In nonstationary noisy systems the traditional cross-correlation method may not appropriately det... more In nonstationary noisy systems the traditional cross-correlation method may not appropriately detect all cases of interdependencies between coupled systems. The phase-synchronization method was previously found useful in detecting synchronization in several systems. We here applied the phase-synchronization decay to study the synchronization between six combinations of binocular fixational eye movement components. We found that only two components were synchronized: the right and left horizontal with each other and the right and left vertical. Furthermore, the vertical-vertical components were much more synchronized than the horizontal.
Publisher Summary This chapter reviews that the core pathology of PD is degeneration of the dopam... more Publisher Summary This chapter reviews that the core pathology of PD is degeneration of the dopamine neurons in the midbrain and the resulting depletion of striatal dopamine. The striatum is the major input stage of the basal ganglia, receiving input from the cerebral cortex and thalamus, and projecting directly and indirectly to the output stages of the basal ganglia – the internal segment of the globus pallidus (GPi) and the substantia nigra pars reticulata (SNr). The dopamine precursor l-DOPA remains the gold standard for the treatment of PD. However, long-term use of l-DOPA is associated with the development of motor complications. It discusses that the multi-stage therapy of Parkinson's disease (PD), from dopamine replacement methods to modulation of the activity of the basal ganglia structures using deep Brain Stimulation DBS, reinstates interest in identifying the critical features of abnormal basal ganglia activity that follow striatal dopamine depletion and lead to the symptoms. The chapter summarizes the main physiological findings in the 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) primate model of PD, and compares them to the recent physiological findings in human patients. There is an accumulation of data linking excessive synchrony at low frequencies in basal ganglia-thalamo-cortical loops to impaired motor processing in PD. Whether synchronization is an epiphenomenon or truly pathogenic in PD, it provides a clear biological marker for the disease process. Recent studies indicate the differential roles or correlates of the distinctive bands of oscillatory activity in the pathogenesis of PD. It suggests that amelioration of specific domains of basal ganglia-cortical synchronized oscillatory activity could form the basis for future closed-loop stimulation regimes for human PD patients.
... Avi Gozolchiani1, Shay Moshel1, Jeffrey M. Hausdorff2, Ely Simon2, Jürgen Kurths3, Shlomo Hav... more ... Avi Gozolchiani1, Shay Moshel1, Jeffrey M. Hausdorff2, Ely Simon2, Jürgen Kurths3, Shlomo Havlin1 1Minerva Center and Department of Physics, Bar-Ilan University, Ramat-Gan 52900, Israel 2Movement Disorders Unit, Tel-Aviv ... [1] AS Pikovsky, MG Rosenblum, GV Osipov, J ...
In Parkinson's disease, pathological synchronous oscillations divide the subthalamic nucleus ... more In Parkinson's disease, pathological synchronous oscillations divide the subthalamic nucleus (STN) of patients into a dorsolateral oscillatory region and ventromedial nonoscillatory region. This bipartite division reflects the motor vs. the nonmotor (associative/limbic) subthalamic areas, respectively. However, significant topographic differences in the neuronal discharge rate between these two STN subregions in Parkinsonian patients is still controversial. In this study, 119 STN microelectrode trajectories (STN length > 2 mm, mean = 5.32 mm) with discernible oscillatory and nonoscillatory regions were carried on 60 patients undergoing deep brain stimulation surgery for Parkinson's disease. 2,137 and 2,152 multiunit stable signals were recorded (recording duration > 10 s, mean = 21.25 s) within the oscillatory and nonoscillatory STN regions, respectively. Spike detection and sorting were applied offline on every multiunit stable signal using an automatic method with sy...
doi: 10.3389/fnsys.2013.00069 Asymmetric right/left encoding of emotions in the human subthalamic... more doi: 10.3389/fnsys.2013.00069 Asymmetric right/left encoding of emotions in the human subthalamic nucleus
Freezing of gait (FoG), a paroxysmal gait disturbance commonly experienced by patients with Parki... more Freezing of gait (FoG), a paroxysmal gait disturbance commonly experienced by patients with Parkinson’s disease (PD), is characterized by sudden episodes of inability to generate effective forward stepping. Recent studies have shown an increase in beta frequency of local-field potentials in the basal-ganglia during FoG, however, comprehensive research on the synchronization between different brain locations and frequency bands in PD patients is scarce. Here, by developing tools based on network science and non-linear dynamics, we analyze synchronization networks of electroencephalography (EEG) brain waves of three PD patient groups with different FoG severity. We find higher EEG amplitude synchronization (stronger network links) between different brain locations as PD and FoG severity increase. These results are consistent across frequency bands (theta, alpha, beta, gamma) and independent of the specific motor task (walking, still standing, hand tapping) suggesting that an increase ...
Local Field potential (LFP) in the basal ganglia (BG) nuclei in the brain has attracted much rese... more Local Field potential (LFP) in the basal ganglia (BG) nuclei in the brain has attracted much research and clinical interest. However, the origin of this signal is still under debate throughout the last decades. The question is whether it is a local sub threshold phenomena, a synaptic inputs to neurons or it is a flow of electrical signals merged as volume conduction which are generated from simultaneous firing neurons in the cerebral cortex and obeys the Maxwell equations. In this study, we recorded in monkey brain simultaneously LFP’s from the cerebral cortex, in the frontal lobe and primary motor cortex (M1) and in sites in all BG nuclei: the striatum, globus pallidus and subthalamic nucleus. All the records were taken from human primate model (vervet monkey), during spontaneous activity. Developing and applying a novel method to identify significant cross correlations (potential links) while removing ”spurious” correlations, we found a tool that may discriminate between the two m...
We describe the effects of the asymmetry of cycles and non-stationarity in time series on the pha... more We describe the effects of the asymmetry of cycles and non-stationarity in time series on the phase synchronization method. We develop a modified method that overcomes these effects and apply this method to study parkinsonian tremor. Our results indicate that there is synchronization between two different hands and provide information about the time delay separating their dynamics. These findings suggest that this method may be useful for detecting and quantifying weak synchronization between two non-stationary signals.
NMDA (N-methyl-D-aspartate) antagonists are widely used in anesthesia, pain management, schizophr... more NMDA (N-methyl-D-aspartate) antagonists are widely used in anesthesia, pain management, schizophrenia animal model studies and recently as potential antidepressants. However the mechanisms underlying their anesthetic, psychotic, cognitive and emotional effects are still elusive. The basal-ganglia (BG) integrate input from different cortical domains through its dopamine modulated connections, to achieve optimal behavior control. NMDA antagonists have been shown to induce gamma oscillations in human EEG recordings and in rodents cortical and BG networks. However network relations and implication to the primate brain are still unclear. We recorded local field potentials (LFPs) simultaneously from the primary motor cortex (M1) and the external globus pallidus (GPe) of four vervet monkeys (26 sessions, 97 and 76 cortical and pallidal LFPs, respectively) before and after administration of ketamine (NMDA antagonist, 10mg/kg IM). Ketamine induced robust spontaneous gamma (30-50 Hz) oscillat...
... Avi Gozolchiani1, Shay Moshel1, Jeffrey M. Hausdorff2, Ely Simon2, Jürgen Kurths3, Shlomo Hav... more ... Avi Gozolchiani1, Shay Moshel1, Jeffrey M. Hausdorff2, Ely Simon2, Jürgen Kurths3, Shlomo Havlin1 1Minerva Center and Department of Physics, Bar-Ilan University, Ramat-Gan 52900, Israel 2Movement Disorders Unit, Tel-Aviv ... [1] AS Pikovsky, MG Rosenblum, GV Osipov, J ...
When we fixate our gaze on a stable object, our eyes move continuously with extremely small invol... more When we fixate our gaze on a stable object, our eyes move continuously with extremely small involuntary and autonomic movements, that even we are unaware of during their occurrence. One of the roles of these fixational eye movements is to prevent the adaptation of the visual system to continuous illumination and inhibit fading of the image. These random, small movements are restricted at long time scales so as to keep the target at the centre of the field of view. In addition, the synchronisation properties between both eyes are related to binocular coordination in order to provide stereopsis. We investigated the roles of different time scale behaviours, especially how they are expressed in the different spatial directions (vertical versus horizontal). We also tested the synchronisation between both eyes. Results show different scaling behaviour between horizontal and vertical movements. When the small ballistic movements, i.e., microsaccades, are removed, the scaling behaviour in both axes becomes similar. Our findings suggest that microsaccades enhance the persistence at short time scales mostly in the horizontal component and much less in the vertical component. We also applied the phase synchronisation decay method to study the synchronisation between six combinations of binocular fixational eye movement components. We found that the vertical-vertical components of right and left eyes are significantly more synchronised than the horizontal-horizontal components. These differences may be due to the need for continuously moving the eyes in the horizontal plane in order to match the stereoscopic image for different viewing distances.
Eye movements during fixation of a stationary target prevent the adaptation of the visual system ... more Eye movements during fixation of a stationary target prevent the adaptation of the visual system to continuous illumination and inhibit fading of the image. These random, involuntary, small movements are restricted at long time scales so as to keep the target at the center of the field of view. Here we use detrended fluctuation analysis in order to study the properties of fixational eye movements at different time scales. Results show different scaling behavior between horizontal and vertical movements. When the small ballistic movements, i.e., microsaccades, are removed, the scaling exponents in both planes become similar. Our findings suggest that microsaccades enhance the persistence at short time scales mostly in the horizontal component and much less in the vertical component. This difference may be due to the need for continuously moving the eyes in the horizontal plane, in order to match the stereoscopic image for different viewing distances.
In nonstationary noisy systems the traditional cross-correlation method may not appropriately det... more In nonstationary noisy systems the traditional cross-correlation method may not appropriately detect all cases of interdependencies between coupled systems. The phase-synchronization method was previously found useful in detecting synchronization in several systems. We here applied the phase-synchronization decay to study the synchronization between six combinations of binocular fixational eye movement components. We found that only two components were synchronized: the right and left horizontal with each other and the right and left vertical. Furthermore, the vertical-vertical components were much more synchronized than the horizontal.
Publisher Summary This chapter reviews that the core pathology of PD is degeneration of the dopam... more Publisher Summary This chapter reviews that the core pathology of PD is degeneration of the dopamine neurons in the midbrain and the resulting depletion of striatal dopamine. The striatum is the major input stage of the basal ganglia, receiving input from the cerebral cortex and thalamus, and projecting directly and indirectly to the output stages of the basal ganglia – the internal segment of the globus pallidus (GPi) and the substantia nigra pars reticulata (SNr). The dopamine precursor l-DOPA remains the gold standard for the treatment of PD. However, long-term use of l-DOPA is associated with the development of motor complications. It discusses that the multi-stage therapy of Parkinson's disease (PD), from dopamine replacement methods to modulation of the activity of the basal ganglia structures using deep Brain Stimulation DBS, reinstates interest in identifying the critical features of abnormal basal ganglia activity that follow striatal dopamine depletion and lead to the symptoms. The chapter summarizes the main physiological findings in the 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) primate model of PD, and compares them to the recent physiological findings in human patients. There is an accumulation of data linking excessive synchrony at low frequencies in basal ganglia-thalamo-cortical loops to impaired motor processing in PD. Whether synchronization is an epiphenomenon or truly pathogenic in PD, it provides a clear biological marker for the disease process. Recent studies indicate the differential roles or correlates of the distinctive bands of oscillatory activity in the pathogenesis of PD. It suggests that amelioration of specific domains of basal ganglia-cortical synchronized oscillatory activity could form the basis for future closed-loop stimulation regimes for human PD patients.
... Avi Gozolchiani1, Shay Moshel1, Jeffrey M. Hausdorff2, Ely Simon2, Jürgen Kurths3, Shlomo Hav... more ... Avi Gozolchiani1, Shay Moshel1, Jeffrey M. Hausdorff2, Ely Simon2, Jürgen Kurths3, Shlomo Havlin1 1Minerva Center and Department of Physics, Bar-Ilan University, Ramat-Gan 52900, Israel 2Movement Disorders Unit, Tel-Aviv ... [1] AS Pikovsky, MG Rosenblum, GV Osipov, J ...
In Parkinson's disease, pathological synchronous oscillations divide the subthalamic nucleus ... more In Parkinson's disease, pathological synchronous oscillations divide the subthalamic nucleus (STN) of patients into a dorsolateral oscillatory region and ventromedial nonoscillatory region. This bipartite division reflects the motor vs. the nonmotor (associative/limbic) subthalamic areas, respectively. However, significant topographic differences in the neuronal discharge rate between these two STN subregions in Parkinsonian patients is still controversial. In this study, 119 STN microelectrode trajectories (STN length > 2 mm, mean = 5.32 mm) with discernible oscillatory and nonoscillatory regions were carried on 60 patients undergoing deep brain stimulation surgery for Parkinson's disease. 2,137 and 2,152 multiunit stable signals were recorded (recording duration > 10 s, mean = 21.25 s) within the oscillatory and nonoscillatory STN regions, respectively. Spike detection and sorting were applied offline on every multiunit stable signal using an automatic method with sy...
doi: 10.3389/fnsys.2013.00069 Asymmetric right/left encoding of emotions in the human subthalamic... more doi: 10.3389/fnsys.2013.00069 Asymmetric right/left encoding of emotions in the human subthalamic nucleus
Freezing of gait (FoG), a paroxysmal gait disturbance commonly experienced by patients with Parki... more Freezing of gait (FoG), a paroxysmal gait disturbance commonly experienced by patients with Parkinson’s disease (PD), is characterized by sudden episodes of inability to generate effective forward stepping. Recent studies have shown an increase in beta frequency of local-field potentials in the basal-ganglia during FoG, however, comprehensive research on the synchronization between different brain locations and frequency bands in PD patients is scarce. Here, by developing tools based on network science and non-linear dynamics, we analyze synchronization networks of electroencephalography (EEG) brain waves of three PD patient groups with different FoG severity. We find higher EEG amplitude synchronization (stronger network links) between different brain locations as PD and FoG severity increase. These results are consistent across frequency bands (theta, alpha, beta, gamma) and independent of the specific motor task (walking, still standing, hand tapping) suggesting that an increase ...
Local Field potential (LFP) in the basal ganglia (BG) nuclei in the brain has attracted much rese... more Local Field potential (LFP) in the basal ganglia (BG) nuclei in the brain has attracted much research and clinical interest. However, the origin of this signal is still under debate throughout the last decades. The question is whether it is a local sub threshold phenomena, a synaptic inputs to neurons or it is a flow of electrical signals merged as volume conduction which are generated from simultaneous firing neurons in the cerebral cortex and obeys the Maxwell equations. In this study, we recorded in monkey brain simultaneously LFP’s from the cerebral cortex, in the frontal lobe and primary motor cortex (M1) and in sites in all BG nuclei: the striatum, globus pallidus and subthalamic nucleus. All the records were taken from human primate model (vervet monkey), during spontaneous activity. Developing and applying a novel method to identify significant cross correlations (potential links) while removing ”spurious” correlations, we found a tool that may discriminate between the two m...
We describe the effects of the asymmetry of cycles and non-stationarity in time series on the pha... more We describe the effects of the asymmetry of cycles and non-stationarity in time series on the phase synchronization method. We develop a modified method that overcomes these effects and apply this method to study parkinsonian tremor. Our results indicate that there is synchronization between two different hands and provide information about the time delay separating their dynamics. These findings suggest that this method may be useful for detecting and quantifying weak synchronization between two non-stationary signals.
NMDA (N-methyl-D-aspartate) antagonists are widely used in anesthesia, pain management, schizophr... more NMDA (N-methyl-D-aspartate) antagonists are widely used in anesthesia, pain management, schizophrenia animal model studies and recently as potential antidepressants. However the mechanisms underlying their anesthetic, psychotic, cognitive and emotional effects are still elusive. The basal-ganglia (BG) integrate input from different cortical domains through its dopamine modulated connections, to achieve optimal behavior control. NMDA antagonists have been shown to induce gamma oscillations in human EEG recordings and in rodents cortical and BG networks. However network relations and implication to the primate brain are still unclear. We recorded local field potentials (LFPs) simultaneously from the primary motor cortex (M1) and the external globus pallidus (GPe) of four vervet monkeys (26 sessions, 97 and 76 cortical and pallidal LFPs, respectively) before and after administration of ketamine (NMDA antagonist, 10mg/kg IM). Ketamine induced robust spontaneous gamma (30-50 Hz) oscillat...
... Avi Gozolchiani1, Shay Moshel1, Jeffrey M. Hausdorff2, Ely Simon2, Jürgen Kurths3, Shlomo Hav... more ... Avi Gozolchiani1, Shay Moshel1, Jeffrey M. Hausdorff2, Ely Simon2, Jürgen Kurths3, Shlomo Havlin1 1Minerva Center and Department of Physics, Bar-Ilan University, Ramat-Gan 52900, Israel 2Movement Disorders Unit, Tel-Aviv ... [1] AS Pikovsky, MG Rosenblum, GV Osipov, J ...
When we fixate our gaze on a stable object, our eyes move continuously with extremely small invol... more When we fixate our gaze on a stable object, our eyes move continuously with extremely small involuntary and autonomic movements, that even we are unaware of during their occurrence. One of the roles of these fixational eye movements is to prevent the adaptation of the visual system to continuous illumination and inhibit fading of the image. These random, small movements are restricted at long time scales so as to keep the target at the centre of the field of view. In addition, the synchronisation properties between both eyes are related to binocular coordination in order to provide stereopsis. We investigated the roles of different time scale behaviours, especially how they are expressed in the different spatial directions (vertical versus horizontal). We also tested the synchronisation between both eyes. Results show different scaling behaviour between horizontal and vertical movements. When the small ballistic movements, i.e., microsaccades, are removed, the scaling behaviour in both axes becomes similar. Our findings suggest that microsaccades enhance the persistence at short time scales mostly in the horizontal component and much less in the vertical component. We also applied the phase synchronisation decay method to study the synchronisation between six combinations of binocular fixational eye movement components. We found that the vertical-vertical components of right and left eyes are significantly more synchronised than the horizontal-horizontal components. These differences may be due to the need for continuously moving the eyes in the horizontal plane in order to match the stereoscopic image for different viewing distances.
Eye movements during fixation of a stationary target prevent the adaptation of the visual system ... more Eye movements during fixation of a stationary target prevent the adaptation of the visual system to continuous illumination and inhibit fading of the image. These random, involuntary, small movements are restricted at long time scales so as to keep the target at the center of the field of view. Here we use detrended fluctuation analysis in order to study the properties of fixational eye movements at different time scales. Results show different scaling behavior between horizontal and vertical movements. When the small ballistic movements, i.e., microsaccades, are removed, the scaling exponents in both planes become similar. Our findings suggest that microsaccades enhance the persistence at short time scales mostly in the horizontal component and much less in the vertical component. This difference may be due to the need for continuously moving the eyes in the horizontal plane, in order to match the stereoscopic image for different viewing distances.
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