Global collision-risk hotspots of marine traffic and the world's largest fish, the whale shark.

Marine traffic is increasing globally yet collisions with endangered megafauna such as whales, sea turtles, and planktivorous sharks go largely undetected or unreported. Collisions leading to mortality can have population-level consequences for endangered species. Hence, identifying simultaneous space use of megafauna and shipping throughout ranges may reveal as-yet-unknown spatial targets requiring conservation. However, global studies tracking megafauna and shipping occurrences are lacking. Here we combine satellite-tracked movements of the whale shark, Rhincodon typus, and vessel activity to show that 92% of sharks' horizontal space use and nearly 50% of vertical space use overlap with persistent large vessel (>300 gross tons) traffic. Collision-risk estimates correlated with reported whale shark mortality from ship strikes, indicating higher mortality in areas with greatest overlap. Hotspots of potential collision risk were evident in all major oceans, predominantly from overlap with cargo and tanker vessels, and were concentrated in gulf regions, where dense traffic co-occurred with seasonal shark movements. Nearly a third of whale shark hotspots overlapped with the highest collision-risk areas, with the last known locations of tracked sharks coinciding with busier shipping routes more often than expected. Depth-recording tags provided evidence for sinking, likely dead, whale sharks, suggesting substantial "cryptic" lethal ship strikes are possible, which could explain why whale shark population declines continue despite international protection and low fishing-induced mortality. Mitigation measures to reduce ship-strike risk should be considered to conserve this species and other ocean giants that are likely experiencing similar impacts from growing global vessel traffic.

Stepping in circles: how locomotor signals of rotation adapt over time.

KEY POINTS: While it has been well described that prolonged rotational stepping will adapt the podokinetic sense of rotation, the mechanisms involved are not clearly understood. By studying podokinetic after-rotations following conditioning rotations not previously reported we have shown that slower rotational velocities are more readily adapted than faster velocities and adaptation occurs more quickly than previously thought. We propose a dynamic feedback model of vestibular and podokinetic adaptation that can fit rotation trajectories across multiple conditions and data sets. Two adaptation processes were identified that may reflect central and peripheral processes and the discussion unifies prior findings in the podokinetic literature under this new framework. The findings show the technique is feasible for people with locomotor turning problems. ABSTRACT: After a prolonged period stepping in circles, people walk with a curved trajectory when attempting to walk in a straight line without vision. Podokinetic adaptation shows promise in clinical populations to improve locomotor turning; however, the adaptive mechanisms involved are poorly understood. The first phase of this study asks: how does the podokinetic conditioning velocity affect the response velocity and how quickly can adaptation occur? The second phase of the study asks: can a mathematical feedback model account for the rotation trajectories across different conditioning parameters and different datasets? Twelve healthy participants stepped in place on the axis of a rotating surface ranging from 4 to 20 deg s-1 for durations of 1-10 min, while using visual cues to maintain a constant heading direction. Afterward on solid ground, participants were blindfolded and attempted to step without rotating. Participants unknowingly stepped in circles opposite to the direction of the prior platform rotation for all conditions. The angular velocity of this response peaked within 1 min and the ratio of the stimulus-to-response peak velocity fitted a decreasing power function. The response then decayed exponentially. The feedback model of podokinetic and vestibular adaptive processes had a good fit with the data and suggested that podokinetic adaptation is explained by a short (141 s) and a long (27 min) time constant. The podokinetic system adapts more quickly than previously thought and subjects adapt more readily to slower rotation than to faster rotation. These findings will have implications for clinical applications of the technique.

Everyday memory: towards a translationally effective method of modelling the encoding, forgetting and enhancement of memory.

The testing of cognitive enhancers could benefit from the development of novel behavioural tasks that display better translational relevance for daily memory and permit the examination of potential targets in a within-subjects manner with less variability. We here outline an optimized spatial 'everyday memory' task. We calibrate it systematically by interrogating certain well-established determinants of memory and consider its potential for revealing novel features of encoding-related gene activation. Rats were trained in an event arena in which food was hidden in sandwells in a different location everyday. They found the food during an initial memory-encoding trial and were then required to remember the location in six alternative choice or probe trials at various time-points later. Training continued daily over a period of 4 months, realizing a stable high level of performance and characterized by delay-dependent forgetting over 24 h. Spaced but not massed access to multiple rewards enhanced the persistence of memory, as did post-encoding administration of the PDE4 inhibitor Rolipram. Quantitative PCR and then genome-wide analysis of gene expression led to a new observation - stronger gene-activation in hippocampus and retrosplenial cortex following spaced than massed training. In a subsidiary study, a separate group of animals replicated aspects of this training profile, going on to show enhanced memory when training was subject to post-encoding environmental novelty. Distinctive features of this protocol include its potential validity as a model of memory encoding used routinely by human subjects everyday, and the possibility of multiple within-subject comparisons to speed up assays of novel compounds.

Facial rejuvenation via the sequential combined use of multiple laser modalities: Safety and efficacy.

BACKGROUND AND OBJECTIVES: Multi-modal combination treatments for facial rejuvenation offer the potential to achieve superior results in a single treatment session. In this study, we evaluate the safety and efficacy of combining multiple laser modalities in a single treatment session. METHODS: Fifty patients underwent a multi-modal facial laser resurfacing procedure consisting of the sequential use of 595 nm pulsed dye laser, 755 nm alexandrite laser, superficial fractionated and fully ablative CO2 laser, superficial fully ablative erbium-YAG laser, and deep fractionated ablative CO2 laser in a single treatment session. Improvements in dyspigmentation, rhytides, telangiectasia, and skin texture were assessed. Patient satisfaction, healing times, and tolerability of procedure was also evaluated. RESULTS: Highly significant improvements in all clinical parameters were demonstrated at both short- and long-term follow-up evaluations. Patients reported a high satisfaction rate. CONCLUSION: Mega-combination treatment utilizing a variety of laser devices in a single treatment session is safe and highly effective at achieving facial rejuvenation. This approach represents an efficient use of both patient and physician time and resources. Lasers Surg. Med. 48:577-583, 2016. © 2016 Wiley Periodicals, Inc.

Delayed granulomatous reactions to facial cosmetic injections of polymethylmethacrylate microspheres and liquid injectable silicone: A case series.

Polymethylmethacrylate microsphere (PMMA) and liquid injectable silicone (LIS) fillers are non-biodegradable, synthetic polymers utilized for long-term soft-tissue augmentation. Delayed granulomatous reactions to permanent fillers are a rare yet significant event that can occur months to years post procedure and are often refractory to treatment and associated with significant cosmetic morbidity. We report a case series of 4 patients who developed granulomatous reactions to PMMA or LIS, 15 months to 5 years post injection. The etiology of granulomatous reactions to permanent fillers is still poorly understood, with foreign-body reactions and/or biofilms purported to play a role. Real-time biochemical analysis with polymerase chain reaction should be performed when the index of suspicion for the presence of a biofilm is high.

Comparative Results in Treatment of Keloids With Intralesional 5-FU/Kenalog, 5-FU/Verapamil, Enalapril Alone,Verapamil Alone, and Laser: A Case Report and Review of the Literature.

BACKGROUND: The pathogenesis of keloids involves a hyperproliferative state due to molecular abnormalities, cellular driving pathways, such as TGF, VEGF, and the inactivation of proapoptotic genes. We reviewed the literature and compared various treatment combina- tions in the treatment of keloids in a one patient observation. METHODS AND MATERIALS: Treatment modalities consisted of: intralesional 5- uorouracil (5-FU)/triamcinolone (TMC), 5-FU/verapamil, enal- april alone, verapamil alone, and fractional carbon dioxide laser. Size, height, and softness of the keloid, pain, itching, and pain were assessed. RESULTS: 5-FU based treatments proved to be more ef cacious than the other modalities. 5-FU + TMC demonstrated the largest reduc- tion in keloid height and rmness. The greatest degree of scar softening and average size reduction was achieved with 5-FU/ TMC (80% and 70% reduction, respectively), followed by 5-FU/verapamil (50% and 33% reduction, respectively). The same combinations led to the greatest reduction in scar height (70% and 33%, respectively). All treatments led to resolution of pain and itching in the keloid. CONCLUSION: The favorable effects of the 5-FU + verapamil combination are new and deserve further exploration. J Drugs Dermatol. 2016;15(11):1442-1447..

Passive motion reduces vestibular balance and perceptual responses.

With the hypothesis that vestibular sensitivity is regulated to deal with a range of environmental motion conditions, we explored the effects of passive whole-body motion on vestibular perceptual and balance responses. In 10 subjects, vestibular responses were measured before and after a period of imposed passive motion. Vestibulospinal balance reflexes during standing evoked by galvanic vestibular stimulation (GVS) were measured as shear reaction forces. Perceptual tests measured thresholds for detecting angular motion, perceptions of suprathreshold rotation and perceptions of GVS-evoked illusory rotation. The imposed conditioning motion was 10 min of stochastic yaw rotation (0.5-2.5 Hz ≤ 300 deg s(-2) ) with subjects seated. This conditioning markedly reduced reflexive and perceptual responses. The medium latency galvanic reflex (300-350 ms) was halved in amplitude (48%; P = 0.011) but the short latency response was unaffected. Thresholds for detecting imposed rotation more than doubled (248%; P < 0.001) and remained elevated after 30 min. Over-estimation of whole-body rotation (30-180 deg every 5 s) before conditioning was significantly reduced (41.1 to 21.5%; P = 0.033). Conditioning reduced illusory vestibular sensations of rotation evoked by GVS (mean 113 deg for 10 s at 1 mA) by 44% (P < 0.01) and the effect persisted for at least 1 h (24% reduction; P < 0.05). We conclude that a system of vestibular sensory autoregulation exists and that this probably involves central and peripheral mechanisms, possibly through vestibular efferent regulation. We propose that failure of these regulatory mechanisms at different levels could lead to disorders of movement perception and balance control during standing.

Ablative CO2 lasers for skin tightening: traditional versus fractional.

BACKGROUND: With patients more resistant to invasive treatments and those that result in significant downtime, there has been a rise in using lasers to improve skin laxity and induce tissue tightening as an alternative to surgery. Traditional and fractional ablative resurfacing induces skin tightening through precise dermal heating and a wound-healing effect. OBJECTIVE: The purpose of this review was to discuss the mechanism of action of using ablative lasers to induce skin tightening and compare traditional versus fractional technologies. MATERIALS AND METHODS: A review of the literature was performed. RESULTS: The authors discuss traditional and fractional ablative lasers for achieving skin tightening. CONCLUSION: Neocollagenesis and dermal remodeling seen after ablative resurfacing contributes to the clinical improvement seen in tissue tightening. Fractional photothermolysis may enhance tissue tightening effects of ablative lasers because of its ability to ablate deeper into the reticular dermis without significant risk for scarring.

Comparison of intense pulsed light with 1,927-nm fractionated thulium fiber laser for the rejuvenation of the chest.

BACKGROUND: Rejuvenation of the aging chest is important to prevent noticeable disparities between the treated skin of the face and that of the untreated chest. OBJECTIVE: To compare a high-density thulium fiber laser (TFL)-based protocol for the rejuvenation of the aging chest with intense pulsed light (IPL). METHODS AND MATERIALS: We conducted a retrospective chart review comparing patients treated with IPL and those treated with TFL in combination with a quality-switched alexandrite laser and long pulsed dye laser. Blinded photographic assessment of overall improvement, rhytides, skin texture, dyspigmentation, and telangiectasia was performed. Patient satisfaction was assessed in a standardized follow-up survey. Cost and practicality were compared. RESULTS: At a mean follow-up of 45.8 days for IPL and 78.3 days for TFL, the two protocols had comparable clinical efficacy in achieving rejuvenation of the chest. Differences existed in terms of cost and practicality. CONCLUSION: TFL can be used at high density and in simultaneous combination with other targeted laser modalities to achieve rejuvenation of the aging chest. IPL achieves similar clinical efficacy. The choice between treatment modalities depends on physician and patient preferences.

Personal electric deterrents can reduce shark bites from the three species responsible for the most fatal interactions.

The frequency of unprovoked shark bites is increasing worldwide, leading to a growing pressure for mitigation measures to reduce shark-bite risk while maintaining conservation objectives. Personal shark deterrents are a promising and non-lethal strategy that can protect ocean users, but few have been independently and scientifically tested. In Australia, bull (Carcharhinus leucas), tiger (Galeocerdo cuvier), and white sharks (Carcharodon carcharias) are responsible for the highest number of bites and fatalities. We tested the effects of two electric deterrents (Ocean Guardian's Freedom+ Surf and Freedom7) on the behaviour of these three species. The surf product reduced the probability of bites by 54% across all three species. The diving product had a similar effect on tiger shark bites (69% reduction) but did not reduce the frequency of bites from white sharks (1% increase), likely because the electrodes were placed further away from the bait. Electric deterrents also increased the time for bites to occur, and frequency of reactions and passes for all species tested. Our findings reveal that both Freedom+ Surf and Freedom7 electric deterrents affect shark behaviour and can reduce shark-bite risk for water users, but neither product eliminated the risk of shark bites entirely. The increasing number of studies showing the ability of personal electric deterrents to reduce shark-bite risk highlights personal protection as an effective and important part of the toolbox of shark-bite mitigation measures.

From little things big things grow: enhancement of an acoustic telemetry network to monitor broad-scale movements of marine species along Australia's east coast.

BACKGROUND: Acoustic telemetry has become a fundamental tool to monitor the movement of aquatic species. Advances in technology, in particular the development of batteries with lives of > 10 years, have increased our ability to track the long-term movement patterns of many species. However, logistics and financial constraints often dictate the locations and deployment duration of acoustic receivers. Consequently, there is often a compromise between optimal array design and affordability. Such constraints can hinder the ability to track marine animals over large spatial and temporal scales. Continental-scale receiver networks have increased the ability to study large-scale movements, but significant gaps in coverage often remain. METHODS: Since 2007, the Integrated Marine Observing System's Animal Tracking Facility (IMOS ATF) has maintained permanent receiver installations on the eastern Australian seaboard. In this study, we present the recent enhancement of the IMOS ATF acoustic tracking infrastructure in Queensland to collect data on large-scale movements of marine species in the northeast extent of the national array. Securing a relatively small initial investment for expanding receiver deployment and tagging activities in Queensland served as a catalyst, bringing together a diverse group of stakeholders (research institutes, universities, government departments, port corporations, industries, Indigenous ranger groups and tourism operators) to create an extensive collaborative network that could sustain the extended receiver coverage into the future. To fill gaps between existing installations and maximise the monitoring footprint, the new initiative has an atypical design, deploying many single receivers spread across 2,100 km of Queensland waters. RESULTS: The approach revealed previously unknown broad-scale movements for some species and highlights that clusters of receivers are not always required to enhance data collection. However, array designs using predominantly single receiver deployments are more vulnerable to data gaps when receivers are lost or fail, and therefore "redundancy" is a critical consideration when designing this type of array. CONCLUSION: Initial results suggest that our array enhancement, if sustained over many years, will uncover a range of previously unknown movements that will assist in addressing ecological, fisheries, and conservation questions for multiple species.

Identifying priority sites for whale shark ship collision management globally.

The expansion of the world's merchant fleet poses a great threat to the ocean's biodiversity. Collisions between ships and marine megafauna can have population-level consequences for vulnerable species. The Endangered whale shark (Rhincodon typus) shares a circumglobal distribution with this expanding fleet and tracking of movement pathways has shown that large vessel collisions pose a major threat to the species. However, it is not yet known whether they are also at risk within aggregation sites, where up to 400 individuals can gather to feed on seasonal bursts of planktonic productivity. These "constellation" sites are of significant ecological, socio-economic and cultural value. Here, through expert elicitation, we gathered information from most known constellation sites for this species across the world (>50 constellations and >13,000 individual whale sharks). We defined the spatial boundaries of these sites and their overlap with shipping traffic. Sites were then ranked based on relative levels of potential collision danger posed to whale sharks in the area. Our results showed that researchers and resource managers may underestimate the threat posed by large ship collisions due to a lack of direct evidence, such as injuries or witness accounts, which are available for other, sub-lethal threat categories. We found that constellations in the Arabian Sea and adjacent waters, the Gulf of Mexico, the Gulf of California, and Southeast and East Asia, had the greatest level of collision threat. We also identified 39 sites where peaks in shipping activity coincided with peak seasonal occurrences of whale sharks, sometimes across several months. Simulated collision mitigation options estimated potentially minimal impact to industry, as most whale shark core habitat areas were small. Given the threat posed by vessel collisions, a coordinated, multi-national approach to mitigation is needed within priority whale shark habitats to ensure collision protection for the species.

Blood pressure and the contractility of a human leg muscle.

These studies investigate the relationships between perfusion pressure, force output and pressor responses for the contracting human tibialis anterior muscle. Eight healthy adults were studied. Changing the height of tibialis anterior relative to the heart was used to control local perfusion pressure. Electrically stimulated tetanic force output was highly sensitive to physiological variations in perfusion pressure showing a proportionate change in force output of 6.5% per 10 mmHg. This perfusion-dependent change in contractility begins within seconds and is reversible with a 53 s time constant, demonstrating a steady-state equilibrium between contractility and perfusion pressure. These stimulated contractions did not produce significant cardiovascular responses, indicating that the muscle pressor response does not play a major role in cardiovascular regulation at these workloads. Voluntary contractions at forces that would require constant motor drive if perfusion pressure had remained constant generated a central pressor response when perfusion pressure was lowered. This is consistent with a larger cortical drive being required to compensate for the lost contractility with lower perfusion pressure. The relationship between contractility and perfusion for this large postural muscle was not different from that of a small hand muscle (adductor pollicis) and it responded similarly to passive peripheral and active central changes in arterial pressure, but extended over a wider operating range of pressures. If we consider that, in a goal-oriented motor task, muscle contractility determines central motor output and the central pressor response, these results indicate that muscle would fatigue twice as fast without a pressor response. From its extent, timing and reversibility we propose a testable hypothesis that this change in contractility arises through contraction- and perfusion-dependent changes in interstitial K(+) concentration.

Treatment of melasma with the 1,927-nm fractional thulium fiber laser: a retrospective analysis of 20 cases with long-term follow-up.

BACKGROUND: Melasma is a common acquired symmetrical hyperpigmentation that is often recurrent and refractory. OBJECTIVES: To investigate the efficacy and safety of a single administration of high-density fractional thulium fiber laser (1,927 nm) for the treatment of refractory melasma in 20 patients. MATERIALS AND METHODS: A retrospective chart and photographs review of 20 women (Fitzpatrick skin type II-IV) with clinical diagnosis of melasma treated with the 1,927-nm fractionated thulium laser at 10 or 20 mJ/cm(2) , with 60-70% surface area coverage. Four investigators independently evaluated Melasma Area Severity Index (MASI) scores before, 4 weeks, 3-6 months, and 6-12 months after treatment. RESULTS: Mean MASI scores decreased dramatically from 13.2 ± 5.4 before treatment to 8.5 ± 3.5 at 4 weeks after laser treatment (P = 0.004). Patient assessment revealed that 12 of the 20 subjects had more than 50% clearance of their melasma. Recurrence was reported by 7 out of 15 patients who were successfully followed-up (mean 10.2 months). Two patients developed postinflammatory hyperpigmentation that subsided with topical bleaching after 3 months. CONCLUSION: High-density coverage fractional 1,927-nm thulium laser proved to be safe and effective for melasma with long-term remission.

Exploring Compassion towards Laboratory Animals in UK- and China-Based Undergraduate Biomedical Sciences Students.

Taking a compassionate approach to the non-human animals used in biomedical research is in line with emerging ideas around a "culture of care". It is important to expose biomedical sciences students to the concept of a culture of care at an early stage and give them opportunities to explore related practices and ideas. However, there is no simple tool to explore biomedical sciences students' attitudes towards laboratory animals. Accordingly, there is little understanding of students' feelings towards these animals, or a means of quantifying potential changes to these feelings. We developed a 12-item questionnaire designed to explore compassion (the Laboratory Animal Compassion Scale; LACS) and used it with UK-based and China-based samples of undergraduate biomedical sciences students. In the same samples, we also explored a harm-benefit analysis task and students' beliefs regarding some mental characteristics of laboratory animals, then drew correlations with the quantitative measure of compassion. Compassion levels were stable across years of study and were not related to students' level of experience of working with laboratory animals. We observed a higher level of compassion in females versus males overall, and a higher level overall in the UK-based versus China-based sample. In a task pitting animal suffering against human wellbeing, students' compassion levels correlated negatively with their acceptance of animal suffering. Compassion levels correlated positively with a belief in animals being conscious and possessing emotions. These data are in line with studies that show compassion is gender- and nationality/culture-dependent, and points to links between compassion, beliefs, and choices.

Perception of the postural vertical and falls in older people.

BACKGROUND: Research on the relationship between vestibular function and falls in older people is sparse. The perception of the postural vertical (PPV) provides an indicator measure of vestibular (otolith) function in the absence of visual input and diminished somatosensory feedback. OBJECTIVE: This study examined whether impaired PPV is associated with falls in this group. METHODS: One hundred and ninety-five people aged 70 plus years stood blindfolded on a motorised platform that could be tilted in the roll plane and attempted to adjust it so that their bodies were aligned to the vertical. Somatosensory feedback was minimised as the base and vertical support surfaces on the tilting platform were covered in thick soft foam rubber. PPV error from true vertical and PPV variability (°) were calculated. Participants also underwent an assessment of distal tactile sensitivity and the physiological profile assessment (PPA); fallers were defined as those who had one or more falls during a prospective 12-month follow-up period. RESULTS: Eighty-eight participants (45%) reported falling in the follow-up year. Increased PPV error and variability were correlated with increased lateral sway in a condition of absent visual input and reduced foot somatosensory feedback (eyes closed/foam; r range = 0.16-0.20, p < 0.05) and with composite PPA fall risk scores (r range = 0.22-0.26, p < 0.05). PPV variability was a significant and independent predictor of falls after adjusting for the composite PPA scores, age and gender [adjusted RR = 1.42 (1.01-1.98)]. CONCLUSIONS: Older people with increased PPV variability are at increased risk of falls. These findings indicate that assessment of PPV may augment fall risk assessments in older people.

Repigmentation of hypopigmented scars using an erbium-doped 1,550-nm fractionated laser and topical bimatoprost.

BACKGROUND: Hypopigmented scarring is a challenging condition to treat, with current treatments showing limited efficacy and temporary results. Nonablative fractional resurfacing has been demonstrated to be an effective and safe modality in the treatment of hypopigmented scars. OBJECTIVES: To demonstrate the efficacy and safety of combining fractional resurfacing with topical bimatoprost and topical tretinoin or pimecrolimus for the treatment of hypopigmented scars. MATERIALS AND METHODS: Fourteen patients with hypopigmented scars were treated with a mean of 4.5 sessions of a fractionated 1,550-nm erbium-doped laser at 4- to 8-week intervals and subsequently started topical bimatoprost and tretinoin or pimecrolimus. An independent physician evaluated digital photographs taken before and 4 weeks after the last laser treatment using a quartile grading scale (grade 1, ≤25% improvement; grade 2, 26-50% improvement; grade 3, 51-75% improvement; grade 4, >75% improvement). RESULTS: Five patients had >75% improvement in hypopigmentation, and 12 had >50% improvement. After a mean follow-up of 20.1 months, all patients demonstrated prolonged results. Side effects were limited to transitory post-treatment edema and erythema. CONCLUSION: The combination of fractional resurfacing, topical bimatoprost, and tretinoin or pimecrolimus is a potential effective resource for the treatment of hypopigmented scars, with long-lasting results.

Laser treatment of scars.

Recent advances in optical technologies have produced laser systems capable of optimizing the appearance of scars from various etiologies. Laser treatment can commence as early as the time of the initial injury and as late as several years after the injury. Optimal results can now be attained with minimal down time. Herein, we review several available optical technologies for treatment of surgical, traumatic, and inflammatory scars, based upon our clinical experience.

Validation Through Collaboration: Encouraging Team Efforts to Ensure Internal and External Validity of Computational Models of Biochemical Pathways.

Computational modelling of biochemical reaction pathways is an increasingly important part of neuroscience research. In order to be useful, computational models need to be valid in two senses: First, they need to be consistent with experimental data and able to make testable predictions (external validity). Second, they need to be internally consistent and independently reproducible (internal validity). Here, we discuss both types of validity and provide a brief overview of tools and technologies used to ensure they are met. We also suggest the introduction of new collaborative technologies to ensure model validity: an incentivised experimental database for external validity and reproducibility audits for internal validity. Both rely on FAIR principles and on collaborative science practices.

The sense of self-motion, orientation and balance explored by vestibular stimulation.

The sense of orientation during locomotion is derived from our spatial relationship with the external environment, sensed predominantly by sight and sound, and from internal signals of motion, generated by the vestibular sense and the pattern of efferent and afferent signals to the muscles and joints. The sensory channels operate in different reference frames and have different time-dependent adaptive properties and yet the inputs are combined by the central nervous system to create an internal representation of self-motion. In normal circumstances vestibular, visual and proprioceptive cues provide congruent information on locomotor trajectory; however, in cases of sensory discord there must be a recalibration of sensory signals to provide a unitary representation. We develop a means of studying these fusion processes by perturbing each channel in isolation about a consistent behavioural axis. This review focuses on creating the vestibular perturbation of the orientation sense by transmastoidal galvanic stimulation, a technique generally used to evoke balance reflexes. Vector summation across the population of semicircular canal afferents creates a net signal that is interpreted by the brain as a vector of angular acceleration in a craniocentric reference frame. The signal feeds perceptual processes of orientation after transformation that resolves the 3-D signal onto the terrestrial or behavioural plane. Changing head posture changes the interpretation of the galvanic vestibular signal for balance and orientation responses. With appropriate head alignments during locomotion, the galvanic stimulus can be used to either steer trajectory over the terrestrial plane or perturb balance.