or greenish. Both types of measurement were made in the presence of a steady background that was metameric to equal-energy white. In a limited region from desaturated yellow to desaturated blue, an enhanced discrimination is found near the subjective transition between reddish and greenish hues. This line of optimal discrimination is not aligned with either of the cardinal axes of color space: In a MacLeod-Boynton chromaticity diagram, it runs obliquely with negative slope.

Danilova M.V.,RAS Pavlov Institute of Physiology | Mollon J.D.,RAS Pavlov Institute of Physiology
Proceedings. Biological sciences / The Royal Society | Year: 2014

The human visual system imposes discrete perceptual categories on the continuous input space that is represented by the ratios of excitations of the cones in the retina. Is discrimination enhanced at the boundaries between perceptual hues, in the way that discrimination may be enhanced at the boundaries between speech sounds in hearing? In the chromaticity diagram, the locus of unique green separates colours that appear yellowish from those that appear bluish. Using a two-alternative spatial forced choice and an adapting field equivalent to the Daylight Illuminant D65, we measured chromatic discrimination along lines orthogonal to the locus of unique green. In experimental runs interleaved with these performance measurements, we obtained estimates of the phenomenological boundary from the same observers. No enhancement of objectively measured discrimination was observed at the category boundary between yellowish and bluish hues. Instead, thresholds were minimal at chromaticities where the ratio of long-wave to middle-wave cone excitation was the same as that for the background adapting field.

Danilova M.V.,RAS Pavlov Institute of Physiology | Mollon J.D.,Downing St.
Vision Research | Year: 2012

Human color vision depends on the relative rates at which photons are absorbed by the three classes of retinal cone cell. The ratios of these cone absorptions can be represented in a continuous two-dimensional space, but human perception imposes discrete hue categories on this space. We ask whether discrimination is enhanced at the boundary between color categories, as it is at the boundary between speech sounds. Measuring foveal color discrimination under neutral conditions of adaptation, we find a region of enhanced discrimination in color space that corresponds approximately to the subjective category boundary between reddish and greenish hues. We suggest that these chromaticities are ones at which an opponent neural channel is in equilibrium. This channel would be 'non-cardinal', in that its signals would not correspond to either axis of the MacLeod-Boynton chromaticity diagram. © 2012 Elsevier Ltd.

Filaretova L.,RAS Pavlov Institute of Physiology
Therapeutic Advances in Chronic Disease | Year: 2011

Stress may contribute to the development and progression of gastrointestinal disorders. Activation of the hypothalamic-pituitary-adrenocortical (HPA) axis is one of the main characteristics of stress. For several decades it was generally accepted that glucocorticoids released during stress are ulcerogenic hormones. We designed some experimental studies in rats to clarify the validity of this widely held view. To achieve this goal, we examined the effect of glucocorticoid deficiency followed by corticosterone replacement or the glucocorticoid receptor antagonist, RU-38486, on stress-induced gastric erosion and the parameters of gastric function in rats. The data obtained shows that the reduction in the stress-induced corticosterone release, or its actions, aggravates stress-caused gastric erosion. It is suggested that an acute increase in corticosterone during stress protects the stomach against stress-induced injury. According to our results, various ulcerogenic stimuli, similar to stress, induce an increase in corticosterone that helps the gastric mucosa to resist against a harmful action of ulcerogenic stimuli. Glucocorticoids exhibit their gastroprotective effect by both maintaining local defensive factors and inhibiting pathogenic elements. Furthermore, the contribution of glucocorticoids to gastroprotection is tightly related to their contribution to general body homeostasis. Glucocorticoids provide gastroprotective actions in co-operation with prostaglandins, nitric oxide and capsaicin-sensitive sensory neurons. The results obtained do not support the traditional paradigm and suggest that glucocorticoids released during acute activation of the HPA axis are naturally occurring gastroprotective factors. In this article, we review our recent publications on the role of glucocorticoids in gastroprotection. © The Author(s), 2011.

Danilova M.V.,RAS Pavlov Institute of Physiology | Mollon J.D.,Downing Street
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2012

We measured chromatic discrimination under conditions where the target fields could be distinguished only by the ratio of excitation of the long-(L) and middle-wavelength (M) cones. The excitation level of the short-wavelength (S) cones was varied in the experiments, although for any given measurement the S-cone excitation was common to the two target fields and could not be directly used for discrimination. Adaptation was maintained by a steady neutral background metameric to Illuminant D65. Thresholds varied substantially and systematically with the S-cone level of the target probes, but in a complex way: when the ratio of L:M cone excitation was low, an increase in S-cone excitation reduced the thresholds, but when the L:M ratio was higher, an increase in Scone excitation raised the thresholds. To account for the pattern of results, we postulate a neural channel that draws synergistic inputs from L and S cones and an opposed input from M cones. The proposed channel has a compressive response function and is most sensitive at the point set by the steady background. © 2012 Optical Society of America.

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