The objective of this study was to construct peristimulus time histogram (PSTH) and peristimulus frequencygram (PSF) using single motor unit recordings to further characterize the previously documented immediate sensorimotor effects of spinal manipulation. Single pulse transcranial magnetic stimulation (TMS) via a double cone coil over the tibialis anterior (TA) motor area during weak isometric dorsiflexion of the foot was used on two different days in random order; pre/post spinal manipulation (in eighteen subjects) and pre/post a control (in twelve subjects) condition. TA electromyography (EMG) was recorded with surface and intramuscular fine wire electrodes. Three subjects also received sham double cone coil TMS pre and post a spinal manipulation intervention. From the averaged surface EMG data cortical silent periods (CSP) were constructed and analysed. Twenty-one single motor units were identified for the spinal manipulation intervention and twelve single motor units were identified for the control intervention. Following spinal manipulations there was a shortening of the silent period and an increase in the single unit I-wave amplitude. No changes were observed following the control condition. The results provide evidence that spinal manipulation reduces the TMS-induced cortical silent period and increases low threshold motoneurone excitability in the lower limb muscle. These finding may have important clinical implications as they provide support that spinal manipulation can be used to strengthen muscles. This could be followed up on populations that have reduced muscle strength, such as stroke victims.
The electrical activity of muscles can interfere with the electroencephalogram (EEG) signal considering the anatomical locations of facial or masticatory muscles surrounding the skull. In this study, we evaluated the possible interference of the resting activity of the temporalis muscle on the EEG under conventional EEG recording conditions. In 9 healthy adults EEG activity from 19 scalp locations and single motor unit (SMU) activity from anterior temporalis muscle were recorded in three relaxed conditions; eyes open, eyes closed, jaw dropped. The EEG signal was spike triggered averaged (STA) using the action potentials of SMUs as triggers to evaluate their reflections at various EEG recording sites. Resting temporalis SMU activity generated prominent reflections with different amplitudes, reaching maxima in the proximity of the recorded SMU. Interference was also notable at the scalp sites that are relatively far from the recorded SMU and even at the contralateral locations. Considering the great number of SMUs in the head and neck muscles, prominent contamination from the activity of only a single MU should indicate the susceptibility of EEG to muscle activity artifacts even under the rest conditions. This study emphasizes the need for efficient artifact evaluation methods which can handle muscle interferences.
Our aim was to investigate the jaw reflexes using both the probability- and the discharge rate-based analysis methods. Twelve consenting volunteer subjects participated in this study. Subjects bit gently on bite bars that carried the impression of their teeth. Surface and intramuscular electrical activity of the masseter was recorded. With the help of audio feedback from one motor unit, each subject bit to discharge the unit at a fixed rate. While the subject continuously activated the selected motor unit, 4-N stimuli were delivered to the upper right central incisor either at a rapid or a slow rate. For each trial, ≥300 stimuli were delivered, and, once a trial was completed, local anesthetic block was applied around the stimulated tooth, and the experiment was repeated. While preceding local anesthesia, the rapid-rate stimuli ("tap") induced substantial inhibitory reflex responses; during local anesthetic block, the same stimulus induced excitatory and inhibitory reflex responses. Slow-rate stimuli ("push"), on the other hand, usually generated a combination of inhibitory and excitatory responses that disappeared completely during the local anesthetic block. This study discovered that the strength of the inhibitory reflex response to a tooth-tap stimulus was much larger than previously reported. This study also found that whereas the probability-based analyses were better for illustrating the existence and latency of small earlier responses, the discharge rate-based method was better for indicating the duration of earlier responses and the existence, sign, and duration of later responses.
Objective: the purpose of this study was to test the occlusal analysis system t-scan ii for the detection of a bite force reflex and to determine the net jaw reflex modulation during a rapid voluntary clench. Materials and Methods:Eleven subjects were asked to bite as fast as possible on the pressure-sensitive sheet using occlusal scanning system t-scan ii. the bite force reflex parameters were determined from the occlusal force curve.Results:the inhibitory bite force reflex occurred in nine subjects with a latency of 34.0 ± 7.8 ms, duration of 17.0 ± 2.8 ms and strength of 1.6% ± 0.3%. a strong correlation was detected between the latency of the reflex and the time to reach 80% of the maximal relative bite force (r = 0.833; p < 0.01). a moderate correlation was found between the relative bite force at the moment of the first turning point of the reflex and the change of this force during the reflex (r = 0.677; p < 0.05).Conclusion: the reflex modulation confirms the protective role of the jaw reflex: during faster bites the latency of the bite force reflex was shorter and with a higher bite force the strength of the reflex was greater.Keywords: bite force reflex, Human, Occlusal scanning, Rapid voluntary clench, Relative bite force ÖZET Amaç: bu çalışmada, ısırma refleksi kuvvetini belirlemek için t-scan ii okluzal analiz sistemi kullanmak ve hızlı istemli diş sıkma sırasında net çene refleksindeki değişimi değerlendirmek amaçlanmıştır.Gereç ve Yöntem : Çalışmamıza, 11 gönüllü denek katılmıştır. Denekler, t-scan ii okluzal analiz isteminin basınca duyarlı ısırma sensörlerini ısırabildikleri en hızlı şekilde ısırmışlardır. Okluzal kuvvet eğrisi aracılığıyla ısırma refleks parametreleri belirlenmiştir. Bulgular: Onbir deneğin 9'unda inhibitor ısırma refleksi tespit edilmiştir. bu refleksin latans değeri 34,0±7,8 ms, süresi 17,0±2,8 ms ve kuvveti % 1,6±%0,3 olarak hesaplanmıştır. isırma refleks latansı ile maksimum nispi ısırma kuvvetinin %80'ine ulaşmak için gereken zaman arasında güçlü bir ilişki gözlenmiştir (r=0,833; p<0,01). isırma refleksinin ilk anındaki nispi ısırma kuvveti ile bu kuvvetin refleks boyunca değişimi arasındaki ilişki ise orta derecelidir ( r=0,677; p<0,05).Sonuç: isırma refleksindeki değişim, çene refleksinin koruyucu rolünü destekler. Hızlı ısırma sırasında, kısa latanslı bir ısırma refleksi oluşur. isırma kuvveti yükseldiğinde, refleksin kuvveti artar.
We examined the reflex response of the human masseter muscle to electrical stimulation of the lip using both single motor unit and surface electromyogram based methods. Using the classical analysis methods, reflex response to mild electrical stimuli generated two distinct short-lasting inhibitions. This pattern may reflect the development of combinations of short- and long-latency inhibitory postsynaptic potentials as a result of the mildly painful electrical lip stimulation. However, this pattern appearing in the classical analysis methods may have developed as a consequence of earlier responses and may not be genuine. This study examined the genuineness of these responses using both the classical analysis methods and the discharge rate method to uncover the realistic postsynaptic potentials in human trigeminal motor nucleus. Using the discharge rate method, we found that the electrical lip stimulation only generated a long-lasting single or compound inhibitory response that is followed by late, long-lasting excitation. These findings have important implications on the redrawing of the neuronal pathways of the trigeminal nerve that are frequently used to judge neuromuscular disorders of the trigeminal region. We examined the human masseter reflex response to electrical stimulation of lower lip to uncover realistic postsynaptic potentials in the trigeminal motor nucleus. We found that the stimulation generates a long-lasting single or compound inhibitory response that is followed by a late, long-lasting excitation. These findings have important implications on the redrawing of the neuronal pathways of the trigeminal nerve that are frequently used to judge neuromuscular disorders of the trigeminal region.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.