Takumi Ikuta

Sex differences in the human group mean SEP

The following results were obtained with SEPs recorded from strictly age-matched normal human subjects, 100 males and 100 females, 22.29 +/- 1.90 years. (1) The sex factor on the wave form of SEP was confirmed highly significant by MANOVA. (2) It was confirmed that the group mean SEP of each sex each converges to a given wave form which significantly differed from each other. (3) The differences in the wave form of the group mean SEP between sexes were established. The group mean SEP for females consisted of the 12 components, N1, P1, N2, P2, N3, P3, N4, P4, N5, P5, N6 and P6, and was approximately tetraphasic within 500 msec in latency, while that for males consisted of the same components except for N4 and P4. The baseline amplitude of the wave form of the group mean SEP, smaller in males than in females, differed significantly between sexes, corresponding to the most remarkable difference in its wave form, in the descending slope from the highest positive peak P2 to the deep negative trough N6, where there was a high convex arch with P4 (80 msec) in females, a low hollow slope without the peak in males. The latencies of the components tended to be longer in males than in females. (4) With scaled SEPs, which were converted from SEPs by amplitude scaling, results were similar to those with SEPs, and the sex difference in the scaled group mean SEP was also verified to be significant. These results indicate the further possibility of data reduction by amplitude scaling.

The waveform of the group mean SEP of normal human subjects

The following conclusions were deduced from 200 SEPs recorded from 100 male and 100 female controls, of average age 22.34 +/- 1.70 years. (1) It was confirmed that the waveforms of a group mean SEP and of a group SD converge to a waveform which is not a flat horizontal line. (2) The waveform of the group mean SEP for the 200 normal subjects consisted of 12 components and was tetraphasic within 500 msec latency. The waveform of the group SD for the 200 normal subjects was also shown. (3) Some coincidences were established in early components within 50 msec latency, between the group mean SEP obtained in the present study and the group schematic SEPs reported by others, but large discrepancies were noted in later components. (4) With scaled SEPs, which were converted from unscaled SEPs by amplitude scaling in order to eliminate individual variation in absolute amplitude, similar results were obtained to those with unscaled SEPs. These results indicate the possibility of data reduction by amplitude scaling.

Sexual intercourse as a precipitating factor of transient global amnesia.

Abstract: A Japanese female case of transient global amnesia (TGA), who developed an amnesic episode after sexual intercourse, is reported. The mechanism of how TGA in the present case is precipitated by sexual intercourse could be explained by the elevated blood pressure during sexual intercourse that drops rapidly, causing a temporal ischemia in the distribution of the basilar artery. Furthermore, the importance of sexual intercourse as a precipitating factor of TGA is stressed.

Electroencephalographic changes during and after water intoxication.

Abstract: A case of water intoxication with remarkable hyponatremia was investigated with a special reference to EEG changes during and after the episode. The patient recovered his EEG as his consciousness disturbance had improved through an intravenous infusion of high osmolality saline, correlating with the serum sodium level. Further, the clinical importance of recording EEG for water intoxication was stressed.

Recovery of high speed memory scanning after transient global amnesia: A case report

Abstract We described the case of a 59 year old female with transient global amnesia (TGA) who had been examined neuropsychologically using Sternbergs paradigm and a random number generation (RNG) task on the following day, 1 week and 4 weeks after a TGA episode. The slope value of the linear function, a measure of cognitive memory scanning speed, decreased with time and showed a marked decrease 1 week after TGA, suggesting that the stage of serial and exhaustive scanning recovered within 1 week. The zero‐intercept value, on the other hand, increased during 1 week but decreased 4 weeks later and was not related directly to recovery from TGA. The performance in RNG task improved 1 week later, but deteriorated 4 weeks after the episode. Such a change in RNG was in accordance with that of the zero‐intercept value, predicting a relationship. It is concluded that the subclinical memory deficit, detected with these tasks, persisted longer than clinical recovery from TGA.

Three year outcome of the residents in a special nursing home

Abstract The 3 year outcome of 48 residents in a special nursing home was investigated, using Hasegawas dementia rating scale (HDS) and activities of daily living (ADL). For all the residents, HDS score correlates well with age (P < 0.01) and ADL score (P < 0.001). Nineteen residents (40.4%) died during the period surveyed. Two‐thirds of the residents with low ADL score died during the period, whereas 70% of the residents with high ADL score are alive. Of these scales, ADL correlated well with the fatal prognosis, suggesting that ADL is a valuable prognostic tool. As for the causes of death, pulmonary disease was prominent (n= 12, 63.2%). Consequently, the prevention of pulmonary disease is needed to achieve a good outcome in the management of nursing home residents.

The Complex Episode of Transient Global Amnesia

Abstract: In most reports, Transient Global Amnesia (TGA) consisted of a single episode of total amnesia. The detailed investigation on the process of recovery from amnesia in the present two cases of TGA indicated the existence of a complex episode of TGA which consisted of a sequence of episodes of total amnesia.

The Group Mean SEP of Normal Human Subjects

Abstract: The following conclusions were deduced from the SEPs of 100 normal human subjects, whose mean age was 21.80 ± 1.62. It was confirmed that the waveform of a Group Mean SEP and of a Group SD each converges to a waveform different from a flat horizontal line. The waveform of the Group Mean SEP consisted of 12 components, and was roughly tetraphasic within 500 msec in latency. Large discrepancies were found in the later components between the Group Mean SEP and the Group Schematic SEPs reported by others, although some coincidences were shown in the early components within 100 msec in latency.

The Waveforms of the Group Mean SEP of Each Sex

Abstract: With SEPs recorded from age‐matched normal human subjects, 100 males and 100 females, 22.34 ± 1.69 years, it was confirmed that the Group Mean SEP of each sex each converges to a given waveform which significantly differed from each other. The waveform of the Group Mean SEP for females consisted of the 12 components, and was approximately tetraphasic within 500 msec in latency, while that for males consisted of the same components except for N4 and P4. There was a high convex arch with P4 (82 msec) between P2 and N6 for females, but a low hollow slope without the peak for males. With Scaled SEPs, which were converted from SEPs by Amplitude Scaling, the results similar to those with SEPs were obtained.

Differences in Human Group Mean SEP between Sexes: with Reference to the Rohrer's Index*

Abstract: With 200 SEPs of normal subjects, the differences in the Group Mean SEP between sexes were defined eliminating the differences attributable to another peripheral factor relating to the nutritional condition represented by the Rohrers index. The differences in the baseline amplitude of the Group Mean SEP between males vs. females in the sections between roughly 23–111 msec, around 330 msec, and behind 389 msec in latency were verified, subtracting the differences between the groups with a high vs. low value of the Rohrers index, not attributable to the different nutritional condition, and might be the central origin. Applying the Amplitude Scaling, the differences in the sections 23–104 msec in latency were verified similarly, being more a significant indication of the sex difference per se.