Pair Of Needle Electrodes Research Articles

Barley systemic bioelectrical changes detect pathogenic infection days before the first disease symptoms

Plant electrome corresponds to the emergent set of plant bioelectrical activity. The infection of plant tissues by different fungi alters this bioelectrical activity and can originate different electrical signatures, which can be used to identify the potential pathogenic agent. In this work, we evaluated the systemic variations of the electrome of barley triggered by the inoculation of Blumeria graminis and Bipolaris sorokiniana on the leaves. Therefore, approximately 50 days-old barley plants were placed within a Faraday cage under controlled conditions. A pair of needle electrodes was inserted in the culm for the recording of bioelectrical data. The plants were then inoculated with the pathogen in the last completely expanded leaf. Each pathogen was inoculated in different plants. Plants exposed to the same procedures as the inoculated ones, but without the fungi, served as controls. The electromes were recorded through 48 h, 24 h of which before the fungi inoculation or the control treatment. The bioelectrical data collected were analysed as time series through the following techniques: descriptive statistics, Bayesian change point (BCP) analysis, approximate entropy (ApEn), and autocorrelation. The results of these analyses were used as features, hence creating the dataset used in the machine learning (cluster analysis). The results indicate that the inoculation of pathogenic fungi culminated in a greater electrome variation (EV) when compared with the control (simulated inoculation). The pathogen inoculation generated peculiarities in the EV distribution for each pathogen. Therefore, the inoculation of B. graminis or B. sorokiniana created an electrical signature specific for each pathogen. This signature allows identifying the presence of pathogenic infection in the first minutes after contact with the host surface.

SURG-34. INTRAOPERATIVE CORTICOBULBAR MOTOR EVOKED POTENTIALS RELIABLY PREDICT FACIAL NERVE FUNCTION IN ELDERLY PATIENTS WITH CEREBELLOPONTINE ANGLE TUMORS. A CLINICAL AND NEUROPHYSIOLOGY STUDY

Abstract BACKGROUND Cerebellopontine angle (CPA) surgery for extra-axial lesions in elderly patients could be hampered by concerns regarding functional outcomes. However, an overall ageing society warrants an improved approach. Intraoperative neuromonitoring is crucial for facial nerve (FN) preservation: intraoperative cortico-bulbar facial motor evoked potentials (FMEPs) can be effectively coupled to standard techniques. In a previous work, we validated the use of FMEPs as preditors of early and late post-operative FN function (FNF). Aim of this study was to re-evaluate FMEP role in patients beyond 65 years of age. METHODS An institutional series of 83 patients was reported. A pair of needle electrodes was used to record FMEP from orbicularis oculi (OOc) and orbicularis oris (OOr) muscles; baseline, final and minimum values were recorded. From FMEP amplitudes, minimum-to-baseline (MBR) and final-to-baseline (FBR) amplitude ratios, and recovery value (RV=FBR-MBR), were calculated. These indices were correlated to early (at discharge) and late (at 1-year) post-operative FNF. RESULTS 23 (27.7%) patients were older than 65 years. Among these, 52.2% and 81% had a good early and late FNF, respectively. Early and late FNF were not associated to age (p > 0.99 and p=0.72, respectively). In elderly patients, higher FBR (from OOc and OOr) and MBR (from OOc) were associated to a good early FN recovery (p=0.01, p=0.009, and p=0.03, respectively). Conversely, MBR from OOr was the only parameter significantly associated with late FN function (p=0.049). ROC analysis confirmed that, in elderly patients, the most accurate index for predicting late FN function was MBR as measured from OOr (AUC=0.869, cut-off value 12.5%). The most accurate index for predicting early FN function was FBR from OOc (AUC=0.865). CONCLUSION Cortico-bulbar FMEPs are reliable predictors of early and late post-operative FNF in elderly patients and allow a safe and feasible surgery in this important cohort.

Intraoperative Corticobulbar Motor Evoked Potential in Cerebellopontine Angle Surgery: A Clinically Meaningful Tool to Predict Early and Late Facial Nerve Recovery.

Intraoperative neuromonitoring is crucial for facial nerve preservation in cerebellopontine angle (CPA) surgery. Among the available techniques, the role of intraoperative corticobulbar facial motor evoked potentials (FMEPs) is unclear. To evaluate the significance of intraoperative FMEPs as indicators for early and late postoperative facial nerve function (FNF) in CPA tumor resection and the feasibility of their integration with standard monitoring techniques. An institutional series of 83 patients who underwent surgery under intraoperative monitoring for CPA extra-axial tumor resection was reported. A pair of needle electrodes was used to record FMEP from orbicularis oculi (OOc) and orbicularis oris (OOr) muscles at baseline, at the end of surgery and minimum values recorded. From FMEP amplitudes, minimum-to-baseline amplitude ratio (MBR), final-to-baseline amplitude ratio (FBR), and recovery value, intended as FBR minus MBR, were calculated. These indices were correlated with early and late postoperative FNF. Our analysis demonstrated that higher FBR (both from OOc and OOr) and MBR (from OOr only) were associated with a good early and late FNF; a higher MBR from OOc was significantly associated with a good late FNF. The most accurate index in predicting early FNF was FBR measured from OOr with a cutoff of 35.56%, whereas the most accurate index in predicting late FNF was FBR as measured from OOc with a cutoff of 14.29%. Our study confirmed that FMEPs are reliable predictors of early and late postoperative FNF in CPA surgery and could be easily integrated with standard intraoperative neuromonitoring techniques.

Electroporation safety factor of 300 nanosecond and 10 millisecond defibrillation in Langendorff-perfused rabbit hearts.

AimsRecently, a new defibrillation modality using nanosecond pulses was shown to be effective at much lower energies than conventional 10 millisecond monophasic shocks in ex vivo experiments. Here we compare the safety factors of 300 nanosecond and 10 millisecond shocks to assess the safety of nanosecond defibrillation.Methods and resultsThe safety factor, i.e. the ratio of median effective doses (ED50) for electroporative damage and defibrillation, was assessed for nanosecond and conventional (millisecond) defibrillation shocks in Langendorff-perfused New Zealand white rabbit hearts. In order to allow for multiple shock applications in a single heart, a pair of needle electrodes was used to apply shocks of varying voltage. Propidium iodide (PI) staining at the surface of the heart showed that nanosecond shocks had a slightly lower safety factor (6.50) than millisecond shocks (8.69), p = 0.02; while PI staining cross-sections in the electrode plane showed no significant difference (5.38 for 300 ns shocks and 6.29 for 10 ms shocks, p = 0.22).ConclusionsIn Langendorff-perfused rabbit hearts, nanosecond defibrillation has a similar safety factor as millisecond defibrillation, between 5 and 9, suggesting that nanosecond defibrillation can be performed safely.

Selective Stimulation of a Target Neuron in Micropatterned Neuronal Circuits Using a Pair of Needle Electrodes

Selective Stimulation of a Target Neuron in Micropatterned Neuronal Circuits Using a Pair of Needle Electrodes

Extracellular Stimulation of a Target Neuron in Micro-Patterned Neuronal Circuits Using a Pair of Needle Electrodes

BACKGROUND: Electrical stimulation of neurons is essential to control neuronal activities. Thus far, direct stimulation by whole-cell patch-clamp methods [1] and extracellular stimulation using multi-electrode arrays (MEAs) [2] have been performed commonly. While the whole-cell patch-clamp method merits from the precise control of stimulation, the use of MEAs takes advantage of maintaining neuronal activity over a long period owing to its non-invasiveness. An optogenetic technique [3] has a targeting precision of a single-cell level, but this has difficulties in applying fast stimulation patterns due to the slow photoresponse of opsin [4]. Alternative non-invasive methods capable of targeting a single neuron with arbitrary stimulation patterns open new possibility of controlling and monitoring neuronal activities over a long duration.In this presentation, we propose a novel method to combine cell-patterning techniques [5] with electrical stimulation of a target cell with a pair of needle electrodes [6]. We show that the firing of a single neuron cultured on the micropattern can be controlled by the proposed method. We also show the controllability of the stimulation by analogue circuit simulation of a neuron stimulated electrically by a pair of needle electrodes via culture medium.EXPERIMENTAL METHODS: Neurons were cultured on a micropatterned glass substrates in isolation. A pair of tungsten needles except for their tip apexes were coated with an insulating polymer and mounted on manipulators. Two needles were immersed in the medium so that the target neuron is placed in-between. The distance from the neuron to the needle tip was controlled to be several tens to 100 μm. A bipolar square pulse was applied between electrodes, and the neuronal activity was visualized by Ca imaging.SIMULATION: The membrane potential response of a neuron to extracellular stimulation was analysed using LTspice simulator [7]. The circuit model is shown in Fig. 1a. The integrate-and-fire neuron was connected electrically with two needle electrodes via the electric double layers and solution resistances. The key of the circuit simulation is to divide the neuron into two compartments, each is stimulated with either of two needle electrodes. We conjecture that the neuron fires if the membrane potential either of two compartments exceeds the threshold upon the electrical stimulation. We investigated the membrane potential response when the resistance corresponding to the relative distance from the neuron to the electrode, the capacitive component of the needles, and the shape of voltage input pulses were changed.RESULTS AND DISSCUSSION: As shown in Fig. 1b, the neuron fires if the amplitude of the bipolar square pulse exceeds 5 Vp-p. The amplitude required for the neuron firing decreases with increasing distance from the neuron to the needle electrodes. The LTspice simulation provided the following results: (i) The positive electrode hyperpolarizes the membrane potential, whereas the negative electrode depolarizes it, indicating the membrane potential of two compartments changes to inverse direction even if a bipolar pulse was applied, as shown in Fig. 1c. (ii) The closer the electrode is to the cell, the more the membrane potential of the neuron changes and the voltage drop in the solution resistance is comparatively small. (iii) The main factor of neuronal firing is the transient potential fluctuation caused by the capacitive component of the electrical double layer and the neuronal membrane. (iv) The membrane potential of both the compartments is sensitive to transient change of tip voltage and does not change if the system reaches the steady state. This is also true if the DC voltage is continuously applied. These results indicate that applying a voltage pulse of appropriate amplitude can stimulate only cells in the vicinity of needle electrodes. Only a single neuron in neuronal culture can be stimulated by the needle electrodes by placing the target neuron between two needles. The non-invasive stimulation can also be used for long-term stimulation and monitoring.[1] E. Neher, et al., Nature 260(1976) 799.[2] C.A. Thomas Jr., et al., Exp. Cell Res. 74(1972) 61.[3] K. Deisseroth, et al., J. Neurosci. 26(2006) 10380.[4] B.D. Allen, et al., Learn. Mem. 22(2015) 232.[5] L. Bekar, et al., Nat. Med. 14(2008) 75.[6] H. Yamamoto, et al., Appl. Phys. Lett. 113(2018) 133703.[7] https://www.analog.com/en/design-center/design-tools-and-calculators/ltspice-simulator.html# Figure 1

2-3-13. Components analysis of transcranial electrical stimulation motor evoked potentials

Muscle action potentials induced by transcranial electrical stimulation (TCSMEP) are well used to know the impairment of motor function under general anesthesia. Though the components of waveforms are not known. We analyzed the origin or meaning of TCSMEP waveforms. All data were obtained from gastrocnemius with a pair of needle electrodes (belly-tendon method) during six times spinal surgeries (intramedurally tumor 5, disk herniation 1). Waveforms consisted of the initial negative spiky wave’s complex (INSWC) and the dull wave of the latter half (LHDW). The smallest negative peak amplitude (SNPA) had positive correlation with the average of other negative peak amplitudes among the initial wave complex. And SNPA is not affected by the fluctuation of positive waveforms. SNPA seemed to be suitable for the indicator of intraoperative monitoring. Furthermore, there was a positive relationship between SNPA and the positive peak amplitudes of LHDW. LHDW seemed to show the difference of electrical potentials that resulted from the shortening of gap distance while the muscle contracted. TCSMEP waveform may consist of major 2 parts at least. INSWC is electrical activity around EC junctions. LHDW is mechanical activity of muscle contractions. These findings are helpful to evaluate and assess TCSMEP precisely.

Multi-parametric study of temperature and thermal damage of tumor exposed to high-frequency nanosecond-pulsed electric fields based on finite element simulation

High-frequency nanosecond-pulsed electric fields were recently introduced for tumor or abnormal tissue ablation to solve some problems of conventional electroporation. However, it is necessary to study the thermal effects of high-field-intensity nanosecond pulses inside tissues. The multi-parametric analysis performed here is based on a finite element model of liver tissue with a tumor that has been punctured by a pair of needle electrodes. The pulse voltage used in this study ranges from 1 to 4 kV, the pulse width ranges from 50 to 500 ns, and the repetition frequency is between 100 kHz and 1 MHz. The total pulse length is 100 μs, and the pulse burst repetition frequency is 1 Hz. Blood flow and metabolic heat generation have also been considered. Results indicate that the maximum instantaneous temperature at 100 µs can reach 49 °C, with a maximum instantaneous temperature at 1 s of 40 °C, and will not cause thermal damage during single pulse bursts. By parameter fitting, we can obtain maximum instantaneous temperature at 100 µs and 1 s for any parameter values. However, higher temperatures will be achieved and may cause thermal damage when multiple pulse bursts are applied. These results provide theoretical basis of pulse parameter selection for future experimental researches.

The functional role of the pharyngeal plexus in vocal cord innervation in humans.

Classical understanding of the function of the pharyngeal plexus in humans is that it relies on both motor branches for innervation of the majority of pharyngeal muscles and sensory branches for the pharyngeal wall sensation. To date there has been no reported data on the role of the pharyngeal plexus in vocal cord innervation. The aim of this study is to evaluate whether or not the plexus pharyngeus contributes to the innervation of the vocal cords. One hundred twenty-five sides from 79 patients (59 female, 20 male) undergoing thyroid surgery with intraoperative neuromonitoring were prospectively evaluated. While vocal cord function was evaluated with endotracheal tube surface electrodes, cricothyroid and cricopharyngeal muscle electromyographic recordings were obtained with a pair of needle electrodes. The ipsilateral pharyngeal plexus, external branch of the superior laryngeal nerve, and recurrent laryngeal nerve were stimulated with a monopolar probe at 1mA. With stimulation of the plexus pharyngeus on 125 operated sides, positive electromyographic waveforms were detected from five ipsilateral vocal cords (accounting for 3.2% of all vocal cords monitored and 6.3% of patients). The mean EMG amplitude of the vocal cords with stimulation of the plexus pharyngeus was 147±35.5 μV (range 110-203). In one case, the long latency time of 19.8ms correlated with innervation by the glottic closure reflex pathway. The short latencies seen in the other four cases [3.9±1.1ms (range 3.2-5.5)] correlated with direct innervation. In some cases, the plexus pharyngeus may contribute to vocal cord innervation by reflex or direct innervation patterns in humans.

Fast conductivity imaging in magnetic resonance electrical impedance tomography (MREIT) for RF ablation monitoring

Purpose: This study shows the potential of magnetic resonance electrical impedance tomography (MREIT) as a non-invasive RF ablation monitoring technique.Materials and methods: We prepared bovine muscle tissue with a pair of needle electrodes for RF ablation, a temperature sensor, and two pairs of surface electrodes for conductivity image reconstructions. We used the injected current non-linear encoding with multi-echo gradient recalled echo (ICNE-MGRE) pulse sequence in a series of MREIT scans for conductivity imaging. We acquired magnetic flux density data induced by externally injected currents, while suppressing other phase artefacts. We used an 8-channel RF head coil and 8 echoes to improve the signal-to-noise ratio (SNR) in measured magnetic flux density data. Using the measured data, we reconstructed a time series of 180 conductivity images at every 10.24 s during and after RF ablation.Results: Tissue conductivity values in the lesion increased with temperature during RF ablation. After reaching 60 °C, a steep increase in tissue conductivity values occurred with relatively little temperature increase. After RF ablation, tissue conductivity values in the lesion decreased with temperature, but to values different from those before ablation due to permanent structural changes of tissue by RF ablation.Conclusion: We could monitor temperature and also structural changes in tissue during RF ablation by producing spatio-temporal maps of tissue conductivity values using a fast MREIT conductivity imaging method. We expect that the new monitoring method could be used to estimate lesions during RF ablation and improve the efficacy of the treatment.

Selective intraoperative stimulation of the human larynx

Laryngeal contraction normally entails activation of mutually cooperative intrinsic laryngeal muscles (ILMs). Unfortunately, standard stimulating methods do not completely mimic the normal ongoing synchrony between the muscles. We submit that this problem can be addressed by modifying the stimulating waveform. This study extends prior canine research to the human using quasitrapezoidal (QT) currents instead of standard square waves, which while valuable incompletely express normal ILM interactions. In two patients undergoing laryngectomy for cancer, the recurrent laryngeal nerve on the uninvolved side received QT pulses (4 Hz, 60-2,000 μA, 100-500 μs width, 0-500-μs decay) via a bipolar cuff electrode. Pairs of needle electrodes placed into the posterior cricoarytenoideus (PCA), lateral cricoarytenoideus (LCA), and thyroarytenoideus (TA) were used to record electromyography amplitudes, and waveforms were analyzed by a specially designed computer program. With activity from square waves serving as control, we observed statistically significant (P < .05) shifts in mutual relationships among PCA, LCA, and TA for an array of specific QT configurations. Our preliminary data on selective ILM manipulation offer promise for improved dynamic control of faulty laryngeal contraction patterns.

Intraoperative electromyography for identification of the trapezius muscle innervation: clinical proof of a new anatomical concept.

There is still considerable controversy among surgeons on trapezius muscle innervation. In addition, the rate of unexpected postoperative trapezius pareses is unacceptably high. Recent anatomical findings might answer most of the questions. The objective of the present study was to clinically prove the recent anatomical findings, especially the concept of the innervation of the descending part of the trapezius muscle. Intraoperative electromyography of the spinal accessory nerve and its branches in the posterior triangle of the neck. Intraoperative electromyography was performed during 17 modified radical neck dissections on 14 patients of both sexes ranging in age from 44 to 68 years (mean age, 56 y). Potentials were registered through pairs of needle electrodes placed in each of the three parts of the trapezius muscle. Intraoperatively, the spinal accessory nerve and its fine cranial branch passing toward the descending part of the muscle were identified and stimulated in the posterior triangle of the neck.RESULTS Stimulation of the fine cranial branch of the spinal accessory nerve led to a clearly visible and recordable contraction in the descending part of the trapezius muscle in all patients. Stimulation of the main trunk of the spinal accessory nerve in the posterior triangle of the neck distal to the above-mentioned branching led to a clearly visible and recordable contraction in the transverse and ascending parts of the muscle. The results strongly support recent anatomical findings showing that, functionally, the most important descending part of the trapezius muscle is innervated by a fine single branch arising from the spinal accessory nerve in the posterior triangle of the neck. This may help to prevent more patients undergoing modified radical neck dissections from shoulder-arm syndrome.

Can continuous intraoperative facial electromyography predict facial nerve function following cerebellopontine angle surgery?

Intraoperative cranial nerve monitoring has significantly improved the preservation of facial nerve function following surgery in the cerebellopontine angle (CPA). Facial electromyography (EMG) was performed in 60 patients during CPA surgery. Pairs of needle electrodes were placed subdermally in the orbicularis oris and orbicularis oculi muscles. The duration of facial EMG activity was noted. Facial EMG potentials occurring in response to mechanical or metabolic irritation of the corresponding nerve were made audible by a loudspeaker. Immediate (4-7 days after tumor excision) and late (6 months after surgery) facial nerve function was assessed on a modified House-Brackmann scale. Late facial nerve function was good (House-Brackmann 1-2) in 29 of 60 patients, fair (House-Brackmann 3-4) in 14, and poor (House-Brackmann 5-6) in 17. Postmanipulation facial EMG activity exceeding 5 minutes in 15 patients was associated with poor late function in five, fair function in six, and good function in four cases. Postmanipulation facial EMG activity of 2-5 minutes in 30 patients was associated with good late facial nerve function in 20, fair in eight, and poor in two. The loss of facial EMG activity observed in 10 patients was always followed by poor function. Facial nerve function was preserved postoperatively in all five patients in whom facial EMG activity lasted less than 2 minutes. Facial EMG is a sensitive method for identifying the facial nerve during surgery in the CPA. EMG bursts are a very reliable indicator of intraoperative facial nerve manipulation, but the duration of these bursts do not necessarily correlate with short- or long-term facial nerve function despite the fact that burst duration reflects the severity of mechanical aggression to the facial nerve.

139超音波歪計測に基づく組織弾性再構成法のハイパーサーミア治療効果のモニタリング技法としての可能性

We have developed the ultrasonic (US) strain measurement-based shear modulus reconstruction technique. Briefly, we developed the iterative US rf-echo phase matching method using successively acquired rf-echo data frames for measuring strains generated in vivo in soft tissues due to spontaneous heart motion and/or externally applied pressures. Moreover, we developed the method using the measured strain data for stably reconstructing the globally relative shear modulus distribution with respect to reference shear moduli. As the elasticity of the soft tissues irreversibly changes by heating, we propose that the developed shear modulus reconstruction technique is used as a monitoring technique for the effectiveness of thermal therapy. Particularly in this report, we applied the reconstruction technique to interstitial RF electromagnetic wave thermal therapy. To verify the feasibility we conducted in vivo experiment using a fresh calf liver. The pair of needle electrodes with the diameter of 2 mm were inserted into the liver tissue and the electric current with the frequency of 13.56 MHz was injected. During heating the tissues, we collected rf-echo data frames containing the heated region. Obtained reconstructions could satisfactorily visualize the expansion of heated regions. This result indicates that it has a high potential value as a practical tool for monitoring the effectiveness of thermal therapy.

An opioid peptide inhibits capsaicin-sensitive vasodilatation in the Pig's skin

Microcirculatory effects of electrical stimulation of nerves through a pair of needle electrodes in the skin of anaesthetized pigs were studied by using the laser Doppler flowmetric method. Electrical stimulation (0.3–30 Hz) evoked a short-lasting decrease in capillary blood flux (vasoconstriction) followed by an increase (vasodilatation), of longer duration. Vasoconstriction was inhibited by local guanethidine, but not by capsaicin pretreatment, whereas vasodilatation was blocked by local capsaicin, but not by guanethidine. Both phases of the response were suppressed by local application of tetrodotoxin. Thus, vasoconstriction due to electrical stimulation seems to be of sympathetic origin, while vasodilatation is a result of a release of vasoactive substances from capsaicin-sensitive nerve endings. Vasodilatation due to electrical stimulation was strongly and dose-dependently inhibited by the opioid peptide [D-Met 2, Pro 5] enkephalinamide, while vasoconstriction remained apparently unchanged. At both doses of the opioid peptide tested (0.03 and 0.15 μmol/kg i.m.) inhibition of vasodilatation was larger at lower than at higher frequencies of stimulation. Guanethidine pretreatment did not influence the inhibitory action of [D-Met 2, Pro 5] enkephalinamide. Naloxone (1.5 μmol/kg i.m.) reversed or prevented the inhibitory action of the opioid peptide; naloxone on its own did not influence responses due to 0.3–30 Hz stimulation. [D-Met 2, Pro 5] enkephalinamide (0.15 μmol/kg i.m.) did not influence basal blood flux in the skin, mean arterial blood pressure, respiratory minute volume or respiratory frequency. It was concluded that stimulation of opioid receptors by [D-Met 2, Pro 5] enkephalinamide is likely to inhibit stimulation-evoked vasodilatation by reducing the release of vasoactive substances from capsaicin-sensitive afferent neurons, an effect that does not depend on functional integrity of sympathetic nerves. Endogenous opioids probably do not modulate the capsaicin-sensitive vasodilatation.

Central nervous pathways underlying synchronization of human motor unit firing studied during voluntary contractions.

1. Motor unit firing has been studied during weak voluntary isometric contractions with pairs of needle electrodes in normal human subjects. 2. Pre- and post-stimulus time histograms of the firing time of firing of one event unit before and after the time of firing of another reference (stimulus) unit showed a clear central peak, indicative of synchronization. 3. Synchronization was seen in all the muscles studied. The mean strength of synchronization, expressed as the number of concomitant discharges of the two units as a proportion of the number of stimulus unit discharges, was 0.095 extra event unit spikes/reference unit spike (range 0.042-0.28) for first dorsal interosseous muscle, 0.016 extra event unit spikes per reference unit spike (range 0-0.043) for medial gastrocnemius and 0.056 extra event unit spikes per reference unit spike range 0.016-0.079) for tibialis anterior. 4. The mean duration of synchronization was 11.3 ms (range 5.0-21.0 ms) for first dorsal interosseous, 10.3 ms (range 3.5-21.7 ms) for medial gastrocnemious and 13.5 ms (range 3.0-25.0) for tibialis anterior. 5. Seven patients with radiographically and clinically identified central strokes were studied while they made weak voluntary isometric contractions. The duration of synchronization was significantly prolonged compared to that found in normal subjects. In these stroke patients the mean duration of synchronization on the affected side was longer than that seen in the normal subjects, and in first dorsal interosseous muscle was 35.4 ms (range 12.0-65.0 ms), in medial gastrocnemius was 21.3 ms (range 4.0-43.0 ms) and in tibialis anterior was 28.8 ms (range 14.0-49.0 ms). 6. The mean strength of synchronization of motor unit discharge was found to be greater in the stroke patients than that seen in the normal subjects for first dorsal interosseous muscle (0.161 extra event unit spikes per reference unit spike, range 0.017-0.391) and for medial gastrocnemius (0.030 extra event unit spikes per reference unit spike) but only significantly so when pooled data was compared. There was no difference in the strength of motor unit synchronization in tibialis anterior between stroke patients and normal subjects. 7. Broad duration synchronization among first dorsal interosseous motor units was also found in a patient with a rostral cervical spine lesion (total duration range 43-46 ms; n = 2), but not in a patient with a caudal (thoracic) spinal lesion.(ABSTRACT TRUNCATED AT 400 WORDS)

Polygraphical study on the wakefulness-sleep cycle of the rat

A normal wakefulness-sleep cycle of the male adult rat was observed polygraphically for 24 hrs. The male rats, albino or hooded, of 6 to 8 months, weighting over 350g, were used. There were little differences in EEG sleep patterns between the albino and hooded rats. Stainless-steel electrodes were implanted chronically in the frontal and occipital cortex and the dorsal hippocampus to record EEG monopolarly. A pair of stainless-steel electrodes were inserted into the orbit to record eye movements. Another pair of needle-electrodes were placed in the neck muscles to record the EMG. A small connector is attached to the skull with dental resin. The experiment was made about one week after operation. The rat was observed in a box placed in the soundproof and air conditioned room: the room temperature was controlled above 18°C, and the room was continuously illuminated during recording. Polygraphical recordings began between 6 and 11 p.m. and continued for 24 hrs. Daring recording, rats were free to move around in the box and were allowed to take food and water in the box. All polygraphical data were classified every 10 sec by inspection as either Awake (A), Light sleep (L), Deep sleep (D), or Paradoxical sleep (P) (Fig. 3, Table 1).Table 2 shows the appearance ratios of the four EEG patterns for all 10 rats, and Fig. 4 shows the temporal changes of EEG patterns in Rat 7 during 24 hrs. The pattern proceeds gradually A→L→D→P, and the stage of P suddenly changes to A. In the rat's EEG, there are more than ten wakefulness-sleep cycles a day. The cycle has a span of about 0.5 to 3 hrs. That is, the rat's sleep is polyphasic and it appears more frequent in day time than at night. Fig. 5-8 show the appearance ratios of the EEG patterns per hour, which indicate:1. Pattern A appears more often at night than in day time, 1. Patterns D and P appear more often in day time than at night, 3. Pattern L appears about 20% throughout the day.Table 3 shows the appearance ratios of the A, L, D and P patterns on each subject in day time (7:00 a.m.-7:00 p.m.) and at night (7:00 p.m.-7:00 a.m. next day), and matched t's between day and night. All ten subjects show a greater ratio in the Pattern A at night than in day time, and this difference is significant at the 0.1% level. 9 rats show the greater appearance ratios of Patterns D and P in day time than at night. Both differences are significant at the 1% level. In this study also activity pattern of the rat is nocturnal type as many other studies have shown.Matsumoto, et al. reported that the appearance ratio of P per day was 7.0%, and according to Jo it was 7.3%, while Michel, et al. reported 10-15%, which is more similar to our own data. Further studies are necessary to clarify these differences.

Effects of illumination of the eye on the vestibular responses in the pigeon.

Experiments on vestibular physiology of the pigeon had given us the opportunity to observe a remarkable effect of a light stimulation of the eye on pre-and post-rotatory nystagmus. The existence of head-nystagmus vestibular responses in the pigeon has been taken advantage of in earlier experiments in which vestibular reactions were recorded by the electromyograms of the neck muscles. For this purpose, two pairs of needle electrodes are fitted in both the left and right neck-muscle masses, which are particularly well developed in the pigeon. The muscular-action potentials are amplified and recorded as usual (van Eyck, 1953).