Variability of pulse width in transcranial magnetic stimulation

The effect of electroconvulsive therapy (ECT) performed with ultrabrief pulse (UBP) stimulation has been found inferior to brief pulse (BP) ECT in various studies. We reinvestigated this issue using a new dosing strategy that is based on seizure quality instead of seizure threshold. There is a long history of studies associating ictal characteristics of ECT with the clinical outcome. Accordingly, we used the clinical status of the patient and the quality of the prior seizure to determine the dosage for the upcoming treatment-referred to as Clinical and Seizure Based Stimulation (CASBAS). This approach aims at continuously providing high-quality seizures to optimize the outcome. While this dosing strategy was applied in our department, the pulse width was changed for a period of time from BP to UBP. It was hypothesized that the procedure would: (1) maintain seizure quality and clinical outcome under both conditions and would; and (2) compensate the lesser clinical efficacy of UBP by an increase in stimulus intensity. 245 patients received an ECT course according to the dosing strategy described, 162 with brief pulse (BP) and 83 with ultrabrief pulse ECT (UBP). In a retrospective evaluation, seizure quality and clinical outcome (available in a 20% subgroup of patients) did not differ between both groups in most of the examined parameters, while stimulus intensity was found to be significantly higher in the UBP group. As hypothesized, UBP was less efficient than BP in providing comparable ictal quality and clinical outcome. In a first test of concept the dosing strategy CASBAS seemed suitable to continuously adjust the stimulus intensity in ECT and maintain the seizure quality.

Functional near-infrared spectroscopy (fNIRS) is a brain imaging technique particularly suitable for hearing studies. However, the nature of fNIRS responses to auditory stimuli presented at different stimulus intensities is not well understood. In this study, we investigated whether fNIRS response amplitude was better predicted by stimulus properties (intensity) or individually perceived attributes (loudness). Twenty-two young adults were included in this experimental study. Four different stimulus intensities of a broadband noise were used as stimuli. First, loudness estimates for each stimulus intensity were measured for each participant. Then, the 4 stimulation intensities were presented in counterbalanced order while recording hemoglobin saturation changes from cortical auditory brain areas. The fNIRS response was analyzed in a general linear model design, using 3 different regressors: a non-modulated, an intensity-modulated, and a loudness-modulated regressor. Higher intensity stimuli resulted in higher amplitude fNIRS responses. The relationship between stimulus intensity and fNIRS response amplitude was better explained using a regressor based on individually estimated loudness estimates compared with a regressor modulated by stimulus intensity alone. Brain activation in response to different stimulus intensities is more reliant upon individual loudness sensation than physical stimulus properties. Therefore, in measurements using different auditory stimulus intensities or subjective hearing parameters, loudness estimates should be examined when interpreting results.

Previous studies have shown visual evoked potential (VEP) abnormalities in infants and animals born small for gestational age (SGA) compared with controls. The current exploratory study aims to investigate whether VEP abnormalities persist in older ages. Pattern VEP latencies were obtained in 21 children (11 girls, 10 boys), born SGA and moderately preterm, at an average age of 5 years and 8 months. Fifty-one children (24 girls, 27 boys, mean age of 5 years and 7 months), also born moderately preterm but with normal height and weight at birth, served as controls Visual evoked potential results showed no significant differences in latency between children born SGA and controls born appropriate for gestational age (AGA) for either binocular stimulation, right eye or left eye stimulation. Our findings do not indicate any differences in VEP latency at preschool age for children born SGA compared with children born AGA. The results may support previous studies, suggesting that children born SGA show accelerated neurophysiologic maturation during their first year of life and that previously delayed VEP latencies after catch-up stay unchanged compared with controls.

As the existing pulse source can not balance pulse width and amplitude, a scheme of based on field effect transistor (MOSFET) and step recovery diode (SRD) combined with picosecond pulse source was put forward. Analyzing traditional designs of several pulse sources, we designed a high repetition rate picosecond pulse generator of 100 volt level and made a design simulation with PSPICE and developed the pulse source PCB board. Measurement shows 2 MHz repetition rate, half amplitude width 400 ps around, range above 110 V and stable waveform. The scheme providedes a new selection for high resolution UWB detection radar transmitter.

Auditory brainstem responses (ABR) are used to evaluate the peripheral and central functions of the auditory tract. Air and bone-conduction auditory stimuli are used to evaluate the type and degree of hearing loss. The wave latencies and interpeak latencies (IPLs) are the important diagnostic data in ABR tests. Gender and age of the patients are some of the factors affecting these latencies. This study investigated the effects of age and gender on the wave and IPLs of bone-conduction ABR. One hundred healthy individuals (50 women and 50 men) aged between 10 and 60 years were enrolled into this study, and both ears of all subjects (200 ears total) were included in the assessments. Based on their age, the subjects were equally divided into five groups, and each group consisted of 10 men and 10 women. The findings showed a significant difference in wave latencies and IPLs between the two genders (p<0.05). Depending on stimulus intensity, wave latencies also showed statistically significant differences between the age groups (p<0.05). However, no significant difference was noted between the age groups regarding IPLs. Normative values that covered wave latencies and IPLs evoked at stimulus intensities of 50, 30, and 10 dB nHL were established for the clinical use and use as a reference for the bone-conduction ABR testing procedure.

Sex difference in seizure susceptibility is one of the unresolved issues of epilepsy. It is known that estrogen is excitatory and progesterone is inhibitory to the central nervous system. Therefore, it is to be expected that seizure susceptibility may be associated with the estrous cycle, which should be tested in epilepsy research. Otherwise, different results in epilepsy studies could be an artifact of the estrous cycle. Reports in the literature are inconsistent about testosterone effects on seizures. In light of these considerations, sex differences in seizure susceptibility were restudied in rats. There was no significant sex difference in mean latencies to picrotoxin-induced seizures; prestrous-females had the shortest latencies to epileptic seizures compared to males and estrousfemales. With testosterone-injected rats, there was either no sex difference in latencies (to akinetic and focal seizures) or females had significantly shorter latencies than males (to status epilepticus, generalized tonic-clonic seizures, and myoclonic seizures). Testosterone-treated male rats had a significantly longer mean latency than controls for status epilepticus only; otherwise, these males showed no significant differences between mean latencies before and after testosterone (to focal, myoclonic, or generalized tonic-clonic seizures). In females, mean latencies to myoclonic seizures and status epilepticus were significantly shorter after testosterone than before. It was concluded that there is a sex difference in susceptibility to epileptic seizures in rats, provided that the estrous cycle is taken into account. Testosterone may increase and decrease seizure susceptibility in females and males, respectively. These effects may be important for understanding the mechanisms of epileptic phenomena and may provide some important clues to epilepsy treatment.

Comparison of the brainstem auditory evoked responses during sevoflurane or alfaxalone anaesthesia in adult cats

There are three senses in which a visual stimulus may be said to persist psychologically for some time after its physical offset. First, neural activity in the visual system evoked by the stimulus may continue after stimulus offset (“neural persistence”). Second, the stimulus may continue to be visible for some time after its offset (“visible persistence”). Finally, information about visual properties of the stimulus may continue to be available to an observer for some time after stimulus offset (“informational persistence”). These three forms of visual persistence are widely assumed to reflect a single underlying process: a decaying visual trace that (1) consists of afteractivity in the visual system, (2) is visible, and (3) is the source of visual information in experiments on decaying visual memory. It is argued here that this assumption is incorrect. Studies of visible persistence are reviewed; seven different techniques that have been used for investigating visible persistence are identified, and it is pointed out that numerous studies using a variety of techniques have demonstrated two fundamental properties of visible persistence: theinverse duration effect (the longer a stimulus lasts, the shorter is its persistence after stimulus offset) and theinverse intensity effect (the more intense the stimulus, the briefer its persistence). Only when stimuli are so intense as to produce afterimages do these two effects fail to occur. Work on neural persistences is briefly reviewed; such persistences exist at the photoreceptor level and at various stages in the visual pathways. It is proposed that visible persistence depends upon both of these types of neural persistence; furthermore, there must be an additional neural locus, since a purely stereoscopic (and hence cortical) form of visible persistence exists. It is argued that informational persistence is defined by the use of the partial report methods introduced by Averbach and Coriell (1961) and Sperling (1960), and the term “iconic memory” is used to describe this form of persistence. Several studies of the effects of stimulus duration and stimulus intensity upon the duration of iconic memory have been carried out. Their results demonstrate that the duration of iconic memory is not inversely related to stimulus duration or stimulus intensity. It follows that informational persistence or iconic memory cannot be identified with visible persistence, since they have fundamentally different properties. One implication of this claim that one cannot investigate iconic memory by tasks that require the subject to make phenomenological judgments about the duration of a visual display. In other words, the so-called “direct methods” for studying iconic memory do not provide information about iconic memory. Another implication is that iconic memory is not intimately tied to processes going on in the visual system (as visible persistence is); provided a stimulus is adequately legible, its physical parameters have little influence upon its iconic memory. The paper concludes by pointing out that there exists an alternative to the usual view of iconic memory as a precategorical sensory buffer. According to this alternative, iconic memory is post-categorical, occurring subsequent to stimulus identification. Here, stimulus identification is considered to be a rapid automatic process which does not require buffer storage, but which provides no information about episodic properties of a visual stimulus. Information about these physical stimulus properties must, in some way, be temporarily attached to a representation of the stimulus in semantic memory; and it is this temporarily attached physical information which constitutes iconic memory.

Subthreshold electrical stimulation with an intensity less than the threshold for evoking M-waves is applied repetitively to the common peroneal nerve via surface electrodes. The stimulation intensity is varied by adjusting the pulse width from 0 to 240 micros, while the pulse interval (40 ms) and current amplitude are kept constant. Single magnetic stimuli are applied to the motor cortex using a circular coil. Motor evoked potentials are recorded from the anterior tibial muscle in six normal subjects for various subthreshold stimulation intensities. Signal processing (filtering in the time and frequency domains) removes the artifact caused by the subthreshold electrical stimulation from the motor evoked potential. Statistically significant motor evoked potential facilitation (p < 0.05) is observed for pulse widths ranging from 72 to 240 micros in all the tested subjects. A pulse width corresponding to 90% of the electrical threshold facilitated the motor evoked potential in five of the six subjects.

Objective: To evaluate the clinical effects of Ming Mu-11 (MM-11) in the treatment of stage Ⅰ diabetic retinopathy (DR). Methods: One hundred twenty patients (120 eyes) with stage Ⅰ DR in the Affiliated Hospital of Inner Mongolia University for the Nationalities were selected from July 2016 to March 2017. The 120 eyes with stage Ⅰ DR were divided into two groups: a Mongolian medicine group and a control group (60 eyes each). The control group was treated with calcium dobesilate capsules and the Mongolian medicine group was also treated with MM-11 pills. There were three courses of treatment in total and 28 days in each course. Patients in both groups underwent multifocal electroretinogram (mfERG) and ultra-wide angle fundus photography examinations before and after the treatment. The latencies and amplitudes of the N1 wave and P1 wave were recorded as well as the number of retinal microaneurysms and hemorrhagic spots. Data were analyzed by t-test and Chi-square test. Results: The results of mfERG were as follows. There were significant differences in the amplitude density values of P1 in the R1-R5 regions before and after treatment (tcontrol group=66.86, 18.05, 36.33, 47.43, 30.56, P<0.001; tmongolian medicine group=31.52, 54.56, 101.98, 127.02, 45.74, P<0.001). There were significant differences in the amplitude density value of N1 in the R1-R5 regions before and after treatment (tcontrol group=70.18, 47.02, 78.08, 57.44, 64.51, P<0.001; tmongolian medicine group=46.09, 140.47, 145.14, 50.46, 73.94, P<0.001). Compared to the control group, the amplitude density value differences in the R1-R5 P1 and R1-R3 N1 regions in the Mongolian medicine group were significantly different before and after treatment (tP1=8.96, 23.96, 25.10, 28.80, 13.67, P<0.001; tN1=9.38, 30.34, 52.06, P<0.001). However, there was no significant difference in the amplitude density value in the R4-R5 N1 regions. There was no significant difference in the latency of P1 in the R1-R5 regions before and after treatment. There was no significant difference in the latency of N1 in the R1-R5 regions before and after treatment. The results of fundus color photography were as follows. The difference in microaneurysms and number of bleeding points before and after treatment were statistically significant in the Mongolian medicine group (t=2.08, P=0.042; t=2.07, P=0.043). The effective rates of the eye fundus photography in the Mongolian medicine group and the control group were 88% and 73%, respectively, which were analyzed by a chi-square test. The difference was statistically significant (χ2=4.36, P=0.037). Conclusions: MM-11 is very effective for treating the damage of retinal functions in stage Ⅰ DR and therefore can be considered as a drug for routine use. Key words: Mongolian medicine Ming Mu-11 Pills; multifocal electroretinogram; diabetic retinopathy; ultra-wideangle fundus photography

We demonstrate a variable pulse width, internally-frequency-converted, near-diffraction-limited Nd:YAG laser with output power up to 40 Watts at 532 nm and pulse widths electronically adjustable over a 40-300 ns range. The variable pulse width is achieved by clipping the pulse decaying edge with the Q-switch in a laser cavity optimized for post-pulse gain insensitivity. This approach makes possible frequency converted lasers with pulse width and output power substantially independent of repetition rate.

Aim of this study is to extract near-continuously respiratory rate by a contactless method. An industrial camera was used to record subjects face. Video data were processed offline to derive the video-photoplethysmographic (videoPPG) signal. Three features were extracted from videoPPG and finger PPG signal: pulse rate variability (PRV), pulse amplitude variability (PAV) and pulse width variability (PWV). A combination of these methods has been exploited to estimate the respiratory rate for each time window of 5 second. The results showed relative error with median around 0.5% and interquartile range of 5% both for finger PPG and videoPPG system.

What is the central question of this study? A transcranial magnetic stimulation (TMS)-induced twitch applied on isolated single breaths over the motor cortex somatotopic representation of the tongue briefly recruits submental muscles and improves airflow dynamics of flow-limited respiratory cycles without arousing sleep apnoea patients. However, the mechanical impact of the TMS-induced twitch applied during consecutive breathing cycles on airflow dynamics remains unknown. What is the main finding and what is its importance? Our results show that application of TMS with the stimulator output set at the sleep submental motor threshold intensity on consecutive respiratory cycles increases inspiratory flow and reduces the turbulent airflow component. These results indicate an improvement of airflow pattern after two single consecutive TMS-induced twitches without arousing sleep apnoea patients. Transcranial magnetic stimulation (TMS)-induced twitches applied on isolated breaths briefly recruit upper airway dilator muscles and improve airflow and inspiratory volume without arousing apnoeic patients from sleep, but the effects of applying such twitches consecutively on airflow dynamics is unknown. The objective of this study was to quantify the effects of five consecutive TMS-induced twitches applied on sleep-induced obstructive hypopnoeic breaths in 10 obstructive sleep apnoea patients. Submental muscle motor threshold (SUBMT) and motor-evoked potential were measured during wakefulness and sleep. The TMS-induced twitches were applied during stable non-rapid eye movement (NREM) sleep, at the beginning of inspiration of consecutive flow-limited respiratory cycles, with the stimulator output set at sleep SUBMT. Maximal inspiratory flow, inspiratory volume, inspiratory time, shifts of electroencephalogram frequency and pulse rate variability were assessed. During sleep, SUBMT increased (wakefulness, 25.3 ± 4.9%; NREM sleep, 27.0 ± 6.2%; P = 0.02). During each series of stimulations there was a rise in maximal inspiratory flow (from 306.7 ± 123.2 to 359.8 ± 154.1 ml s(-1); P = 0.0002) and in inspiratory volume (from 346.1 ± 128.1 to 414.9 ± 171.2 ml; P = 0.02) without differences in thoraco-abdominal efforts and inspiratory time. These responses were observed in the absence of arousals and ceased immediately after TMS interruption. Transcranial magnetic stimulation-induced cortical and/or autonomic arousal was observed in 30.2% of all series of stimulation. Consecutive twitch TMS of submental muscles may lead to arousals in a minority of patients but can be applied on consecutive respiratory cycles during sleep and can significantly improve maximal inspiratory flow and inspiratory volume of flow-limited cycles.

A high-intensity pulsed ion source of TEMP-type series, operating in bipolar mode, has been developed as a unique pulsed energy source to produce a high-intensity pulsed ion beam (HIPIB) for surface modification of materials. To generate the ion beam, a specially shaped bipolar pulse, consisting of a first negative pulse and a second delayed positive pulse both of nanosecond width, is formed by a double coaxial pulse-forming line (PFL) powered with a Marx generator and supplied to a magnetically insulated ion diode (MID) by a self-magnetic field. It is found that the efficient generation of a HIPIB is mainly dependent on the delay time of the bipolar pulse, adjusted by pressure ratio in the two gas switches of a PFL, and the anode–cathode (A–K) gap distance in the self-magnetic field MID. The delay time determines the effective area on the anode surface for plasma generation and the A–K gap distance ensures the stability of the process. A proper delay time and a proper A–K gap distance are obtained by a series of experimental investigations. Under delay time from 30 to 280 ns and several different A–K gap distances, the typical wave forms of the bipolar pulses at a dc charging voltage of 45 kV to Marx generator are illustrated to clarify the effects of delay time and A–K gap distance on the ion beam generation. The proper A–K gap distance is not uniform, varied from 6 to 8 mm, and the corresponding proper delay time is 250 ns. The most efficient plasma generation leads to a maximum output of HIPIB with a peak ion current density of 350 A cm−2 and a beam pulse width of 75 ns (full width at half maximum), at an accelerating pulse of 220 kV with a pulse width of 100 ns.

A short pulse width, high repetition rate, pulsed supersonic beam source is described. Pulse widths in the range 17-45 mu s (30 mu s FWHM typically) at repetition rates up to 120 Hz are obtained. The gas pulse shape and velocity distribution are fully characterised. Its application to the photodissociation dynamics of CS2 at 193 nm is presented. The vibrational populations for both CS2 to CS+S(1D, 3P) pathways are given and the branching ratio is found to be approximately 70% S(1D), 30% S(3P).