TY  - JOUR
AU  - Kalauzi, Aleksandar
AU  - Spasić, Slađana
AU  - Petrović, Jelena
AU  - Ciric, Jelena
AU  - Šaponjić, Jasna
PY  - 2012
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/550
AB  - This study was aimed to explore the sleep/wake states related cortico-pontine theta carrier frequency phase shift following a systemically induced chemical axotomy of the monoaminergic afferents within a brain of the freely moving rats. Our experiments were performed in 14 adult, male Sprague Dawley rats, chronically implanted for sleep recording. We recorded sleep during baseline condition, following sham injection (saline i.p. 1 ml/kg), and every week for 5 weeks following injection of the systemic neurotoxins (DSP-4 or PCA; 1 ml/kg, i.p.) for chemical axotomy of the locus coeruleus (LC) and dorsal raphe (DR) axon terminals. After sleep/wake states identification, FFT analysis was performed on 5 s epochs. Theta carrier frequency phase shift (Delta Phi) was calculated for each epoch by averaging theta Fourier component phase shifts, and the Delta Phi values were plotted for each rat in control condition and 28 days following the monoaminergic lesions, as a time for permanently established DR or LC chemical axotomy. Calculated group averages have shown that Delta Phi increased between pons and cortex significantly in all sleep/wake states (Wake, NREM and REM) following the monoaminergic lesions, with respect to controls. Monoaminergic lesions established the pontine leading role in the brain theta oscillations during all sleep/wake states.
PB  - General Physiol And Biophysics, Bratislava
T2  - General Physiology and Biophysics
T1  - Cortico-pontine theta carrier frequency phase shift across sleep/wake states following monoaminergic lesion in rat
EP  - 171
IS  - 2
SP  - 163
VL  - 31
DO  - 10.4149/gpb_2012_018
ER  - 

@article{
author = "Kalauzi, Aleksandar and Spasić, Slađana and Petrović, Jelena and Ciric, Jelena and Šaponjić, Jasna",
year = "2012",
abstract = "This study was aimed to explore the sleep/wake states related cortico-pontine theta carrier frequency phase shift following a systemically induced chemical axotomy of the monoaminergic afferents within a brain of the freely moving rats. Our experiments were performed in 14 adult, male Sprague Dawley rats, chronically implanted for sleep recording. We recorded sleep during baseline condition, following sham injection (saline i.p. 1 ml/kg), and every week for 5 weeks following injection of the systemic neurotoxins (DSP-4 or PCA; 1 ml/kg, i.p.) for chemical axotomy of the locus coeruleus (LC) and dorsal raphe (DR) axon terminals. After sleep/wake states identification, FFT analysis was performed on 5 s epochs. Theta carrier frequency phase shift (Delta Phi) was calculated for each epoch by averaging theta Fourier component phase shifts, and the Delta Phi values were plotted for each rat in control condition and 28 days following the monoaminergic lesions, as a time for permanently established DR or LC chemical axotomy. Calculated group averages have shown that Delta Phi increased between pons and cortex significantly in all sleep/wake states (Wake, NREM and REM) following the monoaminergic lesions, with respect to controls. Monoaminergic lesions established the pontine leading role in the brain theta oscillations during all sleep/wake states.",
publisher = "General Physiol And Biophysics, Bratislava",
journal = "General Physiology and Biophysics",
title = "Cortico-pontine theta carrier frequency phase shift across sleep/wake states following monoaminergic lesion in rat",
pages = "171-163",
number = "2",
volume = "31",
doi = "10.4149/gpb_2012_018"
}

Kalauzi, A., Spasić, S., Petrović, J., Ciric, J.,& Šaponjić, J.. (2012). Cortico-pontine theta carrier frequency phase shift across sleep/wake states following monoaminergic lesion in rat. in General Physiology and Biophysics
General Physiol And Biophysics, Bratislava., 31(2), 163-171.
https://doi.org/10.4149/gpb_2012_018

Kalauzi A, Spasić S, Petrović J, Ciric J, Šaponjić J. Cortico-pontine theta carrier frequency phase shift across sleep/wake states following monoaminergic lesion in rat. in General Physiology and Biophysics. 2012;31(2):163-171.
doi:10.4149/gpb_2012_018 .

Kalauzi, Aleksandar, Spasić, Slađana, Petrović, Jelena, Ciric, Jelena, Šaponjić, Jasna, "Cortico-pontine theta carrier frequency phase shift across sleep/wake states following monoaminergic lesion in rat" in General Physiology and Biophysics, 31, no. 2 (2012):163-171,
https://doi.org/10.4149/gpb_2012_018 . .

TY  - JOUR
AU  - Spasić, Slađana
AU  - Nikolić, Ljiljana M.
AU  - Mutavdžić, Dragosav
AU  - Šaponjić, Jasna
PY  - 2011
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/468
AB  - We applied a combination of fractal analysis and Independent Component Analysis (ICA) method to detect the sources of fractal complexity in snail Br neuron activity induced by static magnetic field of 2.7 mT. The fractal complexity of Br neuron activity was analyzed before (Control), during (MF), and after (AMF) exposure to the static magnetic field in six experimental animals. We estimated the fractal dimension (FD) of electrophysiological signals using Higuchi's algorithm, and empirical FD distributions. By using the Principal Component Analysis (PCA) and FastICA algorithm we determined the number of components, and defined the statistically independent components (ICs) in the fractal complexity of signal waveforms. We have isolated two independent components of the empirical FD distributions for each of three groups of data by using FastICA algorithm. ICs represent the sources of fractal waveforms complexity of Br neuron activity in particular experimental conditions. Our main results have shown that there could be two opposite intrinsic mechanisms in single snail Br neuron response to static magnetic field stimulation. We named identified ICs that correspond to those mechanisms - the component of plasticity and the component of elasticity. We have shown that combination of fractal analysis with ICA method could be very useful for the decomposition and identification of the sources of fractal complexity of bursting neuronal activity waveforms.
PB  - Elsevier Ireland Ltd, Clare
T2  - Computer Methods and Programs in Biomedicine
T1  - Independent complexity patterns in single neuron activity induced by static magnetic field
EP  - 218
IS  - 2
SP  - 212
VL  - 104
DO  - 10.1016/j.cmpb.2011.07.006
ER  - 

@article{
author = "Spasić, Slađana and Nikolić, Ljiljana M. and Mutavdžić, Dragosav and Šaponjić, Jasna",
year = "2011",
abstract = "We applied a combination of fractal analysis and Independent Component Analysis (ICA) method to detect the sources of fractal complexity in snail Br neuron activity induced by static magnetic field of 2.7 mT. The fractal complexity of Br neuron activity was analyzed before (Control), during (MF), and after (AMF) exposure to the static magnetic field in six experimental animals. We estimated the fractal dimension (FD) of electrophysiological signals using Higuchi's algorithm, and empirical FD distributions. By using the Principal Component Analysis (PCA) and FastICA algorithm we determined the number of components, and defined the statistically independent components (ICs) in the fractal complexity of signal waveforms. We have isolated two independent components of the empirical FD distributions for each of three groups of data by using FastICA algorithm. ICs represent the sources of fractal waveforms complexity of Br neuron activity in particular experimental conditions. Our main results have shown that there could be two opposite intrinsic mechanisms in single snail Br neuron response to static magnetic field stimulation. We named identified ICs that correspond to those mechanisms - the component of plasticity and the component of elasticity. We have shown that combination of fractal analysis with ICA method could be very useful for the decomposition and identification of the sources of fractal complexity of bursting neuronal activity waveforms.",
publisher = "Elsevier Ireland Ltd, Clare",
journal = "Computer Methods and Programs in Biomedicine",
title = "Independent complexity patterns in single neuron activity induced by static magnetic field",
pages = "218-212",
number = "2",
volume = "104",
doi = "10.1016/j.cmpb.2011.07.006"
}

Spasić, S., Nikolić, L. M., Mutavdžić, D.,& Šaponjić, J.. (2011). Independent complexity patterns in single neuron activity induced by static magnetic field. in Computer Methods and Programs in Biomedicine
Elsevier Ireland Ltd, Clare., 104(2), 212-218.
https://doi.org/10.1016/j.cmpb.2011.07.006

Spasić S, Nikolić LM, Mutavdžić D, Šaponjić J. Independent complexity patterns in single neuron activity induced by static magnetic field. in Computer Methods and Programs in Biomedicine. 2011;104(2):212-218.
doi:10.1016/j.cmpb.2011.07.006 .

Spasić, Slađana, Nikolić, Ljiljana M., Mutavdžić, Dragosav, Šaponjić, Jasna, "Independent complexity patterns in single neuron activity induced by static magnetic field" in Computer Methods and Programs in Biomedicine, 104, no. 2 (2011):212-218,
https://doi.org/10.1016/j.cmpb.2011.07.006 . .

TY  - JOUR
AU  - Spasić, Slađana
AU  - Kalauzi, Aleksandar
AU  - Kesic, Srdjan
AU  - Obradović, Milica
AU  - Šaponjić, Jasna
PY  - 2011
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/460
AB  - We used spectral analysis and Higuchi fractal dimension (FD) to correlate the EEG spectral characteristics of the sensorimotor cortex, hippocampus, and pons with their corresponding EEG signal complexities in anesthetized rats. We have explored the quantitative relationship between the mean FDs and EEG wide range high frequency (8-50 Hz) activity during ketamine/xylazine versus nembutal anesthesia at surgical plane. Using FD we detected distinct inter-structure complexity pattern and uncovered for the first time that the polygraphically and behaviorally defined anesthetized state at surgical plane as equal during experiment in two anesthetic regimens, is not the same with respect to the degree of neuronal activity (degree of generalized neuronal inhibition achieved) at different brain levels. Using the correlation of certain brain structure EEG spectral characteristics with their corresponding FDs, and the surrogate data modeling, we determined what particular frequency band contributes to EEG complexities in ketamine/xylazine versus nembutal anesthesia. In this study we have shown that the quantitative relationship between higher frequency EEG amplitude and EEG complexity is the best-modeled by surrogate data as a 3rd order polynomial. On the base of our EEG amplitude/EEG complexity relationship model, and the evidenced spectral differences in ketamine versus nembutal anesthesia we have proved that higher amplitudes of sigma, beta, and gamma frequency in ketamine anesthesia yields to higher FDs.
PB  - Academic Press Ltd- Elsevier Science Ltd, London
T2  - Journal of Theoretical Biology
T1  - Surrogate data modeling the relationship between high frequency amplitudes and Higuchi fractal dimension of EEG signals in anesthetized rats
EP  - 166
SP  - 160
VL  - 289
DO  - 10.1016/j.jtbi.2011.08.037
ER  - 

@article{
author = "Spasić, Slađana and Kalauzi, Aleksandar and Kesic, Srdjan and Obradović, Milica and Šaponjić, Jasna",
year = "2011",
abstract = "We used spectral analysis and Higuchi fractal dimension (FD) to correlate the EEG spectral characteristics of the sensorimotor cortex, hippocampus, and pons with their corresponding EEG signal complexities in anesthetized rats. We have explored the quantitative relationship between the mean FDs and EEG wide range high frequency (8-50 Hz) activity during ketamine/xylazine versus nembutal anesthesia at surgical plane. Using FD we detected distinct inter-structure complexity pattern and uncovered for the first time that the polygraphically and behaviorally defined anesthetized state at surgical plane as equal during experiment in two anesthetic regimens, is not the same with respect to the degree of neuronal activity (degree of generalized neuronal inhibition achieved) at different brain levels. Using the correlation of certain brain structure EEG spectral characteristics with their corresponding FDs, and the surrogate data modeling, we determined what particular frequency band contributes to EEG complexities in ketamine/xylazine versus nembutal anesthesia. In this study we have shown that the quantitative relationship between higher frequency EEG amplitude and EEG complexity is the best-modeled by surrogate data as a 3rd order polynomial. On the base of our EEG amplitude/EEG complexity relationship model, and the evidenced spectral differences in ketamine versus nembutal anesthesia we have proved that higher amplitudes of sigma, beta, and gamma frequency in ketamine anesthesia yields to higher FDs.",
publisher = "Academic Press Ltd- Elsevier Science Ltd, London",
journal = "Journal of Theoretical Biology",
title = "Surrogate data modeling the relationship between high frequency amplitudes and Higuchi fractal dimension of EEG signals in anesthetized rats",
pages = "166-160",
volume = "289",
doi = "10.1016/j.jtbi.2011.08.037"
}

Spasić, S., Kalauzi, A., Kesic, S., Obradović, M.,& Šaponjić, J.. (2011). Surrogate data modeling the relationship between high frequency amplitudes and Higuchi fractal dimension of EEG signals in anesthetized rats. in Journal of Theoretical Biology
Academic Press Ltd- Elsevier Science Ltd, London., 289, 160-166.
https://doi.org/10.1016/j.jtbi.2011.08.037

Spasić S, Kalauzi A, Kesic S, Obradović M, Šaponjić J. Surrogate data modeling the relationship between high frequency amplitudes and Higuchi fractal dimension of EEG signals in anesthetized rats. in Journal of Theoretical Biology. 2011;289:160-166.
doi:10.1016/j.jtbi.2011.08.037 .

Spasić, Slađana, Kalauzi, Aleksandar, Kesic, Srdjan, Obradović, Milica, Šaponjić, Jasna, "Surrogate data modeling the relationship between high frequency amplitudes and Higuchi fractal dimension of EEG signals in anesthetized rats" in Journal of Theoretical Biology, 289 (2011):160-166,
https://doi.org/10.1016/j.jtbi.2011.08.037 . .

TY  - JOUR
AU  - Spasić, Slađana
AU  - Kesic, Srdjan
AU  - Kalauzi, Aleksandar
AU  - Šaponjić, Jasna
PY  - 2011
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/443
AB  - The complexity, entropy and other non-linear measures of the electroencephalogram ( EEG), such as Higuchi fractal dimension (FD), have been recently proposed as the measures of anesthesia depth and sedation. We hypothesized that during unconciousness in rats induced by the general anesthetics with opposite mechanism of action, behaviorally and poligraphically controlled as appropriately achieved stable anesthesia, we can detect distinct inter-structure brain dynamic using mean FDs. We used the surrogate data test for nonlinearity in order to establish the existence of nonlinear dynamics, and to justify the use of FD as a nonlinear measure in the time series analysis. The surrogate data of predefined probability distribution and autocorrelation properties have been generated using the algorithm of statically transformed autoregressive process (STAP). FD then is applied to quantify EEG signal complexity at the cortical, hippocampal and pontine level during stable general anesthesia (ketamine/xylazine or nembutal anesthesia). Our study showed for the first time that global neuronal inhibition caused by different mechanisms of anesthetic action induced distinct brain inter- structure complexity gradient in Sprague Dawley rats. EEG signal complexities were higher at cortical and hippocampal level in ketamine/ xylazine vs. nembutal anesthesia, with the dominance of hippocampal complexity. In nembutal anesthesia the complexity dominance moved to pontine level, and ponto- hippocampocortical decreasing complexity gradient was established. This study has proved the Higuchi fractal dimension as a valuable tool for measuring the anesthesia induced inter- structure EEG complexity.
PB  - World Scientific Publ Co Pte Ltd, Singapore
T2  - Fractals-Complex Geometry Patterns and Scaling in Nature and Society
T1  - Different anesthesia in rat induces distinct inter-structure brain dynamic detected by higuchi fractal dimension
EP  - 123
IS  - 1
SP  - 113
VL  - 19
DO  - 10.1142/S0218348X1100521X
ER  - 

@article{
author = "Spasić, Slađana and Kesic, Srdjan and Kalauzi, Aleksandar and Šaponjić, Jasna",
year = "2011",
abstract = "The complexity, entropy and other non-linear measures of the electroencephalogram ( EEG), such as Higuchi fractal dimension (FD), have been recently proposed as the measures of anesthesia depth and sedation. We hypothesized that during unconciousness in rats induced by the general anesthetics with opposite mechanism of action, behaviorally and poligraphically controlled as appropriately achieved stable anesthesia, we can detect distinct inter-structure brain dynamic using mean FDs. We used the surrogate data test for nonlinearity in order to establish the existence of nonlinear dynamics, and to justify the use of FD as a nonlinear measure in the time series analysis. The surrogate data of predefined probability distribution and autocorrelation properties have been generated using the algorithm of statically transformed autoregressive process (STAP). FD then is applied to quantify EEG signal complexity at the cortical, hippocampal and pontine level during stable general anesthesia (ketamine/xylazine or nembutal anesthesia). Our study showed for the first time that global neuronal inhibition caused by different mechanisms of anesthetic action induced distinct brain inter- structure complexity gradient in Sprague Dawley rats. EEG signal complexities were higher at cortical and hippocampal level in ketamine/ xylazine vs. nembutal anesthesia, with the dominance of hippocampal complexity. In nembutal anesthesia the complexity dominance moved to pontine level, and ponto- hippocampocortical decreasing complexity gradient was established. This study has proved the Higuchi fractal dimension as a valuable tool for measuring the anesthesia induced inter- structure EEG complexity.",
publisher = "World Scientific Publ Co Pte Ltd, Singapore",
journal = "Fractals-Complex Geometry Patterns and Scaling in Nature and Society",
title = "Different anesthesia in rat induces distinct inter-structure brain dynamic detected by higuchi fractal dimension",
pages = "123-113",
number = "1",
volume = "19",
doi = "10.1142/S0218348X1100521X"
}

Spasić, S., Kesic, S., Kalauzi, A.,& Šaponjić, J.. (2011). Different anesthesia in rat induces distinct inter-structure brain dynamic detected by higuchi fractal dimension. in Fractals-Complex Geometry Patterns and Scaling in Nature and Society
World Scientific Publ Co Pte Ltd, Singapore., 19(1), 113-123.
https://doi.org/10.1142/S0218348X1100521X

Spasić S, Kesic S, Kalauzi A, Šaponjić J. Different anesthesia in rat induces distinct inter-structure brain dynamic detected by higuchi fractal dimension. in Fractals-Complex Geometry Patterns and Scaling in Nature and Society. 2011;19(1):113-123.
doi:10.1142/S0218348X1100521X .

Spasić, Slađana, Kesic, Srdjan, Kalauzi, Aleksandar, Šaponjić, Jasna, "Different anesthesia in rat induces distinct inter-structure brain dynamic detected by higuchi fractal dimension" in Fractals-Complex Geometry Patterns and Scaling in Nature and Society, 19, no. 1 (2011):113-123,
https://doi.org/10.1142/S0218348X1100521X . .

TY  - JOUR
AU  - Kalauzi, Aleksandar
AU  - Culic, M
AU  - Martać, Ljiljana
AU  - Grbic, G
AU  - Šaponjić, Jasna
AU  - Jovanović, A
AU  - Janković, B
AU  - Spasić, Slađana
PY  - 2003
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/85
AB  - The aim of this study was to reveal the nature and meaning of interspike background activity (RBA) recorded in Purkinje cell layer of rat cerebellum. We compared Fourier amplitude spectra of recorded, extracted and averaged simple spike(s) - SS and complex spike(s) - CS with the mean amplitude spectrum of the remaining interspike RBA. A much greater similarity of spectral characteristics was noticed between SS and RBA, than between CS and RBA. Then, we simulated background activity (SBA), by superimposing averaged SS with randomized amplitudes and time delays. There was a significant correlation (p lt 0.005) between linearly transformed simulated and recorded amplitude spectra. Mean amplitude spectra of SBA were positively correlated with the number of superimposed SS. We propose to use this fact as a qualitative indication about the direction of change in the mean activity of surrounding neuronal population.
PB  - Wiley, Hoboken
T2  - Neuroscience Research Communications
T1  - New view on cerebellar cortical background activity in rat: Simulation
EP  - 217
IS  - 3
SP  - 211
VL  - 32
DO  - 10.1002/nrc.10075
ER  - 

@article{
author = "Kalauzi, Aleksandar and Culic, M and Martać, Ljiljana and Grbic, G and Šaponjić, Jasna and Jovanović, A and Janković, B and Spasić, Slađana",
year = "2003",
abstract = "The aim of this study was to reveal the nature and meaning of interspike background activity (RBA) recorded in Purkinje cell layer of rat cerebellum. We compared Fourier amplitude spectra of recorded, extracted and averaged simple spike(s) - SS and complex spike(s) - CS with the mean amplitude spectrum of the remaining interspike RBA. A much greater similarity of spectral characteristics was noticed between SS and RBA, than between CS and RBA. Then, we simulated background activity (SBA), by superimposing averaged SS with randomized amplitudes and time delays. There was a significant correlation (p lt 0.005) between linearly transformed simulated and recorded amplitude spectra. Mean amplitude spectra of SBA were positively correlated with the number of superimposed SS. We propose to use this fact as a qualitative indication about the direction of change in the mean activity of surrounding neuronal population.",
publisher = "Wiley, Hoboken",
journal = "Neuroscience Research Communications",
title = "New view on cerebellar cortical background activity in rat: Simulation",
pages = "217-211",
number = "3",
volume = "32",
doi = "10.1002/nrc.10075"
}

Kalauzi, A., Culic, M., Martać, L., Grbic, G., Šaponjić, J., Jovanović, A., Janković, B.,& Spasić, S.. (2003). New view on cerebellar cortical background activity in rat: Simulation. in Neuroscience Research Communications
Wiley, Hoboken., 32(3), 211-217.
https://doi.org/10.1002/nrc.10075

Kalauzi A, Culic M, Martać L, Grbic G, Šaponjić J, Jovanović A, Janković B, Spasić S. New view on cerebellar cortical background activity in rat: Simulation. in Neuroscience Research Communications. 2003;32(3):211-217.
doi:10.1002/nrc.10075 .

Kalauzi, Aleksandar, Culic, M, Martać, Ljiljana, Grbic, G, Šaponjić, Jasna, Jovanović, A, Janković, B, Spasić, Slađana, "New view on cerebellar cortical background activity in rat: Simulation" in Neuroscience Research Communications, 32, no. 3 (2003):211-217,
https://doi.org/10.1002/nrc.10075 . .