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20. Wakefulness delta waves increase after cortical plasticity induction
Society Proceedings / Clinical Neurophysiology 124 (2013) e189–e223
did not show statistical significance between schizophrenic patients and normal controls, the cold pain threshold approached the statistical significance (P = 0.08, unpaired t-test). Conversely the amplitude of all LEP components was significantly lower in patients than in controls (P < 0.05). These preliminary data suggest that schizophrenic patients have an abnormal processing of nociceptive input. These abnormalities might reflect a dopaminergic dysfunction. doi:10.1016/j.clinph.2013.06.043
17. Peripheral and central nervous contribution to gastrointestinal symptoms in diabetic patients with autonomic neuropathy—M. Valeriani, C. Brock, C. Graversen, J.B. Frøkjaer, E. Søfteland, A.M. Drewes (Aalborg, Denmark) To explore the role of diabetic autonomic neuropathy (DAN) in patients with long-standing diabetes mellitus (DM), we investigated psychophysical responses and neuronal activity recorded as evoked brain potentials and dipolar source modelling. Fifteen healthy volunteers and 14 type-1 DM patients with DAN were assessed with a symptom score index characterizing upper GI abnormalities. Multichannel electroencephalography was recorded during painful electrical stimulation of the lower oesophagus. Brain activity to painful stimulations was modelled using Brain Electrical Source Analysis. Diabetic patients had higher stimulus intensities to evoke painful sensation (p 6 0.001), longer latencies of N2 and P2 components (both p 6 0.001), and lower amplitudes of P1–N2 and N2–P2 complexes (p 6 0.001; p = 0.02). Inverse modelling of brain sources showed deeper bilateral insular dipolar source localization (p = 0.002). Symptom score index was negatively correlated with the depth of insular activity (p = 0.004) and positively correlated with insular dipole strength (p = 0.03). DM patients show peripheral and central neuroplastic changes. Moreover, the role of abnormal insular processing may explain the appearance and persistence of GI symptoms related to DAN. doi:10.1016/j.clinph.2013.06.044
18. Circadian hyperactivity of the lower limb Adelta-system in idiopathic Restless Legs Syndrome: A CO2 Laser Evoked Potential study—C. Vollono, G. Della Marca, E. Testani, D. Ferraro, D. Virdis, D. Le Pera, R. Miliucci, P.M. Rossini, M. Valeriani (Rome, Modena, Aalborg, Denmark) Aim of the study was to assess the A-delta nociceptive system during the night and afternoon in idiopathic Restless Legs Syndrome (RLS) patients, by recording the Laser Evoked Potentials (LEPs). We studied 11 patients (mean age 53.40 ± 18.59 years; 6 males, 5 females) affected by idiopathic RLS. LEPs were recorded to stimulation of the right foot, hand and perioral region. LEPs were recorded at night (between 9.00 PM and 11.00 PM) and in the early afternoon (between 1.00 PM and 3.00 PM). Two consecutive averages (20 trials each) were obtained for each stimulation site. LEPs were recorded from 3 recording electrodes placed at Cz, Fz, and T3 sites of the 10–20 International System. In RLS patients, we found a significant increase of N2–P2 amplitude after foot stimulation during nighttime session (p = 0.008) when compared to daytime. The N2/P2 amplitude after hand and face stimulation was not significantly different during both sessions (p > 0.05). We did not find any impairment of the Adelta-fiber system. However, there is a prevailing activity of the Adelta nociceptive system of
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lower limbs during nighttime. These findings suggest, in idiopathic RLS, a circadian disinhibition in the central processing of the lower limb Adelta-fiber inputs. doi:10.1016/j.clinph.2013.06.045
19. Slow spindles’ cortical generators overlap with the epileptogenic zone in temporal epileptic patients: An electrical source imaging study—A. Del Felice, C. Arcaro, S.F. Storti, A. Fiaschi, P. Manganotti (Verona, Venice) Our aim was to determine whether temporal epileptic patients and normal volunteers display similar sleep spindles’ cortical generators as determined by electrical source imaging (ESI), and whether such generators overlap in epilepsy patients with the epileptogenic zone identified by ESI. Thirteen healthy subjects and eight temporal lobe pharmaco-resistant epileptic patients underwent a 256-channel EEG recording during a daytime nap. Sleep spindles were analyzed off line, distinguishing slow (10–12 Hz) and fast (12–14 Hz) ones, and the final averaged signal was projected onto an MNI (Montreal Neurological Institute) space to localize cortical generators. The same procedure was performed for averaged epileptic spikes, obtaining their cortical source. Intra- and inter-group statistical analysis were conducted. Multiple, concomitant generators were detected in both populations for slow and fast spindles. Slow spindles in epileptics displayed higher source amplitude in comparison to healthy volunteers (p = 0.042), as well as a preferential localization over the temporal cortices (p = 0.035). Interestingly, at least one of slow spindles’ generators overlapped with the epileptogenic zone. Slow spindles, but not fast ones, in temporal epilepsy are mainly generated by the affected temporal lobe. These results point to the strict relation between sleep and epilepsy and to possible cognitive implications. doi:10.1016/j.clinph.2013.06.046
20. Wakefulness delta waves increase after cortical plasticity induction—G. Assenza, G. Pellegrino, M. Tombini, G. Di Pino, L. Tomasevic, F. Tecchio, V. Di Lazzaro (Rome) Delta waves (Dw) during sleep are considered effectors of synaptic plasticity. During wakefulness Dw appear when brain lesions occur, but their functional meaning is not unanimously recognized. We aimed at testing whether Dw change after inducing cortical plasticity by intermittent theta burst stimulation (iTBS). Thirteen healthy subjects underwent iTBS on left primary motor cortex to induce long term potentiation (LTP) like phenomena. Five-minutes resting opened-eyes 32-channels EEG, right opponens pollicis motor evoked potentials (MEP) and alertness behavioural scales were collected before and up to 30 min after iTBS. Power spectral density (PSD) from delta to beta frequency bands of bilateral sensorimotor areas was calculated. iTBS induced a significant increase of both MEP amplitude and bilateral Dw (+87.5%) lasting up to 30 min after stimulation. No changes on behavioural scales were found. Our data showed that motor LTP induction during wakefulness, by means of iTBS, is accompanied by a large and enduring increase of Dw over sensorimotor areas. Present results evidenced that Dw own a prominent role in neural plasticity processes in the awake state. doi:10.1016/j.clinph.2013.06.047
did not show statistical significance between schizophrenic patients and normal controls, the cold pain threshold approached the statistical significance (P = 0.08, unpaired t-test). Conversely the amplitude of all LEP components was significantly lower in patients than in controls (P < 0.05). These preliminary data suggest that schizophrenic patients have an abnormal processing of nociceptive input. These abnormalities might reflect a dopaminergic dysfunction. doi:10.1016/j.clinph.2013.06.043
17. Peripheral and central nervous contribution to gastrointestinal symptoms in diabetic patients with autonomic neuropathy—M. Valeriani, C. Brock, C. Graversen, J.B. Frøkjaer, E. Søfteland, A.M. Drewes (Aalborg, Denmark) To explore the role of diabetic autonomic neuropathy (DAN) in patients with long-standing diabetes mellitus (DM), we investigated psychophysical responses and neuronal activity recorded as evoked brain potentials and dipolar source modelling. Fifteen healthy volunteers and 14 type-1 DM patients with DAN were assessed with a symptom score index characterizing upper GI abnormalities. Multichannel electroencephalography was recorded during painful electrical stimulation of the lower oesophagus. Brain activity to painful stimulations was modelled using Brain Electrical Source Analysis. Diabetic patients had higher stimulus intensities to evoke painful sensation (p 6 0.001), longer latencies of N2 and P2 components (both p 6 0.001), and lower amplitudes of P1–N2 and N2–P2 complexes (p 6 0.001; p = 0.02). Inverse modelling of brain sources showed deeper bilateral insular dipolar source localization (p = 0.002). Symptom score index was negatively correlated with the depth of insular activity (p = 0.004) and positively correlated with insular dipole strength (p = 0.03). DM patients show peripheral and central neuroplastic changes. Moreover, the role of abnormal insular processing may explain the appearance and persistence of GI symptoms related to DAN. doi:10.1016/j.clinph.2013.06.044
18. Circadian hyperactivity of the lower limb Adelta-system in idiopathic Restless Legs Syndrome: A CO2 Laser Evoked Potential study—C. Vollono, G. Della Marca, E. Testani, D. Ferraro, D. Virdis, D. Le Pera, R. Miliucci, P.M. Rossini, M. Valeriani (Rome, Modena, Aalborg, Denmark) Aim of the study was to assess the A-delta nociceptive system during the night and afternoon in idiopathic Restless Legs Syndrome (RLS) patients, by recording the Laser Evoked Potentials (LEPs). We studied 11 patients (mean age 53.40 ± 18.59 years; 6 males, 5 females) affected by idiopathic RLS. LEPs were recorded to stimulation of the right foot, hand and perioral region. LEPs were recorded at night (between 9.00 PM and 11.00 PM) and in the early afternoon (between 1.00 PM and 3.00 PM). Two consecutive averages (20 trials each) were obtained for each stimulation site. LEPs were recorded from 3 recording electrodes placed at Cz, Fz, and T3 sites of the 10–20 International System. In RLS patients, we found a significant increase of N2–P2 amplitude after foot stimulation during nighttime session (p = 0.008) when compared to daytime. The N2/P2 amplitude after hand and face stimulation was not significantly different during both sessions (p > 0.05). We did not find any impairment of the Adelta-fiber system. However, there is a prevailing activity of the Adelta nociceptive system of
e193
lower limbs during nighttime. These findings suggest, in idiopathic RLS, a circadian disinhibition in the central processing of the lower limb Adelta-fiber inputs. doi:10.1016/j.clinph.2013.06.045
19. Slow spindles’ cortical generators overlap with the epileptogenic zone in temporal epileptic patients: An electrical source imaging study—A. Del Felice, C. Arcaro, S.F. Storti, A. Fiaschi, P. Manganotti (Verona, Venice) Our aim was to determine whether temporal epileptic patients and normal volunteers display similar sleep spindles’ cortical generators as determined by electrical source imaging (ESI), and whether such generators overlap in epilepsy patients with the epileptogenic zone identified by ESI. Thirteen healthy subjects and eight temporal lobe pharmaco-resistant epileptic patients underwent a 256-channel EEG recording during a daytime nap. Sleep spindles were analyzed off line, distinguishing slow (10–12 Hz) and fast (12–14 Hz) ones, and the final averaged signal was projected onto an MNI (Montreal Neurological Institute) space to localize cortical generators. The same procedure was performed for averaged epileptic spikes, obtaining their cortical source. Intra- and inter-group statistical analysis were conducted. Multiple, concomitant generators were detected in both populations for slow and fast spindles. Slow spindles in epileptics displayed higher source amplitude in comparison to healthy volunteers (p = 0.042), as well as a preferential localization over the temporal cortices (p = 0.035). Interestingly, at least one of slow spindles’ generators overlapped with the epileptogenic zone. Slow spindles, but not fast ones, in temporal epilepsy are mainly generated by the affected temporal lobe. These results point to the strict relation between sleep and epilepsy and to possible cognitive implications. doi:10.1016/j.clinph.2013.06.046
20. Wakefulness delta waves increase after cortical plasticity induction—G. Assenza, G. Pellegrino, M. Tombini, G. Di Pino, L. Tomasevic, F. Tecchio, V. Di Lazzaro (Rome) Delta waves (Dw) during sleep are considered effectors of synaptic plasticity. During wakefulness Dw appear when brain lesions occur, but their functional meaning is not unanimously recognized. We aimed at testing whether Dw change after inducing cortical plasticity by intermittent theta burst stimulation (iTBS). Thirteen healthy subjects underwent iTBS on left primary motor cortex to induce long term potentiation (LTP) like phenomena. Five-minutes resting opened-eyes 32-channels EEG, right opponens pollicis motor evoked potentials (MEP) and alertness behavioural scales were collected before and up to 30 min after iTBS. Power spectral density (PSD) from delta to beta frequency bands of bilateral sensorimotor areas was calculated. iTBS induced a significant increase of both MEP amplitude and bilateral Dw (+87.5%) lasting up to 30 min after stimulation. No changes on behavioural scales were found. Our data showed that motor LTP induction during wakefulness, by means of iTBS, is accompanied by a large and enduring increase of Dw over sensorimotor areas. Present results evidenced that Dw own a prominent role in neural plasticity processes in the awake state. doi:10.1016/j.clinph.2013.06.047