- Email: [email protected]
‘Odddball’ event-related potential during REM and NREM sleep
16P
Society Proceedings
tude shifts of EP components may significantly contribute to the understanding of the genesis of the observed signals, which reflect complicated cognitive brain processes. 14.
Are multi-modality evoked potentials sensitive markers of perinatal risk factors? - S. Silver a,1, J. Kapituinik b, H. Sohmer a (aDepartment of Physiology, Hebrew University, Hadassah Medical School, Jerusalem. bDepartment of Pharmacology, Hebrew University, Hadassah Medical School, Jerusalem, lpresent address: The Institute for Child Development and The Pediatric Neurology Unit, The Division of Pediatrics, Tel-Aviv Medical Center, TeI-Aviv)
In order to study whether auditory (ABR), visual (VEP) and somatosensory (SEP) evoked potentials are sensitive to perinatal risk factors, a rat model of chronic jaundice (homozygous, recessive, jaundiced (jj) Gunn rats) was used. Asphyxia was induced on PND 1 and in other rats on PND 10 in jj rats and in heterozygous, nonjaundiced (Jj) littermates. A sharp, acute elevation of bilirubin was induced by injection on PND 21 of sulfadimethoxine, which displaces bilirubin from its albumin binding sites. During development, only the cortical visual evoked potential (VEP) exhibited pronounced changes (7-30% latency prolongation; 30-50% amplitude decrease) in young jj rats compared to Jj littermates. Hearing threshold (ABR) and SEP (peripheral nerve and brainstern responses) were normal in jj rats. Only the combination of asphyxia (PND 10 only) and high plasma bilirobin levels led to a progressive hearing loss (about 18 dB in adults). Marked SEP changes were also abserved in jj rats following asphyxia. The sharp, acute bilirubin elevation led to 4-20% latency prolongations of all modalities, but only to a small (4 dB) hearing (ABR) threshold shift. It thus seems that each of the evoked potentials studied is a sensitive marker of the effects of perinatal risk factors on different regions of the nervous system, which are expressed at different ages. These results may have clinical importance in the management of newborns suffering from neonatal jaundice and other risk factors.
15.
H-reflex recovery in patients with unilateral lumbar disc herniation following spinal manipulation. - A.N. Gilai, N. Liram, Y. Floman (Clinical Neurophysiology Unit, Aiyn Orthopedic Hospital and Spinal Surgery Unit, Hadassah University Hospital, Jerusalem)
The binaural interaction (BI) of human auditory brainstem evoked potentials (ABEPs) was studied in 15 normal hearing subjects by subtracting the response to binaural clicks, with and without high- and low-pass filtered masking, from the algebraic sum of monaural responses. Cut-off frequencies were 2000 Hz for low-passed noise and 1000 and 2000 Hz for high-passed noise (96 dB/octave slopes). Noise was presented ipsilateral to the clicks, or binaurally. ABEPs were recorded in response to 1 l/s, 65 dB nHL, alternating polarity clicks, and unfiltered noise level was just sufficient to mask the ABEPs. Analysis included peak-to-prestimulus baseline amplitudes and latencies of BI peaks and troughs from the vertex-mastoid (A), and vertex-neck (Z) channels. The results indicate that the effect of high-pass filtered masking noise, with a cut-off frequency of either 1000 Hz or 2000 Hz, on the amplitudes of BI, from both the A and Z channels, was larger in comparison to that of low-pass filtered masking noise. These results suggest that binaural interaction in the human brainstem involves mainly the high-frequency binaural neurons. 17.
Auditory stimuli consisting of (1) the subject's own name, and (2) an irrelevant word, were presented to 15 subjects during natural sleep. Stimulus probabilities were 30% or 70% counterbalanced during the night. PCA (principal component analysis) was performed on evoked potentials and ANOVA was applied to the eigenvector coefficients. During NREM sleep the prominent waveform of a K-complex, consisting of N350, N550 and PI000 was observed, in addition to a parietal P450, more prominent during stage 2. During REM sleep a frontocentral negativity which resembled NREM N350, a parietal positivity at about ,150 ms and a large N700 were detected. ANOVA on PCA coefficients at Pz during each of the sleep stages showed, in stage 2, a significant effect of stimulus type on an eigenvector which included peaks at 350, 450 and 550 ms. Stage 3 coefficients showed no significant effects and REM sleep coefficients showed a significant effect of stimulus probability on an eigenvector consisting of a prominent P450, suggesting a resemblance between REM sleep and awake P300. This could not be demonstrated during NREM sleep. 18.
The aim of this study was to determine whether abnormal H-reflex amplitude and conduction in patients with nerve-root compression (unilateral disc herniation at L5/S1 level) may be improved by singlesession spinal manipulation. H-reflex amplitude in mV (HR-A) and Hreflex latency in ms (HR-L) were measured and compared for the affected side and the healthy, noninvolved side. The mean HR-A level (13 patients) was found to be significantly lower in the affected side as compared to the contralateral normal side (2.7 mV versus 7.1 mV, P = 0.003). Following manipulation, the abnormal HR-A increased significantly on the affected side while the normal HR-A on the healthy side remained unchanged (mean HR-A after manipulation was 4.5 mV versus 7,4 mV on the nonaffected side, P = 0.004). There was a significant difference between the mean HR-L of the affected side and the contralateral side (32.2 ms versus 30.9 ms). This study shows in a small group of patients that spinal manipulation may cause immediate changes in the H-reflex parameters of patients with unilateral nerveroot compression by disc herniation, perhaps indicating recovery from the nerve conduction block. This may be due to a realignment of the myelin sheath of the nerve-root, thus promoting electrical conduction in the previously blocked area and increasing the H-reflex amplitude.
16.
Frequency specificity of the binaual interaction of human auditory brainstem evoked potentials. - A. Polyakov, H. Pratt (Evoked Potentials Laboratory, Technion, Israel Institute of Technology, Haifa, Israel)
'Odddball' event-related potential during REM and NREM sleep. - I. Berlad, H. Pratt (Evoked Potentials and Sleep Laboratories, Technion, Israel Instiute of Technology, Haifa, Israel)
Estimation and visualization with MRI data of short latency visual evoked potentials generators. - A.B. Geva a, N. Bleich b, R. Ben-Kish a, H. Pratt b (aBen-Gurion University of the Negev, Beer-Sheva, Israel. bTechnion, Israel Institute of Technology, Haifa, Israel)
In previous reports we presented an algorithm for a physiologicallymotivated wavelet-type decomposition of EPs, and demonstrated its utility for source estimation of EPs from different modalities. This source estimation algorithm provides a feasible solution without any additional assumptions nor initial conditions, by using a wavelet-type temporal model of the coherent mass activity of a large population of neurons which generate the EPs. Structural brain imaging, like magnetic resonance imaging (MRI), provides high spatial resolution of the head model, as well as anatomical imaging of specific brain structures, which is not available when using EPs. We incorporate MRI data into the source estimation algorithm by creating a more accurate geometrical and physical head model. In this study we obtain magnetic resonance images of the subject's head, with the electrode locations marked by fatty substances to enhance their identification. The individual images thus include accurate mapping of the brain and the positions of all recording electrodes relative to it. Visually evoked potentials were recorded from 32 electrodes distributed over the scalp, in response to monochromatic flashes, to each eye in turn. These short-latency evoked potentials represent a sequence of deep (sub-cortical) and superficial (cortical) sources, oriented horizontally, along the visual pathway.
Society Proceedings
tude shifts of EP components may significantly contribute to the understanding of the genesis of the observed signals, which reflect complicated cognitive brain processes. 14.
Are multi-modality evoked potentials sensitive markers of perinatal risk factors? - S. Silver a,1, J. Kapituinik b, H. Sohmer a (aDepartment of Physiology, Hebrew University, Hadassah Medical School, Jerusalem. bDepartment of Pharmacology, Hebrew University, Hadassah Medical School, Jerusalem, lpresent address: The Institute for Child Development and The Pediatric Neurology Unit, The Division of Pediatrics, Tel-Aviv Medical Center, TeI-Aviv)
In order to study whether auditory (ABR), visual (VEP) and somatosensory (SEP) evoked potentials are sensitive to perinatal risk factors, a rat model of chronic jaundice (homozygous, recessive, jaundiced (jj) Gunn rats) was used. Asphyxia was induced on PND 1 and in other rats on PND 10 in jj rats and in heterozygous, nonjaundiced (Jj) littermates. A sharp, acute elevation of bilirubin was induced by injection on PND 21 of sulfadimethoxine, which displaces bilirubin from its albumin binding sites. During development, only the cortical visual evoked potential (VEP) exhibited pronounced changes (7-30% latency prolongation; 30-50% amplitude decrease) in young jj rats compared to Jj littermates. Hearing threshold (ABR) and SEP (peripheral nerve and brainstern responses) were normal in jj rats. Only the combination of asphyxia (PND 10 only) and high plasma bilirobin levels led to a progressive hearing loss (about 18 dB in adults). Marked SEP changes were also abserved in jj rats following asphyxia. The sharp, acute bilirubin elevation led to 4-20% latency prolongations of all modalities, but only to a small (4 dB) hearing (ABR) threshold shift. It thus seems that each of the evoked potentials studied is a sensitive marker of the effects of perinatal risk factors on different regions of the nervous system, which are expressed at different ages. These results may have clinical importance in the management of newborns suffering from neonatal jaundice and other risk factors.
15.
H-reflex recovery in patients with unilateral lumbar disc herniation following spinal manipulation. - A.N. Gilai, N. Liram, Y. Floman (Clinical Neurophysiology Unit, Aiyn Orthopedic Hospital and Spinal Surgery Unit, Hadassah University Hospital, Jerusalem)
The binaural interaction (BI) of human auditory brainstem evoked potentials (ABEPs) was studied in 15 normal hearing subjects by subtracting the response to binaural clicks, with and without high- and low-pass filtered masking, from the algebraic sum of monaural responses. Cut-off frequencies were 2000 Hz for low-passed noise and 1000 and 2000 Hz for high-passed noise (96 dB/octave slopes). Noise was presented ipsilateral to the clicks, or binaurally. ABEPs were recorded in response to 1 l/s, 65 dB nHL, alternating polarity clicks, and unfiltered noise level was just sufficient to mask the ABEPs. Analysis included peak-to-prestimulus baseline amplitudes and latencies of BI peaks and troughs from the vertex-mastoid (A), and vertex-neck (Z) channels. The results indicate that the effect of high-pass filtered masking noise, with a cut-off frequency of either 1000 Hz or 2000 Hz, on the amplitudes of BI, from both the A and Z channels, was larger in comparison to that of low-pass filtered masking noise. These results suggest that binaural interaction in the human brainstem involves mainly the high-frequency binaural neurons. 17.
Auditory stimuli consisting of (1) the subject's own name, and (2) an irrelevant word, were presented to 15 subjects during natural sleep. Stimulus probabilities were 30% or 70% counterbalanced during the night. PCA (principal component analysis) was performed on evoked potentials and ANOVA was applied to the eigenvector coefficients. During NREM sleep the prominent waveform of a K-complex, consisting of N350, N550 and PI000 was observed, in addition to a parietal P450, more prominent during stage 2. During REM sleep a frontocentral negativity which resembled NREM N350, a parietal positivity at about ,150 ms and a large N700 were detected. ANOVA on PCA coefficients at Pz during each of the sleep stages showed, in stage 2, a significant effect of stimulus type on an eigenvector which included peaks at 350, 450 and 550 ms. Stage 3 coefficients showed no significant effects and REM sleep coefficients showed a significant effect of stimulus probability on an eigenvector consisting of a prominent P450, suggesting a resemblance between REM sleep and awake P300. This could not be demonstrated during NREM sleep. 18.
The aim of this study was to determine whether abnormal H-reflex amplitude and conduction in patients with nerve-root compression (unilateral disc herniation at L5/S1 level) may be improved by singlesession spinal manipulation. H-reflex amplitude in mV (HR-A) and Hreflex latency in ms (HR-L) were measured and compared for the affected side and the healthy, noninvolved side. The mean HR-A level (13 patients) was found to be significantly lower in the affected side as compared to the contralateral normal side (2.7 mV versus 7.1 mV, P = 0.003). Following manipulation, the abnormal HR-A increased significantly on the affected side while the normal HR-A on the healthy side remained unchanged (mean HR-A after manipulation was 4.5 mV versus 7,4 mV on the nonaffected side, P = 0.004). There was a significant difference between the mean HR-L of the affected side and the contralateral side (32.2 ms versus 30.9 ms). This study shows in a small group of patients that spinal manipulation may cause immediate changes in the H-reflex parameters of patients with unilateral nerveroot compression by disc herniation, perhaps indicating recovery from the nerve conduction block. This may be due to a realignment of the myelin sheath of the nerve-root, thus promoting electrical conduction in the previously blocked area and increasing the H-reflex amplitude.
16.
Frequency specificity of the binaual interaction of human auditory brainstem evoked potentials. - A. Polyakov, H. Pratt (Evoked Potentials Laboratory, Technion, Israel Institute of Technology, Haifa, Israel)
'Odddball' event-related potential during REM and NREM sleep. - I. Berlad, H. Pratt (Evoked Potentials and Sleep Laboratories, Technion, Israel Instiute of Technology, Haifa, Israel)
Estimation and visualization with MRI data of short latency visual evoked potentials generators. - A.B. Geva a, N. Bleich b, R. Ben-Kish a, H. Pratt b (aBen-Gurion University of the Negev, Beer-Sheva, Israel. bTechnion, Israel Institute of Technology, Haifa, Israel)
In previous reports we presented an algorithm for a physiologicallymotivated wavelet-type decomposition of EPs, and demonstrated its utility for source estimation of EPs from different modalities. This source estimation algorithm provides a feasible solution without any additional assumptions nor initial conditions, by using a wavelet-type temporal model of the coherent mass activity of a large population of neurons which generate the EPs. Structural brain imaging, like magnetic resonance imaging (MRI), provides high spatial resolution of the head model, as well as anatomical imaging of specific brain structures, which is not available when using EPs. We incorporate MRI data into the source estimation algorithm by creating a more accurate geometrical and physical head model. In this study we obtain magnetic resonance images of the subject's head, with the electrode locations marked by fatty substances to enhance their identification. The individual images thus include accurate mapping of the brain and the positions of all recording electrodes relative to it. Visually evoked potentials were recorded from 32 electrodes distributed over the scalp, in response to monochromatic flashes, to each eye in turn. These short-latency evoked potentials represent a sequence of deep (sub-cortical) and superficial (cortical) sources, oriented horizontally, along the visual pathway.