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P9.8 Cortical effective connectivity across the sleep wake cycle: an intracerebral study in humans
14th ECCN / 4th ICTMS/DCS we hope to be able to monitor disease progression and assess medication efficiency. P9.8 Cortical effective connectivity across the sleep wake cycle: an intracerebral study in humans A. Pigorini1 , C. Szymanski1 , S. Casarotto1 , A. Casali1 , M. Rosanova1 , G. Lo Russo2 , M. Mariotti1 , L. Nobili2 , M. Massimini1 1 Department of Clinical Sciences ’L. Sacco’, University of Milan, Milan, Italy, 2 Centre of Epilepsy Surgery “C. Munari”, Department of Neuroscience, Niguarda Hospital, Milan, Italy Introduction and Objectives: Recent studies have combined Transcranial Magnetic Stimulation (TMS) and high density Electroencephalography (hdEEG) to evaluate how cortico-cortical information transmission changes upon falling asleep (Massimini et al., 2007, Massimini et al., 2005). These experiments show that during slow wave sleep (SWS) TMS-evoked responses are larger, more stereotypical and more local than during wakefulness. This suggests that a break-down of effective connectivity may underlie the loss of consciousness that occurs in SWS. However, the interpretation of TMS/hd-EEG recordings is limited by a coarse spatial grain. In the present study we employ intracerebral stimulations and recordings in humans to validate and generalize TMS/hd-EEG results on a finer spatial scale (mm). Methods: Five patients with drug resistant epilepsy had been implanted with multi-channels depth electrodes for clinical evaluation (Nobili et al., 2006). During wakefulness and SWS, stimulation trains (30 shocks, 1 Hz, 5 mA) were delivered through one single channel, while recordings of local field potentials were obtained from all other channels. Results: Morphology of intracerebral evoked potentials (iEP) changed markedly upon falling asleep. The number of oscillations and the complexity of the signal decreased during SWS. In addition, while during wakefulness the stimulation of one channel resulted in a widespread response which involved distant cortical areas, during SWS the iEPs remained rather localized around the stimulation site. Conclusion: Intracerebral stimulations and recordings show that the brain’s response to direct cortical perturbation becomes more stereotypical and local upon falling asleep. These results are consistent with previous TMS/hd-EEG recordings. Thus, these invasive experiments support the idea that changes in effective connectivity may underlie the loss of consciousness during SWS and be reliably studied using noninvasive techniques such as TMS/hd-EEG. Reference(s) [1] Massimini, M., Ferrarelli, F., Esser, S. K., Riedner, B. A., Huber, R., Murphy, M., Peterson, M. J. & Tononi, G. 2007. Triggering sleep slow waves by transcranial magnetic stimulation. Proc Natl Acad Sci U S A, 104, 8496 501. [2] Massimini, M., Ferrarelli, F., Huber, R., Esser, S. K., Singh, H. & Tononi, G. 2005. Breakdown of cortical effective connectivity during sleep. Science, 309, 2228 32. [3] Nobili L, Sartori I, Terzaghi M, Stefano F, Mai R, Tassi L, Parrino L, Cossu M, Lo Russo G. Relationship of epileptic discharges to arousal instability and periodic leg movements in a case of nocturnal frontal lobe epilepsy: a stereo-EEG study. Sleep. 2006 May 1; 29(5): 701 4. P9.9 Towards noninvasive multi-unit spike recordings: mapping 1 kHz EEG signals over human somatosensory cortex T. Fedele Fedele1 , H.J. Scheer2 , G. Waterstraat1 , B. Telenczuk1 , M. Burghoff2 , G. Curio1 1 Neurophysics Group, Department of Neurology, Charit´ e Campus Benjamin Franklin, Hindenburgdamm 30, 12200 Berlin, Germany, Berlin, Germany, 2 Physikalisch-Technische Bundesanstalt/Institute Berlin, Abbestr. 2 12, 10587 Berlin, Germany, Berlin, Germany Introduction: Scalp-derived human somatosensory evoked potentials (SEPs) contain high-frequency oscillations (600 Hz; sigma-burst). These potentials were shown to reflect concomitant spike bursts of single neurons in primary somatosensory cortex that repeat regularly at 600 Hz.. Notably, human intracranial SEP revealed also 1 kHz activity (‘k-burst’), possibly reflecting non-rhythmic spiking summed over multiple cells (MUA: multi-unit activity). Objective: The noninvasive detection of EEG signals at 1 kHz typical for spikes has always been limited by noise contributions from both, amplifier
S103 and body/electrode interface. Accordingly, we developed a low-noise recording set up striving to map noninvasively 1 kHz SEP components. Methods: 28-channel SEP was recorded upon 4 Hz right and left median nerve stimulation in 3 healthy human subjects. Scalp potentials were acquired inside an electrically and magnetically shielded room using lownoise custom-made amplifiers. To further reduce noise level, electrode impedances were adjusted to < 1 kOhm. Responses averaged after repeated presentation of the stimulus (n = 4000 trials) were evaluated by spatio-temporal pattern analyses in different spectral bands. Results: Three distinct spectral components were identified: N20 (< 100 Hz), sigma-burst (450 750 Hz), and k-burst (850 1200 Hz). The two frequency bands in high-frequency range (sigma-burst and k-burst) exhibited distinct and partially independent spatiotemporal evolutions in all three subjects, indicating subcortical as well as several cortical generators. Conclusions: Using a dedicated low-noise set up, human SEP ‘k-bursts’ at 1 kHz were mapped noninvasively. Their topographies point to a set of subcortical/cortical generators, at least partially distinct from the topography of previously-described sigma-bursts. Augmenting the standard, low-frequency SEP, the surface mapping of 1 kHz EEG signals may represent an essential step towards noninvasive monitoring of multiunit spike activity. Supported by BFNT-Berlin B1. P9.10 Auditory event related potentials in children with developmental coordination disorder I. Holeckova1 , L. Cepicka2 , P. Mautner3 , R. Moucek3 Department of Neurosurgery, University Hospital, Plzen, Czech Republic, 2 Faculty of Education, University of West Bohemia, Plzen, Czech Republic, 3 Faculty of Applied Sciences, University of West Bohemia, Plzen, Czech Republic
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Introduction: Developmental Coordination Disorder (DCD) is a term related to poor motor proficiency. DCD interferes significantly with the child’s academic achievement and normally daily activities. DCD occurs in about 6% of children in school age. Thus another study of developmental coordination disorder is required. Objective: The purpose of this study was to investigate and compare the mechanisms of brain activity as revealed by event-related potentials (ERPs) and gross motor quotient (GMQ) in children with (DCD) and typically developing children. Methods: Ten children with DCD and ten typically developing children mean age 5.87 years (SD 0.55 years) were tested with a passive audio odd ball paradigm with standard tone, deviant tone and non target vocal emotional stimulus. EEG activity was recoded at 24 scalp sites following the extended International 10 20 System. EEG was analyzed using the software package BRAINAMP. The classical peaks of auditory ERPs were identified in the grand average responses. Statistical significance of these components was assessed using unilateral t test and ANOVA test. GMQ was been used to evaluate the coordination. Results: Children with DCD showed significantly lower GMQ score, differences in morphology of N1 response to standard stimuli and smaller P3 amplitude to vocal emotional stimulus. Conclusion: DCD is not related to motor demonstration only. Children with low score of GMQ reflect different processing of auditory stimuli at sensory level and different stimulus triggered orienting and engagement of attention and categorization of stimuli. P9.11 Category-specific neural processing for recognition of animal and tool words: an ERP study in Persian A. Khatoonabadi1 , S. Sadeh2 , A. Grippo3 , B. Mahmoodi-Bakhtiari1 , M. Guarnieri4 , S. Faghihzadeh5 , M. Saadati5 1 Tehran University of Medical Sciences, Speech and Language Pathology Department, Tehran, Iran, Islamic Republic of, 2 School of Cognitive Science (IPM), Teheran, Iran, Islamic Republic of, 3 Neurofisiopatologia, DAI Neuroscienze, Azienda Ospedaliera Universitaria Careggi, Firenze, Italy, 4 EBNeuro Company, Firenze, Italy, 5 Tarbiat Modarres University, Tarbiat, Iran, Islamic Republic of Objective: Questions about the organization of conceptual knowledge can be addressed by studying the ways different semantic domains are represented and processed in the human brain.
S103 and body/electrode interface. Accordingly, we developed a low-noise recording set up striving to map noninvasively 1 kHz SEP components. Methods: 28-channel SEP was recorded upon 4 Hz right and left median nerve stimulation in 3 healthy human subjects. Scalp potentials were acquired inside an electrically and magnetically shielded room using lownoise custom-made amplifiers. To further reduce noise level, electrode impedances were adjusted to < 1 kOhm. Responses averaged after repeated presentation of the stimulus (n = 4000 trials) were evaluated by spatio-temporal pattern analyses in different spectral bands. Results: Three distinct spectral components were identified: N20 (< 100 Hz), sigma-burst (450 750 Hz), and k-burst (850 1200 Hz). The two frequency bands in high-frequency range (sigma-burst and k-burst) exhibited distinct and partially independent spatiotemporal evolutions in all three subjects, indicating subcortical as well as several cortical generators. Conclusions: Using a dedicated low-noise set up, human SEP ‘k-bursts’ at 1 kHz were mapped noninvasively. Their topographies point to a set of subcortical/cortical generators, at least partially distinct from the topography of previously-described sigma-bursts. Augmenting the standard, low-frequency SEP, the surface mapping of 1 kHz EEG signals may represent an essential step towards noninvasive monitoring of multiunit spike activity. Supported by BFNT-Berlin B1. P9.10 Auditory event related potentials in children with developmental coordination disorder I. Holeckova1 , L. Cepicka2 , P. Mautner3 , R. Moucek3 Department of Neurosurgery, University Hospital, Plzen, Czech Republic, 2 Faculty of Education, University of West Bohemia, Plzen, Czech Republic, 3 Faculty of Applied Sciences, University of West Bohemia, Plzen, Czech Republic
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Introduction: Developmental Coordination Disorder (DCD) is a term related to poor motor proficiency. DCD interferes significantly with the child’s academic achievement and normally daily activities. DCD occurs in about 6% of children in school age. Thus another study of developmental coordination disorder is required. Objective: The purpose of this study was to investigate and compare the mechanisms of brain activity as revealed by event-related potentials (ERPs) and gross motor quotient (GMQ) in children with (DCD) and typically developing children. Methods: Ten children with DCD and ten typically developing children mean age 5.87 years (SD 0.55 years) were tested with a passive audio odd ball paradigm with standard tone, deviant tone and non target vocal emotional stimulus. EEG activity was recoded at 24 scalp sites following the extended International 10 20 System. EEG was analyzed using the software package BRAINAMP. The classical peaks of auditory ERPs were identified in the grand average responses. Statistical significance of these components was assessed using unilateral t test and ANOVA test. GMQ was been used to evaluate the coordination. Results: Children with DCD showed significantly lower GMQ score, differences in morphology of N1 response to standard stimuli and smaller P3 amplitude to vocal emotional stimulus. Conclusion: DCD is not related to motor demonstration only. Children with low score of GMQ reflect different processing of auditory stimuli at sensory level and different stimulus triggered orienting and engagement of attention and categorization of stimuli. P9.11 Category-specific neural processing for recognition of animal and tool words: an ERP study in Persian A. Khatoonabadi1 , S. Sadeh2 , A. Grippo3 , B. Mahmoodi-Bakhtiari1 , M. Guarnieri4 , S. Faghihzadeh5 , M. Saadati5 1 Tehran University of Medical Sciences, Speech and Language Pathology Department, Tehran, Iran, Islamic Republic of, 2 School of Cognitive Science (IPM), Teheran, Iran, Islamic Republic of, 3 Neurofisiopatologia, DAI Neuroscienze, Azienda Ospedaliera Universitaria Careggi, Firenze, Italy, 4 EBNeuro Company, Firenze, Italy, 5 Tarbiat Modarres University, Tarbiat, Iran, Islamic Republic of Objective: Questions about the organization of conceptual knowledge can be addressed by studying the ways different semantic domains are represented and processed in the human brain.