Analysis of motoneuron responses to composite synaptic volleys (computer simulation study)

This paper deals with the analysis of changes in motoneuron (MN) firing evoked by repetitively applied stimuli aimed toward extracting information about the underlying synaptic volleys. Spike trains were obtained from computer simulations based on a threshold-crossing model of tonically firing MN, subjected to stimulation producing postsynaptic potentials (PSPs) of various parameters. These trains were analyzed as experimental results, using the output measures that were previously shown to be most effective for this purpose: peristimulus time histogram, raster plot and peristimulus time intervalgram. The analysis started from the effects of single excitatory and inhibitory PSPs (EPSPs and IPSPs). The conclusions drawn from this analysis allowed the explanation of the results of more complex synaptic volleys, i.e., combinations of EPSPs and IPSPs, and the formulation of directions for decoding the results of human neurophysiological experiments in which the responses of tonically firing MNs to nerve stimulation are analyzed

İnsan motor nöronlarında sinaptik gürültünün ve postsinaptik potansiyellerin hesaplanması

Aim: The objective of this experiment is to estimate amount of synaptic noise (SN) and excitatory post-synaptic potential (EPSP) on human motoneurones using peristimulus time histogram (PSTH), peristimulus frequencygram (PSF) and membrane potential trajectory methods. Material and Methods: Nine female and 5 male healthy subjects who did not have any neurological disorders were tested. The subjects layed prone on a physiotherapy table. Electrical stimuli were delivered to the tibial nerve in popliteal fossa randomly every 1 to 2 s. The data were recorded using both surface electromyogram (SEMG) and single motor unit potentials (SMUP) in soleus muscle. Results: A total of 42 soleus motor units were analysed. The average SEMG recordings showed three conditions: H- reflex only (H-only), high amplitude H-reflex with low amplitude M-response (m+H), and low amplitude H-reflex with high amplitude M-response (M+h). Thus, the data were analysed according to the three groups. Our results demonstrated that there were no statistically significant differences between PSTH-EPSP and PSF-EPSP2 amplitudes in all groups (p;gt;0,017). Furthermore, the EPSP amplitudes calculated by both methods were found to be about 2 mV. The total synaptic noise (TSN) on the human motoneurones was estimated using only PSF method and was found to be 5,2 mV. Conclusion: We concluded that both methods can be used with confidence to estimate the EPSP amplitude and SN amplitude can be estimated only by the PSF method on the human motoneurones.Bu çalışmanın amacı, insan motor nöronları üzerinde oluşan sinaptik gürültüyü (SG) ve eksite edici postsinaptik potansiyel (EPSP) genliğini peristimulus time histogram (PSTH) ve peristimulus frekansgram (PSF) yöntemlerini kullanarak, membran potansiyeli trajektörü (yolu) yöntemi üzerinden hesaplamaktır. Gereç ve Yöntem: Araştırmaya herhangi bir nörolojik rahatsızlığı olmayan dokuz kadın ve beş erkek gönüllü katıldı. Denekler yüzükoyun olarak bir fizyoterapi masasına yatırıldı. Elektriksel uyarılar sağ bacak popliteal fossa (fossa poplitea / popliteal çukur / diz ardı çukuru) üzerinden tibial sinire 1–2 saniye aralıklarla rastgele olarak verildi. Kayıtlar soleus kasından, yüzeysel elektromiyogram (SEMG) ve tek motor ünite aksiyon potansiyelleri (SMUP) şeklinde kaydedildi. Bulgular: On dört denekten toplam olarak 42 tek motor ünite (SMU) elde edildi. Elde edilen bu motor üniteler, ortalaması alınmış SEMG’deki genlik büyüklüklerine göre, sadece H-refleksi, büyük genlikli H ile birlikte küçük genlikli m (m+H) ve büyük genlikli M ile birlikte küçük genlikli h (M+h) olacak şekilde üç gruba ayrıldı. Sonuçlar incelendiğinde PSTH-EPSP genliği ile PSF-EPSP2 genliği değerleri arasında istatistiksel olarak anlamlı bir farkın bulunmadığı görüldü (p>0,017). Her iki yöntemde hesaplanan EPSP genlikleri yaklaşık olarak 2 mV civarında bulundu. Sadece PSF yöntemi ile hesaplanan insan motor nöronlarındaki toplam sinaptik gürültü (TSG) değeri ise 5,2 mV olarak tespit edildi. Sonuç: PSF yöntemi EPSP genliğinin hesaplanmasında PSTH yöntemi kadar güvenilir bir yöntemdir. Dahası bu yöntem, insan motor nöronlarındaki SG genliğinin hesaplanması için güvenle kullanılabilir bir yöntem olup, bu anlamda PSTH yönteminden daha başarılıdır

Farklı frekanslardaki ve şiddetlerdeki işitsel uyaranların insanda basit reaksiyon zamanına etkileri

Several studies have been performed on the reaction time stimuli of different modalities in man. However, studies concerned with how ;amp;#8216;Simple Reaction Time;amp;#8217; (SRT) is affected by auditory stimuli with different intensities and frequencies are rare. In this study, we aimed at determining the pure sound tone of which frequency and intensity affects SRT the most. For this purpose, the subjects were classified according to age and sex and SRTs were measured by changing the sound intensity and frequency one at a time. Healthy male and female adults, aged between 17 and 24 (mean age: 20.65 yrs in both groups) were included in the study. Sound frequencies used were 500 Hz, 1 kHz, 2 kHz and 4 kHz. Each pure tone was applied at three different intensities; 60, 70 and 80 dB. It was observed that SRT gets shorter statistically significantly as the stimulus intensity is increased and that SRT changes significantly with frequency. The mean reaction time of all subjects regardless of sex for all intensities was calculated. It was shortest for 500 Hz and longest for 2 kHz. It has been concluded that among the stimuli used in this study the tone beep with a frequency of 500 Hz and intensity level 80 dB is the most effective stimulus which causes the shortest auditory reaction time in our subjects. Simple reaction times of all subjects regardless of gender to all stimuli fell in the range of 160- 190 ms.İşitsel, görsel ve taktil uyaranlara reaksiyon zamanı (RZ) üzerinde birçok çalışma yapılmıştır. Ancak basit reaksiyon zamanının (BRZ) değişik şiddet düzeylerinde ve frekanslardaki işitsel uyaranlardan nasıl etkilendiği iyi bilinmemekte-dir. Özellikle, ses frekansının BRZ’ye etkisi ile ilgili çalışmalar nadirdir. Bu çalışma ile hangi frekans ve şiddet düzeylerindeki ses uyaranlarının BRZ’yi en çok etkilediğini saptamayı amaçladık. Bu amaçla denekler cinsiyete ve yaşa göre gruplandırıldı. Her grup için ses şiddet düzeyi ve frekansı değiştirilerek BRZ’ler ölçüldü. Deneye sağlıklı, erişkin ve bilinen bir işitsel rahatsızlığı olmayan yaşları 17-24 arasında değişen 20 kadın ve 20 erkek denek (her iki grupta ortalama yaş: 20.65) dahil edildi. Ses uyaranları olarak, insan kulağının en duyarlı olduğu frekans aralığında yer alan 1kHz, 2kHz ve 4kHz frekanslı saf ses tonları ile bu aralığın dışında kalan 500 Hz frekanslı saf ses tonu kullanıldı. Her ses üç değişik şiddet düzeyinde (60, 70 ve 80 dB) uygulandı. BRZ’nin şiddet düzeyi artışıyla anlamlı ölçüde kısaldığı görüldü. BRZ’nin frekansa göre de anlamlı olarak değiştiği saptandı. Şiddet düzeyi ve cinsiyet ayrımına gidilmeden tüm verilerin genel ortalaması alındığında BRZ’nin en kısa 500 Hz’de, en uzun 2 kHz’de olduğu gözlendi. Kullanılan uyaranlar arasında 500 Hz - 80 dB şiddet düzeyli sesin insanda işitsel uyaranlara reaksiyon vermede en etkili uyaran olduğu sonucuna varıldı. Tüm deneklerin tüm uyaranlara reaksiyon zamanları 160- 190 ms aralığında bulundu. Bu reaksiyon zamanı aralığı benzer çalışmalardan elde edilen değerlerle uyumludur

The effect of motivational climate and conscientiousness on athletes’ maximal voluntary contraction level of biceps brachii muscle

We investigated the effect of induced motivational climates (a mastery climate and a performance climate) on maximal voluntary contraction (MVC) level of the biceps brachii muscle. We also aimed to explore whether motivational orientations, together with conscientiousness, are associated with MVC level in mastery and performance climate conditions. The sample consisted of 53 college student athletes ranging in age from 20 to 26. Participants first completed the Task and Ego Orientation in Sport Questionnaire and items relating to conscientiousness from the Short Form of the Five Factor Personality Inventory. Then, during isometric elbow flexion, MVCs were measured in a neutral condition. Afterwards, participants were informed of their MVC levels measured in the neutral condition via biofeedback software, and randomly assigned to either the mastery or the performance condition. Participants in the mastery climate condition were instructed to exceed their own highest MVC level observed in the neutral condition. In contrast, participants in the performance climate condition were instructed to exceed an unrealistic MVC level described as the best ever recorded so far. Results indicated that percentage change in MVC differed significantly between the mastery and performance climate conditions. Specifically, while there was a 13.5% increase in MVC value in the performance climate condition, there was an 8.8% decrease in the mastery climate condition. Results also showed that regardless of motivational climate, the percentage change in MVC was unrelated to motivational orientations and conscientiousness. © 2017 Springer Science+Business Media, LL

The effect of motivational climate and conscientiousness on athletes’ maximal voluntary contraction level of biceps brachii muscle

2-s2.0-85039060305We investigated the effect of induced motivational climates (a mastery climate and a performance climate) on maximal voluntary contraction (MVC) level of the biceps brachii muscle. We also aimed to explore whether motivational orientations, together with conscientiousness, are associated with MVC level in mastery and performance climate conditions. The sample consisted of 53 college student athletes ranging in age from 20 to 26. Participants first completed the Task and Ego Orientation in Sport Questionnaire and items relating to conscientiousness from the Short Form of the Five Factor Personality Inventory. Then, during isometric elbow flexion, MVCs were measured in a neutral condition. Afterwards, participants were informed of their MVC levels measured in the neutral condition via biofeedback software, and randomly assigned to either the mastery or the performance condition. Participants in the mastery climate condition were instructed to exceed their own highest MVC level observed in the neutral condition. In contrast, participants in the performance climate condition were instructed to exceed an unrealistic MVC level described as the best ever recorded so far. Results indicated that percentage change in MVC differed significantly between the mastery and performance climate conditions. Specifically, while there was a 13.5% increase in MVC value in the performance climate condition, there was an 8.8% decrease in the mastery climate condition. Results also showed that regardless of motivational climate, the percentage change in MVC was unrelated to motivational orientations and conscientiousness. © 2017, Springer Science+Business Media, LLC

The effect of motivational climate and conscientiousness on athletes’ maximal voluntary contraction level of biceps brachii muscle

We investigated the effect of induced motivational climates (a mastery climate and a performance climate) on maximal voluntary contraction (MVC) level of the biceps brachii muscle. We also aimed to explore whether motivational orientations, together with conscientiousness, are associated with MVC level in mastery and performance climate conditions. The sample consisted of 53 college student athletes ranging in age from 20 to 26. Participants first completed the Task and Ego Orientation in Sport Questionnaire and items relating to conscientiousness from the Short Form of the Five Factor Personality Inventory. Then, during isometric elbow flexion, MVCs were measured in a neutral condition. Afterwards, participants were informed of their MVC levels measured in the neutral condition via biofeedback software, and randomly assigned to either the mastery or the performance condition. Participants in the mastery climate condition were instructed to exceed their own highest MVC level observed in the neutral condition. In contrast, participants in the performance climate condition were instructed to exceed an unrealistic MVC level described as the best ever recorded so far. Results indicated that percentage change in MVC differed significantly between the mastery and performance climate conditions. Specifically, while there was a 13.5% increase in MVC value in the performance climate condition, there was an 8.8% decrease in the mastery climate condition. Results also showed that regardless of motivational climate, the percentage change in MVC was unrelated to motivational orientations and conscientiousness. © 2017, Springer Science+Business Media, LLC

Simplified Sympes Codec with Positive DC Offset

In this paper, further improvement is reported in the simplified version of the Sympes voice encoding algorithm. A drastic reduction in the computation time of the algorithm is achieved by introducing an offset in the amplitude of the normalized speech signals which enables trusted, secure and real time voice communication over computer networks and internet