Reiko Tsukahara

The recruitment pattern of single vasoconstrictor neurons in human.

The aim of this study is to determine the recruitment pattern among individual vasoconstrictor neurons under the baroreceptor-mediated influence in man. Spikes of single vasoconstrictor units were detected from microneurograms with a template-matching method. A total of 39 single vasoconstrictor units were detected. Single vasoconstrictor units were different from each other in their susceptibility to be activated in response to changes in the R-R interval or blood pressure. The units with higher firing probability had a shorter threshold R-R interval and a higher threshold diastolic blood pressure than units with lower firing probability. In sympathetic responses consisting of only one spike (single-spike responses), units with a lower threshold frequently appeared and units with a higher threshold joined mull-spike responses. The units with a short threshold R-R interval tended to have a long inhibitory latency from R wave, suggesting low conduction velocity. The correlation between firing probability and firing threshold and that between appearance in single-spike response and multi-spike response suggest a hierarchical manner of recruitment of vasoconstrictor units. For beat-to-beat responses, however, some deviation from the hierarchical recruitment was also observed.

Effects of premotion silent period on single motor unit firing at initiation of rapid contraction

We compared the single motor unit (SMU) activity between movements with a premotion silent period (PMSP) and without PMSP in EMG. Fourteen SMUs in the gastrocnemius muscle and 6 SMUs in the soleus muscle were recorded from 5 volunteers during isometric plantar flexion. Tonically firing SMUs failed to fire just before the onset of a rapid contraction with PMSP more frequently than without PMSP. SMUs tended to fire within 10 msec (the gastrocnemius SMUs) or 20 msec (the soleus SMUs) from the onset of the phasic EMG discharge when PMSP occurred. In a rapid contraction without PMSP, the initial firing of SMUs occurred with longer latency than that in a rapid contraction with PMSP. The latency of the initial SMU firing in a rapid contraction related to the preceding time of the last SMU firing during a sustained contraction to the onset of the phasic EMG discharge. When the preceding firing was long enough, the latency distributed around 10 msec. On the other hand, for shorter preceding times, the latency lengthened with shortening of the preceding time. It is suggested that the PMSP makes the preceding time long and increases the susceptibility of motor units to the descending command at the initiation of a rapid contraction.

Arousal electrical stimuli evoke sudomotor activity related to P300, and skin vasoconstrictor activity related to N140 in humans.

OBJECTIVE Arousal stimuli evoke bursts of skin sympathetic nerve activity (SSNA). SSNA usually contains sudomotor and vasoconstrictor neural spikes. The aim of this study was to elucidate which components of event-related potentials (ERPs) are related to sudomotor and vasoconstrictor responses comprising arousal SSNA bursts. METHODS We recorded SSNA from the tibial nerve by microneurography, with corresponding sympathetic skin response (SSR), sympathetic flow response (SFR), and ERPs in 10 healthy subjects. Electrical stimulation of the median nerve was used to induce arousal responses. ERPs were classified by the occurrence of SSR and SFR. RESULTS SSNA bursts followed by SSR were associated with larger P300 than SSNA bursts followed by no SSR. For N140, no difference in the amplitude was found between SSNA bursts with and without SSR. SSNA bursts followed by SFR were associated with larger N140 than SSNA bursts followed by no SFR. However, there were no differences in the amplitude of P300 between SSNA bursts with and without SFR. CONCLUSIONS Sudomotor and skin vasoconstrictor responses to arousal stimuli were differently associated with distinct ERP components. SIGNIFICANCE The possibility that sudomotor and skin vasoconstrictor activities comprising arousal SSNA reflect different stages of the cognitive process is suggested.

11. Relationships between skin sympathetic nerve activities and evoked potentials induced by voluntary or involuntary muscle contractions: Comparison between sudomotor and vasoconstrictor components

Human brain mapping with near infrared spectroscopy (NIRS) measurements poses two major problems that limit its effectiveness for localizing cortical activation. One is lower spatial resolution and the other is artifacts due to physiological noises most exemplified by non-cortical skin blood flow changes. In this study, we propose a novel solution for these problems by simultaneously implementing a high-density probe arrangement and independent component analysis (ICA)-based signal processing. To achieve high spatial information density, oxygenated hemoglobin signals during a fast-finger-tapping (4 Hz) task were measured with double-density optical topography (DDOT), which consists of data from two alternately embedded single-density optical topographies (SDOT). Then, the measured signals were subjected to ICA to extract the signal components representing cortical activation. DDOT data can be decomposed into two different sets of SDOT data. Comparisons between SDOT and DDOT data revealed that DDOT portrayed both the spatially focused activation and the temporal structure relevant to hemodynamic response, whereas the SDOT data could only portray one or the other. The spatial resolution of DDOT might appear excessive, but it does indeed enable more efficient source separation than SDOT, leading to more robust spatial and temporal analyzes.

P2-23 Time relationship between motor and sympathetic activation in a voluntary handgrip

intervals of heart rate and brain waves were analyzed for the evaluation of ANS and CNS function, respectively. This study was approved by the Ethics Committee of Shizuoka University. Results: Inhalation of the odor from YBGE in most subjects, but not all, tended to produce an increase in both parasympathetic nervous activity and in brain wave alpha/beta ratio. Conclusions: The odor of YBGE tended to stimulate ANS and CNS activity in within human subjects, but the extent of these changes varied individually, suggesting that an association between ANS and CNS is involved in odor-induced anti-stress in nervous system function. Further studies are required to further elucidate the effects of odor of green plants on the nervous system.

P36-22 Relationship between cognitive function and sympathetic skin response evoked by muscle contraction

Conclusion: The symmetrically distributed PCA component during BP and NS could reflect activity of the premotor areas with radially oriented cortical generators. A second component started to appear during BP but was maximal and prevalent during MP. It probably represents bilateral activity of the motor cortex with generators oriented tangentially. Using PCA, it is possible to distinguish different components of the SRCP, probably corresponding to premotor and motor cortical activity.

Personal computer communication board for the severely handicapped enable to speak

本研究ではパーソナルコンピュータを使用して, 発声・発語の困難な重症心身障害児 (者) のコミュニケーション支援機器を開発した. 文字の選択方法は, ひらがな五十音表の行と列を順次走査する方法によった.開発した機器を使用して, キーボード操作のできない重度脳性麻痺児を対象に, 語彙, 暗唱, 作文の課題を実施した. その結果, 重症児においても自由に単語や文章を書くことのできることが明らかとなった. また, 走査時間やスイッチの最適条件が示唆され, 重症児の言語習得レベルの評価が可能となった. 以上の結果から, 本研究で開発した機器は, 発声・発語の困難な重症児のコミュニケーションに有効であることが示唆された.