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An analysis of event related potentials elicited by CV syllables: in relation to shortened successive vowels
48P
Society proceedings/Electroencephalography
In 10 subjects, one of the bifurcated P3 peaks showed significant latency differences among the 3 blocks, whereas the other peak with shorter latency showed no significant latency differences. Thus, the bifurcated P3 components in these subjects were constituted of task-irrelevant P3a and task-relevant P3b. In 6 subjects, the earlier peak of bifurcated P3 was larger than the later peak, and both peaks showed significant latency differences among the 3 blocks. Slow wave also showed differences in latency and amplitude. Thus, in 3 subjects, latency jitter might result in the bifurcated P3. The bifurcated P3 in the other 3 subjects might be resulting from P3b and a portion of slow waves. Measurement of the maximal point alone did not correctly evaluate P3b. Thus, the SSA based on RT was proven to be useful to evaluate the bifurcated P3.
22. Study of event-related potential (ERP) correlates of semantic priming. - M. Osawa, Y. Nageishi, R. Ushijima and M. Iwata (Tokyo) ERP correlates of semantic priming were studied. Subjects included normal adult women aged 23-27 years. In session 1, 1 word at a time was shown on a CRT, which subjects were instructed to classify into 1 of 5 categories as they liked. In session 2, subjects were instructed to perform calculations for 3 min. In session 3, a categorical classification paradigm was performed. One word at a time was shown. Words belonging to one category were shown as a target at a frequency of 33%, and those belonging to the other category as a non-target of 67%. Half of the target words were displayed in session 1 (old), and the remainder were shown for the first time in session 3 (new). Single trials of ERPs were recorded from Fz, Cz, and Pz referred to linked earlobes. ERPs for targets were off-line averaged, and evaluated along with reaction time (RT) separately between old and new words. ERPs for old words were shifted negatively at a latency 200 msec after those for new ones, and RTs for the former were about 20 msec shorter than for the latter. In conclusion, ERP may be useful as an indicator of semantic priming.
23. An analysis of event related potentials elicited by CV syllables: in relation to shortened successive vowels. - Y. Matsumaru, H. Ozaki and H. Suzuki (Mito) We studied the discriminative process of Japanese CV (consonant + vowel) syllables in respect to the shortened duration of the following vowels. Three series of CV syllables ( / s a / , / t a / , / n a / ) were presented randomly to normal adults; the subjects listened to those CV syllables passively. Each series was composed of 3 different combinations of an initial consonant (C) and a vowel (V), i.e., without a vowel ((C + V0)), with a vowel lasting 3 msec ((C + V3)) and with a vowel lasting 13 msec ((C + V13)). Event related potentials (ERPs) were compared between different durations of vowels within each series, through grand averaged waves by the average reference method, their difference and the Global Dissimilarity index between the potential maps. Distinct components were noticed: (1) at about 280 msec in ERPs to (C + V13) of the / s a / s e r i e s , (2) at about 190 msec in ERPs to (C + V3) and (C + VI3) of t h e / t a / series, and (3) at about 230 msec in ERPs to (C + V13) of the / n a / series. These components appeared mainly around central a n d / o r fronto-central areas. It was inferred that different time courses of these ERPs may reflect the temporally different categorizing process of CV syllables due to the specific acoustic characteristics of each speech sound.
and clinical Neurophysiology 98 (1996) 44P-52P handed male subjects performed the force production task which required them to pull a trigger of the apparatus and to exert an impulsive force in an attempt to produce the target force. Two conditions were conducted. In the constant practice condition, subjects attempted to produce a target force of 1300 gf. In the variable practice condition, they performed 2 additional target forces of 500 gf or 2100 gf. The subjects performed 4 runs, 2 for each condition. The runs, each of which consisted of 70 trials, were arranged in an ABBA sequence counterbalanced across subjects. Only EEGs preceding to the 1300 gf trials were averaged. The RP amplitude was larger in the variable practice condition than in the constant practice condition. In addition, the enhancement was specific to the NS' (negative slope). In the variable practice condition, the subjects had to reconstruct the motor plan on subsequent 1300 gf trials. Hence, it was assumed that reconstruction of motor plan might be responsible for the enhanced NS' in the variable practice condition.
25. rCBF measured simultaneously with P300 recording. - M. Mochida, Y. Koga, K. Fujita, Y. Shutara, K. Nakagawa, Y. Saito, U. Kihara, K. Takemasa, K. Nagata, I. Kanno and H. Fujita (Tokyo) The purpose of this study was to clarify the areas of the brain which affect scalp P300 during the processing of an auditory input. P300s were recorded during an auditory oddball task in 7 healthy males, and rCBF was measured simultaneously in 24 ROls using a PET scanner. P300 amplitude positively correlated with the rCBF value in the right orbitofrontal area, bilateral superior temporal gyri, right middle temporal gyrus and the bilateral angular gyri. It was negatively correlated with the value in the right piriform area and bilateral thalami. The P300 latency positively correlated with the rCBF value in the right hippocampus and the right transverse gyrus of Heschl, while it was negatively correlated in the bilateral nuclei accumbens septi. These results may indicate that the processing reflected in the P300 is activated by an increase of rCBF in the auditory areas. It is also suggested that the limbic system plays an important role in generating or modulating the scalp P300.
26. Altered P300 event-related potential latencies and subclinical brain infarcts in patients with diabetes mellitus. - A. Kurita, K. Katayama and S. Mochio (Tokyo) Recent neurobehavioral studies have revealed cognitive decline in diabetic patients. To neurophysiologically investigate the influence of diabetes on higher brain functions, and to examine whether subclinical brain infarcts alter cognitive status in diabetic patients, we studied auditory P300 event-related potentials (ERPs) in 18 non-insulin-dependent diabetic (NIDDM) patients with consideration of head MRI findings. None of the patients had any history, signs or symptoms of stroke, dementia or any other neurological diseases except for diabetic peripheral neuropathy. Twenty neurologically healthy volunteers served as control subjects. To obtain ERPs, a conventional recording technique with an acoustic odd-ball paradigm was used. Compared with controls, diabetic patients had significantly longer P300 latencies. MRI examination revealed isehemic lesions in 4 diabetic patients. Their P300 latencies varied from normal into the pathological range, with a value exceeding the mean + 3 S.D. of controls. In the remaining 14 patients, MRI findings were unremarkable, but the mean P300 latency was significantly longer than that of controls. These findings suggest that NIDDM can independently alter higher cognitive functions as assessed by P300 latencies. Cerebrovascular ischemia, if present, appears to contribute in part to cognitive alterations in NIDDM patients.
24. The effects of variability in practice on readiness potential. - H. Masaki, N. Takasawa and K. Yamazaki (Tokyo)
27. Visual verbal and non-verbal P300 in total aphasia and dementia. - T. Ito, R. Neshige, K. Momota, S. Talmyanagi and S. Nakamura (Fukuoka)
The present study was designed to investigate the relationship between the readiness potential (RP) and variations of a task. Nine right-
P300 was recorded by visual oddball paradigm, using non-verbal (target (20%); X, non-target (80%); 0) as well as verbal stimuli (target
Society proceedings/Electroencephalography
In 10 subjects, one of the bifurcated P3 peaks showed significant latency differences among the 3 blocks, whereas the other peak with shorter latency showed no significant latency differences. Thus, the bifurcated P3 components in these subjects were constituted of task-irrelevant P3a and task-relevant P3b. In 6 subjects, the earlier peak of bifurcated P3 was larger than the later peak, and both peaks showed significant latency differences among the 3 blocks. Slow wave also showed differences in latency and amplitude. Thus, in 3 subjects, latency jitter might result in the bifurcated P3. The bifurcated P3 in the other 3 subjects might be resulting from P3b and a portion of slow waves. Measurement of the maximal point alone did not correctly evaluate P3b. Thus, the SSA based on RT was proven to be useful to evaluate the bifurcated P3.
22. Study of event-related potential (ERP) correlates of semantic priming. - M. Osawa, Y. Nageishi, R. Ushijima and M. Iwata (Tokyo) ERP correlates of semantic priming were studied. Subjects included normal adult women aged 23-27 years. In session 1, 1 word at a time was shown on a CRT, which subjects were instructed to classify into 1 of 5 categories as they liked. In session 2, subjects were instructed to perform calculations for 3 min. In session 3, a categorical classification paradigm was performed. One word at a time was shown. Words belonging to one category were shown as a target at a frequency of 33%, and those belonging to the other category as a non-target of 67%. Half of the target words were displayed in session 1 (old), and the remainder were shown for the first time in session 3 (new). Single trials of ERPs were recorded from Fz, Cz, and Pz referred to linked earlobes. ERPs for targets were off-line averaged, and evaluated along with reaction time (RT) separately between old and new words. ERPs for old words were shifted negatively at a latency 200 msec after those for new ones, and RTs for the former were about 20 msec shorter than for the latter. In conclusion, ERP may be useful as an indicator of semantic priming.
23. An analysis of event related potentials elicited by CV syllables: in relation to shortened successive vowels. - Y. Matsumaru, H. Ozaki and H. Suzuki (Mito) We studied the discriminative process of Japanese CV (consonant + vowel) syllables in respect to the shortened duration of the following vowels. Three series of CV syllables ( / s a / , / t a / , / n a / ) were presented randomly to normal adults; the subjects listened to those CV syllables passively. Each series was composed of 3 different combinations of an initial consonant (C) and a vowel (V), i.e., without a vowel ((C + V0)), with a vowel lasting 3 msec ((C + V3)) and with a vowel lasting 13 msec ((C + V13)). Event related potentials (ERPs) were compared between different durations of vowels within each series, through grand averaged waves by the average reference method, their difference and the Global Dissimilarity index between the potential maps. Distinct components were noticed: (1) at about 280 msec in ERPs to (C + V13) of the / s a / s e r i e s , (2) at about 190 msec in ERPs to (C + V3) and (C + VI3) of t h e / t a / series, and (3) at about 230 msec in ERPs to (C + V13) of the / n a / series. These components appeared mainly around central a n d / o r fronto-central areas. It was inferred that different time courses of these ERPs may reflect the temporally different categorizing process of CV syllables due to the specific acoustic characteristics of each speech sound.
and clinical Neurophysiology 98 (1996) 44P-52P handed male subjects performed the force production task which required them to pull a trigger of the apparatus and to exert an impulsive force in an attempt to produce the target force. Two conditions were conducted. In the constant practice condition, subjects attempted to produce a target force of 1300 gf. In the variable practice condition, they performed 2 additional target forces of 500 gf or 2100 gf. The subjects performed 4 runs, 2 for each condition. The runs, each of which consisted of 70 trials, were arranged in an ABBA sequence counterbalanced across subjects. Only EEGs preceding to the 1300 gf trials were averaged. The RP amplitude was larger in the variable practice condition than in the constant practice condition. In addition, the enhancement was specific to the NS' (negative slope). In the variable practice condition, the subjects had to reconstruct the motor plan on subsequent 1300 gf trials. Hence, it was assumed that reconstruction of motor plan might be responsible for the enhanced NS' in the variable practice condition.
25. rCBF measured simultaneously with P300 recording. - M. Mochida, Y. Koga, K. Fujita, Y. Shutara, K. Nakagawa, Y. Saito, U. Kihara, K. Takemasa, K. Nagata, I. Kanno and H. Fujita (Tokyo) The purpose of this study was to clarify the areas of the brain which affect scalp P300 during the processing of an auditory input. P300s were recorded during an auditory oddball task in 7 healthy males, and rCBF was measured simultaneously in 24 ROls using a PET scanner. P300 amplitude positively correlated with the rCBF value in the right orbitofrontal area, bilateral superior temporal gyri, right middle temporal gyrus and the bilateral angular gyri. It was negatively correlated with the value in the right piriform area and bilateral thalami. The P300 latency positively correlated with the rCBF value in the right hippocampus and the right transverse gyrus of Heschl, while it was negatively correlated in the bilateral nuclei accumbens septi. These results may indicate that the processing reflected in the P300 is activated by an increase of rCBF in the auditory areas. It is also suggested that the limbic system plays an important role in generating or modulating the scalp P300.
26. Altered P300 event-related potential latencies and subclinical brain infarcts in patients with diabetes mellitus. - A. Kurita, K. Katayama and S. Mochio (Tokyo) Recent neurobehavioral studies have revealed cognitive decline in diabetic patients. To neurophysiologically investigate the influence of diabetes on higher brain functions, and to examine whether subclinical brain infarcts alter cognitive status in diabetic patients, we studied auditory P300 event-related potentials (ERPs) in 18 non-insulin-dependent diabetic (NIDDM) patients with consideration of head MRI findings. None of the patients had any history, signs or symptoms of stroke, dementia or any other neurological diseases except for diabetic peripheral neuropathy. Twenty neurologically healthy volunteers served as control subjects. To obtain ERPs, a conventional recording technique with an acoustic odd-ball paradigm was used. Compared with controls, diabetic patients had significantly longer P300 latencies. MRI examination revealed isehemic lesions in 4 diabetic patients. Their P300 latencies varied from normal into the pathological range, with a value exceeding the mean + 3 S.D. of controls. In the remaining 14 patients, MRI findings were unremarkable, but the mean P300 latency was significantly longer than that of controls. These findings suggest that NIDDM can independently alter higher cognitive functions as assessed by P300 latencies. Cerebrovascular ischemia, if present, appears to contribute in part to cognitive alterations in NIDDM patients.
24. The effects of variability in practice on readiness potential. - H. Masaki, N. Takasawa and K. Yamazaki (Tokyo)
27. Visual verbal and non-verbal P300 in total aphasia and dementia. - T. Ito, R. Neshige, K. Momota, S. Talmyanagi and S. Nakamura (Fukuoka)
The present study was designed to investigate the relationship between the readiness potential (RP) and variations of a task. Nine right-
P300 was recorded by visual oddball paradigm, using non-verbal (target (20%); X, non-target (80%); 0) as well as verbal stimuli (target