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ID 222 – Cortical markers of pain memorisation – A study with intra-cerebral recordings in Humans
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Abstracts / Clinical Neurophysiology 127 (2016) e18–e132
ID 222 – Cortical markers of pain memorisation – A study with intra-cerebral recordings in Humans—A. Chapon, C. Perchet, L. Garcia-Larrea, M. Frot (Neurosciences Research Center of Lyon, INSERM U1028, Lyon, France, University Claude Bernard Lyon 1, Lyon, France) This study proposes to highlight cortical regions involved in a short-term memory painful task, and their interactions by using intra-cerebral recordings from 10 epileptic patients. In order to emphasize pain memory specificity, three different stimulations were used: painful, somatosensory non-painful and auditory. Two different intensities were delivered in each condition, and patients had to compare stimulation from the previous one, delivered 8– 10 s before. In a control task, patients had to read numbers on a screen between two stimuli, in order to ensure that they did not memorize anything about the stimulation. Data were analyzed in terms of evoked potentials and time frequency during retention phase. When painful stimuli had to be memorized, early components of evoked potentials showed an increased amplitude as compared to the control task, in regions involved in affective aspects of pain (anterior insula, prefrontal cortex). Moreover a specific late negativity was observed only for painful stimuli memorisation, which suggests an enhanced arousal. Time-frequency analysis showed an alpha desynchronisation in memory tasks during retention phase in regions involved in cognitive and affective dimensions of pain (anterior insula, anterior cingulate cortex, prefrontal cortex) which might be related to cognitive processing and mechanisms of attention. doi:10.1016/j.clinph.2015.11.391
ID 226 – Inter-individual differences in laser-evoked potentials and operculo-insular morphology—C. Bradley, L. Nguyen, L. Garcia-Larrea (NEUROPAIN – Centre de Recherche en Neurosciences de Lyon, University Claude Bernard Lyon1, Lyon, France) Laser-evoked potentials are a useful tool to evaluate the functional state of the spino-thalamic system. While late vertex potentials N2 and P2 are commonly assessed, middle-latency components such as the N1–P1 are under-utilized, due to their smaller amplitude and high inter-individual variability. To optimize their use, we investigate the possible relationship between this variability and anatomo-morphological variations in the operculo-insular region. We recorded laser-evoked potentials using high-density EEG (128 electrodes) in 15 healthy participants. Over the 30 ms following the appearance of the first lateralized N1–P1 scalp topography, the electrodes recording a frontal maximum and a temporo-central minimum were selected. Their positions were put in relation with the orientation of several sulci in the posterior operculo-insular cortex, measured on individual T1-3D MRIs. In all but two participants, a clear lateralized dipolar structure appeared 154 ms (±18 ms) after stimulation. There was a significant correlation (r2 = 0.43, p = 0.02, n = 12) between the negative maximum (N1) electrode coordinate in a coronal plane and the orientation of the posterior superior operculo-insular fold (MRI coronal plane). N1–P1 topography is highly related to operculo-insular anatomomorphology.
It remains to be studied whether N1–P1 topography can predict operculo-insular anatomy at the individual level and be used in routine clinical settings. doi:10.1016/j.clinph.2015.11.392
ID 246 – Pain-related cortex function in patients with Alzheimer disease. Preliminary results—G. Di Stefano, A. Pepe, S. La Cesa, C. Leone, F. D’Antonio, A. Trebbastoni, C. De Lena, G. Cruccu, A. Truini (Department of Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy) Introduction: Previous studies found that patients with Alzheimer’s disease (AD) have increased pain threshold and pain tolerance. Nevertheless it is still unclear whether these findings are explained by communication problems, or rather they are associated with degenerative processes affecting pain-related cortex. In this neurophysiological study we aimed at assessing pain-related cortex function, by recording laser evoked potentials (LEPs) after hand stimulation in patients with AD. Methods: We enrolled 10 patients with a diagnosis of probable mild-to-moderate AD, recruited from the Alzheimer Evaluation Unit of ‘‘Sapienza” University of Rome. In all patients we recorded the SII-generated N1-LEP, and the N2–P2 complex of LEPs, generated in the insula and cingulate cortex. All patients also underwent the recording of Ab-fibre mediated somatosensory evoked potentials (SEP), after median nerve stimulation. LEP and SEP variables were compared with normative reference ranges, matched for age and gender. Results: Whereas SEP variables, and the N1-LEP component came within reference values in all patients, the N2–P2 complex of LEP was dampened or absent in 7 patients. Conclusions: Our findings suggest that in patients with AD the degenerative processes affect pain-related cortex. This damage predominantly involves the insular cortex and the anterior cingulate cortex. doi:10.1016/j.clinph.2015.11.393
ID 304 – A comparison of the cerebral networks activated by painful and non-painful stimulations in humans: an intracerebral recording study—C. Perchet a, M. Frot a, N. Vartiainen a, L. Claude a, L. Garcia-Larrea a, H. Bastuji a,b (a INSERM U 1028, Centre de Recherche en Neurosciences de Lyon, Lyon, France, b Hospices Civils de Lyon, Lyon, France) We highlight and compare the different cerebral networks responding to the activation of the spinothalamic (STT) and lemniscal (LT) pathways. Eight epileptic patients (6 men, 34 ± 10 years) with intracortical implanted electrodes participated to the experiment. A non painful tactile (LT) and two painful stimuli, laser Nd: YAP (STT) and concentric electrode (STT+LT), were delivered on the dorsum of the hand contralateral to the electrode implantation. Evoked responses to the three types of stimulation were analysed in term of latency, amplitude and topography, in various cortical areas. Responses of similar morphology were recorded in posterior insula, supra-sylvian operculum and parietal cortex (BA 40), their latencies being longer for laser as compared to the others. In the mid cingulate gyrus and the premotor cortex (BA 6), while responses
Abstracts / Clinical Neurophysiology 127 (2016) e18–e132
ID 222 – Cortical markers of pain memorisation – A study with intra-cerebral recordings in Humans—A. Chapon, C. Perchet, L. Garcia-Larrea, M. Frot (Neurosciences Research Center of Lyon, INSERM U1028, Lyon, France, University Claude Bernard Lyon 1, Lyon, France) This study proposes to highlight cortical regions involved in a short-term memory painful task, and their interactions by using intra-cerebral recordings from 10 epileptic patients. In order to emphasize pain memory specificity, three different stimulations were used: painful, somatosensory non-painful and auditory. Two different intensities were delivered in each condition, and patients had to compare stimulation from the previous one, delivered 8– 10 s before. In a control task, patients had to read numbers on a screen between two stimuli, in order to ensure that they did not memorize anything about the stimulation. Data were analyzed in terms of evoked potentials and time frequency during retention phase. When painful stimuli had to be memorized, early components of evoked potentials showed an increased amplitude as compared to the control task, in regions involved in affective aspects of pain (anterior insula, prefrontal cortex). Moreover a specific late negativity was observed only for painful stimuli memorisation, which suggests an enhanced arousal. Time-frequency analysis showed an alpha desynchronisation in memory tasks during retention phase in regions involved in cognitive and affective dimensions of pain (anterior insula, anterior cingulate cortex, prefrontal cortex) which might be related to cognitive processing and mechanisms of attention. doi:10.1016/j.clinph.2015.11.391
ID 226 – Inter-individual differences in laser-evoked potentials and operculo-insular morphology—C. Bradley, L. Nguyen, L. Garcia-Larrea (NEUROPAIN – Centre de Recherche en Neurosciences de Lyon, University Claude Bernard Lyon1, Lyon, France) Laser-evoked potentials are a useful tool to evaluate the functional state of the spino-thalamic system. While late vertex potentials N2 and P2 are commonly assessed, middle-latency components such as the N1–P1 are under-utilized, due to their smaller amplitude and high inter-individual variability. To optimize their use, we investigate the possible relationship between this variability and anatomo-morphological variations in the operculo-insular region. We recorded laser-evoked potentials using high-density EEG (128 electrodes) in 15 healthy participants. Over the 30 ms following the appearance of the first lateralized N1–P1 scalp topography, the electrodes recording a frontal maximum and a temporo-central minimum were selected. Their positions were put in relation with the orientation of several sulci in the posterior operculo-insular cortex, measured on individual T1-3D MRIs. In all but two participants, a clear lateralized dipolar structure appeared 154 ms (±18 ms) after stimulation. There was a significant correlation (r2 = 0.43, p = 0.02, n = 12) between the negative maximum (N1) electrode coordinate in a coronal plane and the orientation of the posterior superior operculo-insular fold (MRI coronal plane). N1–P1 topography is highly related to operculo-insular anatomomorphology.
It remains to be studied whether N1–P1 topography can predict operculo-insular anatomy at the individual level and be used in routine clinical settings. doi:10.1016/j.clinph.2015.11.392
ID 246 – Pain-related cortex function in patients with Alzheimer disease. Preliminary results—G. Di Stefano, A. Pepe, S. La Cesa, C. Leone, F. D’Antonio, A. Trebbastoni, C. De Lena, G. Cruccu, A. Truini (Department of Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy) Introduction: Previous studies found that patients with Alzheimer’s disease (AD) have increased pain threshold and pain tolerance. Nevertheless it is still unclear whether these findings are explained by communication problems, or rather they are associated with degenerative processes affecting pain-related cortex. In this neurophysiological study we aimed at assessing pain-related cortex function, by recording laser evoked potentials (LEPs) after hand stimulation in patients with AD. Methods: We enrolled 10 patients with a diagnosis of probable mild-to-moderate AD, recruited from the Alzheimer Evaluation Unit of ‘‘Sapienza” University of Rome. In all patients we recorded the SII-generated N1-LEP, and the N2–P2 complex of LEPs, generated in the insula and cingulate cortex. All patients also underwent the recording of Ab-fibre mediated somatosensory evoked potentials (SEP), after median nerve stimulation. LEP and SEP variables were compared with normative reference ranges, matched for age and gender. Results: Whereas SEP variables, and the N1-LEP component came within reference values in all patients, the N2–P2 complex of LEP was dampened or absent in 7 patients. Conclusions: Our findings suggest that in patients with AD the degenerative processes affect pain-related cortex. This damage predominantly involves the insular cortex and the anterior cingulate cortex. doi:10.1016/j.clinph.2015.11.393
ID 304 – A comparison of the cerebral networks activated by painful and non-painful stimulations in humans: an intracerebral recording study—C. Perchet a, M. Frot a, N. Vartiainen a, L. Claude a, L. Garcia-Larrea a, H. Bastuji a,b (a INSERM U 1028, Centre de Recherche en Neurosciences de Lyon, Lyon, France, b Hospices Civils de Lyon, Lyon, France) We highlight and compare the different cerebral networks responding to the activation of the spinothalamic (STT) and lemniscal (LT) pathways. Eight epileptic patients (6 men, 34 ± 10 years) with intracortical implanted electrodes participated to the experiment. A non painful tactile (LT) and two painful stimuli, laser Nd: YAP (STT) and concentric electrode (STT+LT), were delivered on the dorsum of the hand contralateral to the electrode implantation. Evoked responses to the three types of stimulation were analysed in term of latency, amplitude and topography, in various cortical areas. Responses of similar morphology were recorded in posterior insula, supra-sylvian operculum and parietal cortex (BA 40), their latencies being longer for laser as compared to the others. In the mid cingulate gyrus and the premotor cortex (BA 6), while responses