Duration Of Stimulation Research Articles

Metabonomics and Transcriptomics Analyses Reveal the Underlying HPA-Axis-Related Mechanisms of Lethality in Larimichthys polyactis Exposed to Underwater Noise Pollution

The problem of marine noise pollution has a long history. Strong noise (>120 dB re 1 µPa) will affects the growth, development, physiological responses, and behaviors of fish, and also can induce the stress response, posing a mortal threat. Although many studies have reported that underwater noise may affect the survival of fish by disturbing their nervous system and endocrine system, the underlying causes of death due to noise stimulation remain unknown. Therefore, in this study, we used the underwater noise stress models to conduct underwater strong noise (50–125 dB re 1 µPa, 10–22,000 Hz) stress experiments on small yellow croaker for 10 min (short-term noise stress) and 6 days (long-term noise stress). A total of 150 fishes (body weight: 40–60 g; body length: 12–14 cm) were used in this study. Omics (metabolomics and transcriptomics) studies and quantitative analyses of important genes (HPA (hypothalamic–pituitary–adrenal)-axis functional genes) were performed to reveal genetic and metabolic changes in the important tissues associated with the HPA axis (brain, heart, and adrenal gland). Finally, we found that the strong noise pollution can significantly interfere with the expression of HPA-axis functional genes (including corticotropin releasing hormone (CRH), corticotropin releasing hormone receptor 2 (CRHR2), and arginine vasotocin (AVT)), and long-term stimulation can further induce metabolic disorders of the functional tissues (brain, heart, and adrenal gland), posing a lethal threat. Meanwhile, we also found that there were two kinds of death processes, direct death and chronic death, and both were closely related to the duration of stimulation and the regulation of the HPA axis.

Molecular signaling predicts corticospinal axon growth state and muscle response plasticity induced by neuromodulation

Electrical motor cortex stimulation can produce corticospinal system plasticity and enhance motor function after injury. We investigate molecular mechanisms of structural and physiological plasticity following electrical neuromodulation, focusing on identifying molecular predictors, or biomarkers, for durable plasticity. We used two neuromodulation protocols, repetitive multipulse stimulation (rMPS) and patterned intermittent theta burst stimulation (iTBS), incorporating different stimulation durations and follow-up periods. We compared neuromodulation efficacy in promoting corticospinal tract (CST) sprouting, motor cortex muscle evoked potential (MEP) LTP-like plasticity, and their associated molecular underpinnings. Only iTBS produced CST sprouting after short-term neuromodulation (1 d of stimulation; 9-d survival for sprouting expression); both iTBS and rMPS produced sprouting with long-term (10-d) neuromodulation. Significant mTOR signaling activation and phosphatase and tensin homolog (PTEN) protein deactivation predicted axon growth across all neuromodulation conditions that produced significant sprouting. Both neuromodulation protocols, regardless of duration, were effective in producing MEP enhancement. However, persistent LTP-like enhancement of MEPs at 30 d was only produced by long-term iTBS. Statistical modeling suggests that Stat3 signaling is the key mediator of MEP enhancement. Cervical spinal cord injury (SCI) alone did not affect baseline molecular signaling. Whereas iTBS and rMPS after SCI produced strong mTOR activation and PTEN deactivation, only iTBS produced Stat3 activation. Our findings support differential molecular biomarkers for neuromodulation-dependent structural and physiological plasticity and show that motor cortex epidural neuromodulation produces molecular changes in neurons that support axonal growth after SCI. iTBS may be more suitable for repair after SCI because it promotes molecular signaling for both CST growth and MEP plasticity.

Evaluation of tolerability and safety of transcranial electrical stimulation with gel particle electrodes in healthy subjects.

With the advancement of transcranial electrical stimulation (tES) technology, an increasing number of stimulation devices and treatment protocols have emerged. However, safety and tolerability remain critical concerns before new strategies can be implemented. Particularly, the use of gel particle electrodes brings new challenges to the safety and tolerability of tES, which hinders its widespread adoption and further research. Our study utilized a specially designed and validated transcranial electrical stimulation stimulator along with preconfigured gel particle electrodes placed at F3 and F4 in the prefrontal lobes. We aimed to assess the tolerance and safety of these electrodes in healthy subjects by administering different durations and types of tES. Each participant underwent ten sessions of either transcranial direct current stimulation (tDCS) or transcranial alternating current stimulation (tACS), with session durations varying. In the experiment, we collected various measurement data from participants, including self-report questionnaire data and behavioral keystroke data. Tolerability was evaluated through adverse events (AEs), the relationship of adverse events with tES (AEs-rela), the Self-Rating Anxiety Scale (SAS), and the Visual Analog Mood Scale-Revised (VAMS-R). Safety was assessed using the Visual Analog Scale (VAS), the Skin Sensation Rating (SSR), Montreal Cognitive Assessment (MoCA), and Stroop task. These data were analyzed to determine the impact of different parameters on the tolerability and safety of tES. There were no significant changes in the results of the MoCA and SAS scales before and after the experiment. However, significant differences were observed in VAS, SSR, AEs, and AEs-rela between tDCS and tACS. Additionally, fatigue increased, and energy levels decreased on VAMS-R with longer durations. No significant differences were found in other neuropsychological tests. Our study revealed significant differences in tolerability and safety between tDCS and tACS, underscoring the importance of considering the stimulation type when evaluating these factors. Although tolerance and safety did not vary significantly across different stimulation durations in this study, future research may benefit from exploring shorter durations to further assess tolerability and safety efficiently.

Basal forebrain activation improves working memory in senescent monkeys.

Brain aging contributes to cognitive decline and risk of dementia. Degeneration of the basal forebrain cholinergic system parallels these changes in aging, Alzheimer's dementia, Parkinson's dementia, and Lewy body dementia, and thus is a common element linked to executive function across the lifespan and in disease states. Here, we tested the potential of one-hour daily intermittent basal forebrain stimulation to improve cognition in senescent monkeys, and its mechanisms of action. Stimulation in five animals improved working memory duration in 8-12 weeks across all animals, with peak improvements observed in the first four weeks. In an ensuing three month period without stimulation, improvements were retained. With additional stimulation, performance remained above baseline throughout the 15 months of the study. Studies with a cholinesterase inhibitor produced inconsistent improvements in behavior. One of five animals improved significantly. Manipulating the stimulation pattern demonstrated selectivity for both stimulation and recovery period duration. Brain stimulation led to acute increases in cerebrospinal levels of tissue plasminogen activator, which is an activating element for two brain neurotrophins, Nerve Growth Factor (NGF) and Brain-Derived Growth Factor (BDNF). Stimulation also led to improved glucose utilization in stimulated hemispheres relative to contralateral. Glucose utilization also consistently declines with aging and some dementias. Together, these findings suggest that intermittent stimulation of the nucleus basalis of Meynert improves executive function and reverses some aspects of brain aging.

The importance of muscle activation on the interpretation of muscle mechanical performance.

The work loop technique was developed to assess muscle performance during cyclical length changes with phasic activation, simulating the in vivo conditions of many muscles, particularly during locomotion. To estimate muscle function in vivo, the standard approach involves subjecting a muscle to length trajectories and activation timings derived from in vivo measurements, whilst simultaneously measuring force. However, the stimulation paradigm typically used, supramaximal, 'square-wave' stimulation, does not accurately reflect the graded intensity of activation observed in vivo. While the importance of the timing and duration of stimulation within the cycle on estimates of muscle performance has long been established, the importance of graded muscle activation has not been investigated. In this study, we investigated how the activation pattern affects muscle performance by comparing square-wave, supramaximal activation with a graded in vivo activation pattern. First, we used in vivo electromyography-derived activation patterns and fibre strains from the rabbit digastric muscle during mastication and replayed them in situ. Second, we used Hill-type musculoskeletal model-derived activation patterns and fibre strains in a trotting mouse, replayed ex vivo in the soleus (SOL) and extensor digitorum longus (EDL) muscles. In the rabbit digastric muscle, square-wave activation led to an 8-fold higher estimate of net power, compared with the in vivo graded activation pattern. Similarly, in the mouse SOL and EDL, supramaximal, square-wave activation resulted in significantly greater positive and negative muscle work. These findings highlight that realistic interpretations of in vivo muscle function rely upon more accurate representations of muscle activation intensity.

Progestin-primed ovarian stimulation outcomes in in-vitro fertilization (IVF) – A systematic review of the literature

Background: Progestin-primed ovarian stimulation (PPOS) stimulates ovaries to block the premature surge of luteinizing hormone (LH) by using micronized progesterone or a progestin during the follicular phase instead of the conventional gonadotropin-releasing hormone (GnRH) analogues or GnRH antagonists downregulating LH to obtain multi-follicle engagement. Current work aims to assess the influence of progestogen treatment on ovarian stimulation and the ability to control LH surge, its efficacy and suitability in retrieving oocytes, without affecting the embryo quality and its benefit among infertile women long-term outcomes on children compared to standard stimulation protocols. Materials and Methods: The literature review used the randomized control trials published in the Pubmed database from January 2015 to April 2021. To generate the citation list, the following keywords were used: ‘progestin-primed ovarian stimulation’, ‘PPOS’, ‘micronized progesterone’, ‘medroxyprogesterone’, and/or ‘dydrogesterone’. The selected articles analyzed the cohort, intervention, and scheme of the progestin-primed ovarian stimulation protocol in controlled ovarian stimulation (COS) for in-vitro fertilization (IVF)/intra cytoplasmic sperm injection (ICSI) used in Assisted Reproductive Technologies (ART). Results: Overall we concluded that PPOS for IVF/ICSI in ART results in a higher number of obtained embryos, lower incidence of OHSS, equal duration of stimulation, number of retrieved oocytes, and number of MII oocytes. It is also suggested that long-term safety in children shows no significant difference between the study and control groups. Conclusions: Despite the outcomes of progestin stimulation cycles among all cohorts, we concluded that poor ovarian responders, patients with PCOS, women of advanced age and oocyte donors benefit the most from using PPOS.

Factors affecting the outcomes of in vitro fertilization in women with endometriosis: Preliminary data from Vietnam

Objectives: This study aimed to assess the efficacy of in vitro fertilization (IVF) in patients with endometriosis and identify related factors that may influence treatment outcomes. Methods: This retrospective descriptive study was conducted between November 2018 and November 2022. The study group comprised individuals who were diagnosed with endometriosis (endometrioma and/or adenomyosis) indicated for in vitro fertilization. The control group (129 patients with 249 cycles), which included patients without endometriosis and had an equivalent mean age as the study group patients. Results: In the endometriosis group, the quantities of retrieved oocytes and Anti-Müllerian Hormone (AMH) were reduced compared to the control group. The overall dose of gonadotropin and the duration of ovarian stimulation were significantly higher than the control group. The endometriosis group exhibited a Metaphase II (MII) oocyte rate of 82.3% and an oocyte fertilization rate of 82.2%. However, in patients with endometriosis, the rates of implantation, clinical pregnancy, and ongoing pregnancy were significantly lower than in patients without endometriosis. Besides, the clinical pregnancy rate of women with endometriosis was remarkably higher in the groups with maternal age ⩽35 years, a ratio of Follicle-stimulating Hormone to Luteinizing Hormone (FSH/LH) ⩽1.5, and over 10 retrieved oocytes. Conclusion: Endometriosis was associated with a decreased rate of implantation, clinical pregnancy, and ongoing pregnancy after in vitro fertilization treatment compared with patients without endometriosis. In vitro fertilization outcomes in patients with endometriosis were influenced by maternal age ⩽35 years, FSH/LH ratio ⩽1.5, and number of retrieved oocytes over 10.

Impact of GnRH antagonist pretreatment on oocyte yield after ovarian stimulation: A retrospective analysis.

The study investigates whether a 3-day pretreatment course with a GnRH antagonist in the early follicular phase has an impact on the number of retrieved COCs in a GnRH antagonist stimulation protocol. This is a retrospective single center crossover study involving women who did not conceive after one GnRH antagonist stimulation cycle ("standard cycle") and proceeded with another GnRH antagonist stimulation cycle preceded by early administration of GnRH antagonist for 3 days ("pretreatment cycle") with fresh embryo transfer or frozen embryo transfer. 430 patients undergoing 860 cycles were included. The mean female age was 34.4 ± 4.8 years. Indications for fertility treatment included unexplained infertility (34.3%), male-factor infertility (33.3%), age (16.9%), PCOS (8.2%), tubal (4.7) and endometriosis (2.6%). All cycles were divided into two groups: group 1 (standard, 430 cycles) and group 2 (pretreatment, 430 cycles). The mean duration of stimulation was similar in both groups (10.3 vs 10.3 days, p = 0.28). The starting dose of gonadotropin (234.9 vs 196.8 IU, p<0.001), total amount of gonadotropin used (2419 vs 2020 IU, p<0.001), the total number of retrieved COCs (10 vs 7.8 p<0.001) and the number of mature oocytes (8 vs 5.8 p<0.001) were significantly higher in group 2 than in group 1. The Generalized estimating equation (GEE) regression analysis showed that the pretreatment strategy had a significant positive effect on the number of COCs (coefficient 2.4, p <0.001 after adjusting for known confounders (age, indication, stimulation dose, type, and duration of stimulation). In conclusion, A 3-day course of GnRH antagonist pretreatment increases the number of COCs obtained after ovarian stimulation.

Effects of ovarian stimulation on embryo euploidy: an analysis of 12874 oocytes and 3106 blastocysts in cycles with preimplantation genetic testing for monogenic disorders.

Does ovarian stimulation and the ovarian response affect embryo euploidy? Ovarian stimulation and the ovarian response in women undergoing preimplantation genetic testing for monogenic disorders (PGT-M) cycles did not affect the rates of blastocyst euploidy. Whether or not ovarian stimulation in IVF-embryo transfer has potential effects on embryo euploidy is controversial among studies for several reasons: (i) heterogeneity of the study populations, (ii) biopsies being performed at different stages of embryo development and (iii) evolution of the platforms utilized for ploidy assessment. Patients who undergo PGT-M cycles typically have no additional risks of aneuploidy, providing an ideal study population for exploring this issue. A retrospective cohort study including embryos undergoing PGT-M was conducted at a single academically affiliated fertility clinic between June 2014 and July 2021. A total of 617 women with 867 PGT-M cycles involving 12874 retrieved oocytes and 3106 trophectoderm biopsies of blastocysts were included. The primary outcome of the study was median euploidy rate, which was calculated by dividing the number of euploid blastocysts by the total number of biopsied blastocysts for each cycle. Secondary outcomes included the median normal fertilization rate (two-pronuclear (2PN) embryos/metaphase II oocytes) and median blastulation rate (blastocyst numbers/2PN embryos). Comparable euploidy rates and fertilization rates were observed across all age groups, regardless of variations in ovarian stimulation protocols, gonadotropin dosages (both the starting and total dosages), stimulation durations, the inclusion of human menopausal gonadotrophin supplementation, or the number of oocytes retrieved (all P > 0.05). Blastulation rates declined with increasing starting doses of gonadotropins in women aged 31-34 years old (P = 0.005) but increased with increasing gonadotrophin starting doses in women aged 35-37 years old (P = 0.017). In women aged 31-34, 35-37, and 38-40 years old, blastulation rates were significantly reduced with increases in the number of oocytes retrieved (P = 0.001, <0.001, and 0.012, respectively). Limitations include the study's retrospective nature and the relatively small number of patients of advanced age, especially patients older than 40 years old, leading to quite low statistical power. Second, as we considered euploidy rates as outcome measures, we did not analyze the effects of ovarian stimulation on uniform aneuploidy and mosaicism, respectively. Finally, we did not consider the effects of paternal characteristics on embryo euploidy status due to the fact that blastocyst aneuploidy primarily originates from maternal meiosis. However, sperm factors might have an effect on embryo development and the blastulation rate, and therefore also the number of blastocysts analyzed. The exclusion of patients with severe teratozoospermia and the fact that only ICSI was used as the insemination technique for women undergoing PGT-M contributed to minimize the effect of paternal factors. Ovarian stimulation and response to stimulation did not affect blastocyst euploidy rates in women undergoing PGT-M cycles. However, in women aged 31-40 years old, there was a significant decline in blastulation rates as the number of retrieved oocytes increased. This study was supported by the National Natural Science Foundation of China (Grant No. 81701407, 82301826); the National Key Research and Development Program of China (2022YFC2702901, 2022YFC2703004); China Postdoctoral Science Foundation (2022M710261), and China Postdoctoral Innovation Talent Support Program (BX20220020). There is no conflict of interest. N/A.

In Vitro Fertilization (IVF) Outcomes in Patients With Endometriosis Compared to Patients With Tubal Factor Infertility in Indonesia: A Retrospective Study.

Endometriosis is a disease characterized by dysmenorrhea, chronic pelvic pain, and infertility. The pathogenesis of endometriosis and its relationship to infertility are still not fully understood. In vitro fertilization (IVF) is considered an effective treatment for patients with endometriosis-associated infertility. This study compared the pregnancy rates of endometriosis patients who underwent IVF with those of patients with tubal obstruction. This was a retrospective cross-sectional study of 225 patients with endometriosis and tubal factor infertility who underwent IVF at Yasmin Clinic, Dr. Cipto Mangunkusumo National General Hospital, Jakarta, Indonesia, between January 2013 and August 2021. Demographic data, anti-Mullerian hormone (AMH) levels, the initial and total dose of recombinant follicle stimulating hormone (rFSH), the total dose of recombinant luteinizing hormone (rLH), stimulation duration, oocyte maturation rates, fertilization rates, embryo cleavage rates, and pregnancy rates (biochemical, clinical and ongoing) were obtained. AMH level, number of oocytes retrieved, and embryo cleavage rates were significantly lower in the endometriosis group. Initial and total doses of rFSH and total dose of rLH were higher, and the duration of stimulation was longer in the endometriosis group compared to the tubal factor group. In the endometriosis group, the biochemical (47.3% vs. 52.7%, p=0.375), clinical (43.1% vs. 56.9%, p=0.215), and ongoing (45.5% vs. 54.5%, p=0.511) pregnancy rates were lower than those in the tubal factor group. However, there were no statistically significant differences between the two groups. There was no significant difference in pregnancy rates between the short antagonist and ultra-long protocols (three months of downregulation). From multivariate analysis, only rLH supplementation was found to be significantly related to pregnancy outcomes in patients with endometriosis. AMH levels, number of oocytes retrieved, and embryo cleavage rates were lower in patients with endometriosis. However, pregnancy rates were not significantly different from patients with tubal factors. Supplementation with rLH may improve pregnancy rates in patients with endometriosis who have undergone IVF programs.

Impact of BMI on fertility in an otherwise healthy population: a systematic review and meta-analysis.

An increased body mass index (BMI) can lead to subfertility; however, current literature fails to exclude the effect of other confounding medical conditions, raising questions regarding the direct link between increased BMI and fertility outcomes. To conduct a systematic review and meta-analysis to elucidate the effects of increased BMI on fertility outcomes in females with no other comorbidities. A comprehensive search was conducted using EMBASE, MEDLINE and the Cochrane library from January 2000 until July 2023. Two authors independently conducted data extraction and assessed study quality. Odds ratio (OR) (dichotomous data), standardised mean difference (SMD) (continuous data) and 95% CIs were calculated. Nine eligible studies were identified: one natural conception and eight assisted reproductive technology (ART). Aggregated data revealed women with BMI ≥25 were less likely to attain clinical pregnancy (OR 0.76, 95% CIs 0.62 to 0.93, p=0.007), with BMI ≥30 associated with a further decreased likelihood of clinical pregnancy (OR 0.61, 95% CIs 0.39 to 0.98, p=0.04). Women with raised BMI required longer duration of stimulation (SMD=0.08, 95% CIs 0.00 to 0.16, p=0.04) and obtained reduced oocytes (SMD=-0.11, 95% CIs -0.18 to -0.04, p=0.002). These data demonstrate an adverse impact of being overweight/obese on ART outcomes in women with no other diagnosed medical comorbidities and highlight the distinct lack of data concerning the effects of isolated obesity on natural conception. Infertility represents an enormous burden for couples and society; it is essential to identify and tackle modifiable risk factors to improve chances of conception. CRD42022293631.

Lasting effects of transcranial direct current stimulation on the inducibility of synaptic plasticity by paired-associative stimulation in humans

BackgroundTranscranial direct current stimulation (tDCS) is capable of eliciting changes in cortical neuroplasticity. Increasing duration or repetition of tDCS during the after-effects of a first stimulation has been hypothesized to enhance efficacy. Computational models suggest sequential stimulation patterns with changing polarities to further enhance effects. Lasting tDCS effects on neural plasticity are of great importance for clinical applications.ObjectiveThe study systematically examined the influence of different tDCS paradigms on long term potentiation (LTP)-like plasticity in humans, focusing on stimulation duration, repetition frequency and sequential combinations of changing polarities as the underlying characteristics.MethodsAmplitude changes of motor evoked potentials (MEP) were measured in response to paired associative stimulation (PAS) 6 h after application of different tDCS protocols. In total, 36 healthy participants completed the study, randomised into three groups with different stimulation protocols (N = 12 each).ResultstDCS was able to display lasting modulatory effects on the inducibility of LTP-like plasticity in the human motor cortex 6 h after stimulation. TDCS with the anode on primary motor cortex significantly increased MEP amplitudes following PAS induction. Further analyses highlighted single stimulation block duration to be of higher importance than repetitive protocols for efficacy of effects.ConclusionstDCS is capable of inducing lasting changes in the brain’s capability to interact with future stimuli. Especially, effects on the inducibility of LTP-like plasticity might only be detectable with specific tests such as PAS and might otherwise be overlooked. Refined tDCS protocols should focus on higher current and duration of single stimulations instead of implementing complex repetitive schedules.

Endocytosis of Synaptic Vesicle in Motor Nerve Endings of FUS Transgenic Mice with a Model of Amyotrophic Lateral Sclerosis.

In experiments on the motor nerve endings of the diaphragm of transgenic FUS mice with a model of amyotrophic lateral sclerosis at the pre-symptomatic stage of the disease, the processes of transmitter release and endocytosis of synaptic vesicles were studied. In FUS mice, the intensity of transmitter release during high-frequency stimulation of the motor nerve (50 imp/sec) was lowered. At the same duration of stimulation, the loading of fluorescent dye FM1-43 was lower in FUS mice. However, at the time of stimulation, during which an equal number of quanta are released in wild-type and FUS mice, no differences in the intensity of dye loading were found. Thus, endocytosis is not the key factor in the mechanism of synaptic dysfunction in FUS mice at the pre-symptomatic stage.

New chronology evidence of prehistoric human activities indicated by pottery luminescence dating in the humid subtropical mountains of South China

The age of prehistoric human sites serves as a fundamental basis for studying the relationship between human activities and landscape changes in the humid subtropical mountains of South China. The presence of pottery in these archaeological sites is widespread and offers a valuable resource for precise dating purposes. The Longtoushan (LTS) site, located in the northern mountains of Fujian Province, contains a rich variety of pottery types from various periods, representing a rare multi-period stratigraphic overlap in this area and playing a crucial role in constructing the cultural sequence and lineage of prehistoric and ancient times in this region. In this study, we employed thermoluminescence (TL) and optically stimulated luminescence (OSL) techniques to establish the age of pottery samples collected from the LTS site situated in the upper Minjiang River region of southeast China for the first time, while also comparing our findings with other dating methods to construct a chronological framework for the site. The results showed that: (1) The samples analyzed in this study can be classified according to the peak strength of 325 °C TL signal at natural and regenerative doses of quartz. Samples with weak TL signal at 325 °C (type II samples) showed high recuperation and equivalent dose underestimation at a low preheat temperature (220 °C) in OSL test. (2) Conventional SAR procedures employed for type I samples are not suitable for type II samples. Type II samples require additional OSL stimulation towards the end of the cycle and an extended stimulation duration. (3) The application of various dating methods has revealed that the LTS site represents a long-term settlement in the humid subtropical mountains of South China, commencing around 4.6–4.4 thousand years ago (ka). Specifically, the dating of pottery pieces from kiln sites and tombs in the late Neolithic period provides a specific temporal reference for further understanding of prehistoric human culture and production behavior in the humid mountains of Fujian.

Impact of Stimulation Duration in taVNS-Exploring Multiple Physiological and Cognitive Outcomes.

Transcutaneous auricular vagus nerve stimulation (taVNS) is a non-invasive neuromodulation technique that modulates the noradrenergic activity of the locus coeruleus (LC). Yet, there is still uncertainty about the most effective stimulation and reliable outcome parameters. In a double blind, sham-controlled study including a sample of healthy young individuals (N = 29), we compared a shorter (3.4 s) and a longer (30 s) stimulation duration and investigated the effects of taVNS (real vs. sham) on saliva samples (alpha amylase and cortisol concentration), pupil (pupillary light reflex and pupil size at rest) and EEG data (alpha and theta activity at rest, ERPs for No-Go signals), and cognitive tasks (Go/No-Go and Stop Signal Tasks). Salivary alpha amylase concentration was significantly increased in the real as compared to sham stimulation for the 30 s stimulation condition. In the 3.4 s stimulation condition, we found prolonged reaction times and increased error rates in the Go/No-Go task and increased maximum acceleration in the pupillary light reflex. For the other outcomes, no significant differences were found. Our results show that prolonged stimulation increases salivary alpha-amylase, which was expected from the functional properties of the LC. The finding of longer response times to short taVNS stimulation was not expected and cannot be explained by an increase in LC activity. We also discuss the difficulties in assessing pupil size as an expression of taVNS-mediated LC functional changes.

Auditory confounds can drive online effects of transcranial ultrasonic stimulation in humans.

Transcranial ultrasonic stimulation (TUS) is rapidly emerging as a promising non-invasive neuromodulation technique. TUS is already well-established in animal models, providing foundations to now optimize neuromodulatory efficacy for human applications. Across multiple studies, one promising protocol, pulsed at 1000 Hz, has consistently resulted in motor cortical inhibition in humans (Fomenko et al., 2020). At the same time, a parallel research line has highlighted the potentially confounding influence of peripheral auditory stimulation arising from TUS pulsing at audible frequencies. In this study, we disentangle direct neuromodulatory and indirect auditory contributions to motor inhibitory effects of TUS. To this end, we include tightly matched control conditions across four experiments, one preregistered, conducted independently at three institutions. We employed a combined transcranial ultrasonic and magnetic stimulation paradigm, where TMS-elicited motor-evoked potentials (MEPs) served as an index of corticospinal excitability. First, we replicated motor inhibitory effects of TUS but showed through both tight controls and manipulation of stimulation intensity, duration, and auditory masking conditions that this inhibition was driven by peripheral auditory stimulation, not direct neuromodulation. Furthermore, we consider neuromodulation beyond driving overall excitation/inhibition and show preliminary evidence of how TUS might interact with ongoing neural dynamics instead. Primarily, this study highlights the substantial shortcomings in accounting for the auditory confound in prior TUS-TMS work where only a flip-over sham and no active control was used. The field must critically reevaluate previous findings given the demonstrated impact of peripheral confounds. Furthermore, rigorous experimental design via (in)active control conditions is required to make substantiated claims in future TUS studies. Only when direct effects are disentangled from those driven by peripheral confounds can TUS fully realize its potential for research and clinical applications.

Auditory confounds can drive online effects of transcranial ultrasonic stimulation in humans

Transcranial ultrasonic stimulation (TUS) is rapidly emerging as a promising non-invasive neuromodulation technique. TUS is already well-established in animal models, providing foundations to now optimize neuromodulatory efficacy for human applications. Across multiple studies, one promising protocol, pulsed at 1000 Hz, has consistently resulted in motor cortical inhibition in humans (Fomenko et al., 2020). At the same time, a parallel research line has highlighted the potentially confounding influence of peripheral auditory stimulation arising from TUS pulsing at audible frequencies. In this study, we disentangle direct neuromodulatory and indirect auditory contributions to motor inhibitory effects of TUS. To this end, we include tightly matched control conditions across four experiments, one preregistered, conducted independently at three institutions. We employed a combined transcranial ultrasonic and magnetic stimulation paradigm, where TMS-elicited motor-evoked potentials (MEPs) served as an index of corticospinal excitability. First, we replicated motor inhibitory effects of TUS but showed through both tight controls and manipulation of stimulation intensity, duration, and auditory masking conditions that this inhibition was driven by peripheral auditory stimulation, not direct neuromodulation. Furthermore, we consider neuromodulation beyond driving overall excitation/inhibition and show preliminary evidence of how TUS might interact with ongoing neural dynamics instead. Primarily, this study highlights the substantial shortcomings in accounting for the auditory confound in prior TUS-TMS work where only a flip-over sham and no active control was used. The field must critically reevaluate previous findings given the demonstrated impact of peripheral confounds. Furthermore, rigorous experimental design via (in)active control conditions is required to make substantiated claims in future TUS studies. Only when direct effects are disentangled from those driven by peripheral confounds can TUS fully realize its potential for research and clinical applications.

Presynaptic quantal size enhancement counteracts post-tetanic release depression.

Repetitive synaptic stimulation can induce different forms of synaptic plasticity but may also limit the robustness of synaptic transmission by exhausting key resources. Little is known about how synaptic transmission is stabilized after high-frequency stimulation.In the present study, we observed that tetanic stimulation of the Drosophila neuromuscular junction (NMJ) decreases quantal content, release-ready vesicle pool size and synaptic vesicle density for minutes after stimulation. This was accompanied by a pronounced increase in quantal size. Interestingly, action potential-evoked synaptic transmission remained largely unchanged. EPSC amplitude fluctuation analysis confirmed the post-tetanic increase in quantal size and the decrease in quantal content, suggesting that the quantal size increase counteracts release depression to maintain evoked transmission. The magnitude of the post-tetanic quantal size increase and release depression correlated with stimulation frequency and duration, indicating activity-dependent stabilization of synaptic transmission. The post-tetanic quantal size increase persisted after genetic ablation of the glutamate receptor subunits GluRIIA or GluRIIB, and glutamate receptor calcium permeability, as well as blockade of postsynaptic calcium channels. By contrast, it was strongly attenuated by pharmacological or presynaptic genetic perturbation of the GTPase dynamin. Similar observations were made after inhibition of the H+-ATPase, suggesting that the quantal size increase is presynaptically driven. Additionally, dynamin and H+-ATPase perturbation resulted in a post-tetanic decrease in evoked amplitudes. Finally, we observed an increase in synaptic vesicle diameter after tetanic stimulation. Thus, a presynaptically-driven quantal size increase, likely mediated by larger synaptic vesicles, counterbalances post-tetanic release depression, thereby conferring robustness to synaptic transmission on the minute time scale. KEY POINTS: Many synapses transmit robustly aftersustained activity despite the limitation of key resources, such as release-ready synaptic vesicles. We report robust synaptic transmission after sustained high-frequency stimulation of the Drosophila neuromuscular junction despite a reduction in release-ready vesicle number. An increased postsynaptic response to individual vesicles, likely driven by an increase in vesicle size due to endocytosis defects, stabilizes synaptic efficacy for minutes after sustained activity. Our study provides novel insights into the mechanisms governing synaptic stability after sustained neural activity.

Evaluation of ovarian reserve and the assisted reproductive technology (ART) cycles’ outcome as well as the relapse rate within one year after ART in women with multiple sclerosis: a case-control study

ObjectiveTo compare the ovarian reserve and the results of infertility treatment, as well as to investigate the relapse rate in the first year after the assisted reproductive technology (ART) cycle in patients with multiple sclerosis (MS) referred to Royan Institute.Materials and methodsThis retrospective study was carried out to evaluate all women diagnosed with MS and referred to Royan Institute for assessment and treatment of possible infertility between 2011 and 2022. The control group consisted of randomly selected healthy women with tubal factor infertility who were referred for treatment during the same time period and matched in terms of age. A comparison was made between groups in terms of ovarian reserve and infertility treatment outcomes. Additionally, patients with MS who met the criteria were monitored via telephone to evaluate the symptoms, disability and relapse rate both pre- and post-ART.ResultsOver the course of a decade, the database documented a total of 60 cases diagnosed with MS. Upon examination of the records, it was found that in 27 patients only admission was done without any hormonal assessment or infertility treatment cycle and 5 patients proceeded with the intrauterine insemination cycle. Eventually, 28 women with MS underwent the ART cycle and all of them were treated with interferon beta, glatiramer acetate, or some oral disease modifying therapies. No statistically significant difference in terms of the basal levels of luteinizing hormone, follicle-stimulating hormone and anti-Müllerian hormone was found between the MS and control groups (P > 0.05). Two groups were comparable in terms of menstrual status. The study revealed that both groups exhibited similarities in terms of the controlled ovarian stimulation protocol and duration, the dosage of gonadotropin administered, as well as the ovarian response type, clinical pregnancy rate, and live birth rate (P > 0.05). After follow up, only 2 patients (9.5%) reported relapse of symptoms within one year after ART.ConclusionThe ovarian reserve and ovarian stimulation cycle and pregnancy outcomes following the ART cycle in MS patients were similar to the age-matched control group. The relapse rate of multiple sclerosis did not show a significant increase within a year following the ART cycle.

Factors affecting biochemical pregnancy loss (BPL) in preimplantation genetic testing for aneuploidy (PGT-A) cycles: machine learning-assisted identification

PurposeTo determine the factors influencing the likelihood of biochemical pregnancy loss (BPL) after transfer of a euploid embryo from preimplantation genetic testing for aneuploidy (PGT-A) cycles.MethodsThe study employed an observational, retrospective cohort design, encompassing 6020 embryos from 2879 PGT-A cycles conducted between February 2013 and September 2021. Trophectoderm biopsies in day 5 (D5) or day 6 (D6) blastocysts were analyzed by next generation sequencing (NGS). Only single embryo transfers (SET) were considered, totaling 1161 transfers. Of these, 49.9% resulted in positive pregnancy tests, with 18.3% experiencing BPL. To establish a predictive model for BPL, both classical statistical methods and five different supervised classification machine learning algorithms were used. A total of forty-seven factors were incorporated as predictor variables in the machine learning models.ResultsThroughout the optimization process for each model, various performance metrics were computed. Random Forest model emerged as the best model, boasting the highest area under the ROC curve (AUC) value of 0.913, alongside an accuracy of 0.830, positive predictive value of 0.857, and negative predictive value of 0.807. For the selected model, SHAP (SHapley Additive exPlanations) values were determined for each of the variables to establish which had the best predictive ability. Notably, variables pertaining to embryo biopsy demonstrated the greatest predictive capacity, followed by factors associated with ovarian stimulation (COS), maternal age, and paternal age.ConclusionsThe Random Forest model had a higher predictive power for identifying BPL occurrences in PGT-A cycles. Specifically, variables associated with the embryo biopsy procedure (biopsy day, number of biopsied embryos, and number of biopsied cells) and ovarian stimulation (number of oocytes retrieved and duration of stimulation), exhibited the strongest predictive power.