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1

Modelling the neural network of the upper layers of the superior colliculus

100%
Wypych M., Mochol G., Waleszczyk W. J., Wrobel A.
Acta Neurobiologiae Experimentalis
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2007
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tom 67
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nr 3
2

Spatially structured synchronized intracortical activity is averages in EEG scull recordings

100%
Ghazaryn A., Bekisz M., Wypych M., Wrobel A.
Acta Neurobiologiae Experimentalis
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2001
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tom 61
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nr 3
3

Role of inhibition in shaping reliability: trial-by-trial variability of visual responses in superior colliculus is influenced by GABA

100%
Wypych M., Mochol G., Foik A., Waleszczyk W. J.
Acta Neurobiologiae Experimentalis
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2011
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tom 71
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nr S
Previously we have shown that variability of visual responses of superior colliculus (SC) neurons depended on whether the main visual input to the cell was of Y- or W-channel origin (Mochol et al. 2010). To better understand the mechanisms underlying previous finding in this study we test whether GABAergic system influences the variability of SC visual responses. In acute experiments on anesthetized cats extracellular responses of single neurons to spot of light moving in broad range of velocities were recorded from retinorecipient, superficial layers of SC, allowing to determine the Y- or W-channel input. Simultaneously local iontophoretic injections of GABA (nonspecific GABA receptors agonist) or bicuculline (GABAA receptors antagonist) were performed. Trial-by-trial variability was assessed with Fano factor (FF; ratio of variance of spike counts to mean number of spikes in a given period of time). In the majority of cells application of GABA resulted in decrease of firing rate (FR) and changes of FF. These changes were consistent with previously found correlations between FR and FF. If major input to the tested neuron was of Y-channel origin and changes in FF correlated negatively with changes in FR, GABA-induced decrease of FR was accompanied by an increase of FF. In the case of major W-type input the result was opposite: FF followed changes in FR, consistent with positive correlation between the two in control trials. Injection of bicuculline however, which typically resulted in an increase of neural activity, did not lead to coherent changes of variability. The FF could change slightly or remain unchanged independently of the correlation of FF and FR in control trials. Our results show that GABAergic system may play different roles in shaping the reliability of visual responses in SC depending on the origin of visual input and types of GABA receptors involved. Supported by Polish MSHE grant N N303 070234.
4

Oscillations in the activity of superior colliculus neurons: locked or non-locked to visual stimulus?

100%
Foik A., Mochol G., Wypych M., Waleszczyk W. J.
Acta Neurobiologiae Experimentalis
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2011
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tom 71
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nr S
It is suggested that oscillatory activity of visual neurons plays an important role in encoding of information about stimuli. There are a number of publications on oscillations in the retino-geniculo-cortical pathway, but less is known about oscillatory activity in the extrageniculate pathway. We try to understand the role of oscillations in the processing of visual information in the superior colliculus (SC), the first, retinorecipient structure of the extrageniculate pathway, playing an important role in visual perception, spatial localization of an object of interest, saccadic eye movements and visually guided behavior. Extracellular single unit activity was recorded from superficial layers of the SC in anesthetized and paralyzed cats. Recordings were performed during periods without visual stimulation and also during visual stimulation with spot of light moving in a broad range of velocities or flashing at different locations of the receptive field in pseudo-random order. Autocorrelation function and Fourier transform were calculated for background as well as for evoked neuronal activity. Two variants of autocorrelation method revealed two kinds of oscillatory patterns: non-locked and locked to stimulus onset. First type of oscillations was found in the majority of analyzed cells during visually evoked activity and the frequency patterns of these oscillations were in many cases similar to those observed in background activity. The stimulus-locked oscillations were observed in about half of recorded cells and strength of these oscillations varied depending on firing rate, stimulus velocity and direction. Such oscillations were clearly visible in the case of fast changes in the receptive field of tested neuron. Since two types of oscillations occurred independently and sometimes simultaneously in the recorded activity, thus they may play different role in the processing of visual information by collicular neurons. Supported by Polish MSHE grant N N303 070234.
5

How does the firing rate of superior colliculus neurons correlate with image of brain activity?

88%
Moloch G., Wypych M., Foik A., Wojcik D., Waleszczyk W. J.
Acta Neurobiologiae Experimentalis
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2011
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tom 71
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nr S
Firing rate of the majority of cells from superficial layers of cat’s superior colliculus (SC) is modulated in relatively long time scale. Such changes in spike generation do not depend on presented visual stimuli. To investigate whether these modulations of firing rate are related to changes in cortical states we analyzed visually evoked activity of SC neurons and electrocorticogram (ECoG) simultaneously recorded from the occipital lobe. The extracellular single unit activity was recorded from superficial, retinorecipient layers of the SC in anaesthetized and paralyzed cats. The level of anaesthesia was kept constant during recordings. As a visual stimulus we used light spot moving with different, randomly selected velocities. On average, each neuron was recorded continuously for 1 hour. Simultaneously we recorded ECoG from contralateral area 18 close to representation of the area centralis. The power spectra of ECoG data were calculated using fast Fourier transform in sliding windows. The firing rate of a given neuron was calculated in the same time windows and then correlated with the power in a given frequency band of ECoG. Most of the observed firing rate modulations were on the time scale from several to tens of minutes and were positively or negatively correlated with the changes in ECoG power in the band between 0.5 to 8 Hz, sometimes even to 13 Hz. For some neurons we also observed correlations between firing rate and power in the beta band (13 – 30 Hz) of ECoG and in most cases those correlations were opposite to correlations in lower bands. Rarely we observed also the relation between firing rate and the power of gamma band. Fast modulations of firing rate were not correlated with changes of ECoG power in any band. These results show that responsiveness of particular subpopulations of collicular neurons is differently related to the global state of brain activity. Supported by Polish MSHE grant N N303 070234.
6

Variability of visual responses of superior colliculus neurons depend on their velocity preferences

88%
Mochol G., Wypych M., Wojcik D. K., Wrobel A., Waleszczyk W. J.
Acta Neurobiologiae Experimentalis
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2007
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tom 67
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nr 3
7

Stimulus dependent oscillations in visually evoked activity of cat's superior colliculus

88%
Foik A., Silva A., Wypych M., Mochol G., Waleszczyk W. J.
Acta Neurobiologiae Experimentalis
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2012
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tom 72
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nr 2
Visual information is transferred from retina to higher order cortical areas by few parallel pathways and encoded in different ways. In this study, we focused on encoding of visual information in the superior colliculus, which is the first stage of extrageniculate pathway. One of ways in which neurons encode information is rate coding based on the change in a number of action potentials in response to stimulus presentation. The other coding scheme is temporal coding, which include information about temporal patterns of neuronal spiking, present, for example, in the form of oscillations. The aim of this study was to reveal the presence of stimulus dependent oscillations in visually evoked activity of neurons in the superficial layers of the cat’s superior colliculus. Neuronal activity was recorded from anesthetized (isoflurane in N2O/O2) animals during visual stimulation by spot of light moving in broad range of velocities as well as during presentation of light spot flashing in random locations within the receptive field of recorded neuron. Oscillations were identified by means of auto-correlation and spectral analyses. We found stimulus dependent oscillations in half of tested neurons. Moreover, oscillatory activity appeared to depend on the stimulus velocity. Different measures of oscillations strength (SO), such as z-score, oscillation score or F-statistics revealed positive correlation between SO and velocity. Stimulus dependent oscillations appeared also in responses to onset of the light spot. These results suggest importance of oscillations for processing of information about fast changes within receptive fields of neurons in the extrageniculate pathway. Supposedly presence of oscillations in responses of collicular cells can increase probability of information transfer to higher level of visual processing. Supported by NCN grant N N303 820640.
8

Beyond the PSTH: point process modeling of spike trains

88%
Wojcik D., Mochol G., Wypych M., Waleszczyk W., Wrobel A.
Acta Neurobiologiae Experimentalis
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2009
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tom 69
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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.
9

Speed tuned cells in feline superior colliculus

88%
Waleszczyk W. J., Nagy A., Eordegh G., Wypych M., Benedek G.
Acta Neurobiologiae Experimentalis
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2003
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tom 63
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nr 5
10

Spatio-temporal receptive field structure and direction preference of neurons in eat's superior colliculus

88%
Wypych M., Ghazaryan A., Borkowski W., Wrobel A., Waleszczyk W. J.
Acta Neurobiologiae Experimentalis
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2005
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tom 65
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nr 3
11

The role of the centromedial subdivision of the human amygdala in signaling surprise during reinforcement learning

76%
Kolada E., Bielski K., Sobczak P., Wypych M., Marchewka A., Szatkowska I.
Acta Neurobiologiae Experimentalis
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2017
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tom 77
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nr Suppl.1
INTRODUCTION: Surprise (i.e., errors in outcome prediction) drives reinforcement learning. Animal studies point to the critical role of the centromedial subdivision (CMA) of the amygdala in signaling reinforcement-related surprise. Little is known as to the role of the CMA in this process in humans, as the problem of functional organization of the human amygdala was undertaken by only few studies. AIM(S): The goal of this study was to investigate the role of the human amygdala subdivisions in signalling surprise during reinforcement learning. METHOD(S): We used a Pavlovian conditioning task. The task was composed of two trial types: aversive and neutral, in which small amounts of aversive (0.4 M NaCl) and neutral (25 mM KCl and 2.5 mM NaHCO3) gustatory stimuli (liquids) were provided to participants. In the beginning of each trial, participants were presented with two visual cues: one associated with a high probability (on 70% of occasions) and the other with a low probability (on 30% of occasions) of obtaining gustatory stimulus. After a few seconds, one of visual cues disappeared and the subjects’ task was to indicate whether the remaining cue forerun liquid delivery. In an fMRI study, we compared the amygdala activity during: 1) reinforcement-related surprise (unexpected vs. expected delivery of aversive stimuli), and 2) surprise not related with the reinforcement (unexpected vs. expected delivery of neutral stimuli). RESULTS: We found the right CMA activation during reinforcement-related surprise, whereas surprise not related with the reinforcement did not activate any amygdala subdivision. CONCLUSIONS: The results showed selective involvement of the CMA in signalling reinforcement-related surprise in humans. Moreover, they prove that investigation of the amygdala at the level of distinct subdivisions using fMRI in humans should be valuable direction for future studies. This work was supported by a grant from the Polish National Science Centre based on decision number DEC-2014/15/B/HS6/03658. FINANCIAL SUPPORT: Polish National Science Centre grant No. DEC-2014/15/B/HS6/03658.
12

Face processing in a case of high functioning autism with developmental prosopagnosia

76%
Cygan H. B., Okuniewska H., Jednorog K., Marchewka A., Wypych M., Nowicka A.
Acta Neurobiologiae Experimentalis
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2018
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tom 78
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nr 2
The ability to “read” the information about facial identity, expressed emotions, and intentions is crucial for non-verbal social interaction. Neuroimaging and clinical studies consequently link face perception with fusiform gyrus (FG) and occipital face area (OFA) activity. Here we investigated face processing in an adult, patient PK, diagnosed with both high functioning autism spectrum disorder (ASD) and developmental prosopagnosia (DP). Both disorders have a significant impact on face perception and recognition, thus creating a unique neurodevelopmental condition. We used eye-tracking and functional magnetic resonance imaging (fMRI) method. Eye-tracking and fMRI results of PK were compared to results of control subjects. Patient PK showed atypical gaze-fixation strategy during face perception and typical patterns of brain activations in the FG and OFA. However, a significant difference between PK and control subjects was found in the left anterior superior temporal sulcus/middle temporal gyrus (aSTS/MTG). In PK the left aSTS/MTG was hypo-activated in comparison to the control subjects. Additionally, functional connectivity analysis revealed decreased inter-hemispheric connectivity between right and left aSTS/MTG in ‘ASD and DP’ patient during face recognition performance as compared to the control subjects. The lack of activity in the left aSTS/MTG observed in the case of the clinical subject, combined with the behavioral, eye-tracking, and neuropsychological results, suggests that impairment of the cognitive mechanism of face recognition involves higher level of processing. It seems to be related to insufficient access to semantic knowledge about the person when prompted by face stimuli.
13
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The total content of nitrogen in leaves and wood of trees growing in the area affected by the Glogow Copper Smelter

76%
Kostecki J., Greinert A., Drab M., Wasylewicz R., Szafraniec M., Stodulski G., Wypych M.
Journal of Elementology
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2015
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tom 20
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nr 1
Soils affected by industrial emissions of a copper smelter may contain high amounts of heavy metals. Heavy metal infiltration across the soil is a potential source of groundwater contamination. Simultaneously, many ions, especially Cu2+ and Pb2+, can be accumulated by plants growing within the emission range. The aim of this study was to determine the influence of high Cu and Pb soil contamination on the total nitrogen content in leaves and wood of trees growing in an area exposed to copper smelter emissions. Samples of leaves and wood of Populus robusta L. and Betula pendula L. as well as soil samples were taken from an area affected by industrial emissions, namely from the former sanitary zone of the Głogów Copper Smelter. The samples were collected in 2010. The particle size distribution, pH, organic carbon, total nitrogen and the total content of Cu and Pb in the soil samples were determined. In the plant samples (foliage and trunks), the total nitrogen was assayed. The results were analysed statistically. The following conclusions were drawn: the litter horizon of soils affected by industrial emissions contains high level of heavy metals (3450-5400 mg Cu kg-1, 1020-1500 mg Pb kg-1), exceeding threshold values for industrial areas. Also the humic horizon is characterised by an increased Cu and Pb content: 174-1530 mg Cu kg-1 and 268-702 mg Pb kg-1. The leaves of the tested species contained more nitrogen than the wood, although the birch wood contained more nitrogen then the poplar. There was no difference in the nitrogen content of the annual tree rings of both species. Despite high levels of copper and lead in the tested soils, there was no effect of this factor on the nitrogen content of the leaves, bark and wood of the studied trees.
14

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

76%
Wypych M., Nagy A., Paroczy Z., Markus Z., Berenyi A., Benedek G., Waleszczyk W.
Acta Neurobiologiae Experimentalis
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2009
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tom 69
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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.
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