Orbicularis oculi muscle activity during computer reading under different degrees of artificially-induced aniseikonia.

Background: Aniseikonia is a binocular vision disorder that has been associated with asthenopic symptoms. However, asthenopia has been evaluated with subjective tests that make difficult to determine the level of aniseikonia. This study aims to objectively evaluate the impact of induced aniseikonia at different levels on visual fatigue by measuring the orbicularis oculi muscle activity in the dominant and non-dominant eyes while performing a reading task. Methods: Twenty-four collegiate students (24.00 ± 3.86 years) participated in this study. Participants read a passage for 7 minutes under four degrees of aniseikonia (0%, 3%, 5% and 10%) at 50 cm. Orbicularis oculi muscle activity of the dominant and non-dominant eye was recorded by surface electromyography. In addition, visual discomfort was assessed after each task by completing a questionnaire. Results: Orbicularis oculi muscle activity increased under induced aniseikonia (i.e., greater values for the 10% condition in comparison to 0%, and 3% conditions (p = 0.034 and p = 0.023, respectively)). No statistically significant differences were observed in orbicularis oculi muscle activity for the time on task and between the dominant and non-dominant eyes. Additionally, higher levels of subjective visual discomfort were observed for lower degrees of induced aniseikonia. Conclusion: Induced aniseikonia increases visual fatigue at high aniseikonia degrees as measured by the orbicularis oculi muscle activity, and at low degrees as measured with subjective questionnaires. These findings may be of relevance to better understand the visual symptomatology of aniseikonia.

Higher order aberrations according to spherical, and astigmatic refractive errors in children.

CLINICAL RELEVANCE: The results of this study present novel insights into the impact of spherical and astigmatic refractive errors on overall, corneal and internal aberrations and may provide a clear understanding of the emmetropisation process and the development of visual function. BACKGROUND: This study aimed to assess the association between overall, corneal and internal higher-order aberrations and the spherical and astigmatic components (magnitude and angle) of refractive error in a large sample of children. METHODS: A total of 311 children aged 7 - 8 years old were classified based on spherical equivalent refraction (myopic, emmetropic and hyperopic); magnitude of astigmatism (none, low and moderate); and angle of astigmatism (with-the-rule, against-the-rule and oblique). Refractive error and overall, corneal and internal higher-order aberrations were measured using the OPD-Scan III workstation. RESULTS: Regarding spherical equivalent refraction, myopic eyes had greater root mean square (RMS) overall higher-order values, total spherical, tetrafoil and secondary astigmatism aberrations, and internal higher-order, total spherical and tetrafoil aberrations in comparison to emmetropic eyes. The magnitude of astigmatism was positively associated with all overall RMS aberrations and with internal higher order, coma, total coma, total spherical and tetrafoil aberrations. Eyes with with-the-rule astigmatism showed higher RMS values of coma and total coma compared to eyes with against-the-rule and oblique astigmatism. CONCLUSIONS: Higher-order aberrations are dependent on the spherical as well as astigmatic components of refractive error. These findings enhance the current understanding of the emmetropisation process and visual function development.

The adhesion G-protein-coupled receptor mayo/CG11318 controls midgut development in Drosophila.

Adhesion G-protein-coupled receptors (aGPCRs) form a large family of cell surface molecules with versatile tasks in organ development. Many aGPCRs still await their functional and pharmacological deorphanization. Here, we characterized the orphan aGPCR CG11318/mayo of Drosophila melanogaster and found it expressed in specific regions of the gastrointestinal canal and anal plates, epithelial specializations that control ion homeostasis. Genetic removal of mayo results in tachycardia, which is caused by hyperkalemia of the larval hemolymph. The hyperkalemic effect can be mimicked by a raise in ambient potassium concentration, while normal potassium levels in mayoKO mutants can be restored by pharmacological inhibition of potassium channels. Intriguingly, hyperkalemia and tachycardia are caused non-cell autonomously through mayo-dependent control of enterocyte proliferation in the larval midgut, which is the primary function of this aGPCR. These findings characterize the ancestral aGPCR Mayo as a homeostatic regulator of gut development.

Gaze behaviour during multiple object tracking is dependent on binocular vision integrity.

INTRODUCTION: Despite the critical importance of binocular vision integrity in daily activities, there exists limited understanding of how alterations in binocular vision integrity impact gaze behaviour during dynamic, complex psychomotor skills. This study aimed to measure how alterations in binocular vision integrity, created by Bangerter filters (BF), affect gaze behaviour during multiple object tracking (MOT). METHODS: During the experiment, 22 volunteers completed the MOT task under three different visual conditions. The first condition involved natural binocular viewing, while the second and third conditions used 0.4 and 0.2 neutral density BF, respectively, resulting in monocular blur in the sensorially dominant eye. During the MOT task, participants were instructed to track three of eight balls for 10 s, and the speed was adjusted using a staircase procedure. Throughout the task, the following gaze parameters were recorded: fixation duration, saccade duration, amplitude and frequency as well as blink rate. RESULTS: During MOT execution, participants employed three gaze strategies regardless of viewing conditions: saccadic movements were predominant, followed by maintaining fixation on a central location throughout the trial and to a lesser extent, smooth pursuit eye movements. There was a significant effect of manipulating viewing conditions on the MOT scores (p = 0.046, η2 = 0.09). As the viewing conditions became more difficult, we observed a decrease in fixation duration (p = 0.004, η2 = 0.16) and blink rate (p < 0.001, η2 = 0.20) and an increase in saccadic amplitude (p < 0.001, η2 = 0.29). CONCLUSIONS: The results support the notion that perceptual-cognitive skills depend on the integrity of binocular vision, underscoring the sensitivity of gaze behaviours to any impairment of binocular function.

Diurnal Variation in Accommodation, Binocular Vergence, and Pupil Size.

SIGNIFICANCE: Our results show significant diurnal variations in accommodative function and the magnitude of the phoria. Therefore, when comparing visual measures in clinical or laboratory settings, performing the visual examination at the same time of day (±1 hour) is encouraged. PURPOSE: The aim of this study was to evaluate the accommodation, binocular vergence, and pupil behavior on three different times during the day. METHODS: Twenty collegiate students (22.8 ± 2.1 years) participated in this study. Participants visited the laboratory on three different days at 2-hourly intervals (morning, 9:00 to 11:00 am ; afternoon, 2:00 to 4:00 pm ; evening, 7:00 to 9:00 pm ). The binocular vergence and accommodative function were measured using clinical optometric procedures, and the accommodative response and pupil function were evaluated in binocular conditions using the WAM-5500 autorefractometer. RESULTS: The accommodative amplitude for the right and left eyes showed statistically significant differences for the time interval ( P = .001 and P = .02, respectively), revealing higher accommodative amplitude in the morning and afternoon in comparison with the evening. Participants were more esophoric when assessed in the morning in comparison with the evening at far and near ( P = .02 and P = .01, respectively) and when assessed in the afternoon in comparison with the evening at far distance ( P = .02). The magnitude of accommodative response was higher in the morning, and it decreased throughout the day at 500 ( P < .001), 40 ( P = .05), and 20 cm ( P < .001). No statistically significant differences were obtained for any other variable. CONCLUSIONS: This study shows small diurnal variations in some accommodative and binocular vergence parameters, but no effects were observed for the pupil response. These outcomes are of special relevance for eye care specialists when performing repeated accommodative or binocular vergence measures. However, the diurnal variations were modest and may not influence a routine orthoptic examination.

Effect of manipulating the vergence/accommodation and image size mismatches of the ±2D flipper test on the frequency and precision of accommodative facility.

PURPOSE: The ±2.00 D accommodative facility test presents several limitations, including the lack of objective information and inherent characteristics such as vergence/accommodative conflict, change in apparent size of the image, subjective criteria for judging blur and motor reaction time. By using free-space viewing conditions and an open-field autorefractor to monitor the refractive state, we examined the impact of manipulating these factors on the qualitative and quantitative assessment of accommodative facility. METHODS: Twenty-five healthy young adults (24.5 ± 4.5 years) took part in this study. Participants performed three accommodative facility tests (adapted flipper, 4D free-space viewing and 2.5D free-space viewing) under both monocular and binocular conditions in random order. A binocular open-field autorefractor was used to assess the accommodative response continuously, and these data were used to characterise accommodative facility quantitatively and qualitatively. RESULTS: There were statistically significant differences between the three testing methods both quantitatively (p < 0.001) and qualitatively (p = 0.02). For the same accommodative demand, a lower number of cycles was obtained for the adapted flipper condition in comparison with the 4D free-space viewing test (corrected p-value < 0.001, Cohen's d = 0.78). However, this comparison did not reach statistical significance for qualitative measures of accommodative facility (corrected p-value = 0.82, Cohen's d 0.05). CONCLUSIONS: These data provide evidence that the qualitative assessment of accommodative facility is not influenced by the inherent limitations of the ±2.00 D flipper test. The use of qualitative outcomes by incorporating an open-field autorefractor allows examiners to increase the validity of the accommodative facility test in both clinical and research settings.

Molecular sensing of mechano- and ligand-dependent adhesion GPCR dissociation.

Adhesion G-protein-coupled receptors (aGPCRs) bear notable similarity to Notch proteins1, a class of surface receptors poised for mechano-proteolytic activation2-4, including an evolutionarily conserved mechanism of cleavage5-8. However, so far there is no unifying explanation for why aGPCRs are autoproteolytically processed. Here we introduce a genetically encoded sensor system to detect the dissociation events of aGPCR heterodimers into their constituent N-terminal and C-terminal fragments (NTFs and CTFs, respectively). An NTF release sensor (NRS) of the neural latrophilin-type aGPCR Cirl (ADGRL)9-11, from Drosophila melanogaster, is stimulated by mechanical force. Cirl-NRS activation indicates that receptor dissociation occurs in neurons and cortex glial cells. The release of NTFs from cortex glial cells requires trans-interaction between Cirl and its ligand, the Toll-like receptor Tollo (Toll-8)12, on neural progenitor cells, whereas expressing Cirl and Tollo in cis suppresses dissociation of the aGPCR. This interaction is necessary to control the size of the neuroblast pool in the central nervous system. We conclude that receptor autoproteolysis enables non-cell-autonomous activities of aGPCRs, and that the dissociation of aGPCRs is controlled by their ligand expression profile and by mechanical force. The NRS system will be helpful in elucidating the physiological roles and signal modulators of aGPCRs, which constitute a large untapped reservoir of drug targets for cardiovascular, immune, neuropsychiatric and neoplastic diseases13.

Influence of the body positions adopted for resistance training on intraocular pressure: a comparison between the supine and seated positions.

OBJECTIVES: A variety of factors are known to mediate on the intraocular pressure (IOP) response to resistance training. However, the influence of the body position adopted during resistance training on IOP remain unknown. The objective of this study was to determine the IOP response to the bench press exercise at three levels of intensity when performed in supine and seated positions. METHODS: Twenty-three physically active healthy young adults (10 men and 13 women) performed 6 sets of 10 repetitions against the 10-RM (repetition maximum) load during the bench press exercise against three levels of intensity (high intensity: 10-RM load; medium intensity: 50% of the 10-RM load; and control: no external load) and while adopting two different body positions (supine and seated). A rebound tonometer was employed to measure IOP in baseline conditions (after 60 s in the corresponding body position), after each of the 10 repetitions, and after 10 s of recovery. RESULTS: The body position adopted during the execution of the bench press exercise significantly affected the changes in IOP (p < 0.001, ηp2 = 0.83), with the seated position providing lower increases in IOP levels compared to the supine position. There was an association between IOP and exercise intensity, with greater IOP values in the more physically demanding conditions (p < 0.001, ηp2 = 0.80). CONCLUSIONS: The use of seated positions, instead of supine positions, for the execution of resistance training should be prioritized for maintaining more stable IOP levels. This set of findings incorporates novel insights into the mediating factors on the IOP response to resistance training. In future studies, the inclusion of glaucoma patients would allow to assess the generalizability of these findings.

Less is more: optimal recording time for measuring the steady-state accommodative response.

Clinical Relevance Background: Steady-state accommodation is frequently evaluated with open-field autorefractors; however there is no consensus regarding the optimal test duration. Our results allow us to standardise the procedure followed for the assessment of the steady-state accommodative response in clinical and laboratory settings and may be of great relevance in time-constrained situations. BACKGROUND: The present study aims to determine the optimal recording time to assess the magnitude and variability of the accommodative response with a binocular open-field autorefractor. METHODS: The steady-state accommodative response of 84 healthy undergraduate students was dynamically measured using the Grand Seiko WAM-5500 autorefractor at 500 cm, 40 cm and 20 cm for 90 s while participants maintained focus on a stationary target. We examined the reliability and level of agreement between four time intervals (the first 10-s, 30-s, 60-s and 90-s) at three accommodative demands (0.2D, 2.5D and 5D). RESULTS: The magnitude of accommodation showed an excellent level of reliability (intraclass correlation coefficient [ICC]> 0.90) for the comparisons between the 90-s, 60-s and 30-s time intervals at the three viewing distances tested. However, when including the 10-s interval, there was a moderate reduction of the reliability indices and an increase of the mean difference between two time intervals (intra-class correlation [ICC] ranging from 0.89 to 0.97; and ESs ranging from 0.16 to 0.42). For the variability of accommodation, we observed an excellent reliability for the comparisons of the 90-s and 60-s measures at the three accommodative demands (ICC: 0.95-0.96), whereas for the rest of comparisons we observed from moderate to good levels of reliability. CONCLUSION: Our data indicate that of 30-s and 60-s are enough to accurately assess the magnitude and variability of the accommodative response with the WAM-5500 autorefractor, respectively.

Blue-blocking filters do not alleviate signs and symptoms of digital eye strain.

CLINICAL RELEVANCE: There is some controversy about the utility of prescribing blue-blocking filters to mitigate digital eye strain. We found that using commercially available blue-blocking filters was ineffective in reducing orbicularis oculi muscle activity and visual symptomatology during a 30-min reading task from a computer screen. BACKGROUND: There are some claims that blue-blocking (B-B) filters may be effective in reducing symptoms and signs of digital eye strain. However, recent studies have suggested that there is no sufficient evidence to support their use. This study assessed the short-term effects of a commercially available, B-B filter on orbicularis oculi (OO) muscle activity and symptoms of digital eye strain during the execution of a 30-min reading tas. METHODS: Twenty-three healthy young adults (22.9 ± 3.2 years of age) performed two reading tasks from a computer screen with or without a B-B filter on two different days. OO muscle activity was recorded by surface electromyography 4-5, 9-10, 14-15, 19-20, 24-25 and 29-30 min into the trial. Participants reported their perceived levels of visual discomfort and activation before and after completing the reading task. RESULTS: A Bayesian analysis favoured the null hypothesis that there was no change in OO muscle activity with or without using the B-B filter (Bayes Factor01 [BF01] = 7.08). Regarding symptomatology, the analysis favoured the time model that reading increased visual fatigue and discomfort but reduced activation levels (BF01 < 0.33 in all cases). However, our data did not support the alternative model that using B-B filter affected these visual symptoms. CONCLUSIONS: The B-B filter did not alter OO muscle activity or visual symptomatology significantly during the execution of a 30-min reading task in asymptomatic subjects. These findings support the idea that B-B filters do not attenuate signs and symptoms of digital eye strain.

Dynamics of the accommodative response and facility with dual-focus soft contact lenses for myopia control.

OBJECTIVE: To assess the impact of using dual-focus soft contact lenses for myopia control on the dynamics of the accommodative response and facility. METHODS: 24 young adult myopes were fitted with dual-focus soft contact lenses for myopia control (MiSight®) and single-vision soft contact lenses (Proclear®). The WAM-5500 open-field autorefractor was used to measure the dynamics of the accommodative response (magnitude and variability) in binocular conditions, with accommodative data being gathered from the dominant eye, at three viewing distances (500 cm, 40 cm, and 20 cm) during 90 s. Also, the binocular accommodative facility was assessed with the WAM-5500 autorefractor. All participants performed the same experimental protocol with the dual-focus (MiSight) and single-vision (Proclear) soft contact lenses, with both experimental sessions being carried in two different days and following a counterbalanced order. RESULTS: This study showed greater lags of accommodation with the MiSight than the Proclear lenses at near distances (40 cm: 1.27 ± 0.77 vs. 0.68 ± 0.37 D, corrected p-value = 0.002, Cohen-d = 0.90; and 20 cm: 1.47 ± 0.84 vs. 1.01 ± 0.52 D, corrected p-value = 0.007, Cohen-d = 0.75), whereas a higher variability of accommodation was observed with the dual-focus than the single-vision lenses at 500 cm (0.53 ± 0.11 vs. 0.23 ± 0.10 D), 40 cm (0.82 ± 0.31 vs. 0.68 ± 0.37 D), and 20 cm (1.50 ± 0.56 vs. 1.15 ± 0.39 D) (corrected p-value < 0.001 in all cases, and Cohen-ds = 0.67-2.33). Also, a worse quantitative (27.75 ± 8.79 vs. 34.29 ± 10.08 cycles per minute, p = 0.029, Cohen-d = 0.48) and qualitative (23.68 ± 7.12 vs. 28.43 ± 7.97 score, p = 0.039, Cohen-d = 0.45) performance was observed with the MiSight when compared to the Proclear lenses. CONCLUSIONS: The use of dual-focus soft contact lenses for myopia control alters the dynamics of accommodative response and facility in the short-term. Although this optical design has demonstrated its effectiveness for myopia control, eye care specialists should be aware of the acute effects of these lenses on accommodation performance.

Effect of wearing different types of face masks during dynamic and isometric resistance training on intraocular pressure.

CLINICAL RELEVANCE: The use of face masks has demonstrated to be an effective strategy to prevent transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Wearing face masks, mainly Filtering Face Piece 2 (FFP2) masks, during exercise practice has demonstrated to affect several physiological measures. BACKGROUND: This study was aimed at assessing the intraocular pressure (IOP) behaviour during the execution of the dynamic and isometric biceps-curl exercise with a surgical and FFP2 face mask. METHODS: Twenty two physically active young adults performed sets of 10 repetitions against the 10-RM (repetition maximum) load and 1-minute isometric effort against a load 15% lower than the 10-RM load with the FFP2 and surgical mask and without any mask. A total of six exercise sets (3 experimental conditions [FFP2, surgical and control] × 2 exercise modalities) were performed. A rebound tonometer was used to measure IOP before, during (10 measurements), and after (30-seconds of passive recovery) each training set. RESULTS: At rest, there were not statistically significant IOP differences (p = 0.222). During dynamic exercise, there was a progressive IOP rise (p < 0.001), and a higher IOP response with the FFP2 than without the mask (corrected p-value = 0.003). For the isometric exercise, there was a greater IOP response as a function of accumulated effort (p < 0.001), which was dependent of the face mask used (FFP2> surgical>control; corrected p-values< 0.01). CONCLUSIONS: The FFP2 masks cause a heightened IOP response during the execution of dynamic and isometric biceps-curl exercise, suggesting that, when possible, glaucoma patients should limit the use of FFP2 masks during resistance training.

Impact of dual-focus soft contact lens wear on near work-induced transient myopia.

CLINICAL RELEVANCE: Dual-focus soft contact lenses are effective in slowing myopia progression; however, their influence on near work-induced transient myopia (NITM) remains unknown. When performing a 5-min near task at 20 cm, we observed that dual-focus soft contact lens wear induced greater lags of accommodation and a lower initial NITM than single-vision soft contact lenses, which provides relevant information for better understanding the impact of using this optical design on the accommodative function. BACKGROUND: NITM has been proposed as a myogenic factor, although it is a matter of debate by the scientific community. The main objective of this study was to assess the short-term effect of wearing dual-focus soft contact lenses for myopia control on the steady-state accommodative response and NITM. METHODS: Twenty-four young myope adults wore, on two different days, dual-focus and single-vision soft contact lenses, while the accommodative response was dynamically measured with an open-field autorefractor during the execution of the NITM task. The shift and the time required to recover baseline levels in the refractive state after performing the 5-min near task (20 cm) were the main dependent variables. RESULTS: We found a lower magnitude of accommodation during the execution of the near task with the dual-focus in comparison to the single-vision soft contact lenses (p < 0.001). There was a lower initial NITM with the dual-focus when compared to the single-vision lenses (corrected p-value = 0.003, Cohen's d = 0.68), but no statistically significant differences were observed for decay duration (p = 0.984). CONCLUSIONS: Dual-focus soft contact lens wear causes a reduced accommodative response during a near task, and an initial small myopic shift at distance after a 5-min period of near viewing. The current findings may help to understand the mechanisms involved in myopia control with this optical strategy.

Validation of a Novel Reaction Time Test Specific for Military Personnel.

A military-specific reaction time (RT) test was developed to explore its reliability and sensitivity to discriminate between military personnel and sport science students. Fifteen male professional Spanish soldiers and 16 male sport science students completed two RT test modalities: military-specific and nonspecific RT tests. For each RT test modality, both the Simple (i.e., one stimulus, one response) and the Go, No-Go RT (i.e., true, and false stimuli, one response) were tested. The military-specific RT test consisted of a video presented through virtual reality glasses of a forest environment in which soldiers would appear from behind different bushes (stimuli) and the response consisted of pressing the button of a gun-shaped mouse (when they saw a soldier pointing a rifle at them). Both Simple and Go, No-Go RT reached acceptable reliability in both populations (coefficient of variation ≤ 9.64%). Military personnel presented a lower RT than sport science students during the military-specific RT test (p ≤ .001), while no differences were obtained during the nonspecific RT test. RT values were not significantly correlated between the military-specific and nonspecific RT tests (r ≤ .02). These findings collectively suggest that the novel military-specific RT test is an ecologically valid alternative to evaluate the information processing abilities of military personnel.

Acute Intraocular Pressure Responses to Resistance Training in Combination With Blood Flow Restriction.

Objective: To determine the effect of blood flow restriction (BFR) applied to the legs at different pressures (40% and 60%) on intraocular pressure (IOP) during the execution of ten repetitions maximum (10RM) in the half-squat exercise. Methods: Quasi-experimental, prospective study with 17 healthy physically active subjects (9 males and 8 females; 24.1 ± 4.2 years). Two sessions were conducted. The 10RM load was determined in the first session. The second session consisted of 10RM under three BFR conditions (no-BFR, 40%-BFR, and 60%-BFR) that were applied in random order. IOP was measured before each condition, immediately after each repetition, and after 1 minute of passive recovery. A two-way repeated-measures ANOVA (restriction type [no-BFR, 40%-BFR, and 60%-BFR] x measurement point [basal, repetitions 1-10, and recovery]) was applied on the IOP measurements. Results: A significant main effect of the BFR condition (p = .022, ƞp2 = 0.21) was observed due to the significantly higher mean IOP values for the 60%-BFR (19.0 ± 0.7 mmHg) compared to the no-BFR (18.0 ± 0.8 mmHg; p = .048, dunb = 1.30). Non-significant differences with a large effect size were reached between 60%-BFR and 40%-BFR (18.1 ± 0.8 mmHg; p = .081, dunb = 1.16) and between no-BFR and 40%-BFR (p = .686, dunb = 0.18). IOP increased approximately 3-4 mmHg from baseline to the last repetition. Conclusions: Low-pressure BFR (40%-BFR) in combination with moderate-load (10RM load) resistance exercise could be an effective and safe strength training strategy while avoiding IOP peaks associated with heavy-load resistance exercises. These findings incorporate novel insights into the most effective exercise strategies in individuals who need to maintain stable IOP levels (e.g., glaucoma patients).

Oral Anticoagulation in Patients with Chronic Kidney Disease and Non-Valvular Atrial Fibrillation: The FAERC Study.

Atrial fibrillation (AF) is the most common arrhythmia in patients with chronic kidney disease (CKD), and its presence is associated with a higher risk of stroke and mortality. MATERIAL AND METHODS: The FAERC study performed a retrospective multicentre analysis of historical cohorts in which data were collected from arrhythmia diagnosis onwards. RESULTS: We analysed a Spanish cohort of 4749 patients with CKD (mean eGFR 33.9 mL/min) followed up in the nephrology clinic, observing a 12.2% prevalence of non-valvular AF. In total, 98.6% of these patients were receiving anticoagulant treatment, mainly with coumarins (79.7%). Using direct-acting oral anticoagulants (DOACs) was associated with fewer cerebrovascular events than using acenocoumarol, but in contrast with other studies, we could not corroborate the association of risk of bleeding, coronary events, or death with a type of anticoagulant prescribed. CONCLUSIONS: Atrial fibrillation is highly prevalent in renal patients. Direct-acting anticoagulants seem to be associated with fewer ischemic-embolic complications, with no differences in bleeding, coronary events, or mortality rates.

p53-dependent c-Fos expression is a marker but not executor for motor neuron death in spinal muscular atrophy mouse models.

The activation of the p53 pathway has been associated with neuronal degeneration in different neurological disorders, including spinal muscular atrophy (SMA) where aberrant expression of p53 drives selective death of motor neurons destined to degenerate. Since direct p53 inhibition is an unsound therapeutic approach due carcinogenic effects, we investigated the expression of the cell death-associated p53 downstream targets c-fos, perp and fas in vulnerable motor neurons of SMA mice. Fluorescence in situ hybridization (FISH) of SMA motor neurons revealed c-fos RNA as a promising candidate. Accordingly, we identified p53-dependent nuclear upregulation of c-Fos protein in degenerating motor neurons from the severe SMNΔ7 and intermediate Smn2B/- SMA mouse models. Although motor neuron-specific c-fos genetic deletion in SMA mice did not improve motor neuron survival or motor behavior, p53-dependent c-Fos upregulation marks vulnerable motor neurons in different mouse models. Thus, nuclear c-Fos accumulation may serve as a readout for therapeutic approaches targeting neuronal death in SMA and possibly other p53-dependent neurodegenerative diseases.

Intraocular pressure responses to a virtual reality shooting simulation in active-duty members of the Spanish Army: The influence of task complexity.

Ocular physiology is sensitive to cognitively demanding tasks. However, it is unknown whether the intraocular pressure is also affected by the cognitive demands of military operations. The main objective was to determine the impact of a virtual reality shooting simulation with two levels of complexity on intraocular pressure levels in military personnel. Eighteen active-duty members of the Spanish Army and eighteen civilians performed two 4 min simulated shooting tasks with two levels of complexity using a virtual reality. In the "easy" task participants performed a simulated shoot when the stimulus (military with a rifle) appeared, while in the "difficult" task the stimulus randomly was a military with a rifle or with his hands on the air and participants were instructed to respond only when the military with a rifle appeared. Intraocular pressure was measured with a rebound tonometer before and immediately after each task. Complementarily, perceived levels of mental load and shooting performance (reaction time) were assessed. Intraocular pressure was greater after completing the more complex task in both military personnel (p-value < 0.01, Cohen´s d = 1.19) and civilians (p-value < 0.01, Cohen´s d = 1.16). Also, perceived levels of task load and reaction time were higher in the difficult compared to the easy shooting tasks (both p < 0.001). The rise in intraocular pressure is positively associated with the cognitive demands of simulated military operations. The potential application of this finding is the development of objective tools based on intraocular pressure for the evaluation of the mental state in real-world contexts, permitting to improve soldiers´ safety and performance.

Association of military-specific reaction time performance with physical fitness and visual skills.

Background: The aim of the present study was to explore whether military-specific reaction time (RT) test performance is affected by individuals' physical and visual skills. Method: In a single testing session, the military-specific Simple and Go, No-Go RT, aerobic power (20-m Multistage Shuttle Run test), maximal upper- and lower-body mechanical capacities (bench press and squat against different loads), and visual skills (multiple object tracking and dynamic visual acuity) of 30 young men (15 active-duty military personnel and 15 sport science students) were evaluated. Results: The main findings revealed that the Simple RT and Go, No-Go RT presented (1) with aerobic power non-significant small correlations in military personnel (r = -0.39 and -0.35, respectively) and non-significant negligible correlations in sport science students (r = -0.10 and 0.06, respectively), (2) inconsistent and generally non-significant correlations with the maximal mechanical capacities of the upper- and lower-body muscles (r range = -0.10, 0.67 and -0.27, 0.48, respectively), (3) non-significant correlations with visual skills (r magnitude ≥ 0.58) with the only exception of the Go, No-Go RT that was significantly correlated to all visual variables in the group of students (i.e., students who achieved better results during visual tests had shorter RT; r magnitude ≥ 0.58), and (4) none of the physical and visual variables significantly predicted the Simple RT or Go, No-Go RT. Conclusion: Altogether, these results indicate that military-specific RT performance is generally independent of physical and visual skills in both military personnel and active university students.

Examining the ability to track multiple moving targets as a function of postural stability: a comparison between team sports players and sedentary individuals.

Background: The ability to track multiple objects plays a key role in team ball sports actions. However, there is a lack of research focused on identifying multiple object tracking (MOT) performance under rapid, dynamic and ecologically valid conditions. Therefore, we aimed to assess the effects of manipulating postural stability on MOT performance. Methods: Nineteen team sports players (soccer, basketball, handball) and sixteen sedentary individuals performed the MOT task under three levels of postural stability (high, medium, and low). For the MOT task, participants had to track three out of eight balls for 10 s, and the object speed was adjusted following a staircase procedure. For postural stability manipulation, participants performed three identical protocols (randomized order) of the MOT task while standing on an unstable platform, using the training module of the Biodex Balance System SD at levels 12 (high-stability), eight (medium-stability), and four (low-stability). Results: We found that the ability to track moving targets is dependent on the balance stability conditions (F2,66 = 8.7, p < 0.001, η² = 0.09), with the disturbance of postural stability having a negative effect on MOT performance. Moreover, when compared to sedentary individuals, team sports players showed better MOT scores for the high-stability and the medium-stability conditions (corrected p-value = 0.008, Cohen's d = 0.96 and corrected p-value = 0.009, Cohen's d = 0.94; respectively) whereas no differences were observed for the more unstable conditions (low-stability) between-groups. Conclusions: The ability to track moving targets is sensitive to the level of postural stability, with the disturbance of balance having a negative effect on MOT performance. Our results suggest that expertise in team sports training is transferred to non-specific sport domains, as shown by the better performance exhibited by team sports players in comparison to sedentary individuals. This study provides novel insights into the link between individual's ability to track multiple moving objects and postural control in team sports players and sedentary individuals.