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ABSTRACT ObjectiveThis study aimed to investigate the potential role of cesium chloride (CsCl), ivabradine (IVA), and isoproterenol (ISO) on the sensory transmission of bladder afferents to graded urinary bladder distension (UBD). We specifically selected these drugs to target the hyperpolarization‐activated cyclic nucleotide‐gated (HCN) cation channels to determine their role in afferent encoding. MethodsThe bladders of C57BL/6 female mice were harvested with attached pelvic nerves in continuity, and the stimulus–response function (SRF) of bladder afferents to stepped bladder distension (20, 40, 60, 80 cmH₂O) was recorded by single‐fiber recordings. Their changes in SRF to bath application of CsCl, IVA, and ISO were then evaluated. The presence of HCN on bladder afferent endings was assessed through immunohistological staining on bladder sections from mice with genetically labeled bladder afferents. ResultsIVA and ISO did not significantly reduce afferent responses to UBD, whereas CsCl increased afferent responses. Bladder afferents in the pelvic nerve pathway were categorized into low‐firing (LF, < 10 Hz) and high‐firing (HF, > 10 Hz) groups. SRF in both the LF and HF groups showed similar trends with no significant changes in response to IVA and ISO. CsCl increased SRF only in the HF group but not in the LF group. Immunohistological staining revealed that HCN1 does not extensively co‐localize with afferent endings, showing only sporadic presence. ConclusionOur targeted pharmacological studies with single‐fiber recordings and immunohistological staining collectively suggest that HCN channels do not play a significant role in bladder afferent sensory transmission. 

Wearable devices for continuous health monitoring in humans are constantly evolving, yet the signal quality may be improved by optimizing electrode placement. While the commonly used locations to measure electrodermal activity (EDA) are at the fingers or the wrist, alternative locations, such as the torso, need to be considered when applying an integrated multimodal approach of concurrently recording multiple bio-signals, such as the monitoring of visceral pain symptoms like those related to irritable bowel syndrome (IBS). This study aims to quantitatively determine the EDA signal quality at four torso locations (mid-chest, upper abdomen, lower back, and mid-back) in comparison to EDA signals recorded from the fingers. Concurrent EDA signals from five body locations were collected from twenty healthy participants as they completed a Stroop Task and a Cold Pressor task that elicited salient autonomic responses. Mean skin conductance (meanSCL), non-specific skin conductance responses (NS.SCRs), and sympathetic response (TVSymp) were derived from the torso EDA signals and compared with signals from the fingers. Notably, TVSymp recorded from the mid-chest location showed significant changes between baseline and Stroop phase, consistent with the TVSymp recorded from the fingers. A high correlation (0.77–0.83) was also identified between TVSymp recorded from the fingers and three torso locations: mid-chest, upper abdomen, and lower back locations. While the fingertips remain the optimal site for EDA measurement, the mid-chest exhibited the strongest potential as an alternative recording site, with the upper abdomen and lower back also demonstrating promising results. These findings suggest that torso-based EDA measurements have the potential to provide reliable measurement of sympathetic neural activities and may be incorporated into a wearable belt system for multimodal monitoring. 

IntroductionWe recently showed that sub-kilohertz electrical stimulation of the afferent somata in the dorsal root ganglia (DRG) reversibly blocks afferent transmission. Here, we further investigated whether similar conduction block can be achieved by stimulating the nerve trunk with electrical peripheral nerve stimulation (ePNS). MethodsWe explored the mechanisms and parameters of conduction block by ePNS via ex vivo single-fiber recordings from two somatic (sciatic and saphenous) and one autonomic (vagal) nerves harvested from mice. Action potentials were evoked on one end of the nerve and recorded on the other end from teased nerve filaments, i.e., single-fiber recordings. ePNS was delivered in the middle of the nerve trunk using a glass suction electrode at frequencies of 5, 10, 50, 100, 500, and 1000 Hz. ResultsSuprathreshold ePNS reversibly blocks axonal neural transmission of both thinly myelinated Aδ-fiber axons and unmyelinated C-fiber axons. ePNS leads to a progressive decrease in conduction velocity (CV) until transmission blockage, suggesting activity-dependent conduction slowing. The blocking efficiency is dependent on the axonal conduction velocity, with Aδ-fibers efficiently blocked by 50–1000 Hz stimulation and C-fibers blocked by 10–50 Hz. The corresponding NEURON simulation of action potential transmission indicates that the disrupted transmembrane sodium and potassium concentration gradients underly the transmission block by the ePNS. DiscussionThe current study provides direct evidence of reversible Aδ- and C-fiber transmission blockage by low-frequency (<100 Hz) electrical stimulation of the nerve trunk, a previously overlooked mechanism that can be harnessed to enhance the therapeutic effect of ePNS in treating neurological disorders. 

Abstract Synthetic aperture radar (SAR) utilizes an aircraft-carried antenna to emit electromagnetic pulses and detect the returning echoes. As the aircraft travels across a designated area, it synthesizes a large virtual aperture to improve image resolution. Inspired by SAR, we introduce synthetic aperture ptycho-endoscopy (SAPE) for micro-endoscopic imaging beyond the diffraction limit. SAPE operates by hand-holding a lensless fiber bundle tip to record coherent diffraction patterns from specimens. The fiber cores at the distal tip modulate the diffracted wavefield within a confined area, emulating the role of the ‘airborne antenna’ in SAR. The handheld operation introduces positional shifts to the tip, analogous to the aircraft’s movement. These shifts facilitate the acquisition of a ptychogram and synthesize a large virtual aperture extending beyond the bundle’s physical limit. We mitigate the influences of hand motion and fiber bending through a low-rank spatiotemporal decomposition of the bundle’s modulation profile. Our tests demonstrate the ability to resolve a 548-nm linewidth on a resolution target. The achieved space-bandwidth product is ~1.1 million effective pixels, representing a 36-fold increase compared to that of the original fiber bundle. Furthermore, SAPE’s refocusing capability enables imaging over an extended depth of field exceeding 2 cm. The aperture synthesizing process in SAPE surpasses the diffraction limit set by the probe’s maximum collection angle, opening new opportunities for both fiber-based and distal-chip endoscopy in applications such as medical diagnostics and industrial inspection.