- Email: [email protected]
Ocular artifacts correction: A comparison of efficiency of methods
256
Posters session 2 / International Journal of Psychophysiology 69 (2008) 242–275
ether, and the brains were removed and frozen for analysis. The brains were processed for Nissle-staining in order to determine the number of neurons in the cerebral cortex and for immunohistochemistry in order to determine the number of Fos-positive neurons. Analysis of the behavior showed that rats of all groups were able to learn the task during the last 30-minute session. There were no significant differences found in the number of neurons between “young” and “old” rats in both anterolateral and retrosplenial cortices. Immunohystochemistry showed the decreased number of Fos-positive neurons in the “old” rat somatosensory cortex as compared to “young” ones. There were no significant differences in the number of Fos-positive neurons of “young” and “old” rats in anterolateral or retrosplenial cortices. Our results show that the number of neurons does not differ on different age stages. However, some of those neurons do not undergo plasticity changes anymore as revealed by decreased c-Fos induction in cells. It might be suggested that individual experience growth with age results in the increase in the number of neuronal systems and, at the same time, in reduced susceptibility of neurons to plasticity changes during learning. The research was funded by the Russian Humanitarian Scientific Fond (grants NN 07-06-00450a, 08-06-00250a).
doi:10.1016/j.ijpsycho.2008.05.171 Paradoxical increase of the alpha rhythm during the aiming in marksmen: Component analysis D.A. Napalkov a, S.L. Shishkin b, M.B. Kolikoff c, R.N. Salykhova a, P.O. Ratmanova a, V.V. Shulgovsky a a M.V. Lomonosov Moscow State University, Faculty of Biology, Department of Higher Nervous Activity, Moscow, Russia b M.V. Lomonosov Moscow State University, Faculty of Biology, Department of Human and Animal Physiology, Moscow, Russia c Russian State University of Physical Education, Sport and Tourism, Department of Shooting Sports, Moscow, Russia Skilled marksmen demonstrate a rise of the power of the EEG alpha rhythm during the aiming period, which is especially strong in the left temporal area. This phenomenon has been considered as a correlate of reduced activation in the related cortical areas during automated performance (Hatfield et al., 2004) or shot-related intention (Shaw, 1996). The existing hypotheses, however, do not explain why comparably strong increase of alpha rhythm is not observed in temporal areas in the tasks not related to aiming. Progress in understanding of the mechanisms of the pre-shooting alpha rhythm increase is prevented by the lack of detailed knowledge of its characteristics. We made an attempt to re-examine the phenomenon by more detailed analysis of the alpha rhythm components in frequency and spatial domains. In the first experiment, EEG was recorded at 13 scalp locations in 5 world-class marksmen (members of Russian National team) and 11 novice shooters, and the spectral power was analyzed in alpha 1 (7–9 Hz), alpha 2 (9–11 Hz) and alpha 3 (11–14 Hz) bands. In al these bands, the spectral power decreased in the novices and increased in the marksmen during the aiming period of a target pistol shooting task comparing to eyes open rest condition. The highest values during the aiming period were obtained in the marksmen in alpha 3 band, where they were significantly higher than in novices at all locations except P3 (pb 0.05, Wilcoxon test). At the occipital electrodes, the alpha 3 power increased in the marksmen in the aiming period even comparing with the eyes closed condition (pb 0.05). In the second experiment, the EEG was recorded from 18 locations in two pre-elite marksmen and one beginner level shooter. Using EEGLAB (Delorme & Makeig, 2004), we processed their pre-shooting EEG with Independent Component Analysis (ICA) followed by equivalent current dipole modeling. In all these sportsmen, independent components with amplitude increase in the aiming period relatively to control rest conditions were found. The equivalent dipoles for most of them were located in the left temporal cortex, an area not typical for strong alpha rhythm sources in normal humans. Our preliminary results suggests that the detailed frequency domain and topographical component analysis are useful for the analysis of the phenomenon of the paradoxical pre-shooting alpha rhythm increase and should be applied more intensively to clarify its mechanisms.
doi:10.1016/j.ijpsycho.2008.05.172
Statistical structure of EEG alpha waves in adolescence with schizophrenic spectrum disorders and age-matched normals A.Ju. Zhigalov, A.A. Pyanova, A.Ya. Kaplan Moscow State University, Department of Human Physiology, Moscow, Russian Federation Objective: Adolescence represents a critical period for maturational processes such as synaptic pruning and myelination in the cortex. Previous research in clinical electroencephalography (EEG) has demonstrated that reduction of alpha frequency (8–13 Hz) EEG activity may have particular relevance to the negative symptoms of schizophrenia (J.H.Gruzelier, 2003; V.B.Streletz et al., 2001, 2006). However the studying of alpha activity was carried out mainly by spectral methods which do not show behavior of real alpha waves. Characteristics of amplitudes and the periods of alpha waves can be various at identical spectra. In the present work both approaches of EEG analysis are combined. Methods: To investigate statistical structure of the alpha waves in EEGs spectral FFT and quantitative period analysis (QPA) of EEG for alpha band was applied in 45 drug-naive schizophrenic adolescence (SA) and 39 and age-matched control subjects (CS). In QPA frequency is measured by the real distance between successive peakswaves or zero-cross points, and is unaffected by the contour of the waveform between those points. On the other hand, FFT decomposes a complex waveform into a series of artificial sinusoidal curves and allocates a proportion of the total power. A major feature of the FFT is the ability to conveniently display data in compressed spectral arrays. Peak-detection permits efficient measurement of both the amplitude and the time interval between successive wave-peaks. Since peak-waves detection is essentially a wave-by-wave analysis, the procedure allows for analysis of statistical structure of alpha waves distribution. RESULTS: We applied the Chi-Square and Kolmogorov–Smirnov Statistics to test whether two distributions of amplitudes or periods of EEG alpha waves for SP and CS are the same. It was shown the differences between SP and CS subjects assessed by comparison of amplitude and period histograms mainly for posterior sites of cortex. Expressiveness and direction of these distinctions depend on initial amplitude of waves. The increase in the periods of alpha waves at SP in comparison with CS was typical for 25% of subjects with the biggest amplitudes of EEG alpha activity (the first quartile). Opposite relations were characteristic for subjects concerning to second quartile on EEG alpha of activity. The similar tendency was appreciable for frontal cortex areas. CONCLUSIONS: These results affirm that dependence of EEG alpha frequency from intensity of local synchronization play an important role in the pathophysiology of schizophrenia.
doi:10.1016/j.ijpsycho.2008.05.173 Ocular artifacts correction: A comparison of efficiency of methods E.P. Tereshchenko, V.A. Ponomarev, Y.D. Kropotov Institute of the Human Brain of RAS, Lab. Neurobiology of Action Programming St. Petersburg, Russia Eye movement artifacts present serious problem for electroencephalographic (EEG) and event-related potential (ERP) data analysis. The most commonly used method for artifacts elimination is rejecting EEG epochs contaminated by eye movement using threshold voltage criteria. Alternatively, a variety of procedures have been proposed to correct ocular artifacts in the EEG, including methods based on regression, principal component analysis (PCA) and independent component analysis (ICA). The current study compared four of these ocular artifacts correction methods and evaluated their efficiency with quantitative EEG and visual ERP analysis. Advantages and disadvantages of the different methods were discussed. We applied each artifact correction procedure to EEG data collected from 70 healthy children from 7 to 14 years performing a visual two-stimulus task (modification of tests employing the GO/NOGO paradigm). Then we quantified the influence of correction procedure on both spectral parameters of the EEG and amplitude of the ERP. The average power of EEG within the theta (4–8 Hz), alpha (8–12 Hz) and beta (12–18 Hz) bands were computed, and correction related changes for each of last three methods and each electrode site was estimated in comparison with the standard method of artifact rejection. Similarly, the average voltage in the 280–380 ms in Pz channel (P3 component for “GO” condition) was used to assess the distortion
Posters session 2 / International Journal of Psychophysiology 69 (2008) 242–275
of ERPs related to artifacts correction procedure. These correction related errors were analyzed for different types of reference montages: linked eyes reference, average reference and weighted average reference. Results have shown that all correction methods effectively reduced ocular artifacts and resulted in relatively small spectral and ERPs distortion independently of references type in most channels of EEG excepting frontal channels (Fp1/Fp2) in case PCA/ICA correction. On the other hand any correction procedure, especially PCA/ICA correction, significantly increases total number of averaging artifact-free epochs or trials that results in better accuracy of estimation of spectral parameters EEG or ERPs parameters. Results supported the use of all analyzed methods of ocular artifact correction but suggested an expediency of wide introduction of PCA/ICA methods in fundamental and applied researches of qEEG and event-related potentials.
doi:10.1016/j.ijpsycho.2008.05.174 Skin conductance versus mental sweating responses to emotional pictures in Japanese men M. Taisne a, T. Kobayashi b, O. Mandai b, H. Sequeira a,c Laboratoire de Neurosciences Fonctionnelles et Pathologies, CNRS, Lille, France b Sleep Research Center, Ashikaga Institute of Technology, Ashikaga, Japan c Neurosciences, Université de Lille 1, Villeneuve d'Ascq, France
a
Autonomic indices are relevant markers classically used to evaluate the somatic impact of emotional processing. In this frame, the electrical activity of eccrine sweat glands, usually recorded as skin conductance (SC), is a very wideused activity allowing to index orientation behavior, motor activity, cognitive processes or emotional states. The major inconvenience of the SC method is related to interferences caused by metallic recording electrodes, when associated with magnetic-sensitive techniques such as fMRI or magnetoencephalography. In a parallel direction some Japanese research teams developed the mental sweating (MS) method which directly records the skin hygrometry related to sweat glands function thanks to a non-metallic probe. Although SC and MS are clearly dependent on sweating activity, no study has correlated the dynamic of both indices in response to the same stimulation. In a first step, we tried to validate MS parameters in comparison with SC classical ones. In a second step, we determined the relevance of MS method to discriminate valence and arousal dimensions of affective pictures. Thirty right-handed Japanese male (21 ± 1 years) took part in the experiment. SC and MS responses were simultaneously recorded. Some tasks were asked to be completed (deep breathing, leg flexion, mental calculation) to ensure to correctly elicit both signals. Then 30 emotional pictures (10 pleasant, 10 neutral and 10 unpleasant) from the International Affective Picture System (IAPS) were presented on a screen for 2 s and participants had to feel as if the scene was happening for real. Afterwards they had to complete the Self Assessment Manikin (SAM) for each picture. The analysis showed a strong correlation for amplitude (higher than .50; p b 0.005) and for area under curve (higher than .60; p b 0.0001) for SC and MS responses. The latency, one-second longer for MS responses, was also correlated (higher than .70; p b 0.0001). Moreover, as for SC responses, MS responses amplitude was correlated with estimated activation values of IAPS pictures. In conclusion, MS responses could be used as a reliable indicator of autonomic activation induced by affective pictures during magnetic neuroimaging brain exploration.
doi:10.1016/j.ijpsycho.2008.05.175 The condition and correction of the homeostatic system of MS patients Z.A. Goncharova Rostov State Medical University, Department of Neurology and Neurosurgery, Rostov-on-Don, Russia On the model of demyelinating diseases – experimental allergic encephalomyelitis (EAE) – we determined the significance pf meaning of certain indices of kallikrein–kinin, antioxidant and immune systems in predicting the clinical EAE manifestations and the possibility to influence the correction process of these indices (Vilkov G.A. et al., 1993). Thus, Unitiol introduction, normalizing the kallikrein activity, prevented the EAE progressing, antioxidants prevented
257
the EAE progressing in guinea-pigs, prooxidants intensified the process in white rats tolerant to EAE. The results were received due to the dynamic study of the required amounts of serum in reproducing EAE on dogs. Similar studies were conducted on MS patients. We have come to the conclusion, that the changes in the adaptive homeostatic systems long before the exacerbation process are principally of the same character. Thus, it is possible not only to predict but also, which is more important, take timely measures with the use of antioxidants, hepatoprotectors, enterosorbents, normalizing the functions of homeostatic system and positively modifying the course of MS. Such correction, along with the traditional methods of treatment, helps to avoid exacerbation and make remission period last longer. We have assessed in dynamics the state of freeradicals oxidation (FRO) and antioxidant system (AOS) by means of chemiluminescence of blood serum (Vladimirov Y.A et al., 1976) in 60 MS patients diagnosed according to Poser's criteria (C.M.Poser et al., 1983) in the state of remission. Chemiluminescence analysis showed a considerable decrease of АОS capacity and the tendency towards the FRO stabilization process as compared to the exacerbation period. The absence of restorative tendencies in AOS is obviously due to the continuity of the neuroimmune degrading process, though not so intensive, even during the remission period. The first group of patients (n = 34) received antioxidant therapy (tokoferoli acetatis, trioviti).The length of therapy was individual and depended on the normalization of the analyzed indices. The second group of patients (n = 26) did not receive antioxidant treatment. The first group of patients had an average remission period of 2.4 ± 0.2 years, which is significantly longer (p b 0.05) if compared to the second group (0.7± 0.1 year).The analysis of chemiluminescence indices has shown the increase of AOS capacity during antioxidant treatment in the first group while there has been further exhaustion of AOS in the second group. The clinical efficiency of the AOS correction can be explained by the fact, that the disease emerges due to the combination of genetic susceptibility and the negative effect of environmental factors (stresses, xenobiotics). The normalization of homeostasis leads to the stabilization of the process. Explicit positive effect of the antioxidant therapy proves pathogenetic importance of the disorder in lipid peroxidation of MS patients and stresses the advisability of antioxidant treatment in order to prolong remission.
doi:10.1016/j.ijpsycho.2008.05.176 An analysis of saccadic eye movement parameters as a technique for diagnosis and therapy control of Parkinson's disease P.O. Ratmanova a, R.R. Bogdanov b, D.A. Napalkov a M.V. Lomonosov Moscow State University, Faculty of Biology, Department of Higher Nervous Activity, Moscow, Russia b M.F. Vladimirsky Moscow Regional Research Clinical Institute, Department of Neurology, Moscow, Russia
a
At present neurological methods are mainly used for diagnosis and treatment control of Parkinson's disease. They are based upon the evaluation of main symptoms of the disease: hypokinesia, rigidity, and tremor. As matters stand, some of the measurements in rating scales are depended on subjective judgment of a neurologist. Furthermore, the main motor symptoms only appear just when 60–80% of the dopamine neurons in the substantia nigra are dead. Thus, there is great demand for developing objective instrument techniques for early diagnosis and medication treatment control of this disease. The aim of the current research is to estimate the validity of the analysis of saccadic eye movement parameters as one of the methods of objective investigation. Patients with a clinical diagnosis of idiopathic Parkinson's disease were examined and compared with control subjects of the same age, who showed no evidence of neurological disorders. None of the parkinsonian patients were receiving any anti-parkinsonian treatment before the examination. Before the course of medication all patients demonstrated hypokinesia, rigidity and tremor, which constitute basic motor syndrome in Parkinson's disease. Along with the symptoms changes in saccadic eye movement parameters were revealed in all patients with Parkinson's disease. The mean saccade latency increased in the patients compared to the control group. Also, patients demonstrated a longer mean time of the gaze shift than control participants. After an additional analysis we found the cause of the mean time increase of the gaze shift. As it turned out, the percentage of the particular saccades (multistep saccades) rose in the patients with Parkinson's disease. In these cases not one but two or three saccades were performed with smaller amplitudes. The changes in saccadic eye movement parameters were more
Posters session 2 / International Journal of Psychophysiology 69 (2008) 242–275
ether, and the brains were removed and frozen for analysis. The brains were processed for Nissle-staining in order to determine the number of neurons in the cerebral cortex and for immunohistochemistry in order to determine the number of Fos-positive neurons. Analysis of the behavior showed that rats of all groups were able to learn the task during the last 30-minute session. There were no significant differences found in the number of neurons between “young” and “old” rats in both anterolateral and retrosplenial cortices. Immunohystochemistry showed the decreased number of Fos-positive neurons in the “old” rat somatosensory cortex as compared to “young” ones. There were no significant differences in the number of Fos-positive neurons of “young” and “old” rats in anterolateral or retrosplenial cortices. Our results show that the number of neurons does not differ on different age stages. However, some of those neurons do not undergo plasticity changes anymore as revealed by decreased c-Fos induction in cells. It might be suggested that individual experience growth with age results in the increase in the number of neuronal systems and, at the same time, in reduced susceptibility of neurons to plasticity changes during learning. The research was funded by the Russian Humanitarian Scientific Fond (grants NN 07-06-00450a, 08-06-00250a).
doi:10.1016/j.ijpsycho.2008.05.171 Paradoxical increase of the alpha rhythm during the aiming in marksmen: Component analysis D.A. Napalkov a, S.L. Shishkin b, M.B. Kolikoff c, R.N. Salykhova a, P.O. Ratmanova a, V.V. Shulgovsky a a M.V. Lomonosov Moscow State University, Faculty of Biology, Department of Higher Nervous Activity, Moscow, Russia b M.V. Lomonosov Moscow State University, Faculty of Biology, Department of Human and Animal Physiology, Moscow, Russia c Russian State University of Physical Education, Sport and Tourism, Department of Shooting Sports, Moscow, Russia Skilled marksmen demonstrate a rise of the power of the EEG alpha rhythm during the aiming period, which is especially strong in the left temporal area. This phenomenon has been considered as a correlate of reduced activation in the related cortical areas during automated performance (Hatfield et al., 2004) or shot-related intention (Shaw, 1996). The existing hypotheses, however, do not explain why comparably strong increase of alpha rhythm is not observed in temporal areas in the tasks not related to aiming. Progress in understanding of the mechanisms of the pre-shooting alpha rhythm increase is prevented by the lack of detailed knowledge of its characteristics. We made an attempt to re-examine the phenomenon by more detailed analysis of the alpha rhythm components in frequency and spatial domains. In the first experiment, EEG was recorded at 13 scalp locations in 5 world-class marksmen (members of Russian National team) and 11 novice shooters, and the spectral power was analyzed in alpha 1 (7–9 Hz), alpha 2 (9–11 Hz) and alpha 3 (11–14 Hz) bands. In al these bands, the spectral power decreased in the novices and increased in the marksmen during the aiming period of a target pistol shooting task comparing to eyes open rest condition. The highest values during the aiming period were obtained in the marksmen in alpha 3 band, where they were significantly higher than in novices at all locations except P3 (pb 0.05, Wilcoxon test). At the occipital electrodes, the alpha 3 power increased in the marksmen in the aiming period even comparing with the eyes closed condition (pb 0.05). In the second experiment, the EEG was recorded from 18 locations in two pre-elite marksmen and one beginner level shooter. Using EEGLAB (Delorme & Makeig, 2004), we processed their pre-shooting EEG with Independent Component Analysis (ICA) followed by equivalent current dipole modeling. In all these sportsmen, independent components with amplitude increase in the aiming period relatively to control rest conditions were found. The equivalent dipoles for most of them were located in the left temporal cortex, an area not typical for strong alpha rhythm sources in normal humans. Our preliminary results suggests that the detailed frequency domain and topographical component analysis are useful for the analysis of the phenomenon of the paradoxical pre-shooting alpha rhythm increase and should be applied more intensively to clarify its mechanisms.
doi:10.1016/j.ijpsycho.2008.05.172
Statistical structure of EEG alpha waves in adolescence with schizophrenic spectrum disorders and age-matched normals A.Ju. Zhigalov, A.A. Pyanova, A.Ya. Kaplan Moscow State University, Department of Human Physiology, Moscow, Russian Federation Objective: Adolescence represents a critical period for maturational processes such as synaptic pruning and myelination in the cortex. Previous research in clinical electroencephalography (EEG) has demonstrated that reduction of alpha frequency (8–13 Hz) EEG activity may have particular relevance to the negative symptoms of schizophrenia (J.H.Gruzelier, 2003; V.B.Streletz et al., 2001, 2006). However the studying of alpha activity was carried out mainly by spectral methods which do not show behavior of real alpha waves. Characteristics of amplitudes and the periods of alpha waves can be various at identical spectra. In the present work both approaches of EEG analysis are combined. Methods: To investigate statistical structure of the alpha waves in EEGs spectral FFT and quantitative period analysis (QPA) of EEG for alpha band was applied in 45 drug-naive schizophrenic adolescence (SA) and 39 and age-matched control subjects (CS). In QPA frequency is measured by the real distance between successive peakswaves or zero-cross points, and is unaffected by the contour of the waveform between those points. On the other hand, FFT decomposes a complex waveform into a series of artificial sinusoidal curves and allocates a proportion of the total power. A major feature of the FFT is the ability to conveniently display data in compressed spectral arrays. Peak-detection permits efficient measurement of both the amplitude and the time interval between successive wave-peaks. Since peak-waves detection is essentially a wave-by-wave analysis, the procedure allows for analysis of statistical structure of alpha waves distribution. RESULTS: We applied the Chi-Square and Kolmogorov–Smirnov Statistics to test whether two distributions of amplitudes or periods of EEG alpha waves for SP and CS are the same. It was shown the differences between SP and CS subjects assessed by comparison of amplitude and period histograms mainly for posterior sites of cortex. Expressiveness and direction of these distinctions depend on initial amplitude of waves. The increase in the periods of alpha waves at SP in comparison with CS was typical for 25% of subjects with the biggest amplitudes of EEG alpha activity (the first quartile). Opposite relations were characteristic for subjects concerning to second quartile on EEG alpha of activity. The similar tendency was appreciable for frontal cortex areas. CONCLUSIONS: These results affirm that dependence of EEG alpha frequency from intensity of local synchronization play an important role in the pathophysiology of schizophrenia.
doi:10.1016/j.ijpsycho.2008.05.173 Ocular artifacts correction: A comparison of efficiency of methods E.P. Tereshchenko, V.A. Ponomarev, Y.D. Kropotov Institute of the Human Brain of RAS, Lab. Neurobiology of Action Programming St. Petersburg, Russia Eye movement artifacts present serious problem for electroencephalographic (EEG) and event-related potential (ERP) data analysis. The most commonly used method for artifacts elimination is rejecting EEG epochs contaminated by eye movement using threshold voltage criteria. Alternatively, a variety of procedures have been proposed to correct ocular artifacts in the EEG, including methods based on regression, principal component analysis (PCA) and independent component analysis (ICA). The current study compared four of these ocular artifacts correction methods and evaluated their efficiency with quantitative EEG and visual ERP analysis. Advantages and disadvantages of the different methods were discussed. We applied each artifact correction procedure to EEG data collected from 70 healthy children from 7 to 14 years performing a visual two-stimulus task (modification of tests employing the GO/NOGO paradigm). Then we quantified the influence of correction procedure on both spectral parameters of the EEG and amplitude of the ERP. The average power of EEG within the theta (4–8 Hz), alpha (8–12 Hz) and beta (12–18 Hz) bands were computed, and correction related changes for each of last three methods and each electrode site was estimated in comparison with the standard method of artifact rejection. Similarly, the average voltage in the 280–380 ms in Pz channel (P3 component for “GO” condition) was used to assess the distortion
Posters session 2 / International Journal of Psychophysiology 69 (2008) 242–275
of ERPs related to artifacts correction procedure. These correction related errors were analyzed for different types of reference montages: linked eyes reference, average reference and weighted average reference. Results have shown that all correction methods effectively reduced ocular artifacts and resulted in relatively small spectral and ERPs distortion independently of references type in most channels of EEG excepting frontal channels (Fp1/Fp2) in case PCA/ICA correction. On the other hand any correction procedure, especially PCA/ICA correction, significantly increases total number of averaging artifact-free epochs or trials that results in better accuracy of estimation of spectral parameters EEG or ERPs parameters. Results supported the use of all analyzed methods of ocular artifact correction but suggested an expediency of wide introduction of PCA/ICA methods in fundamental and applied researches of qEEG and event-related potentials.
doi:10.1016/j.ijpsycho.2008.05.174 Skin conductance versus mental sweating responses to emotional pictures in Japanese men M. Taisne a, T. Kobayashi b, O. Mandai b, H. Sequeira a,c Laboratoire de Neurosciences Fonctionnelles et Pathologies, CNRS, Lille, France b Sleep Research Center, Ashikaga Institute of Technology, Ashikaga, Japan c Neurosciences, Université de Lille 1, Villeneuve d'Ascq, France
a
Autonomic indices are relevant markers classically used to evaluate the somatic impact of emotional processing. In this frame, the electrical activity of eccrine sweat glands, usually recorded as skin conductance (SC), is a very wideused activity allowing to index orientation behavior, motor activity, cognitive processes or emotional states. The major inconvenience of the SC method is related to interferences caused by metallic recording electrodes, when associated with magnetic-sensitive techniques such as fMRI or magnetoencephalography. In a parallel direction some Japanese research teams developed the mental sweating (MS) method which directly records the skin hygrometry related to sweat glands function thanks to a non-metallic probe. Although SC and MS are clearly dependent on sweating activity, no study has correlated the dynamic of both indices in response to the same stimulation. In a first step, we tried to validate MS parameters in comparison with SC classical ones. In a second step, we determined the relevance of MS method to discriminate valence and arousal dimensions of affective pictures. Thirty right-handed Japanese male (21 ± 1 years) took part in the experiment. SC and MS responses were simultaneously recorded. Some tasks were asked to be completed (deep breathing, leg flexion, mental calculation) to ensure to correctly elicit both signals. Then 30 emotional pictures (10 pleasant, 10 neutral and 10 unpleasant) from the International Affective Picture System (IAPS) were presented on a screen for 2 s and participants had to feel as if the scene was happening for real. Afterwards they had to complete the Self Assessment Manikin (SAM) for each picture. The analysis showed a strong correlation for amplitude (higher than .50; p b 0.005) and for area under curve (higher than .60; p b 0.0001) for SC and MS responses. The latency, one-second longer for MS responses, was also correlated (higher than .70; p b 0.0001). Moreover, as for SC responses, MS responses amplitude was correlated with estimated activation values of IAPS pictures. In conclusion, MS responses could be used as a reliable indicator of autonomic activation induced by affective pictures during magnetic neuroimaging brain exploration.
doi:10.1016/j.ijpsycho.2008.05.175 The condition and correction of the homeostatic system of MS patients Z.A. Goncharova Rostov State Medical University, Department of Neurology and Neurosurgery, Rostov-on-Don, Russia On the model of demyelinating diseases – experimental allergic encephalomyelitis (EAE) – we determined the significance pf meaning of certain indices of kallikrein–kinin, antioxidant and immune systems in predicting the clinical EAE manifestations and the possibility to influence the correction process of these indices (Vilkov G.A. et al., 1993). Thus, Unitiol introduction, normalizing the kallikrein activity, prevented the EAE progressing, antioxidants prevented
257
the EAE progressing in guinea-pigs, prooxidants intensified the process in white rats tolerant to EAE. The results were received due to the dynamic study of the required amounts of serum in reproducing EAE on dogs. Similar studies were conducted on MS patients. We have come to the conclusion, that the changes in the adaptive homeostatic systems long before the exacerbation process are principally of the same character. Thus, it is possible not only to predict but also, which is more important, take timely measures with the use of antioxidants, hepatoprotectors, enterosorbents, normalizing the functions of homeostatic system and positively modifying the course of MS. Such correction, along with the traditional methods of treatment, helps to avoid exacerbation and make remission period last longer. We have assessed in dynamics the state of freeradicals oxidation (FRO) and antioxidant system (AOS) by means of chemiluminescence of blood serum (Vladimirov Y.A et al., 1976) in 60 MS patients diagnosed according to Poser's criteria (C.M.Poser et al., 1983) in the state of remission. Chemiluminescence analysis showed a considerable decrease of АОS capacity and the tendency towards the FRO stabilization process as compared to the exacerbation period. The absence of restorative tendencies in AOS is obviously due to the continuity of the neuroimmune degrading process, though not so intensive, even during the remission period. The first group of patients (n = 34) received antioxidant therapy (tokoferoli acetatis, trioviti).The length of therapy was individual and depended on the normalization of the analyzed indices. The second group of patients (n = 26) did not receive antioxidant treatment. The first group of patients had an average remission period of 2.4 ± 0.2 years, which is significantly longer (p b 0.05) if compared to the second group (0.7± 0.1 year).The analysis of chemiluminescence indices has shown the increase of AOS capacity during antioxidant treatment in the first group while there has been further exhaustion of AOS in the second group. The clinical efficiency of the AOS correction can be explained by the fact, that the disease emerges due to the combination of genetic susceptibility and the negative effect of environmental factors (stresses, xenobiotics). The normalization of homeostasis leads to the stabilization of the process. Explicit positive effect of the antioxidant therapy proves pathogenetic importance of the disorder in lipid peroxidation of MS patients and stresses the advisability of antioxidant treatment in order to prolong remission.
doi:10.1016/j.ijpsycho.2008.05.176 An analysis of saccadic eye movement parameters as a technique for diagnosis and therapy control of Parkinson's disease P.O. Ratmanova a, R.R. Bogdanov b, D.A. Napalkov a M.V. Lomonosov Moscow State University, Faculty of Biology, Department of Higher Nervous Activity, Moscow, Russia b M.F. Vladimirsky Moscow Regional Research Clinical Institute, Department of Neurology, Moscow, Russia
a
At present neurological methods are mainly used for diagnosis and treatment control of Parkinson's disease. They are based upon the evaluation of main symptoms of the disease: hypokinesia, rigidity, and tremor. As matters stand, some of the measurements in rating scales are depended on subjective judgment of a neurologist. Furthermore, the main motor symptoms only appear just when 60–80% of the dopamine neurons in the substantia nigra are dead. Thus, there is great demand for developing objective instrument techniques for early diagnosis and medication treatment control of this disease. The aim of the current research is to estimate the validity of the analysis of saccadic eye movement parameters as one of the methods of objective investigation. Patients with a clinical diagnosis of idiopathic Parkinson's disease were examined and compared with control subjects of the same age, who showed no evidence of neurological disorders. None of the parkinsonian patients were receiving any anti-parkinsonian treatment before the examination. Before the course of medication all patients demonstrated hypokinesia, rigidity and tremor, which constitute basic motor syndrome in Parkinson's disease. Along with the symptoms changes in saccadic eye movement parameters were revealed in all patients with Parkinson's disease. The mean saccade latency increased in the patients compared to the control group. Also, patients demonstrated a longer mean time of the gaze shift than control participants. After an additional analysis we found the cause of the mean time increase of the gaze shift. As it turned out, the percentage of the particular saccades (multistep saccades) rose in the patients with Parkinson's disease. In these cases not one but two or three saccades were performed with smaller amplitudes. The changes in saccadic eye movement parameters were more