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WS-32-4 Event-related potentials to auditory and visual stimuli in normal and learning disabled children
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Workshop33. Muscleforce and fatigue measurement
1983), and modified for pronostication by Cornblath (Ann. Neurol. 27 S17-$20, 1990) are not suitable for early diagnosis of an acute demyelinating neuropathy in the first or second week of evolution at least in very young children.
I WS-32-21 Neurophysiological correlates of event-related potentials (ERPs) in normal aging Mikio Osawa. Department of Neurology, Neurological Institute,
Tokyo Women's Medical College The relationship between age and event-related potentials (ERPs), which are believed to reflect cognitive processes, were investigated in normal adult subjects. ERPs included P300 and several earlier negative components such as N200, N2b, mismatch negativity (MMN), and NA in response to auditory and visual stimuli, P300 and N200, which are believed to reflect consciously controlled stages of information processing, were evoked following rare stimuli in oddball paradigm, and N2b, which is the main subcomponent of N200, was obtained by subtracting the frequent stimulus ERP from the rare stimulus ERE MMN, which is another subcomponent of N200 and is believed to reflect the automatic comparison of consecutive stimuli, was obtained by subtracting the standard stimulus ERP from the deviant stimulus ERP recorded in ignore condition. NA, which is believed to be related to pattern recognition processes, was delineated by subtracting ERPs obtained during simple reaction time task from ERPs elicited by rare stimuli in choice reaction time task. P300 peak latency monotonically increased and its amplitude decreased from early adulthood to old age, but its topographic distribution did not significantly change in either auditory or visual oddball paradigm. In normal subjects in their 60's to 70's compared to those in their 20's, N2b peak latency as well as P300 was delayed, and MMN and NA did not significantly change in latency in either stimulus modality. These findings suggest that aging effects may not occur in an automatic mismatch process, but at consciously controlled stages of information processing.
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I
WS-32-3 I P300 in the assessment of aging: facts, foibles, and future
John Polich. Cognitive Electrophysiology Laboratory, Department
of Neuropharmacology, The Scripps Research Institute, La JoUa, California, USA The P300 event-related brain potential (ERP) has demonstrated significant promise as an electrophysiological measure of human cognition, because it reflects individual differences in mental capacity that can vary with age and dementing illness. The theoretical and empirical background for the utility of the P300 as a measure of cognitive aging will be summarized. A meta-analysis of P300 latency data from 32 different normative aging studies then will be presented. Evaluation of statistically significant moderator variables indicates that sample characteristics, stimulus factors, and task conditions all can contribute to the "normal" change in peak latency that occurs with aging. These findings are critiqued in the context of previous reports, with the implications for future applications of ERPs to normative aging outlined. Because the utility of the P300 has been limited by the variability observed for ERP component measures across subjects, sources of this variability will be identified and suggestions for procedures that can delimit it will be proffered. The findings will be discussed in terms of how variation for P300 measures can be minimized when ERPs are used to assess cognitive function in clinical populations.
WS-32-4 ] Event-related potentials to auditory and visual stimuli in normal and learning disabled children Masutomo Miyao. Department of Pediatrics, Jichi Medical School, Tochigi, Japan In our country, interest for learning disabilities (LD) rose, and studies became do in the field of education and medicine. One reason for developing event-related potentials (ERP) indices of LD is the hope that this noninvasive, direct measure of brain activity will allow detection of affected children and hence remedial intervention. LD in our country is applied to children who have difficulty in specific academic area [especially reading and/or writing Chinese characters (Kanji) and Japanese characters (Hiragana)]. I studied the following to make clear mechanism of LD in our country for reason of these in time. Subjects: Twenty-seven healthy children and adult of 5-30 yearold served ad subjects for the normative studies. In addition, seventeen LDs (7 developmental coordination disorder (DCD), 4 developmental reading disorder (DRD), 1 developmental expressive language disorder + developmental expressive writing disorder (DELD + DEWD), 1 developmental arithmetic disorder (DAD), 2 borderline intellectual functioning (BIF), and 2 higher function autistic disorder (HFAD) were studied. Recording procedure: The ERP to 1) auditory stimuli (pure tone) and word ([yama = ILl ] and [tuki = /el 1), 2) visual stimuli (Figure: [O] and [A], Hiragana: [ - ~ ] and [,~:: ], Hiragana [ ~ ~1~ = tlJ ] and [-'~-~- = ,El], Kanji: [ILl] and [/~l]) recorded at the Fz, Cz, Pz, Oz, C3 en C4 regions of the scalp. Results: 1) In 1 of 7 DCD, P300 amplitude for sound stimuli were attenuated in the left hemisphere, 2) in 2 of 4 DRD, P300 latencies for kanji stimuli were prolonged, 3) D E L D + DEWD, P300 latencies for sound stimuli were prolonged, P300 amplitude for Hiragana stimuli were attenuated in the left hemisphere and P300 component were not detected. 4) In DAD, BIF and HFAD, P300 latencies and amplitude latencies and amplitude were normal.
WS-33. MUSCLE FORCE AND FATIGUE MEASUREMENT [ WS-33-1 ] An approach to study the role of the corticospinal tract in central fatigue Reinhard Dengler, Margot Schubert, Kai Wohlfarth, Dirk Czapowski. Dept. of Neurology, Medical University of
Hannover, Germany Although abnormal fatigue is a rather consistent and early sign of corticospinal lesions, the role of this descending fibre tract in the process of fatigue is not very well defined. So far, a distinction between a corticospinal dysfunction and other, e.g. mental components of central fatigue was difficult. Transcranial magnetic stimulation (TMS), however, makes studies of the function of the corticospinal tract possible. Parameters such as the central motor conduction time (CMCT) and the size and shape of motor evoked potentials (MEPs) allow conclusions on the functional state of this descending tract and on possible exercise-induced changes. Therefore, we utilized TMS to study fatigue in lower extremity muscles of normal subjects and patients with multiple eclerosis. Transcranial magnetic stimuli were applied to the cortex before and immediately after a fatiguing walk. Peripheral fatigue was excluded by compound muscle action potentials evoked by supramaximal electrical nerve stimuli. In normal subjects, fatiguing exercise mostly results in slightly shortened CMCTs and decreased MEPs. In pa-
Workshop33. Muscleforce and fatigue measurement
1983), and modified for pronostication by Cornblath (Ann. Neurol. 27 S17-$20, 1990) are not suitable for early diagnosis of an acute demyelinating neuropathy in the first or second week of evolution at least in very young children.
I WS-32-21 Neurophysiological correlates of event-related potentials (ERPs) in normal aging Mikio Osawa. Department of Neurology, Neurological Institute,
Tokyo Women's Medical College The relationship between age and event-related potentials (ERPs), which are believed to reflect cognitive processes, were investigated in normal adult subjects. ERPs included P300 and several earlier negative components such as N200, N2b, mismatch negativity (MMN), and NA in response to auditory and visual stimuli, P300 and N200, which are believed to reflect consciously controlled stages of information processing, were evoked following rare stimuli in oddball paradigm, and N2b, which is the main subcomponent of N200, was obtained by subtracting the frequent stimulus ERP from the rare stimulus ERE MMN, which is another subcomponent of N200 and is believed to reflect the automatic comparison of consecutive stimuli, was obtained by subtracting the standard stimulus ERP from the deviant stimulus ERP recorded in ignore condition. NA, which is believed to be related to pattern recognition processes, was delineated by subtracting ERPs obtained during simple reaction time task from ERPs elicited by rare stimuli in choice reaction time task. P300 peak latency monotonically increased and its amplitude decreased from early adulthood to old age, but its topographic distribution did not significantly change in either auditory or visual oddball paradigm. In normal subjects in their 60's to 70's compared to those in their 20's, N2b peak latency as well as P300 was delayed, and MMN and NA did not significantly change in latency in either stimulus modality. These findings suggest that aging effects may not occur in an automatic mismatch process, but at consciously controlled stages of information processing.
I
I
WS-32-3 I P300 in the assessment of aging: facts, foibles, and future
John Polich. Cognitive Electrophysiology Laboratory, Department
of Neuropharmacology, The Scripps Research Institute, La JoUa, California, USA The P300 event-related brain potential (ERP) has demonstrated significant promise as an electrophysiological measure of human cognition, because it reflects individual differences in mental capacity that can vary with age and dementing illness. The theoretical and empirical background for the utility of the P300 as a measure of cognitive aging will be summarized. A meta-analysis of P300 latency data from 32 different normative aging studies then will be presented. Evaluation of statistically significant moderator variables indicates that sample characteristics, stimulus factors, and task conditions all can contribute to the "normal" change in peak latency that occurs with aging. These findings are critiqued in the context of previous reports, with the implications for future applications of ERPs to normative aging outlined. Because the utility of the P300 has been limited by the variability observed for ERP component measures across subjects, sources of this variability will be identified and suggestions for procedures that can delimit it will be proffered. The findings will be discussed in terms of how variation for P300 measures can be minimized when ERPs are used to assess cognitive function in clinical populations.
WS-32-4 ] Event-related potentials to auditory and visual stimuli in normal and learning disabled children Masutomo Miyao. Department of Pediatrics, Jichi Medical School, Tochigi, Japan In our country, interest for learning disabilities (LD) rose, and studies became do in the field of education and medicine. One reason for developing event-related potentials (ERP) indices of LD is the hope that this noninvasive, direct measure of brain activity will allow detection of affected children and hence remedial intervention. LD in our country is applied to children who have difficulty in specific academic area [especially reading and/or writing Chinese characters (Kanji) and Japanese characters (Hiragana)]. I studied the following to make clear mechanism of LD in our country for reason of these in time. Subjects: Twenty-seven healthy children and adult of 5-30 yearold served ad subjects for the normative studies. In addition, seventeen LDs (7 developmental coordination disorder (DCD), 4 developmental reading disorder (DRD), 1 developmental expressive language disorder + developmental expressive writing disorder (DELD + DEWD), 1 developmental arithmetic disorder (DAD), 2 borderline intellectual functioning (BIF), and 2 higher function autistic disorder (HFAD) were studied. Recording procedure: The ERP to 1) auditory stimuli (pure tone) and word ([yama = ILl ] and [tuki = /el 1), 2) visual stimuli (Figure: [O] and [A], Hiragana: [ - ~ ] and [,~:: ], Hiragana [ ~ ~1~ = tlJ ] and [-'~-~- = ,El], Kanji: [ILl] and [/~l]) recorded at the Fz, Cz, Pz, Oz, C3 en C4 regions of the scalp. Results: 1) In 1 of 7 DCD, P300 amplitude for sound stimuli were attenuated in the left hemisphere, 2) in 2 of 4 DRD, P300 latencies for kanji stimuli were prolonged, 3) D E L D + DEWD, P300 latencies for sound stimuli were prolonged, P300 amplitude for Hiragana stimuli were attenuated in the left hemisphere and P300 component were not detected. 4) In DAD, BIF and HFAD, P300 latencies and amplitude latencies and amplitude were normal.
WS-33. MUSCLE FORCE AND FATIGUE MEASUREMENT [ WS-33-1 ] An approach to study the role of the corticospinal tract in central fatigue Reinhard Dengler, Margot Schubert, Kai Wohlfarth, Dirk Czapowski. Dept. of Neurology, Medical University of
Hannover, Germany Although abnormal fatigue is a rather consistent and early sign of corticospinal lesions, the role of this descending fibre tract in the process of fatigue is not very well defined. So far, a distinction between a corticospinal dysfunction and other, e.g. mental components of central fatigue was difficult. Transcranial magnetic stimulation (TMS), however, makes studies of the function of the corticospinal tract possible. Parameters such as the central motor conduction time (CMCT) and the size and shape of motor evoked potentials (MEPs) allow conclusions on the functional state of this descending tract and on possible exercise-induced changes. Therefore, we utilized TMS to study fatigue in lower extremity muscles of normal subjects and patients with multiple eclerosis. Transcranial magnetic stimuli were applied to the cortex before and immediately after a fatiguing walk. Peripheral fatigue was excluded by compound muscle action potentials evoked by supramaximal electrical nerve stimuli. In normal subjects, fatiguing exercise mostly results in slightly shortened CMCTs and decreased MEPs. In pa-