Phase Advances Research Articles

Light exposure behaviors predict mood, memory and sleep quality

Ample research has shown that light influences our emotions, cognition, and sleep quality. However, little work has examined whether different light exposure-related behaviors, such as daytime exposure to electric light and nighttime usage of gadgets, especially before sleep, influence sleep quality and cognition. Three-hundred-and-one Malaysian adults (MeanAge±SD = 28 ± 9) completed the Light Exposure Behavior Assessment tool that measured five light exposure behaviors. They also completed the Morningness-Eveningness Questionnaire, Positive and Negative Affect Schedule, Pittsburgh Sleep Quality Index, and single items assessing trouble in memory and concentration. A partial least square structural equation model, showing 72.72% predictive power, revealed that less use of wearable blue filters outdoors during the day and more within one hour before sleep predicted early peak time (direct effect = −0.25). Increased time spent outdoors predicted a positive affect (direct effect = 0.33) and a circadian phase advancement (direct effect: rising time = 0.14, peak time = 0.20, retiring time = 0.17). Increased use of mobile phone before sleep predicted a circadian phase delay (direct effect: retiring time = −0.25; rising time = −0.23; peak time = −0.22; morning affect = −0.12), reduced sleep quality (direct effect = 0.13), and increased trouble in memory and concentration (total effect = 0.20 and 0.23, respectively). Increased use of tunable, LED, or dawn-simulating electric light in the morning and daytime predicted a circadian phase advancement (direct effect: peak time = 0.15, morning affect = 0.14, retiring time = 0.15) and good sleep quality (direct effect = −0.16). The results provide valuable insights into developing a healthy light diet to promote health and wellness.

Blue Wavelength Light Treatment for Improving Sleep in Patients with Post-Traumatic Stress Disorder

Traumatic live events comprise the etiology of post-traumatic stress disorder (PTSD). PTSD patients are known to face adverse impacts on their mental and physical health. Symptoms of concern relating to PTSD include heightened anxiety levels, intrusive memories, nightmares, and problems with sleeping. Disrupted sleep leads to exhausted brain function that impedes the daily activities of individuals and impacts their perceived quality of life. Therefore, researchers have sought to examine interventions that help improve sleep and circadian rhythms. Recently, blue-light therapy has been the target of clinical research to understand its role in alleviating PTSD symptoms. Results from clinical trials showed that patients receiving blue light showed significant reductions in daytime sleepiness and fatigue. Furthermore, these individuals showed faster reaction times and greater phase advances in circadian rhythms, leading to earlier sleep onset at night. As we work towards focusing our attention on addressing mental health issues, investigating the benefits of non-pharmacological interventions such as blue-light therapy can help improve the health outcomes of PTSD patients.

Physical design of a compact injector for synchrotron-based proton therapy

A compact room-temperature linear injector has been purposed to accelerate an 18.0 mA proton beam to 7.0 MeV for synchrotron-based proton therapy. The total length is appropriately 5 m. It mainly consists of a 3.01 m radio frequency quadrupole (RFQ) and a 0.82 m compact interdigital H-mode drift tube linac (IH-DTL) structure. Based on a fast-bunching strategy, the RFQ, operated at 325 MHz, accelerates protons to 3.0 MeV. The phase advances have been taken into consideration, and parametric resonance has been carefully avoided by adjusting the vane parameters. After the modulation of the transverse and longitudinal phase advances and a compact external quadrupole triplet, the proton beam is injected into the subsequent IH-DTL. Based on modified Kombinierte Null Grad Strukter (KONUS) beam dynamics, it accelerates protons up to 7.0 MeV, which is composed of a re-bunching section and an accelerating section. The accelerating gradient reaches 4.88 MV/m. The overall dynamic simulation results show that the whole accelerating gradient reaches up to 1.62 MV/m with a transmission efficiency above 95%. The transverse and longitudinal normalized RMS emittances at the exit of the DTL are 0.23 π mm·mrad and 2.216 π keV/u·ns, which meet the synchrotron injection requirements. The details of the specific design of this injector are presented in this paper.

0314 Late Evening Room Light and Sleep Restriction Reverses the Phase Advancing Effect of Bright Morning Light in Adolescents

Abstract Introduction Late bedtimes and sleep restriction are common during adolescence, particularly on school nights. We examined circadian phase advancing effects of bright morning light (ML) with increasing doses of evening room light exposure and sleep restriction due to late bedtimes. Methods Adolescents (n=38, 21 girls) aged 14.1 to 18.0 years completed a 14-day protocol during summer vacation. On days 1-7, they slept at home on individualized 10-h sleep/dark schedules. On days 8-14, they lived in the laboratory. On day 8, we measured their Dim Light Melatonin Onset (DLMO). On days 9 and 10, they were put to bed 1.5h (n=9), 3.0h (n=12), or 4.5h (n=8) later and kept awake in room light (104±11 lux at the angle of gaze). Wake time was unchanged; thus, sleep opportunity was shortened to 8.5h, 7h, and 5.5h, respectively. The fourth group (n=9) kept their baseline bedtime, were not exposed to any additional evening light (EL) and were not sleep restricted. On day 11, all groups were put to bed and awakened 1.5 h earlier and were exposed to intermittent bright ML (three 30-min exposures; 8599±885 lux). On each subsequent day (12 and 13), sleep and ML were advanced 1h. Thus, there were 3 days of a gradually advancing sleep schedule and bright ML. Final DLMO was measured on day 14. Results The 0h EL group showed a large DLMO advance (2.2±1.0 h), but the advance was reduced in the 1.5h EL group (0.5±0.6 h). DLMO delayed in the 3h EL group (-0.9±1.1 h). There was a large phase delay in the 4.5h EL group (-2.6±1.2 h). Phase shifts differed among all groups [F(3,34)=36.7, p<.001]. Conclusion Circadian rhythms of adolescents were advanced when they were exposed to bright ML and a gradually advancing sleep schedule, as shown in many studies of adults. However, when kept up later in ordinary room light, the same advancing sleep schedule and bright ML did not produce as much of an advance. Phase delay shifts occurred when bedtimes were 3h or 4.5h later. EL and sleep restriction can reverse the advancing effect of bright ML. Support (if any) R01 HL146772 (Crowley)

0311 Partial blue light blocking glasses advanced sleep phase but did not alter salivary melatonin secretion in Japanese schoolchildren

Abstract Introduction A late bedtime is one of the most common characteristics of sleep habits in modern society. This is also the case for schoolchildren, with negative consequences for their academic performance. Light exposure at night, particularly blue wavelength light, was thought to delay bedtime, and melatonin suppression via blue light was considered to be one of the mechanisms responsible for the delayed sleep phase. Methods In the current study, we evaluated the effects of partial blue light blocking glasses (JINS Screen Lens Heavy [40%cut]) on salivary melatonin levels, sleep and circadian phase and daytime behavior (via actigraphs and questionnaires), with and without blue light blocking (JINS Standard Clean Lens) glasses in 39 male school children (ages between 10-12). The study design was a cross over design, with respective glasses worn for 3 hours before the habitual bedtime for two weeks, with a one-week washout period (with their own regular glasses) in between sessions. Saliva collections and questionnaires were performed during the first and second weeks of each session, with saliva collected -3, -2, -1, and 0 hours before the habitual bedtime. Actigraph data were collected throughout the evaluation periods. Results We found that while partial blue light blocking glasses had no effect on salivary melatonin levels, they did significantly advance the sleep phase compared to the non-filter session (bedtime: 22.03±0.08h vs. 22.1±0.1h, sleep onset: 22.26±0.08h vs. 22.36±0.10h, p= 0.04). The filter effects were most noticeable in the second week, where significant advances in bedtime (-0.12h, p=0.03), sleep onset (-0.14h, p=0.03), wake up time (-0.13h, p=0.02), and leaving-bed time (-0.14h, p=0.02) from the 1st week were observed, whereas no changes were seen during the control session (without filter). Along with the sleep phase advancement observed, daytime irritability and acting out towards siblings and friends were significantly reduced in the second week of the filter session. Conclusion Our results suggest that partial blue light blocking glasses advanced the sleep phase and improved behavior in schoolchildren, but that the effects were not mediated by changes in melatonin secretion. Further research into the mechanisms involved is warranted. Support (if any) This study was supported by Jins Holdings Inc (SPO236998).

Impacts of Subsurface Dam Construction on Downstream Groundwater Levels and Salinity in Coastal Aquifers.

Subsurface dam is a promising engineering technology for groundwater resources development. However, the possible impacts of these dams on the groundwater environment have been a major concern. Here, we used a three-dimensional (3D), variable-density, unsaturated-saturated groundwater flow model to explore how a groundwater-storage-type subsurface dam, built in the freshwater domain of an unconfined coastal aquifer, affected groundwater levels and salinity in the downstream area. Model results suggested that, after subsurface dam construction, groundwater levels in the downstream area showed intensified fluctuations in terms of phase advances, greater amplitudes, and higher frequencies following heavy rainfall events. Numerical simulations with variable subsurface dam scenarios indicated that the groundwater level fluctuations were further intensified with a higher crest elevation or a shorter distance from the coast. Moreover, during the recharging period of the subsurface reservoir, sea water in the downstream area intruded landward from its initial location, which can at least temporarily threaten water quality near the coast. A higher dam crest elevation prolonged the duration of sea water intrusion, while a dam positioned closer to the coast induced sea water intrusion with a greater horizontal extent. General implications are discussed with respect to improving assessment methodologies and engineering designs of subsurface dams.

Updates and confounding factors in delayed sleep-wake phase disorder.

Delayed sleep-wake phase disorder (DSWPD) is a circadian rhythm sleep disorder characterised by a delay in the main sleep period, with patients experiencing difficulty getting to sleep and waking up at socially appropriate times. This often causes insomnia and compromised sleep, results in impairment to daytime function and is associated with a range of comorbidities. Besides interventions aimed at ameliorating symptoms, there is good evidence supporting successful phase advancement with bright light therapy or melatonin administration. However, no treatment to date addresses the tendency to phase delay, which is a common factor amongst the various contributing causes of DSWPD. Circadian phase markers such as core body temperature and circulating melatonin typically correlate well with sleep timing in healthy patients, but numerous variations exist in DSWPD patients that can make these unpredictable for use in diagnostics. There is also increasing evidence that, on top of problems with the circadian cycle, sleep homeostatic processes actually differ in DSWPD patients compared to controls. This naturally has ramifications for management but also for the current approach to the pathogenesis itself in which DSWPD is considered a purely circadian disorder. This review collates what is known on the causes and treatments of DSWPD, addresses the pitfalls in diagnosis and discusses the implications of current data on modified sleep homeostasis, making clinical recommendations and directing future research.

Activation of mGluR1 negatively modulates glutamate-induced phase shifts of the circadian pacemaker in the mouse suprachiasmatic nucleus

In mammals, photic information delivered to the suprachiasmatic nucleus (SCN) via the retinohypothalamic tract (RHT) plays a crucial role in synchronizing the master circadian clock located in the SCN to the solar cycle. It is well known that glutamate released from the RHT terminals initiates the synchronizing process by activating ionotropic glutamate receptors (iGluRs) on retinorecipient SCN neurons. The potential role of metabotropic glutamate receptors (mGluRs) in modulating this signaling pathway has received less attention. In this study, using extracellular single-unit recordings in mouse SCN slices, we investigated the possible roles of the Gq/11 protein-coupled mGluRs, mGluR1 and mGluR5, in photic resetting. We found that mGluR1 activation in the early night produced phase advances in neural activity rhythms in the SCN, while activation in the late night produced phase delays. In contrast, mGluR5 activation had no significant effect on the phase of these rhythms. Interestingly, mGluR1 activation antagonized phase shifts induced by glutamate through a mechanism that was dependent upon CaV1.3 L-type voltage-gated Ca2+ channels (VGCCs). While both mGluR1-evoked phase delays and advances were inhibited by knockout (KO) of CaV1.3 L-type VGCCs, different signaling pathways appeared to be involved in mediating these effects, with mGluR1 working via protein kinase G in the early night and via protein kinase A signaling in the late night. We conclude that, in the mouse SCN, mGluR1s function to negatively modulate glutamate-evoked phase shifts.

How Sleep Research in Extreme Environments Can Inform the Military: Advocating for a Transactional Model of Sleep Adaptation.

We review the literature on sleep in extreme environments. Accordingly, we present a model that identifies the need for mitigating interventions to preserve sleep quality for military deployments. Situational factors that affect sleep in extreme environments include cold temperatures, isolated and confined areas, fluctuating seasonality, photoperiodicity, and extreme latitudes and altitudes. Results vary across studies, but general effects include decreased total sleep time, poor sleep efficiency, and non-specific phase delays or phase advances in sleep onset and sleep architecture. Considering habitability measures (e.g., light or temperature control) and individual differences such as variable stress responses or sleep need can mitigate these effects to improve mood, cognition, and operational performance. Although the situational demands during military missions inevitably reduce total sleep time and sleep efficiency, mitigating factors can attenuate sleep-related impairments, hence allowing for optimal mission success and personnel safety.

Application and Progress of Cultured Models of Gallbladder Carcinoma.

Gallbladder carcinoma (GBC) is a malignant tumor of the biliary system that is aggressive, difficult to detect early, and has a low surgical resection rate and poor prognosis. Appropriate in vitro growth models are expected to focus on the study of the biological behavior and assess treatment effects. Nonetheless, cancer initiation, progression, and invasion include spatiotemporal changes and changes in the cell microenvironment intracellular communication, and intracellular molecules, making the development of in vitro growth models very challenging. Recent advances in biomaterial methods and tissue engineering, particularly advances in bioprinting procedures, have paved the way for advances in the creative phase of in vitro cancer research. To date, an increasing number of cultured models of gallbladder disease have emerged, such as two-dimensional (2D) GBC growth cell cultures, three-dimensional (3D) GBC growth cell cultures, xenograft models, and 3D bioprinting methods. These models can serve as stronger platforms, focusing on tumor growth initiation, the association with the microenvironment, angiogenesis, motility, aggression, and infiltration. Bioprinted growth models can also be used for high-throughput drug screening and validation, as well as translational opportunities for individual cancer therapy. This study focused on the exploration, progress, and significance of the development of GBC cultural models. We present our views on the shortcomings of existing models, investigate new innovations, and plan future improvements and application possibilities for cancer models.

Circadian disruption does not alter tumorigenesis in a mouse model of lymphoma

Background: Disruption of natural diurnal light cycles, such as that experienced by shift workers, is linked to enhanced cancer incidence. Several mouse models of cancer have been shown to develop more severe disease when exposed to irregular light/dark cycles, further supporting the connection between circadian disruption and increased cancer risk. Cryptochrome 2 (CRY2), a repressive component of the molecular circadian clock, facilitates the turnover of the oncoprotein c-MYC, one mechanism that may link the molecular clock to tumorigenesis. In Eμ-MYC mice, which express transgenic c-MYC in B cells and develop aggressive lymphomas and leukemia, global Cry2 deletion reduces overall survival and enhances tumor formation. Moreover, lighting conditions that mimic the disruption experienced by shift workers dampens Cry2 transcripts in peripheral tissues of C57BL/6J mice. Thus, we hypothesized that exposure to disruptive lighting conditions would enhance tumor burden in Eμ-MYC mice. Methods: We housed Eμ-MYC mice in light-tight boxes set to either the control (continuous cycles of 12-hours of the light followed by 12-hours of dark, LD12:12) or chronic jetlag (eight-hour light phase advances every two to three days, CJL) lighting conditions and assessed the impact of disrupted light cycles on overall survival and tumor formation in Eμ-MYC mice. Results: Environmental disruption of circadian rhythms did not alter tumor location, tumor growth, or overall survival in female or male Eμ-MYC mice. Conclusions: Our findings support emerging evidence that suggests the impact of circadian disruption on tumorigenesis is dependent on the origin of malignancies.

Nonalcoholic Steatohepatitis Disrupts Diurnal Liver Transcriptome Rhythms in Mice

The liver ensures organismal homeostasis through modulation of physiological functions over the course of the day. How liver diseases such as nonalcoholic steatohepatitis (NASH) affect daily transcriptome rhythms in the liver remains elusive. To start closing this gap, we evaluated the impact of NASH on the diurnal regulation of the liver transcriptome in mice. In addition, we investigated how stringent consideration of circadian rhythmicity affects the outcomes of NASH transcriptome analyses. Comparative rhythm analysis of the liver transcriptome from diet-induced NASH and control mice showed an almost 3-hour phase advance in global gene expression rhythms. Rhythmically expressed genes associated with DNA repair and cell-cycle regulation showed increased overall expression and circadian amplitude. In contrast, lipid and glucose metabolism-associated genes showed loss of circadian amplitude, reduced overall expression, and phase advances in NASH livers. Comparison of NASH-induced liver transcriptome responses between published studies showed little overlap (12%) in differentially expressed genes (DEGs). However, by controlling for sampling time and using circadian analytical tools, a 7-fold increase in DEG detection was achieved compared with methods without time control. NASH had a strong effect on circadian liver transcriptome rhythms with phase- and amplitude-specific effects for key metabolic and cell repair pathways, respectively. Accounting for circadian rhythms in NASH transcriptome studies markedly improves DEG detection and enhances reproducibility.

Gulf of Mexico Loop-Current Signature Observed From GNSS-R Phase Altimetry Based on Spire Global CubeSat Data

Global Navigation Satellite System (GNSS) coherent ocean reflections collected at grazing-angles by Spire Global’s CubeSats are explored to retrieve Sea Level Anomalies (SLA) over the Gulf of Mexico. Dual-frequency GPS carrier phase estimations are derived from the 50-Hz I and Q samples generated onboard the low Earth orbit CubeSats. First order ionospheric phase advancement, troposphere delay, and precise orbit solutions for GPS satellites and CubeSats mitigate the range measurement errors. Comparisons between collocated specular reflection tracks from various Spire CubeSats and GPS satellites configurations demonstrate the self-consistency of the resulting SLA solutions. The Spire retrievals are then validated against conventional altimetry SLA products. There is a Root Mean Square (RMS) difference of ~ 20 cm between the Spire and the gridded model mesoscale SLAs, unless the reflected elevations are very low. To better evaluate the performance of the Spire retrievals they are examined over sharp ocean topography. About 40% of coherent reflections with elevations above 12° detected the signature of the energetic Loop-Current during the 2020-2021 period. The Spire retrievals were also compared with collocated Sentinel-3 tracks. One track with elevations above 12° demonstrated high correlation and agreement with the Sentinel-3 retrievals. The other two low-elevation tracks showed large magnitude discrepancies, but similar trends once appropriate scaling factors are applied. The study demonstrates the potential for GNSS reflectometry’s application to SLA mapping while also highlighting where significant improvements in error mitigations are needed. A particularly large error source is the troposphere error for signals with lower elevations.

Optičke i strukturne osobine Nd2O3-SiO2 nanokompozita sintetizovanog iz sol-gel tehnike

Nd2O3-SiO2 nanocomposite was prepared in the current work utilising the sol-gel technique. After being heated in air, the amorphous phase of silicates transformed to crystalline phase via intermediate phase as oxide. Due to its comparatively small operating temperature and ability to form nanostructures with precise size, sol-gel approach is a compelling alternative. X-ray powder diffraction (XRD), Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), which verified the structural characteristics of neodymium silicate (Nd2O3-SiO2) nanocomposites, were used to characterise the synthesised materials. The effect of duration and annealing temperature on the phase advancement of the silicates has been considered thoroughly. It was discovered that the sample was sintered for 3 hours at various temperatures, thus obtaining neodymium silicates. In addition, Optical characterization of Nd2O3 -SiO2 was performed using Photoluminescence Spectroscopy (PL).

The regulation of circadian entrainment in mice by the adenosine the A 2A /A 1 receptor antagonist CT1500.

Circadian entrainment in mice relies primarily on photic cues that trigger the transcription of the core clock genes Period1/2 in the suprachiasmatic nucleus (SCN), thus aligning the phase of the clock with the dawn/dusk cycle. It has been shown previously that this pathway is directly regulated by adenosine signalling and that adenosine A2A/A1 receptor antagonists can both enhance photic entrainment and phase shift circadian rhythms of wheel-running behaviour in mice. In this study, we tested the ability of CT1500, a clinically safe adenosine A2A/A1 receptor antagonist to effect circadian entrainment. We show that CT1500 lengthens circadian period in SCN ex vivo preparations. Furthermore, we show in vivo that a single dose of CT1500 enhances re-entrainment to a shifted light dark cycle in a dose-dependent manner in mice and also phase shifts the circadian clock under constant dark with a clear time-of-day related pattern. The phase response curve shows CT1500 causes phase advances during the day and phase delays at dusk. Finally, we show that daily timed administration of CT1500 can entrain the circadian clock to a 24h rhythm in free-running mice. Collectively, these data support the use of CT1500 in the treatment of disorders of circadian entrainment.

Circadian phase advances in children during camping life according to the natural light-dark cycle

BackgroundIt is known that the circadian rhythm phase in adults can be advanced in a natural light-dark cycle without electrical lighting. However, the effect of advanced sleep-wake timing according to the natural light-dark cycle on children’s circadian phase is unclear. We investigated the effects of approximately 2 weeks of camping life with little access to artificial lighting on children’s circadian phases. We also conducted an exploratory examination on the effects of wake time according to natural sunrise time on the manner of the advance of their circadian phases.MethodsTwenty-one healthy children (mean ± SD age, 10.6 ± 1.4 years) participated in a camping program with wake time (4:00) being earlier than sunrise time (EW condition), and 21 healthy children (10.4 ± 1.1 years) participated in a camping program with wake time (5:00) being almost matched to sunrise time (SW condition). Salivary dim light melatonin onset (DLMO) before the camping program and that after approximately 2 weeks of camping were compared.ResultsDLMO was advanced by approximately 2 h after the camping program compared with the circadian phase in daily life in both conditions. In addition, the advances in DLMO were significantly correlated with mid-sleep points before the camp in both conditions (EW: r = 0.72, p < 0.01, SW: r = 0.70, p < 0.01). These correlations mean that the phase advance was greater for the children with delayed sleep habits in daily life. Furthermore, in the EW condition, mean DLMO after the camp (18:09 ± 0:33 h) was earlier than natural sunset time and there was no significant decrease in interindividual variability in DLMO. On the other hand, in the SW condition, mean DLMO after the camp (18:43 ± 0:20 h) matched natural sunset time and interindividual variability in DLMO was significantly lower than that before the camp.ConclusionsCamping with advanced sleep and wake timing under natural sunlight advances children’s circadian phases. However, DLMO earlier than sunset in an early waking condition may lead to large interindividual variability in the circadian rhythm phase.

Fermionic interpretation of the quantum phase transition in XXZ magnets

Quantum phase transitions in quantum magnets constitute an important field that has attracted great interests. Although a variety of analytic and numerical methods have been introduced in this direction, faithful fermionic descriptions are still desired because they can transform the spin models to a form tractable by conventional many-body techniques, yielding more transparent physical pictures. We generalize the Chern-Simons fermionization approach and apply it to the XXZ quantum magnets. After fermionzation, the Ising interaction of the XXZ spin model leads to a fermion-fermion interaction. We show that the additional fermion-fermion interaction generates an interesting phase transition between two fermionic ordered states, i.e., the Chern-Simons superconductor and the Chern-Simons exciton insulator. We also demonstrate that this transition in the fermionic language essentially describes the quantum phase transition between the planar and out-of-plane N\'eel orders in the spin picture. The fermionic mean-field theory further leads to a nonlinear $\ensuremath{\sigma}$ model that describes the quantum phase transition, which is further supported by our density matrix renormalization group calculations in the original spin model. Our work introduces a fermionic interpretation of quantum phase transitions and advances the existing knowledge of quantum magnets.

Solar Driven Gas Phase Advanced Oxidation Processes for Methane Removal - Challenges and Perspectives.

Methane (CH4 ) is a potent greenhouse gas and the second highest contributor to global warming. CH4 emissions are still growing at an alarmingly high pace. To limit global warming to 1.5 °C, one of the most effective strategies is to reduce rapidly the CH4 emissions by developing large-scale methane removal methods. The purpose of this perspective paper is threefold. (1) To highlight the technology gap dealing with low concentration CH4 (at many emission sources and in the atmosphere). (2) To analyze the challenges and prospects of solar-driven gas phase advanced oxidation processes for CH4 removal. And (3) to propose some ideas, which may help to develop solar-driven gas phase advanced oxidation processes and make them deployable at a climate significant scale.

A prosthesis utilizing natural vestibular encoding strategies improves sensorimotor performance in monkeys.

Sensory pathways provide complex and multifaceted information to the brain. Recent advances have created new opportunities for applying our understanding of the brain to sensory prothesis development. Yet complex sensor physiology, limited numbers of electrodes, and nonspecific stimulation have proven to be a challenge for many sensory systems. In contrast, the vestibular system is uniquely suited for prosthesis development. Its peripheral anatomy allows site-specific stimulation of 3 separate sensory organs that encode distinct directions of head motion. Accordingly, here, we investigated whether implementing natural encoding strategies improves vestibular prosthesis performance. The eye movements produced by the vestibulo-ocular reflex (VOR), which plays an essential role in maintaining visual stability, were measured to quantify performance. Overall, implementing the natural tuning dynamics of vestibular afferents produced more temporally accurate VOR eye movements. Exploration of the parameter space further revealed that more dynamic tunings were not beneficial due to saturation and unnatural phase advances. Trends were comparable for stimulation encoding virtual versus physical head rotations, with gains enhanced in the latter case. Finally, using computational methods, we found that the same simple model explained the eye movements evoked by sinusoidal and transient stimulation and that a stimulation efficacy substantially less than 100% could account for our results. Taken together, our results establish that prosthesis encodings that incorporate naturalistic afferent dynamics and account for activation efficacy are well suited for restoration of gaze stability. More generally, these results emphasize the benefits of leveraging the brain's endogenous coding strategies in prosthesis development to improve functional outcomes.

Phase advancing is a common property of multiple neuron classes in the mouse retina.

Behavioral interactions with moving objects are challenged by response latencies within the sensory and motor nervous systems. In vision, the combined latency from phototransduction and synaptic transmission from the retina to central visual areas amounts to 50–100 ms, depending on stimulus conditions. Time required for generating appropriate motor output adds to this latency and further compounds the behavioral delay. Neuronal adaptations that help counter sensory latency within the retina have been demonstrated in some species, but how general these specializations are, and where in the circuitry they originate, remains unclear. To address this, we studied the timing of object motion-evoked responses at multiple signaling stages within the mouse retina using two-photon fluorescence calcium and glutamate imaging, targeted whole-cell electrophysiology, and computational modeling. We found that both ON-type and OFF-type ganglion cells, as well as the bipolar cells that innervate them, temporally advance the position encoding of a moving object and so help counter the inherent signaling delay in the retina. Model simulations show that this predictive capability is a direct consequence of the spatial extent of the cells’ linear visual receptive field, with no apparent specialized circuits that help predict beyond it.