Strobe Groups Research Articles

Balance Training With Stroboscopic Glasses and Neuromechanics in Patients With Chronic Ankle Instability During a Single-Legged Drop Landing.

Therapeutic interventions for individuals with chronic ankle instability (CAI) are recommended to improve muscle strength, postural control, and range of motion. However, their effects on neuromechanics during a drop landing remain unclear. In addition, even though therapeutic interventions with stroboscopic glasses appear to effectively improve postural control, how they affect landing neuromechanics remains unclear. To identify the effect of balance training with stroboscopic glasses on neuromechanics during a single-legged drop landing in patients with CAI. Randomized controlled clinical trial. Laboratory. A total of 50 participants with CAI were randomly assigned to 1 of 2 groups: strobe (n = 25; age = 22 ± 3 years, height = 174.7 ± 8.2 cm, mass = 71.8 ± 12.2 kg) or control (n = 25; age = 21 ± 2 years, height = 173.1 ± 8.3 cm, mass = 71.1 ± 13.5 kg). The 4-week rehabilitation (3 sessions per week) included hop-based tasks and single-legged stance. The strobe group wore stroboscopic glasses during the training, whereas the control group did not. Ankle-, knee-, and hip-joint kinematics and 4 lower extremity muscle activations 150 milliseconds before and after initial contact during a single-legged drop landing in the 2 groups. The strobe group showed greater eversion (from 150 milliseconds before to 30 milliseconds after initial contact) and dorsiflexion (from 30 to 96 milliseconds after initial contact) angles and peroneal longus (from 35 milliseconds before to 5 milliseconds after initial contact) and tibialis anterior (from 0 to 120 milliseconds after initial contact) activation in the posttest than the pretest. Patients with CAI who underwent a 4-week rehabilitation with stroboscopic glasses demonstrated changes in neuromechanics, including increased ankle-dorsiflexion and -eversion angles and tibialis anterior and peroneus longus activation, during a single-legged drop landing. This finding suggests that use of stroboscopic glasses during rehabilitation could help patients with CAI develop safe landing mechanics.

The Effects of Stroboscopic Training in Athletes With Chronic Ankle Instability

This study aimed to determine the effects of a 6-week stroboscopic balance training program on balance scores in athletes with chronic ankle instability. Balance was evaluated before and after the 6-week balance training program. After the program, there were no differences between the strobe and nonstrobe groups in static balance. In terms of dynamic balance, the strobe group showed a significant increase in limits of stability between pretest and posttest and terms of dynamic balance, the strobe group showed a significant increase in limits of stability between pretest and posttest and had significantly greater limits of stability than the nonstrobe group at posttest. Stroboscopic balance training may be useful in improving dynamic balance in athletes with chronic ankle instability.

A profile of Senaptec strobe in young elite university athletes

Background: Stroboscopic visual training has shown improvement in cognitive skills and perceptual performance by performing motor tasks under situations of intermittent vision. Aim: The aim of this study to compare the improvement of visuomotor skills in athletes after the Stroboscopic visual Training. Methods: Thirty male Athletes were assigned for strobe group (EG n=15), and for control group (CG n=15). 15 Strobe group (SG) took part in SVT programme, and their performance on 6 measures of visual and perceptual skills was compared with 15 Control group (CG) Athletes. Whilst the EG wore Senaptec Strobe and control group CG continued to train with unimpaired vision. Post Training assessment were administered after 10 mins of SVT. Reaction test, Eye Hand coordination was administered pre and post SVT. This involves the Laptop for EHC and iPhone 6S for Reaction test using Reaction Test pro and PT Balance is used to evaluate balance. Results: The strobic effect were absorbed at each time. Baseline performance was significant was significantly related to Post performance immediately 10 min, visual response time (p = 0.001), Reaction time (p = 0.01), Eye hand coordination (p = 0.02). No significant differences were found for NPA, NPC, Balance measures. Conclusion: The analysis of the SVT programme in SG Athletes show consistent improvements in the visual response time at post-test, were the CG Athletes did not. The present research on Stroboscopic Visual Training has the potential to improve the visuomotor skills in the young athletes.

Effects of balance training with stroboscopic glasses on postural control in chronic ankle instability patients.

To compare (1) the effects of balance training with and without stroboscopic glasses on postural control and (2) the effects of the training on visual reliance in patients with CAI. A randomized controlled clinical trial. Twenty-eight CAI patients were equally assigned to one of 2groups: strobe or control group. The strobe group wore stroboscopic glasses during a 4-week balance training. Static postural control, a single-leg hop balance test calculated by Dynamic Postural Stability Index (DPSI), and the Y-Balance test (YBT) were measured. During the tests, there were different visual conditions: eyes-open (EO), eyes-closed (EC), and strobe vision (SV). Romberg ratios were then calculated as SV/EO, and EC/EO and used for statistical analysis. The strobe group showed a higher pretest-posttest difference in velocity in the medial-lateral direction and vertical stability index under SV compared with the control group (p<.05). The strobe group showed higher differences in EC/EO for velocity in the medial-lateral and anterior-posterior directions, and 95% confidence ellipse area (p<.05), and in SV/EO for velocity in the medial-lateral, 95% confidence ellipse area, and YBT-anterior direction (p<.05). The 4-week balance training with stroboscopic glasses appeared to be effective in improving postural control and altering visual reliance in patients with CAI.

The effects of stroboscopic balance training on cortical activities in athletes with chronic ankle instability

ObjectivesTo investigate the effect of a 6-week stroboscopic balance training program on cortical activities in athletes with chronic ankle instability. DesignRandomized controlled trial. Setting: Single-center. ParticipantsThirty-nine participants were assigned to the strobe group (SG, n = 13), non-strobe group (NSG, n = 13), and control group (CG, n = 13). Main outcome measuresCortical activity and balance velocity were evaluated while the athletes were on the HUBER balance device. Electroencephalographic measurements of cortical activity were made at the transition from bipedal stance to single-leg stance. ResultsThe SG showed significant increases in Cz theta and alpha values and COP-v (center of pressure velocity) between pretest and posttest (p < 0.001, p = 0.003, p < 0.001). Posttest Cz theta was significantly higher in the SG compared to the CG (p = 0.009) and posttest Cz alpha was significantly higher in the SG compared to the NSG (p = 0.039) and CG (p = 0.001). Posttest COP-v was significantly higher in the SG than in the CG (p = 0.031) and NSG (p = 0.03). ConclusionsStroboscopic training may be clinically beneficial to improve balance parameters in athletes with CAI, and may have utility in sport-specific activity phases of rehabilitation to reduce visual input and increase motor control.

The effect of stroboscopic visual training on eye\u2013hand coordination

BackgroundStroboscopic visual training (SVT) has been shown to improve cognitive skills and perceptual performance by carrying out events under situations of intermittent vision.AimsThe aim of this study was to investigate whether an SVT training period could improve the eye–hand coordination (EHC) performance on a practiced task for a group of sports participants.MethodsSixty-two male participants were randomly assigned to either a strobe group (SG n = 31), or control group (CG n = 31). The method employed a Sport Vision Trainer™ 80 sensor pad to measure the mean speed of reaction time of participants extinguishing randomly illuminated lights on an electronic board. One trial consists of 20 lights. One week following pre-testing on the Sport Vision Trainer™ (4 × 6 trials), a pre-training baseline assessment of 1 × 6 trials was conducted to measure their abilities to complete the EHC task. Four × six trials (480 lights) were then completed in the training phase with the CG continuing to train with unimpaired vision, whilst the SG wore Nike Vapor Strobe® (controlled rate of 100 ms visible to 150 ms opaque). Post-training assessments were administered immediately, 10 min and 10 days after SVT each consisting of six trials (120 lights). A visual search (VS) non-trained transfer test was also administered pre-SVT and after 10 days. This involved an e-prime programme using a laptop where participants had to identify a target stimulus located amongst distractor stimuli.ResultsTreatment effects were observed at each time point. Baseline performance was significantly related to retention performance immediately (p = .003), 10-min post (p = .001) and 10 days post-training (p = .002). No significant differences were found for the VS test.ConclusionAn acute SVT exposure using stroboscopic goggles significantly improved EHC performance. Future research should explore these mechanisms further using different exposure, frequencies, and focused identification of training drills as a complementary intervention for individual or team sports.

Sonar strobe groups and buzzes are produced before powered flight is achieved in the juvenile big brown bat, Eptesicus fuscus.

Laryngeally echolocating bats produce a rapid succession of echolocation calls just before landing. These landing buzzes exhibit an increase in call rate and a decrease in call peak frequency and duration relative to pre-buzz calls, and resemble the terminal buzz phase calls of an aerial hawking bat's echolocation attack sequence. Sonar strobe groups (SSGs) are clustered sequences of non-buzz calls whose pulse intervals (PIs) are fairly regular and shorter than the PIs both before and after the cluster, but longer than the PIs of buzz calls. Like buzzes, SSGs are thought to indicate increased auditory attention. We recorded the echolocation calls emitted by juvenile big brown bats (Eptesicus fuscus) over postnatal development from birth to 32 days old, when full flight has normally been achieved, and tested the following hypotheses: (i) buzz production precedes the onset of controlled, powered flight; (ii) the emission of SSGs precedes buzzes and coincides with the onset of fluttering behaviour; and (iii) the onset of flight is attained first by young bats with adult-like wing loadings. We found that E. fuscus pups emitted landing buzzes before they achieved powered flight and produced SSGs several days before emitting landing buzzes. Both observations indicate that the onset of adult-like echolocation behaviour occurs prior to adult-like flight behaviour. Pups that achieved flight first were typically those that also first achieved low, adult-like wing loadings. Our results demonstrate that echolocation and flight develop in parallel but may be temporally offset, such that the sensory system precedes the locomotory system during postnatal ontogeny.

Stroboscopic Vision When Interacting With Multiple Moving Objects: Perturbation Is Not the Same as Elimination.

Motivated by recent findings of improved perceptual processing and perceptual-motor skill following stroboscopic vision training, the current study examined the performance and acquisition effects of stroboscopic vision methods that afford a different visual experience. In Experiment 1, we conducted a within-subject design study to examine performance of a multiple object tracking (MOT) task in different stroboscopic vision conditions (Nike Vapor Strobe®, PLATO visual occlusion, and intermittent display presentation) operating at 5.6, 3.2, or 1.8 Hz. We found that participants maintained MOT performance in the Vapor Strobe condition irrespective of strobe rate. However, MOT performance deteriorated as strobe rate was reduced in the other two stroboscopic vision conditions. Moreover, at the lowest strobe rate (1.8 Hz) there was an increase in probe reaction time, thus indicating an increased attentional demand due to the stroboscopic vision. In Experiment 2, we conducted a mixed design study to examine if practice in different stroboscopic vision conditions (Nike Vapor Strobe® and PLATO visual occlusion) influenced acquisition of a novel precision-aiming task [i.e., multiple object avoidance (MOA) task] compared to a normal vision group. Participants in the PLATO visual occlusion group exhibited worse performance during practice than the Vapor Strobe and normal vision groups. At post-test, the Vapor Strobe group demonstrated greater success and reduced end-point error than the normal vision and PLATO groups. We interpret these findings as showing that both an intermittent perturbation (Nike Vapor Strobe®) and elimination (PLATO visual occlusion and intermittent display presentation) of visual motion and form are more attention demanding (Experiment 1), however, the intermittent perturbation, but not elimination, of visual motion and form can facilitate acquisition of perceptual-motor skill (Experiment 2) in situations where it is necessary to maintain and update a spatio-temporal representation of multiple moving objects.

Echolocating Big Brown Bats, Eptesicus fuscus, Modulate Pulse Intervals to Overcome Range Ambiguity in Cluttered Surroundings.

Big brown bats (Eptesicus fuscus) emit trains of brief, wideband frequency-modulated (FM) echolocation sounds and use echoes of these sounds to orient, find insects, and guide flight through vegetation. They are observed to emit sounds that alternate between short and long inter-pulse intervals (IPIs), forming sonar sound groups. The occurrence of these strobe groups has been linked to flight in cluttered acoustic environments, but how exactly bats use sonar sound groups to orient and navigate is still a mystery. Here, the production of sound groups during clutter navigation was examined. Controlled flight experiments were conducted where the proximity of the nearest obstacles was systematically decreased while the extended scene was kept constant. Four bats flew along a corridor of varying widths (100, 70, and 40 cm) bounded by rows of vertically hanging plastic chains while in-flight echolocation calls were recorded. Bats shortened their IPIs for more rapid spatial sampling and also grouped their sounds more tightly when flying in narrower corridors. Bats emitted echolocation calls with progressively shorter IPIs over the course of a flight, and began their flights by emitting shorter starting IPI calls when clutter was denser. The percentage of sound groups containing 3 or more calls increased with increasing clutter proximity. Moreover, IPI sequences having internal structure become more pronounced when corridor width narrows. A novel metric for analyzing the temporal organization of sound sequences was developed, and the results indicate that the time interval between echolocation calls depends heavily on the preceding time interval. The occurrence of specific IPI patterns were dependent upon clutter, which suggests that sonar sound grouping may be an adaptive strategy for coping with pulse-echo ambiguity in cluttered surroundings.

Temporal dynamics of echolocation during clutter navigation in Eptesicus fuscus

The echolocating big brown bat, Eptesicus fuscus, must both avoid background objects that it may collide with such as vegetation or clutter, and identify insect prey targets. When bats fly through clutter, they emit groups of echolocation sounds in rapid succession called strobe groups. Here, we investigate the limitations of strobe grouping for flight guidance during clutter navigation. We hypothesized that as clutter conditions become extreme, bats will be no longer able to use strobe groups to navigate. We exposed bats to our laboratory flight room cluttered with plastic chains—obstacles that are acoustically similar to vegetation. Bats flew down a corridor 1.0 m wide, 0.7 m wide, or 0.4 m wide, and echolocation sounds were recorded with a 22-microphone array. We used a means clustering analysis to quantify inter-pulse intervals (IPIs) as belonging within a strobe group or between strobe groups. We found that bats made significantly more sounds per flight as the corridor width decreased. Strobe groups in the wide condition contained longer within-strobe IPI, while strobe groups in the narrowest condition had the shortest. We also investigated how many sounds per strobe group were used. These results show a relationship between clutter density and the temporal structure of echolocation calls.

Timing patterns of strobe groups for echolocating big brown bats performing a target detection task

While flying in dense clutter or close to objects, bats often produce “strobe groups,” pairs of pulses emitted at short pulse intervals followed by longer pulse intervals. Previous studies of free-flying bats demonstrate relatively consistent trends in strobe groups depending on the degree of clutter. To investigate strobe group production in stationary bats, three big brown bats were trained to perform a target detection task and their echolocation signals were analyzed. Variation in the number of pulses within strobe groups as well as strobe group characteristics varied substantially between individuals and experimental trials, yet when strobe groups were produced the time between pulses and strobe groups remained relatively stable. These data suggest that although bats demonstrate flexibility in the production and characteristics of strobe groups, the inherent timing of pulses within and across strobe groups is stable. These patterns may reflect precise timing adaptations in sound-producing motor circuits of individual bats.

Stroboscopic Training Enhances Anticipatory Timing

The dynamic aspects of sports often place heavy demands on visual processing. As such, an important goal for sports training should be to enhance visual abilities. Recent research has suggested that training in a stroboscopic environment, where visual experiences alternate between visible and obscured, may provide a means of improving attentional and visual abilities. The current study explored whether stroboscopic training could impact anticipatory timing—the ability to predict where a moving stimulus will be at a specific point in time. Anticipatory timing is a critical skill for both sports and non-sports activities, and thus finding training improvements could have broad impacts. Participants completed a pre-training assessment that used a Bassin Anticipation Timer to measure their abilities to accurately predict the timing of a moving visual stimulus. Immediately after this initial assessment, the participants completed training trials, but in one of two conditions. Those in the Control condition proceeded as before with no change. Those in the Strobe condition completed the training trials while wearing specialized eyewear that had lenses that alternated between transparent and opaque (rate of 100ms visible to 150ms opaque). Post-training assessments were administered immediately after training, 10-minutes after training, and 10-days after training. Compared to the Control group, the Strobe group was significantly more accurate immediately after training, was more likely to respond early than to respond late immediately after training and 10 minutes later, and was more consistent in their timing estimates immediately after training and 10 minutes later.

Frequency shifts of echolocation pulses in a cluttered environment: Comparison between Pipistrellus abramus and Miniopterus fuliginosus.

Changes in frequency range (ΔF) of FM echolocation pulses were recorded with an onboard wireless microphone (Telemike) for Pipistrellus abramus and Miniopterus fuliginosus in a cluttered environment created by dense chain‐row obstacles. The duration of echo streams (ESD) from the chains reached ∼40 ms when the bats were flying toward the chain‐row obstacles. P. abramus emitted pulses in pairs (strobe group) with 20–40 ms interpulse intervals (IPIs), which occasionally created pulse‐echo ambiguity (IPI was shorter than ESD). When successive echo streams did not overlap, ΔF within strobe groups was less than 2–3 kHz. When overlap occurred, Δ F increased to 5–6 kHz (F‐test, P < 0.001). By shifting frequency range of successive FM pulses, P. abramus appeared to assign echoes to the corresponding pulses and avoid pulse‐echo ambiguity. Similar finding was previously reported in Eptesicus fuscus. On the other hand, M. fuliginosus never emitted pulses in a strobe group, and IPIs were always adjusted to be longer than ESDs. Thus, the amount of ΔF was less than 2 kHz, which corresponded to that in P. abramus without pulse‐echo ambiguity. These comparative results suggest that echolocation strategy in the cluttered environment is different between two FM bat species. [Work supported by JSPS and ONR.]

Developmental change in ultrasonic echolocation sounds of Japanese echolocating bats, Pipistrellus abramus.

The development of vocalization during the first post‐natal month in Pipistrellus abramus was studied. Vocalizations were recorded from each pup (five pups from two mothers; captive‐born and captive‐raised in a laboratory) everyday when isolated from its mother. The sounds produced by pups on the day of birth were categorized into a long isolation call and seemingly an echolocation precursor call (EP call). The terminal frequencies of the fundamental (TF) was 19.3 ± 1.9 kHz (n = 98), indicating that TF ranges of the second harmonic produced by newborn bats almost corresponded to the fundamental TF of adult pipistrelle (40∼45 kHz). The bats over 2 weeks of age mainly produced EP calls whose characteristics were changed with age. (1) increased TF, (2) decreased pulse duration, (3) increased bandwidth, and (4) constant inter‐pulse interval. The TF at 4 weeks old showed no significant difference from TF of adult pipistrelle (41.6 ± 2.0 kHz, P = 0.8). We recorded echolocation pulses of pups (31 days old) during their first flight in a flight chamber. The results show that (1) practice flights appeared to be unnecessary to modify IPI or duration with a distance and (2) the bats emitted paired pulses (strobe groups) in 2 days after the first flight. [Work supported by JSPS and ONR.]

FM echolocating bats shift frequencies to avoid broadcast-echo ambiguity in clutter.

Sonar broadcasts are followed by echoes at different delays from objects at different distances. When broadcasts are emitted rapidly in cluttered surroundings, echo streams from successive broadcasts overlap and cause ambiguity in matching echoes to corresponding broadcasts. To identify reactions to ambiguity in clutter, echolocating bats that emit multiple-harmonic FM sounds were trained to fly into a dense, extended array of obstacles (multiple rows of vertically hanging chains) while the sonar sounds the bat emitted were recorded with a miniature radio microphone carried by the bat. Flight paths were reconstructed from thermal-infrared video recordings. Successive rows of chains extended more than 6 m in depth, so each broadcast was followed by a series of echoes from multiple rows of chains that lasted up to 40 ms. Bats emitted sounds in pairs ("strobe groups") at short (20-40 ms) interpulse intervals (IPIs) alternating with longer IPIs (>50 ms). For many short IPIs, the stream of echoes from the first broadcast was still arriving when the second broadcast was emitted. This overlap caused ambiguity about matching echoes with broadcasts. Bats shifted frequencies of the first sound in each strobe group upward and the second sound downward by 3-6 kHz. When overlap and ambiguity ceased, frequency shifts ceased also. Frequency differences were small compared with the total broadcast band, which was 75-80 kHz wide, but the harmonic structure of echoes enhances the differences in spectrograms. Bats could use time-frequency comparisons of echoes with broadcasts to assign echoes to the corresponding broadcasts and thus avoid ambiguity.

FM echolocating bats avoid pulse‐echo ambiguity by shifting broadcast frequencies.

Big brown bats pursue flying insects in open areas, but they also hunt for prey near vegetation. The proximity of obstacles requires emission of sounds at short interpulse intervals (IPIs) to guide collision‐avoidance maneuvers, yet the bat has to locate obstacles distributed in depth for path planning, which requires longer IPIs. If IPIs are too short, the stream of echoes for one sound will still be arriving when the second sound is emitted, creating ambiguity about matching echoes to broadcasts. We investigated how bats cope with pulse‐echo ambiguity by recording sounds with a miniature radio microphone (Telemike) carried during flights through a dense array of obstacles (vertically hanging chains) that were distributed in depth. Array density forced bats to emit FM sounds at short intervals (strobe groups) with consequent pulse‐echo ambiguity. We found that when ambiguity occurred, bats shifted the FM sounds in strobe groups upward and downward in frequency by several kiloHertz to distinguish each bro...

Interpulse interval modulation by echolocating big brown bats (Eptesicus fuscus) in different densities of obstacle clutter

Big brown bats (Eptesicus fuscus) use biosonar to find insect prey in open areas, but they also find prey near vegetation and even fly through vegetation when in transit from roosts to feeding sites. To evaluate their reactions to dense, distributed clutter, bats were tested in an obstacle array consisting of rows of vertically hanging chains. Chains were removed from the array to create a curved corridor of three clutter densities (high, medium, low). Bats flew along this path to receive a food reward after landing on the far wall. Interpulse intervals (IPIs) varied across clutter densities to reflect different compromises between using short IPIs for gathering echoes rapidly enough to maneuver past the nearest chains and using longer IPIs so that all echoes from one sound can be received before the next sound is emitted. In high-clutter density, IPIs were uniformly shorter (20-65 ms) than in medium and low densities (40-100 ms) and arranged in "strobe groups," with some overlap of echo streams from different broadcasts, causing pulse-echo ambiguity. As previously proposed, alternating short and long IPIs in strobe groups may allow bats to focus on large-scale pathfinding tasks as well as close-in obstacle avoidance.

Echolocating bats control the directionality of sonar signals to sort out the auditory scene

A primary function of hearing is the localization and identification of sound sources in the auditory scene. Results from humans and other animals have shown that spectral and temporal features, as well as source direction, are important parameters used for organizing acoustic sources. Echolocating bats control the features of vocalizations to shape information carried by echoes from auditory objects. Our research on big brown bats, Eptesicus fuscus, suggests the importance of vocal control for scene analysis: When a bat performs a dual task, requiring both obstacle avoidance and prey capture, it solves the task sequentially, adapting the temporal pattern of its cries to produce sonar strobe groups, strobing first the obstacle and then the prey. Directional control over the sonar beam pattern confirms this sequential processing: The bat alternates fixation of the beam axis on the obstacle and prey. The importance of directionality is corroborated by studies in another bat, Trachops cirrhosus, where behavior and morphology optimize sonar directionality for different tasks. When hanging from a perch T. cirrhosus emits sounds for general orientation with limited demands for directionality. When hunting, prey localization necessitates high directionality associated with sound emission through the nostrils surrounded by the moveable nose leaf.

Active Listening for Spatial Orientation in a Complex Auditory Scene

To successfully negotiate a complex environment, an animal must control the timing of motor behaviors in coordination with dynamic sensory information. Here, we report on adaptive temporal control of vocal–motor behavior in an echolocating bat, Eptesicus fuscus, as it captured tethered insects close to background vegetation. Recordings of the bat's sonar vocalizations were synchronized with high-speed video images that were used to reconstruct the bat's three-dimensional flight path and the positions of target and vegetation. When the bat encountered the difficult task of taking insects as close as 10–20 cm from the vegetation, its behavior changed significantly from that under open room conditions. Its success rate decreased by about 50%, its time to initiate interception increased by a factor of ten, and its high repetition rate “terminal buzz” decreased in duration by a factor of three. Under all conditions, the bat produced prominent sonar “strobe groups,” clusters of echolocation pulses with stable intervals. In the final stages of insect capture, the bat produced strobe groups at a higher incidence when the insect was positioned near clutter. Strobe groups occurred at all phases of the wingbeat (and inferred respiration) cycle, challenging the hypothesis of strict synchronization between respiration and sound production in echolocating bats. The results of this study provide a clear demonstration of temporal vocal–motor control that directly impacts the signals used for perception.