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Roberto Cantello - One of the best experts on this subject based on the ideXlab platform.

  • Intermittent Photic Stimulation affects motor cortex excitability in photosensitive idiopathic generalized epilepsy
    Epilepsy Research, 2012
    Co-Authors: Gionata Strigaro, Paolo Prandi, Claudia Varrasi, Luca Magistrelli, Lina Falletta, Roberto Cantello
    Abstract:

    Summary Purpose To assess the effect of Intermittent Photic Stimulation (IPS) at a common activating frequency, i.e. 20 Hz, on motor cortex excitability by means of transcranial magnetic Stimulation (TMS) in photosensitive patients with idiopathic generalized epilepsy (IGE). Methods We studied 15 photosensitive IGE patients showing a photoparoxysmal response (PPR) to IPS at 20 Hz. Nineteen normal subjects of similar age and sex acted as controls. After the resting motor threshold (rMT) was measured, we studied the corticomotor excitability in two conditions randomly delivered, during IPS (5 s) at 20 Hz and without IPS. Motor evoked potentials (MEPs) were recorded from the right first dorsal interosseous muscle (FDI). We determined the cortical silent period (cSP), the short-latency intracortical inhibition (SICI) at the interstimulus interval (ISI) of 3 and 4 ms and the intracortical facilitation (ICF) at ISIs of 12 and 14 ms. Data were analyzed by means of rmANOVAs. Results IPS at 20 Hz is significantly shortening the cSP in normal subjects, while no significant changes were detected in patients. The rMT was significantly higher in patients than controls, as expected by the concurrent antiepileptic treatment. Other corticomotor excitability measures were unaffected. Conclusions We confirm that IPS has a weak influence on the motor cortical output in patients with IGE and PPR. The loss of the normal shortening of the cSP, otherwise present in healthy subjects in response to IPS, may have a possible protective nature.

  • Intermittent Photic Stimulation affects motor cortex excitability in photosensitive idiopathic generalized epilepsy.
    Epilepsy research, 2012
    Co-Authors: Gionata Strigaro, Paolo Prandi, Claudia Varrasi, Luca Magistrelli, Lina Falletta, Roberto Cantello
    Abstract:

    To assess the effect of Intermittent Photic Stimulation (IPS) at a common activating frequency, i.e. 20Hz, on motor cortex excitability by means of transcranial magnetic Stimulation (TMS) in photosensitive patients with idiopathic generalized epilepsy (IGE). We studied 15 photosensitive IGE patients showing a photoparoxysmal response (PPR) to IPS at 20Hz. Nineteen normal subjects of similar age and sex acted as controls. After the resting motor threshold (rMT) was measured, we studied the corticomotor excitability in two conditions randomly delivered, during IPS (5s) at 20Hz and without IPS. Motor evoked potentials (MEPs) were recorded from the right first dorsal interosseous muscle (FDI). We determined the cortical silent period (cSP), the short-latency intracortical inhibition (SICI) at the interstimulus interval (ISI) of 3 and 4ms and the intracortical facilitation (ICF) at ISIs of 12 and 14ms. Data were analyzed by means of rmANOVAs. IPS at 20Hz is significantly shortening the cSP in normal subjects, while no significant changes were detected in patients. The rMT was significantly higher in patients than controls, as expected by the concurrent antiepileptic treatment. Other corticomotor excitability measures were unaffected. We confirm that IPS has a weak influence on the motor cortical output in patients with IGE and PPR. The loss of the normal shortening of the cSP, otherwise present in healthy subjects in response to IPS, may have a possible protective nature. Copyright © 2012 Elsevier B.V. All rights reserved.

Harry T. Chugani - One of the best experts on this subject based on the ideXlab platform.

  • Brain activation during Intermittent Photic Stimulation: a [15O]-water PET study on photosensitive epilepsy.
    Epilepsia, 1999
    Co-Authors: Ednéa A. Da Silva, Ralph-axel Müller, Diane C. Chugani, Jagdish Shah, Aashit Shah, Craig Watson, Harry T. Chugani
    Abstract:

    Purpose Intermittent Photic Stimulation (IPS) is an activation procedure used during electroencephalogram (EEG) recording to elicit paroxysmal discharges in individuals with photosensitivity. Specific responses on EEG recording may be provoked by IPS at different frequencies of flickering in normal individuals and in patients with photosensitive epilepsy. Methods Changes in regional cerebral blood flow (rCBF) were studied during IPS in two groups of subjects by using [15O]-water positron emission tomography (PET): a control group consisting of eight healthy adults with Photic driving response during IPS on EEG recording (mean age, 25 +/- 10.5 years) without history of neurologic or psychiatric abnormalities and a patient group consisting of four adults (mean age, 33 +/- 7.5 years) with history of photosensitive epilepsy. [15O]-water PET scanning with concomitant EEG monitoring was performed during baseline and IPS at 4-, 14-, and 30-Hz frequencies. Results The control group showed Photic driving response at 14-Hz IPS frequency. The patient group showed photoparoxysmal response at 14 and 30 Hz, but not at 4 Hz. Changes in rCBF were determined by means of statistical parametric mapping. Increases in rCBF in occipital cortex (Brodmann's areas 17, 18, and 19) were observed in both groups. In addition, during Photic driving responses, the control group showed rCBF increases in the insula and in the thalamus, on the right side. The patient group showed a significant rCBF increase in the hypothalamic region inferior to the left caudate nucleus during photoparoxysmal response. This activation was not found in the control group. Increased rCBF also was observed in the patient group in the head of the left caudate nucleus, in the left hippocampus, and in left insula during IPS without photoparoxysmal response. No activations in these regions were observed during photoparoxysmal response. Conclusions These data may indicate involvement of the hypothalamus in photosensitive epilepsy and may suggest a modulatory function of the caudate nucleus, which might be associated with an inhibition of epileptic discharges during IPS in patients with photosensitive epilepsy.

  • Brain activation during Intermittent Photic Stimulation: a [15O]-water PET study on photosensitive epilepsy.
    Epilepsia, 1999
    Co-Authors: Ednéa A. Da Silva, Ralph-axel Müller, Diane C. Chugani, Jagdish Shah, Aashit Shah, Craig Watson, Harry T. Chugani
    Abstract:

    Intermittent Photic Stimulation (IPS) is an activation procedure used during electroencephalogram (EEG) recording to elicit paroxysmal discharges in individuals with photosensitivity. Specific responses on EEG recording may be provoked by IPS at different frequencies of flickering in normal individuals and in patients with photosensitive epilepsy. Changes in regional cerebral blood flow (rCBF) were studied during IPS in two groups of subjects by using [15O]-water positron emission tomography (PET): a control group consisting of eight healthy adults with Photic driving response during IPS on EEG recording (mean age, 25 +/- 10.5 years) without history of neurologic or psychiatric abnormalities and a patient group consisting of four adults (mean age, 33 +/- 7.5 years) with history of photosensitive epilepsy. [15O]-water PET scanning with concomitant EEG monitoring was performed during baseline and IPS at 4-, 14-, and 30-Hz frequencies. The control group showed Photic driving response at 14-Hz IPS frequency. The patient group showed photoparoxysmal response at 14 and 30 Hz, but not at 4 Hz. Changes in rCBF were determined by means of statistical parametric mapping. Increases in rCBF in occipital cortex (Brodmann's areas 17, 18, and 19) were observed in both groups. In addition, during Photic driving responses, the control group showed rCBF increases in the insula and in the thalamus, on the right side. The patient group showed a significant rCBF increase in the hypothalamic region inferior to the left caudate nucleus during photoparoxysmal response. This activation was not found in the control group. Increased rCBF also was observed in the patient group in the head of the left caudate nucleus, in the left hippocampus, and in left insula during IPS without photoparoxysmal response. No activations in these regions were observed during photoparoxysmal response. These data may indicate involvement of the hypothalamus in photosensitive epilepsy and may suggest a modulatory function of the caudate nucleus, which might be associated with an inhibition of epileptic discharges during IPS in patients with photosensitive epilepsy.

Gionata Strigaro - One of the best experts on this subject based on the ideXlab platform.

  • Intermittent Photic Stimulation affects motor cortex excitability in photosensitive idiopathic generalized epilepsy
    Epilepsy Research, 2012
    Co-Authors: Gionata Strigaro, Paolo Prandi, Claudia Varrasi, Luca Magistrelli, Lina Falletta, Roberto Cantello
    Abstract:

    Summary Purpose To assess the effect of Intermittent Photic Stimulation (IPS) at a common activating frequency, i.e. 20 Hz, on motor cortex excitability by means of transcranial magnetic Stimulation (TMS) in photosensitive patients with idiopathic generalized epilepsy (IGE). Methods We studied 15 photosensitive IGE patients showing a photoparoxysmal response (PPR) to IPS at 20 Hz. Nineteen normal subjects of similar age and sex acted as controls. After the resting motor threshold (rMT) was measured, we studied the corticomotor excitability in two conditions randomly delivered, during IPS (5 s) at 20 Hz and without IPS. Motor evoked potentials (MEPs) were recorded from the right first dorsal interosseous muscle (FDI). We determined the cortical silent period (cSP), the short-latency intracortical inhibition (SICI) at the interstimulus interval (ISI) of 3 and 4 ms and the intracortical facilitation (ICF) at ISIs of 12 and 14 ms. Data were analyzed by means of rmANOVAs. Results IPS at 20 Hz is significantly shortening the cSP in normal subjects, while no significant changes were detected in patients. The rMT was significantly higher in patients than controls, as expected by the concurrent antiepileptic treatment. Other corticomotor excitability measures were unaffected. Conclusions We confirm that IPS has a weak influence on the motor cortical output in patients with IGE and PPR. The loss of the normal shortening of the cSP, otherwise present in healthy subjects in response to IPS, may have a possible protective nature.

  • Intermittent Photic Stimulation affects motor cortex excitability in photosensitive idiopathic generalized epilepsy.
    Epilepsy research, 2012
    Co-Authors: Gionata Strigaro, Paolo Prandi, Claudia Varrasi, Luca Magistrelli, Lina Falletta, Roberto Cantello
    Abstract:

    To assess the effect of Intermittent Photic Stimulation (IPS) at a common activating frequency, i.e. 20Hz, on motor cortex excitability by means of transcranial magnetic Stimulation (TMS) in photosensitive patients with idiopathic generalized epilepsy (IGE). We studied 15 photosensitive IGE patients showing a photoparoxysmal response (PPR) to IPS at 20Hz. Nineteen normal subjects of similar age and sex acted as controls. After the resting motor threshold (rMT) was measured, we studied the corticomotor excitability in two conditions randomly delivered, during IPS (5s) at 20Hz and without IPS. Motor evoked potentials (MEPs) were recorded from the right first dorsal interosseous muscle (FDI). We determined the cortical silent period (cSP), the short-latency intracortical inhibition (SICI) at the interstimulus interval (ISI) of 3 and 4ms and the intracortical facilitation (ICF) at ISIs of 12 and 14ms. Data were analyzed by means of rmANOVAs. IPS at 20Hz is significantly shortening the cSP in normal subjects, while no significant changes were detected in patients. The rMT was significantly higher in patients than controls, as expected by the concurrent antiepileptic treatment. Other corticomotor excitability measures were unaffected. We confirm that IPS has a weak influence on the motor cortical output in patients with IGE and PPR. The loss of the normal shortening of the cSP, otherwise present in healthy subjects in response to IPS, may have a possible protective nature. Copyright © 2012 Elsevier B.V. All rights reserved.

Vladimir V. Lazarev - One of the best experts on this subject based on the ideXlab platform.

  • Experimental-design Specific Changes in Spontaneous EEG and During Intermittent Photic Stimulation by High Definition Transcranial Direct Current Stimulation.
    Neuroscience, 2019
    Co-Authors: Vladimir V. Lazarev, Nigel Gebodh, T. Tamborino, Marom Bikson, Egas M. Caparelli-dáquer
    Abstract:

    Abstract Electroencephalography (EEG) as a biomarker of neuromodulation by High Definition transcranial Direct Current Stimulation (HD-tDCS) offers promise as both techniques are deployable and can be integrated into a single head-gear. The present research addresses experimental design for separating focal EEG effect of HD-tDCS in the ‘4-cathode × 1-anode’ (4 × 1) montage over the left motor area (C3). We assessed change in offline EEG at the homologous central (C3, C4), and occipital (O1, O2) locations. Interhemispheric asymmetry was accessed for background EEG at standard frequency bands; and for the Intermittent Photic Stimulation (IPS). EEG was compared post- vs pre-intervention in three HD-tDCS arms: Active (2 mA), Sham (ramp up/down at the start and end), and No-Stimulation (device was not powered), each intervention lasting 20 min. The asymmetric background EEG changes were only in the central areas with right-side amplitude spectra prevalence, most pronounced in the no-Stimulation arm, where they depended on comparison time-points and were consistent with markers of transition between drowsiness and vigilance – bilateral decrease in the delta and asymmetric central increase in the alpha and beta1 bands. For the active arm, similar but less pronounced changes occurred in the alpha band. In contrast, responses to IPS developed similar asymmetric amplitude increase at four harmonics of the IPS of 3 Hz only in the active arm, against a background of a brain-wide symmetric increase in both active and sham arms. Our protocols and analyses suggest methodological caveats for how EEG of tDCS studies could be conducted to isolate putative brain polarization outcomes.

  • Evaluating the Event-Related Synchronization and Desynchronization by means of a Statistical Frequency Test
    2007 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2007
    Co-Authors: Antonio Fernando C. Infantosi, Vladimir V. Lazarev
    Abstract:

    In the present work, a commonly used index for evaluating the Event-Related Synchronization and Desynchronization (ERS/ERD) in the EEGwas expressed as a function of the Spectral F-Test (SFT), which is a statistical test for assessing if two sample spectra are from populations with identical theoretical spectra. The sampling distribution of SFT has been derived, allowing hence ERS/ERD to be evaluated under a statistical basis. An example of the technique was also provided in the EEG signals from 10 normal subjects during Intermittent Photic Stimulation.

  • Spectral F-test power evaluation in the EEG during Intermittent Photic Stimulation.
    Arquivos de neuro-psiquiatria, 2006
    Co-Authors: Mauricio Cagy, Vladimir V. Lazarev, Antonio Fernando Catelli Infantosi
    Abstract:

    Intermittent Photic Stimulation (IPS) is an important functional test, which can induce the Photic driving in the electroencephalogram (EEG). It is capable of enhancing latent oscillation’s manifestations not present in the resting EEG. However, for adequate quantitative evaluation of the Photic driving, these changes should be assessed on a statistical basis. With this aim, the sampling distribution of spectral F test was investigated. On this basis, confidence limits of the SFT-estimate could be obtained for different practical situations, in which the signal-to-noise ratio and the number of epochs used in the estimation may vary. The technique was applied to the EEG of 10 normal subjects during IPS, and allowed detecting responses not only at the fundamental IPS frequency but also at higher harmonics. It also permitted to assess the strength of the Photic driving responses and to compare them in different derivations and in different subjects.

  • spectral f test power evaluation in the eeg during Intermittent Photic Stimulation
    Arquivos De Neuro-psiquiatria, 2006
    Co-Authors: Mauricio Cagy, Vladimir V. Lazarev, Antonio Fernando Catelli Infantosi
    Abstract:

    A fotoestimulacao intermitente (FEI) e um importante teste functional, que pode induzir o fotorecrutamento no eletroencefalograma (EEG), sendo capaz de realcar manifestacoes latentes de oscilacoes nao observadas no EEG de repouso. Entretanto, para uma analise quantitativa adequada do fotorecrutamento, tais alteracoes devem ser avaliadas com base estatistica. Assim, a distribuicao de probabilidade do teste-F espectral (TFE) foi investigada. Neste sentido, limites de confianca para a estimativa do TFE puderam ser obtidos para diferentes situacoes praticas, nas quais a razao sinal-ruido e o numero de epocas usadas na estimacao podem variar. A tecnica foi aplicada ao EEG de 10 sujeitos normais durante FEI, e permitiu a deteccao de respostas nao somente na frequencia fundamental da FEI como tambem em seus harmonicos. Alem disso, permitiu avaliar o grau de fotorecrutamento entre derivacoes distintas e entre diferentes sujeitos.

  • Topographic aspects of Photic driving in the electroencephalogram of children and adolescents
    Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas, 2004
    Co-Authors: Vladimir V. Lazarev, A.f.c. Infantosi, D. Valencio-de-campos, L.c. De Azevedo
    Abstract:

    The electroencephalogram amplitude spectra at 11 fixed frequencies of Intermittent Photic Stimulation of 3 to 24 Hz were combined into driving "profiles" for 14 scalp points in 8 male and 7 female normal subjects aged 9 to 17 years. The driving response varied over frequency and was detected in 70 to 100% of cases in the occipital areas (maximum) and in 27 to 77% of cases in the frontal areas (minimum) using as a criterion peak amplitude 20% higher than those of the neighbors. Each subject responded, on average, to 9.7 ± 1.15 Intermittent Photic Stimulation frequencies in the right occipital area and to 6.8 ± 1.97 frequencies in the right frontal area. Most of the driving responses (in relation to the previous background) were significant according to the spectral F-test (a = 0.05), which also detected changes in some cases of low amplitude responses not revealed by the peak criterion. The profiles had two maxima in the alpha and theta bands in all leads. The latter was not present in the background spectra in the posterior areas and was less pronounced in the anterior ones. The weight of the profile theta maximum increased towards the frontal areas where the two maxima were similar, while the profile amplitudes decreased. The profiles repeated the shape of the background spectra, except for the theta band. The interhemispheric correlation between profiles was high. The theta driving detected in all areas recorded suggests a generalized influence of the theta generators in prepubertal and pubertal subjects.

F. Panzica - One of the best experts on this subject based on the ideXlab platform.

  • Photosensitive epilepsy: Spectral and coherence analyses of EEG using 14 Hz Intermittent Photic Stimulation
    Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology, 2010
    Co-Authors: Elisa Visani, G. Varotto, Silvana Franceschetti, Simona Binelli, L. Fratello, Giuliano Avanzini, F. Panzica
    Abstract:

    Abstract Objective To evaluate the EEG recorded in photosensitive idiopathic generalised epilepsy (IGE) patients at rest and during 14 Hz IPS, frequency capable of inducing photoparoxysmal responses (PPRs). Methods Power spectrum density and coherence profiles were estimated using a block autoregressive parametric model (AR) in 28 patients and 22 controls. Results At rest, the intra- and inter-hemispheric coherence spectra showed a significantly larger number of coherence peaks in the gamma band in patients with respect to controls. During Intermittent Photic Stimulation (IPS), coherent gamma activity is mainly presented as IPS frequency harmonics; moreover, the patients’ mean coherence values significantly increased. In six patients re-evaluated with IPS after putting on glasses with Z1 blue lens (which counteracts PPR) the spectral and coherence profiles tended to return to the resting ones. Conclusions Patients are endowed with inherited EEG hyper-synchrony as shown by the large number of coherence peaks detectable under resting conditions, whereas IPS enhances intra- and inter-hemispheric mean coherence values in the gamma band. The persistence of alpha activity peaks during IPS in most controls but not in patients suggests that the alpha generating network plays a significant role in counteracting PPR. Significance Both gamma and alpha EEG generators are involved in the PPR generation and in the widespread synchronisation characterising the IGE-associated photosensitivity.

  • Spectral and Coherence Analysis of EEG during Intermittent Photic Stimulation in Patients with Photosensitive Epilepsy
    2009
    Co-Authors: G. Varotto, Elisa Visani, Silvana Franceschetti, Giovanni Sparacino, F. Panzica, Carlo Besta
    Abstract:

    Objective: The aim of this study is to assess changes in the EEG dynamics preceding the transition to the photo-paroxismal response (PPR) in photosensitive patients Methods: Occipital EEG derivations were considered in 10 photosensitive patients and 10 controls, both at rest and during Intermittent Photic Stimulation (IPS) at 14, 3, 5, 10, 20 and 40 Hz. The two EEG signals were analysed by means of an autoregressive (AR) bivariate parametric model, and the correspondent autospectra and coherence function were qualitatively and quantitatively assessed. Results: At rest, the coherence function showed an higher number of peaks in the patients compare with the controls, mostly in the gamma band. Also, during IPS at 14 at 10 Hz, where stimulus was more effective in producing PPR, high frequency iper-synchronization in the patients group was enhanced before the appearance of the paroxysmal response. The same did not happen at those frequencies not able to bring about to PPR Conclusion: Results indicate an increased synchronization, mostly in beta and gamma bands, present at those frequencies able to sustain paroxysmal responses.

  • Spectral and Coherence Analysis of EEG during Intermittent Photic Stimulation in Patients with Photosensitive Epilepsy, International Journal of Bioelectromagnetism,
    2009
    Co-Authors: G. Varotto, Elisa Visani, Silvana Franceschetti, Sparacino Giovanni, F. Panzica
    Abstract:

    Objective: The aim of this study is to assess changes in the EEG dynamics preceding the transition to the photo-paroxismal response (PPR) in photosensitive patients Methods: Occipital EEG derivations were considered in 10 photosensitive patients and 10 controls, both at rest and during Intermittent Photic Stimulation (IPS) at 14, 3, 5, 10, 20 and 40 Hz. The two EEG signals were analysed by means of an autoregressive (AR) bivariate parametric model, and the correspondent autospectra and coherence function were qualitatively and quantitatively assessed. Results: At rest, the coherence function showed an higher number of peaks in the patients compare with the controls, mostly in the gamma band. Also, during IPS at 14 at 10 Hz, where stimulus was more effective in producing PPR, high frequency iper-synchronization in the patients group was enhanced before the appearance of the paroxysmal response. The same did not happen at those frequencies not able to bring about to PPR Conclusion: Results indicate an increased synchronization, mostly in beta and gamma bands, present at those frequencies able to sustain paroxysmal responses

  • Rhythmic cortical myoclonus in Niemann-Pick disease type C.
    Movement Disorders, 2006
    Co-Authors: Laura Canafoglia, Silvana Franceschetti, Giuliano Avanzini, Marianna Bugiani, Graziella Uziel, Bernardo Dalla Bernardina, Claudia Ciano, Vidmer Scaioli, F. Panzica
    Abstract:

    We here describe a patient with late-infantile Niemann–Pick disease type C (NPC) presenting with worsening myoclonus, seizures, cerebellar symptoms, mild mental impairment, and gaze palsy. Electroencephalographic (EEG) –polymyographic examinations showed abnormally high and diffuse background alpha-activity, enhanced by Intermittent Photic Stimulation. The electromyographic (EMG) showed quasirhythmic myoclonic jerks during motor activation. EEG–EMG frequency analysis (better than jerk-locked back-averaging) demonstrated the cortical origin of the myoclonus. Our observations indicate that cortical myoclonus may occur as the main symptom of NPC. © 2006 Movement Disorder Society

  • Rhythmic cortical myoclonus in Niemann-Pick disease type C.
    Movement disorders : official journal of the Movement Disorder Society, 2006
    Co-Authors: Laura Canafoglia, Silvana Franceschetti, Giuliano Avanzini, Marianna Bugiani, Graziella Uziel, Bernardo Dalla Bernardina, Claudia Ciano, Vidmer Scaioli, F. Panzica
    Abstract:

    We here describe a patient with late-infantile Niemann-Pick disease type C (NPC) presenting with worsening myoclonus, seizures, cerebellar symptoms, mild mental impairment, and gaze palsy. Electroencephalographic (EEG) -polymyographic examinations showed abnormally high and diffuse background alpha-activity, enhanced by Intermittent Photic Stimulation. The electromyographic (EMG) showed quasirhythmic myoclonic jerks during motor activation. EEG-EMG frequency analysis (better than jerk-locked back-averaging) demonstrated the cortical origin of the myoclonus. Our observations indicate that cortical myoclonus may occur as the main symptom of NPC.