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Topographical display of evoked potentials; its application to cerebrovascular diseases
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hospitalized for,one week. They underwent the following tests while using inverting prisms: behavioral changes, introspective report, various psychological tests, measurement of the times required for writing sentences and for reproducing figures, and polygraphic recording. Differences in the task performance of the four subjects related to their dexterity were noted in the early stages of this experiment. The adaptation was progressive with the lapse of days; thus on the 7th day the subjects were able to do routine work in the psychiatric department. The feeling that the external world looks unusual remained throughout the experiment and there was no upright vision of the visual field, nor any upright vision subjected to the all-or-none law. As for the EM, the total eye movements (TEM) showed gradual increase with the lapse of days, white eyes open saccadic eye movements (SEM) remained comparatively few till the 2nd day and showed marked increase on the 3rd or 4th day of the experiment. Based on these results, the relationship between psychophysiological mechanisms of perceptual behaviordT adaptation and neural process of EM produced by the inverted visual field was discussed. B-9.04 TOPOGRAPHICAL DISPLAY OF EVOKED POTENTIALS; ITS APPLICATION TO CEREBROVASCULAR DISEASES. A. Suzuki, Z. Ito, K. Yoshioka and M. Nara (Akita, Japan) The authors developed a colored topographical display of amplitudes of evoked potentials (EP). Until now, this method has been applied to 43 cases of cerebrovascular disease, and the extent of brain functional damage has been studied In cases with cerebral ischequantitatively. mia, amplitude topograms of somatosensory evoked potentials were studied during blood pressure changes or dehydrator administration. Functional reversibility in the ischemic brain were evaluated from these results. In this congress, the authors will present their system of display of EPs and results of EP topograms in cerebrovascular diseases, especially in cerebral ischemias from the aspect of its functional reversibility. A-7.03 ATTEMPT TO IMPROVE THE RELIABILITY OF ACOUSTICALLY EVOKED SLOW VERTEX RESPONSES. T. Itabashi, G. Ichikawa and N. Uehara (Tokyo, Japan) An attemot to improve the reliability of acoustically evoked slow vertex responses-was desianed and carried out. When the oriqinal EEGs are averaged 100 times, for example, 50 odd number sweeps and 50 even number sweeps are averaged separately on the same oscilloscope side These two averaged EEGs are tentaby side. tively named odd numbered and even numbered The identification of the reaveraged EEGs.
sponses is carried out by detecting the similarit of morphologies which have nearly the same r atency in the odd and eyen number averaged EEGs. The merits of this method are as fol1) the orobabilitv of false oositive relows: sponses is reduced greatly; 2) even'when the responses are not clear, they can be detected somehow. The demerit of this method is that the whole procedure requires a little longer time than the traditional method of detection of slow vertex responses. A-7.06 SHADOW RESPONSE AND ITS MASKING LEVEL IN ELECTRIC RESPONSE AUDIOMETRY (ERA). H. Yoshikawa, G. Ichikawa, T. Uchida, M. Kohda and K. Harada (Hongo, Japan) The phenomenon called shadow hearing exists in subjective audiometry and a similar phenomenon is recognized in ERA. When the difference of hearing threshold between the ears exceeds a certain range, contralateral masking is required but the determination of the proper masking level is difficult. Furthermore, when the hearing threshcannot be old measured for some reason, its determination is still more difficult. So several examinations were carried out in patients with unilateral deafness, for example oivinq some intensities of click into the deaf ear, and then a masking noise of several intensities were applied to the normal side. The results and discussion were as follows; 1) Morphology of the ERA possibly varied with the intensity of the masking noise applied to the contralateral ear. This behavior plays an important role in the neurological interpretation of ERA. 2) ABR and MLR were recorded even if the deaf ear was stimulated and the morphologies were similar to those of the true responses obtained by stimulation of the normal ear. 3) In order to mask the shadow responses generated at lower levels of the auditory pathway, a higher intensity of masking to the contralateral ear was required. B-B.07 ASYMMETRIES OF EVENT RELATED POTENTIALS (ERPs) DURING HUMAN INFORMATION PROCESSING. T. Adachi, H. Goto, M. Yamamoto, T. Okaniwa and T. Utsunomiya (Tokyo, Japan) To find cognitive asynnnetries of human information processing, ERPs to Kanji, Kana words, speech words, Arabic numerals, squares and pure tone sequences were investigated. Seven righthanded healthy subjects were required to press the pertinent switch either to recognising a semantic match or mismatch between two successive Kanji, or two successive trisyllabic Kana words, or two successive trisyllabic speech words; or according to comparing values of two successive Arabic numerals or comparing areas of two successive squares; or to determining a
hospitalized for,one week. They underwent the following tests while using inverting prisms: behavioral changes, introspective report, various psychological tests, measurement of the times required for writing sentences and for reproducing figures, and polygraphic recording. Differences in the task performance of the four subjects related to their dexterity were noted in the early stages of this experiment. The adaptation was progressive with the lapse of days; thus on the 7th day the subjects were able to do routine work in the psychiatric department. The feeling that the external world looks unusual remained throughout the experiment and there was no upright vision of the visual field, nor any upright vision subjected to the all-or-none law. As for the EM, the total eye movements (TEM) showed gradual increase with the lapse of days, white eyes open saccadic eye movements (SEM) remained comparatively few till the 2nd day and showed marked increase on the 3rd or 4th day of the experiment. Based on these results, the relationship between psychophysiological mechanisms of perceptual behaviordT adaptation and neural process of EM produced by the inverted visual field was discussed. B-9.04 TOPOGRAPHICAL DISPLAY OF EVOKED POTENTIALS; ITS APPLICATION TO CEREBROVASCULAR DISEASES. A. Suzuki, Z. Ito, K. Yoshioka and M. Nara (Akita, Japan) The authors developed a colored topographical display of amplitudes of evoked potentials (EP). Until now, this method has been applied to 43 cases of cerebrovascular disease, and the extent of brain functional damage has been studied In cases with cerebral ischequantitatively. mia, amplitude topograms of somatosensory evoked potentials were studied during blood pressure changes or dehydrator administration. Functional reversibility in the ischemic brain were evaluated from these results. In this congress, the authors will present their system of display of EPs and results of EP topograms in cerebrovascular diseases, especially in cerebral ischemias from the aspect of its functional reversibility. A-7.03 ATTEMPT TO IMPROVE THE RELIABILITY OF ACOUSTICALLY EVOKED SLOW VERTEX RESPONSES. T. Itabashi, G. Ichikawa and N. Uehara (Tokyo, Japan) An attemot to improve the reliability of acoustically evoked slow vertex responses-was desianed and carried out. When the oriqinal EEGs are averaged 100 times, for example, 50 odd number sweeps and 50 even number sweeps are averaged separately on the same oscilloscope side These two averaged EEGs are tentaby side. tively named odd numbered and even numbered The identification of the reaveraged EEGs.
sponses is carried out by detecting the similarit of morphologies which have nearly the same r atency in the odd and eyen number averaged EEGs. The merits of this method are as fol1) the orobabilitv of false oositive relows: sponses is reduced greatly; 2) even'when the responses are not clear, they can be detected somehow. The demerit of this method is that the whole procedure requires a little longer time than the traditional method of detection of slow vertex responses. A-7.06 SHADOW RESPONSE AND ITS MASKING LEVEL IN ELECTRIC RESPONSE AUDIOMETRY (ERA). H. Yoshikawa, G. Ichikawa, T. Uchida, M. Kohda and K. Harada (Hongo, Japan) The phenomenon called shadow hearing exists in subjective audiometry and a similar phenomenon is recognized in ERA. When the difference of hearing threshold between the ears exceeds a certain range, contralateral masking is required but the determination of the proper masking level is difficult. Furthermore, when the hearing threshcannot be old measured for some reason, its determination is still more difficult. So several examinations were carried out in patients with unilateral deafness, for example oivinq some intensities of click into the deaf ear, and then a masking noise of several intensities were applied to the normal side. The results and discussion were as follows; 1) Morphology of the ERA possibly varied with the intensity of the masking noise applied to the contralateral ear. This behavior plays an important role in the neurological interpretation of ERA. 2) ABR and MLR were recorded even if the deaf ear was stimulated and the morphologies were similar to those of the true responses obtained by stimulation of the normal ear. 3) In order to mask the shadow responses generated at lower levels of the auditory pathway, a higher intensity of masking to the contralateral ear was required. B-B.07 ASYMMETRIES OF EVENT RELATED POTENTIALS (ERPs) DURING HUMAN INFORMATION PROCESSING. T. Adachi, H. Goto, M. Yamamoto, T. Okaniwa and T. Utsunomiya (Tokyo, Japan) To find cognitive asynnnetries of human information processing, ERPs to Kanji, Kana words, speech words, Arabic numerals, squares and pure tone sequences were investigated. Seven righthanded healthy subjects were required to press the pertinent switch either to recognising a semantic match or mismatch between two successive Kanji, or two successive trisyllabic Kana words, or two successive trisyllabic speech words; or according to comparing values of two successive Arabic numerals or comparing areas of two successive squares; or to determining a