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1
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The need of neuroinformatic approach in functional neurophysiology

100%
Wrobel A.
Acta Neurobiologiae Experimentalis
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2005
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vol. 65
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issue 3
421-423
EN
Despite the enormous growth in the number of facts and regularities observed in neuroscience, the current state of the field does not allow their integration in coherent theoretical frameworks. Neuroinformatics is a new research field devoted to development of neuroscience data bases together with computational models and analytical tools for sharing, integration and analysis of experimental data and the advancement of theories of nervous system function. From 1996 the OECD countries promote fostering neuroinformatics by eliminating the barriers that prevent cooperation and by providing incentives to potential participants. This activity was formulated in the Report on Neuroinformatics from The Global Science Forum Neuroinformatics Working Group of the OECD (2002) as well as in several printed publications by the Neuroinformatics group (Amari et al. 2002, Eckersley et al. 2003). This article summarizes the ideas presented in the Report and stresses the importance of analytical and modeling approach to functional neurophysiology.
2

Functional analysis of evoked potentials in rat?s sensory cortex

100%
Wrobel A.
Postępy Higieny i Medycyny Doświadczalnej
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2002
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vol. 56
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issue 3
273-279
EN
In the barrel cortex of behaving rat potentials evoked to vibrissa stimulation are composed from two main principal components which can be attributed to activation of two pyramidal cell populations: supra- and infragranular. The classical aversive stimulus favors the appearance of EPs dominated by a component characteristic of infragranular cells. We hypothesize that neuromodulatory action elicited by contextual stimulation activates all involved cortical neurons which results in opening the transmission gate to the surrounding columns.
3
Content available remote

Beta activity: a carrier for visual attention

100%
Wrobel A.
Acta Neurobiologiae Experimentalis
|
2000
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vol. 60
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issue 2
247-260
EN
The alpha (8-13 Hz), beta (15-25 Hz) and gamma (30-60 Hz) bands of the EEG have been long studied clinically because of their putative functional importance. Old experimental results indicate that repetitive stimulation of the visual pathway evokes synchronous responses at the cortical level with a gain that depends on frequency; oscillations within relevant bands are less damped at subsequent processing levels than others. Our current results show in the cat that cortico-geniculate feedback has a build-in potentiation mechanism that operates at around the beta frequency and activates thalamic cells thus lowering the threshold for visual information transmission. We have also shown that enhanced beta activity is propagated along this feedback pathway solely during attentive visual behavior. This activity consists of 300-1,000 ms bursts that correlate in time with gamma oscillatory events. Beta-bursting activity spreads to all investigated visual centers, including the lateral posterior and pulvinar complex and higher cortical areas. Other supporting data are discussed that are concerned with the enhanced beta activity during attentive-like behavior of various species, including humans. Finally, we put forward a general hypothesis which attributes the appearance of oscillations within the alpha, beta and gamma bands to different activation states of the visual system. According to this hypothesis, alpha activity characterizes idle arousal of the system, while beta bursts shift the system to an attention state that consequently allows for gamma synchronization and perception.
4
Content available remote

Correlated activity of lateral geniculate neurones in binoculary deprived cats

64%
Michalski A., Wrobel A.
Acta Neurobiologiae Experimentalis
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1994
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vol. 54
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issue 1
3-10
5
Content available remote

Cortical contribution to sensory volleys recorded at thalamic nuclei of lemniscal and paralemniscal pathways

51%
Kublik E., Swiejkowski D. A., Wrobel A.
Acta Neurobiologiae Experimentalis
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2003
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vol. 63
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issue 4
377-382
EN
In order to elucidate the role of cortical input on sensory information processing in different thalamic somatosensory nuclei we recorded potentials evoked (EPs) by whisker deflections of short duration from ventral posteromedial (VPm) and medial posterior (POm) nuclei while manipulating cortico-thalamic activity by means of local cooling, lidocaine application or electrical stimulation. It appeared that only the earliest sub-component of the first negative wave of the EPs resulted from peripheral input, while the rest of the potential?s negativity depended on cortical feedback. The latencies and amplitudes of EPs recorded at both nuclei were not significantly different, which might be attributed to urethane anesthesia.
6
Content available remote

20 Hz bursting beta activity in the cortico-thalmic system of visually attending cats

51%
Wrobel A., Bekisz M., Kublik E., Waleszczyk W.
Acta Neurobiologiae Experimentalis
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1994
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vol. 54
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issue 2
95-107
7
Content available remote

Synaptic excitation of principal cells in the cat's lateral geniculate nucleus during focal epileptic seizures in the visual cortex

51%
Wrobel A., Hedstrom A., Lindstrom S.
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vol. 58
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issue 4
271-276
EN
Principal cells of the lateral geniculate nucleus are intensely activated during focal seizures in the visual cortex. The intracellular recordings technique from geniculate cells was used to show that this activity is induced by a strong excitatory synaptic input from discharging cortico-geniculate neurones in layer 6 of the cortex.
8
Content available remote

Nonlinearities within the cat LGN cell receptive fields in simulated network with recurrent inhibition

51%
Musial P., Panecki S., Gerstein G. L., Wrobel A.
Acta Neurobiologiae Experimentalis
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1996
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vol. 56
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issue 4
927-942
EN
We investigated the receptive fields of principal cells from the cat's lateral geniculate nucleus cells. About 20% of the X type neurones showed clear nonlinearities of summation when stimulated by two simultaneously onset, small bars of light. The possible source of this nonlinearity was studied on a specially designed model of a one-layer neuronal network with inhibitory, recurrent interactions, intended to mimic the inhibitory influence exerted on geniculate relay cells by perigeniculate interneurones. The model, when activated from periphery by two stimuli-like input patterns, produced at the output side the nonsymmetrical profiles of the receptive fields sensitivity, similar to those obtained in real experiments. This nonlinear output appeared when some of the relay cells were inhibited below their firing level threshold and this effect was spread through the network by lateral inhibitory connections. It is concluded that physiologically observed nonlinearities of the order of single receptive field mechanisms can be predicted by a simple recurrent network.
9
Content available remote

Local classifiers for evoked potentials recorded from behaving rats

51%
Jakuczun W., Kublik E., Wojcik D. K., Wrobel A.
Acta Neurobiologiae Experimentalis
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2005
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vol. 65
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issue 3
425-434
EN
Dynamic states of the brain determine the way information is processed in local neural networks. We have applied classical conditioning paradigm in order to study whether habituated and aroused states can be differentiated in single barrel column of rat's somatosensory cortex by means of analysis of field potentials evoked by stimulation of a single vibrissa. A new method using local classifiers is presented which allows for reliable and meaningful classification of single evoked potentials which might be consequently attributed to different functional states of the cortical column.
10
Content available remote

Neuroprotective effect of ACTH (4-9) in degeneration of hippocampal nerve cells caused by dexamethasone: morphological, immunocytochemical and ultrastructural studies

45%
Sekita-Krzak J., Zebrowska-Lupina I., Czerny K., Stepniewska M., Wrobel A.
Acta Neurobiologiae Experimentalis
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2003
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vol. 63
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issue 1
1-8
EN
. Sustained exposure to glucocorticosteroids (GCs), adrenal hormones secreted during stress, can cause neural degeneration. This is particularly so in the hippocampus, a principal neural target site for GCs. The purpose of this research was an assessment of the neuroprotective effect of ACTH (4-9) in degenerative changes of hippocampal neurons induced by synthetic GC - dexamethasone. Experiments were conducted on male Albino-Swiss mice. We studied the morphology of neurons in the dorsal hippocampus in slides stained with cresyl violet. Immunocytochemical analysis was carried out with the use of monoclonal antibody anti-MAP2 in order to detect alterations in the the neuronal cytoskeleton. We also performed ultrastructural examinations of hippocampal neurons. Quantitative analysis of morphological changes was completed using a computer analyser of histological pictures. It was shown that dexamethasone administered in toxic doses evokes neuronal death in layer CA3 of the hippocampus. Results indicate that ACTH (4-9) shows protective effects in that model. Dexamethasone-induced damage to hippocampal pyramidal neurons (assessed by cell counts, immunocytochemical analysis of cytoskeletal alterations and ultrastructural studies) was significantly reduced in animals administered ACTH (4-9).
11
Content available remote

Rapid phase shift of evoked potentials in barrel cortex accompanies conditioning

45%
Wrobel A., Achimowicz J., Musial P., Kublik E., Krol T.
Acta Neurobiologiae Experimentalis
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1995
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vol. 55
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issue 2
147
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