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1

Visual responses of the superior collicular neurons after lesion in the contralateral colliculus cats

100%
Waleszczyk W., Dec K.
Acta Neurobiologiae Experimentalis
|
1992
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tom 52
|
nr 3
2

The spatial structure of the visual recef'tne fields of cat's pretectal neurones

100%
Waleszczyk W., Dec K.
Acta Neurobiologiae Experimentalis
|
1997
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tom 57
|
nr 5
3

Changes in the pattern of 20 Hz synchronization within cat's visual corticothalamic system as a function of attentive perception

81%
Waleszczyk W., Krakowska D., Bekisz M., Wrobel A.
Acta Neurobiologiae Experimentalis
|
1995
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tom 55
|
nr 5
4

Cortical feedback modulates temporal pattern of spontaneous neuronal activity in the cat's dorsal lateral geniculate and perigeniculate nuclei

81%
Radzikowska Z., Waleszczyk W., Bekisz M., Wrobel A.
Acta Neurobiologiae Experimentalis
|
2009
|
tom 69
|
nr 3
In cats with pretrigeminal brainstem transections, reversible inactivation of the primary visual cortex by cooling results in changes of the magnitude of response and spatio-temporal structure of receptive fi elds of neurons from lateral geniculate and perigeniculate nuclei (LGNd and PGN; Waleszczyk et al. 2005). Since cortical inactivation changes also the spontaneous activity of these thalamic neurons, we hypothesized that cortical feedback affects their membrane potential. Both types of investigated cells displayed two modes of activity: a tonic mode, during depolarization; and a burst mode, when the cell is hyperpolarized. In this report we investigated the effect of elimination of cortical feedback by cooling on the temporal pattern of the spontaneous "bursty" activity of single neurons in LGNd and PGN. During such reversible inactivation of areas 17 and 18, in both LGNd and PGN cells, spontaneously occurring bursts exhibited longer interspike intervals (ISIs) and lower number of spikes, while the average burst duration remained unchanged. Longer ISIs suggest that cortical feedback infl uences not only visual responsiveness of thalamic neurons, but also temporal pattern of their spontaneous fi ring, in line with the hypothesis of a tonic cortical modulation of their membrane potential. Supported by the Ministry of Science and Higher Education grant COST/127/2007.
5

The dynamic structure of visual receptive fields in the cat's superior colliculus

81%
Waleszczyk W., Dec K., Wrobel A., Harutiunian-Kozak B.
Acta Neurobiologiae Experimentalis
|
1995
|
tom 55
|
nr 5
6

Adhesive and motile properties of Lewis lung carcinoma LL2 lines

81%
Doroszewski J., Nowak-Wyrzykowska M., Waleszczyk W.
Archivum Immunologiae et Therapiae Experimentalis
|
1989
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tom 37
|
nr 5-6
7

Visual task stirs correlated activity in cat's thalamo-cortical system

81%
Krakowska D., Waleszczyk W., Bekisz M., Wrobel A.
Acta Neurobiologiae Experimentalis
|
1997
|
tom 57
|
nr 5
8

Specvis:free and open-source software for visual field examination

81%
Dzwiniel P., Gola M., Wojcik-Gryciuk A., Waleszczyk W.
Acta Neurobiologiae Experimentalis
|
2015
|
tom 75
|
nr Supl.
BACKGROUND AND AIMS: The main purpose of our work is to create a reliable, free and open-source software for visual field diagnosis, which is mainly designed for the use with personal computers. Our goal is argued by the fact, that professional clinical equipment used for the visual field estimation is very expensive and mostly occur only in specialized medical centers. This, in turn, affects its availability, giving rise to a problem not only for patients requiring frequent and regular testing of the visual field, but also for those, who would like to examine their sight purely preventive. METHODS: To date, the initial version of the application called Specvis was established. It has been satisfactorily tested so far in a brief study on sample of 20 healthy volunteers, where half of them had simulated deficits of the left visual field. The group with „deficits” used specially prepared glasses with covered left and partially right eye, where in contrast „control” group had covered only left eye. Experimental procedure consisted of responding to stimuli appearing in different parts of the screen with simultaneous monitoring of fixation by responding to changes of the centrally located fixation point. RESULTS: The use of specially prepared glasses resulted in the observation of deficits in the left part of visual field in the „deficits” group. Statistical analyzes revealed the existence of differences between both groups in the left part of the visual field. CONCLUSIONS:The brief validation study had shown, that Specvis has the potential worth developing further. Actually our software is being validated in clinical conditions with automated perimetry in the study of visual field deficits of glaucomatous patients. It is worth mentioning, that thanksto wide configuration settings of the stimulus characteristics Specvis is also useful in animal studies. Our work is supported by ERA-NET Neuron grant REVIS.
9

Heterogenous structure of directional receptive fields in the superioe colliculus of the cat

81%
Dec K., Waleszczyk W., Wrobel A.
Acta Neurobiologiae Experimentalis
|
1992
|
tom 52
|
nr 3
10

Electrical activity of the acutely isolated pons in cats

80%
Dec K., Stasiak M., Waleszczyk W., Zernicki B.
Acta Neurobiologiae Experimentalis
|
1996
|
tom 56
|
nr 3
11

Reorganization of the visual cortex following monocular circumscribed retinal lesions: update of Hebbian learning

71%
Waleszczyk W., Wang C., Bardy C., Calford M. M., Dreher B.
Acta Neurobiologiae Experimentalis
|
2009
|
tom 69
|
nr 3
Following circumscribed monocular retinal lesions most cells located in the lesion projection zone (LPZ) in the cat’s primary visual cortices remain binocular but their receptive fi elds (RFs) revealed by stimulation via the lesioned eye, are displaced into proximity of the lesion. The process of topographic reorganization (adaptive learning) of the visual cortex, is based on spike timing-dependent plasticity rather than the classical Hebbian rules [Young et al. (2007) Nat Neurosci 10: 887–895]. The contrast sensitivities of the classical RFs of LPZ neurons revealed by stimulation via the lesioned eye are signifi cantly lower, while the suppresive infl uences of their “silent”, extra-classical RFs are weaker than those of their counterparts revealed by stimulation via non-lesioned eye. Other properties (e.g. orientation, spatial and temporal frequency preferences) however match well the properties of RFs revealed by stimulation via non-lesioned eye. These similarities are presumably visual experience-dependent, that is, they are related to the fact that in the post-lesion period (from adolescence to maturity), the neuronal activities originating from each retina are correlated by effectively synchronized exposure to the same visual stimuli. These results are consistent with the hypothesis that the ectopic RFs are based on enhancement of the synaptic effi cacy of long-range, excitatory intracortical connections. Financial support: Nencki Institute, Poland; NHMRC and ARC grants, Australia.
12

Mechanism that forms Beta band attentional desynchronization in the visual cortex

71%
Gajewska-Dendek E., Waleszczyk W., Bekisz M., Wrobel A., Suffczynski P.
Acta Neurobiologiae Experimentalis
|
2015
|
tom 75
|
nr Supl.
BACKGROUND AND AIMS: Enhanced beta frequency activity (16–24 Hz) serves as a carrier for distributing attentional activation across the visual system. This work aims to characterize beta activity and its generators in the primary visual cortices (V1/2) by measuring the correlations between signals from different cortical locations. In general, the degree of synchronization between two neuronal sites results from interplay of driving sensory inputs, neuronal connectivity and the arousal state. In order to test the mechanisms that influence the high amplitude synchronized beta activity we compared cortical recordings of cats performing visual attentional task and the relevant computational model. METHODS: We recorded local field potentials from several sites of the cats’ V1/2 during stimulus-driven attentional task and measured their correlation strengths. We hypothesized that higher correlation indicated closer functional relation between given signal pair. In parallel we used network model comprising 16 domains representing cortical patches that included mutual lateral inhibitory connections. The model consisted of single compartment excitatory and inhibitory cells with extended Hodgkin-Huxley dynamics. These cells received two kinds of Poisson inputs, representing the bottom-up sensory input and top-down cortical modulation. RESULTS: The physiological recordings showed that correlation strength mostly decreased with higher amplitude beta signals except of few recording pairs, which increased their correlation coefficients close to one. Similar results could be obtained with the modeled network of cortical neurons receiving common sensory input via lateral inhibitory interneurons. CONCLUSIONS: Our modeling study explains the appearance of heterogeneous organization of cortical beta activity obtained in physiological experiments. The synchronized signals activated by common sensory input form patches of cortical mosaic, which are spatially contrasted by lateral inhibitory connections.
13

Beyond the PSTH: point process modeling of spike trains

71%
Wojcik D., Mochol G., Wypych M., Waleszczyk W., Wrobel A.
Acta Neurobiologiae Experimentalis
|
2009
|
tom 69
|
nr 3
A prerequisite for a quantitative theory of neural coding is adequate description of spike trains. Fifty years ago it was understood that the probability to generate a spike at a given time from the stimulus onset – the post-stimulus time histogram (PSTH) – brings in useful information adding to the mean number of spikes in the trial. Today there is a growing consensus that one must go beyond the PSTH building more complex point process models of neural activity which can account, for basic physiological properties of spike fi ring, e.g. for the refractory properties or for adaptation mechanisms of the cell. We shall present some basic concepts of the point process theory in the context of the spike trains and present a simple method of estimation of a class of second order processes for stimulus-evoked activity. We will illustrate the results with an analysis of sample data from the cat superior colliculus. Supported by grants N401 146 31/3239 and 46/N-COST/2007/0.
14

A new method for identification of modulation in neural responses to drifting grating stimulation

61%
Wypych M., Nagy A., Paroczy Z., Markus Z., Berenyi A., Benedek G., Waleszczyk W.
Acta Neurobiologiae Experimentalis
|
2009
|
tom 69
|
nr 3
Temporal modulation of responses to drifting grating stimulation is observed in visual neurons in different brain structures. The common measure of intensity of such modulation is the modulation index (MI; Movshon et al. 1978), defi ned as the ratio of the amplitude of the response component at the stimulus temporal frequency (f1 ) and the net response of the cell. However MI works correctly in a limited range of net responses. If stimulation causes only a weak change in mean fi ring rate, MI can take any value independently of actual modulation in the response. Here we present a new, simple method of determining the strength of modulation, based on the detection of a peak in an amplitude spectrum at the frequency of stimulation. We defi ne modulation strength (MS) as the ratio of f1 value above the mean value of amplitude spectrum and standard deviation (SD) of amplitude values along all frequencies in the spectrum. We assume the response to be modulated if f1 value exceeds the mean amplitude by at least one SD (MS>1). We test the method on data recorded from a number of structures of the extrageniculate visual pathway and compare it to the classical MI and the modulation depth (measure used in the amplitude modulation radio transmission – here the change of the spectrum component at the stimulation frequency between the spontaneous activity and the response). Supported by MNiSW grants: N303 070234, COST/127/2007, N303 046 31/1483, OTKA/NKTH Hungary grant 68594, OTKA grant PD75156.
15

Focal cortical stroke in the cat visual cortex

51%
Szczerba M., Urban P., Foik A., Kublik E., Ghazaryar A., Borowska J., Sadowska M., Jablonka J., Waleszczyk W.
Acta Neurobiologiae Experimentalis
|
2015
|
tom 75
|
nr Supl.
BACKGROUNS AND AIMS: The study develops methodology of photothrombotic stroke (PtS) induction in cats visual cortex for future studies of post-stroke visual recovery. Considering its well known organisation and similarity to the human, cat visual system is a good model for spontaneous and supported brain reorganisation after ischemia. METHODS: Photothrombosis was used as a model of focal ischemic cortical stroke. Standardisation of the methodology of cortical PtS was performed on four experimental cats with parallel local field potential (LFP) recordings in and around the stroke core – before, during and after the infarct. Intravenously injected Bengal Rose was locally irradiated by cold light via an optic bundle placed on the skull, thinned skull or directly on dura surface. Different light source parameters and irradiation time were tested. Postoperatively isolated brains were preserved and frozen, cut and stained. Final position of the electrodes was monitored on dried 50 μm slices. The cytochrome oxidase (CO) activity and Nissl staining were used to monitor the state of the tissue injury. RESULTS: The aimed unilateral stroke was performed in the dorsal zone of the left marginal gyrus over the visual cortex on a border of the cortical areas 17 and 18. CO visualizes the areas of lower mitochondrial activity in the illuminated tissue of the irradiated cortex in comparison to the contralateral intact homotopic areas. The spontaneous LFP dynamic decreased for at least three hours within the irradiated cortex but not in opposite hemisphere or surrounding tissue. CONCLUSIONS: The 25 minutes of the unilateral irradiation directly to the dura surface with the light temperature 2750K resulted in the most accurate lesion covering all the width of the marginal gyrus and partially the sulcus area not spreading on adjacent gyri or further blood vessels. The infarct reaches the white matter without its pronounced injury. Supported by:ERA-NET:REVIS&MNiSW0292/IP1/2013/72.
16

Frequency specific changes in signal power and functional conectivity following stroke in the cat visual cortex

51%
Paulina Urban1, Andrzej Foik1, Anaida Ghazaryan1, Anna Popek1, Jan Jabłonka3, Ewa Kublik2, Maciek Kamiński4, Rafał Kuś4, Jarosław Żygierewicz4, Wioletta Waleszczyk1 P., Folk A., Ghazanyan A., Popek A., Jablonka J., Kublik E., Kaminski M., Kus R., Zygierewicz J., Waleszczyk W.
Acta Neurobiologiae Experimentalis
|
2015
|
tom 75
|
nr Supl.
AIM: The aim of the study wasto characterize early reorganization of cortical electrical activity within and around the stroke-affected area. METHODS: Photothrombotic stroke wasinduced in the visual cortex during the acute experiments in anaesthetized cats. The activity of neuronal populations (local field potential, LFP) were continuously monitored in the central region of the stroke, at the stroke border, and in the healthy tissue, up to three hours after stroke. In the offline analysis, using Welch and autoregressive parametric methods, we evaluated the changes in the frequency spectrum spanning from delta to gamma. Functional connectivity between cortical locations within and outside the stroke region was determined with Directed Transfer Function (DTF). Indirect and direct interactions in different frequency bands were determined by DTF and direct DTF, respectively. RESULTS: The stroke resulted in an overall decrease of the power within full frequency spectrum in the stroke affected region, but not outside this region, where an increase in the spectral power was observed. The most pronounced changes were observed three hours after the stroke. In one cat, we observed increase of the power in the stroke area in low frequency bands while the power in beta-gamma band was diminished. DTF and direct DTF revealed weakening of neuronal connections between the healthy tissue and the stroke region and a transient strengthening of local connections outside the stroke region. The earliest decrease in the strength of connections in stroke affected region was observed in high frequencies (beta and gamma). CONCLUSION: Stroke induce diverse effects in different frequency bands in both the LFP power spectrum and in the functional connectivity indicating complex influence on the neuronal activity within the stroke and in the vicinity of ischemic region. Supported by ERA-NET Neuron project REVIS.
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