Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 8

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1
Content available remote

Sway ratio - a new measure for quantifying postural stability

100%
Blaszczyk J. W.
Acta Neurobiologiae Experimentalis
|
2008
|
vol. 68
|
issue 1
51-57
EN
In the search of a reliable postural stability index, two sway time series: the center-of-mass (COM) and the center-of-foot pressure (COP) were recorded simultaneously in elderly subjects standing quiet with eyes open and with eyes closed. From a battery of commonly use sway measures, only the anteroposterior COM and the COP path lengths proved their high sensitivity and discriminative power to the imposed vision conditions. Based upon these indices, a new measure ? sway ratio (SR) ? was computed, as the COP-to-COM path length ratio. The measure can easily distinguish vision vs. no vision in the elderly. The SR can be successfully accessed base upon the COP signal only. In contrast to traditional sway indices, the SR as a relative measure is insensitive to the length of sampled record and to the signal sampling frequency. Its magnitude can be interpreted as an average amount of balance controlling motor activity that coincides with a unit COM displacement. The SR is recommended as a reliable measure that allows for assessment of postural stability.
2
Content available remote

Startle response to short acoustic stimuli in rats

100%
Blaszczyk J. W.
Acta Neurobiologiae Experimentalis
|
2003
|
vol. 63
|
issue 1
25-30
EN
The acoustic startle (ASR) is a transient motor response to an unexpected, intensive stimulus. The response is determined by stimulus parameters such as its intensity, rise time and duration. The dependence of the ASR on the stimulus duration is more complex than could be assumed from physical properties of acoustic pulse. This effect attracted the attention of few researchers. Some authors reported noticeable changes in the ASR amplitude only for very short (less than 4-6 ms) acoustic pulses. The systematic studies on the effect, however, have not been performed so far. The purpose of this study was to determine to what extent the ASR parameters are affected by the durations of the short stimulus. The amplitude of the acoustic startle reflex was assessed for a fixed tonal frequency (6.9 kHz), and for a variety of stimulus durations ranging between 2 and 10 ms. ASRs were studied in 11 adult, hooded rats exposed to a sequence of tone pulses (110 dB SPL) of different durations, presented in random order, with or without 70 dB white noise as a background. Statistical analysis revealed significant differences between ASR amplitudes for different durations. The startle amplitude increased with acoustic pulse duration and distinguishable differences were seen for stimulus duration between 2 and 8 ms. Further increase of pulse duration had no effect on ASR amplitude. The same pattern of changes was observed when the acoustic stimulus was presented with the white noise. In the tested range of stimulus duration no significant differences in the ASR latency were found. The observed differences may be attributed to changes of stimulus acoustic energy and to physiological characteristic of auditory system in the rat.
3
Content available remote

Effect of unilateral somatosensory cortex lesion upon locomotion in dogs

64%
Blaszczyk J. W., Dobrzecka C.
Acta Neurobiologiae Experimentalis
|
1995
|
vol. 55
|
issue 2
133-140
EN
Locomotive limb movements were studied in 6 dogs before and after unilateral primary somatosensory cortex (SI)lesion. Single limb movement parameters as well as interlimb coordination in lesioned dogs differed significantly from the parameters measured before surgery.Both left limbs showed a proprioceptive deficit and were more flexed during normal posture and during locomotion.This resulted in prolonged stance in the left fore and in the right hind legs.The symptoms were greatly pronounced in the left fore limb compared to a slightly impaired left hindlimb. Due to the proprioceptive deficit, the dogs did not have satisfactory control over the position of the distal part of the front limb which caused frequent stumbling and even falling. The symptoms were transient and fully compensated after 3-4 weeks.
4
Content available remote

Postural stability and fractal dynamics

64%
Blaszczyk J. W., Klonowski W.
Acta Neurobiologiae Experimentalis
|
2001
|
vol. 61
|
issue 2
105-112
EN
Methods of non-linear dynamics and deterministic chaos may provide us with effective quantitative descriptors of the dynamics of postural control. The goal of this study was to introduce a new measure, which would allow to determine the fractal structure of posturographic signals and to measure the effect of the loss of visual feedback information in postural control. The results of the study show that fractal dimension (Df ) is a very useful, reliable and sensitive measure of the complexity of posturographic signals. Therefore Df can be used for the evaluation of postural stability and its changes due to pathology or an age-related decline.
5
Content available remote

Effect of acoustic stimulus characteristics on the startle response in hooded rats

64%
Blaszczyk J. W., Tajchert K.
Acta Neurobiologiae Experimentalis
|
1997
|
vol. 57
|
issue 4
315-321
EN
The acoustic startle response (ASR) depends on stimulus parameters such as duration, intensity and particularly on the stimulus rise time. The aim of our study was to determine to what extent the ASR parameters are affected by the spectral characteristics of the stimulus. Therefore, in this experiment the amplitude and the latency of the acoustic startle reflex were assessed for a fixed pulse duration and for a variety of stimulus frequencies ranging between 3 and 23 kHz. The ASRs were studied in 11 adult hooded rats exposed to 2 ms (120 dB SPL) tone pulses of different frequencies presented in random order, with or without 70 dB white noise background. Statistical analysis of the data revealed significant differences between ASR amplitudes for different frequencies. In our experimental situation the rats responded more readily to a low frequency stimulus. The startle amplitude decreased with tonal frequencies and distinguishable difference were seen for 3, 7, and 10 kHz pulses. However, such differences were not readily observed for higher frequencies i.e. 15, 20, 23 kHz. The same pattern of differences was observed when the acoustic stimulus was presented with the white noise background. The observed differences may be attributed, firstly, to a spectral characteristic of the stimulus and thus to an audibility in rats and secondly to a behavioral meaning of a stimulus of a different frequency. cy.
6
Content available remote

Acoustic startle response in the opossum Monodelphis domestica in comparison with the wistar albino rat

64%
Blaszczyk J. W., Turlejski K.
Acta Neurobiologiae Experimentalis
|
2005
|
vol. 65
|
issue 2
201-204
EN
The acoustic startle response (ASR) was studied in 20 gray short-tailed opossums (Monodelphis domestica) and its characteristics were compared with those obtained from responses of 20 Wistar albino rats. The animals were exposed to 10 ms, 110 dB white noise acoustic pulses in the Coulbourn apparatus. Amplitude of ASR was normalized to the weight of animals and then analyzed. The results show that probability of a freezing response is much higher in the opossums that generally respond with lower startle amplitudes in comparison to rats. These differences may reflect different emotional characteristics of the two species, different reactions to fear in opossum and/or different ecological specializations of the two species.
7
Content available remote

Changes of the acoustic startle reflex in rats with radiation-induced hippocampal lesion

51%
Blaszczyk J. W., Walasek G., Woznicka A., Seress L.
Acta Neurobiologiae Experimentalis
|
1999
|
vol. 59
|
issue 3
171-176
EN
The main question of the study was: to what extent does a neonatal radiation-induced hippocampal lesion lead to emotional changes in adulthood? Acoustic startle response (ASR) was studied in two groups of adult rats. The rats from the first group (14 animals) were exposed to neonatal x-ray irradiation. Their ASR were compared with those from the 10 intact rats that formed a control group. The ASR was tested during two sessions with different illumination of the acoustic chamber. During the first session the rats were tested in the darkness while during the second test the acoustic chamber was illuminated with a 15 W bulb. Irradiation resulted in a significant reduction of granule cells of the hippocampus (about 55%). The lesion resulted in emotional and behavioral changes evidenced by modification of the ASR. The irradiated rats exhibited a significantly increased amplitude of the startle response. In contrast to the light condition, the darkness context caused a decline of the ASR amplitude in the control group and failed to elicit significant changes in the lesioned animals. The results support the hypothesis that hippocampal lesions disrupt motor inhibition.
8
Content available remote

Effect of nonaversive and aversive stimulations in infancy on the acoustic startle response in adult rats

51%
Blaszczyk J. W., Tajchert K., Werka T.
Acta Neurobiologiae Experimentalis
|
1999
|
vol. 59
|
issue 1
9-14
EN
Two groups, each consisting of 8 three-week-old rat pups, were exposed to different behavioral treatments with the aim to determine how the experimental manipulation influenced their adult emotional reactivity. Every day for two weeks the pups from the first group received 15 min of handling whereas the animals from the second group were exposed to various aversive stimuli, differing each day. Following these manipulations, after a 5-day break the acoustic startle response (ASR) was measured in all animals and the testing was repeated after another four weeks. Statistical analysis of the data revealed significant differences between g<->roups in the ASR parameters. Surprisingly, in the test which directly followed the treatment the mean ASR amplitudes were similar in both g<->roups. Highly significant differences, however, were observed in the ASR amplitude four weeks later. The rats from the handling group responded with greater amplitudes. The latency of the ASR was significantly shorter in the nonaversive group compared with the second group exposed to aversive stimuli. The results suggest that early exposure to aversive stimulation significantly decreases rats emotional reactivity whereas nonaversive and impoverished stimulation clearly elevates arousal levels when the animal is placed in a novel situation.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.