Drinking on the wing: water collection in polarotactic horseflies.

Many insects detect water bodies by observing the linearly polarised light which is reflected from the water surface. Polarotactic horseflies exhibit acrobatic manoeuvres above the water and are able to plunge on its surface, collect a droplet and fly away. This behaviour is extremely fast and has not yet been analysed. We recorded the flight patterns and kinematics of drinking horseflies using a pair of high-speed cameras. The animals of both sexes are attracted to water puddles where they make short, millisecond pitstops to collect a droplet of water that is then presumably drank "on the wing". Before the collection, the flies perform several low-altitude flybys above the puddle. After a few passes, the fly suddenly reverses its body orientation, decelerates, briefly touches the water surface and immediately flies away, usually with a droplet carried between its front legs. During the approach flight, the horseflies fly low but do not show any angular preference. Thus, they view the reflections from the sky, sun, or vegetation with a wide band of ventral ommatidia. Polarotaxis in drinking horseflies is a very robust visually guided behaviour, which operates at a broad range of intensities and various spectral compositions of reflected light.

Moderate mass loss enhances flight performance via alteration of flight kinematics and postures in a passerine bird.

Many birds experience fluctuations in body mass throughout the annual life cycle. The flight efficiency hypothesis posits that adaptive mass loss can enhance avian flight ability. However, whether birds can increase additional wing loading following mass loss and how birds adjust flight kinematics and postures remain largely unexplored. We investigated physiological changes in body condition in breeding female Eurasian tree sparrows (Passer montanus) through a dietary restriction experiment and determined the changes in flight kinematics and postures. Body mass decreased significantly, but the external maximum load and mass-corrected total load increased significantly after 3 days of dietary restriction. After 6 days of dietary restriction (DR6), hematocrit, pectoralis and hepatic fat content, take-off speed, theoretical maximum range speed and maximum power speed declined significantly. Notably, the load capacity and power margin remained unchanged relative to the control group. The wing stroke amplitude and relative downstroke duration were not affected by the interaction between diet restriction and extra load. Wing stroke amplitude significantly increased after DR6 treatment, while the relative downstroke duration significantly decreased. The stroke plane angle significantly increased after DR6 treatment only in the load-free condition. In addition, the sparrows adjusted their body angle and stroke plane angle in response to the extra load, but stroke amplitude and wingbeat frequency remained unchanged. Therefore, birds can maintain and even enhance their flight performance by adjusting flight kinematics and postures after a short-term mass loss.

Fin and body neuromuscular coordination changes during walking and swimming in Polypterus senegalus.

The ability to modulate the function of muscle is integral to an animal's ability to function effectively in the face of widely disparate challenges. This modulation of function can manifest through short-term changes in neuromuscular control, but also through long-term changes in force profiles, fatiguability and architecture. However, the relative extent to which shorter-term modulation and longer-term plasticity govern locomotor flexibility remains unclear. Here, we obtain simultaneously recorded kinematic and muscle activity data of fin and body musculature of an amphibious fish, Polypterus senegalus After examining swimming and walking behaviour in aquatically raised individuals, we show that walking behaviour is characterized by greater absolute duration of muscle activity in most muscles when compared with swimming, but that the magnitude of recruitment during walking is only increased in the secondary bursts of fin muscle and in the primary burst of the mid-body point. This localized increase in intensity suggests that walking in P. senegalus is powered in a few key locations on the fish, contrasting with the more distributed, low intensity muscle force that characterizes the stroke cycle during swimming. Finally, the increased intensity in secondary, but not primary, bursts of the fin muscles when walking probably underscores the importance of antagonistic muscle activity to prevent fin collapse, add stabilization and increase body support. Understanding the principles that underlie the flexibility of muscle function can provide key insights into the sources of animal functional and behavioural diversity.

Flight and seizure motor patterns in Drosophila mutants: simultaneous acoustic and electrophysiological recordings of wing beats and flight muscle activity.

Abstract Tethered flies allow studies of biomechanics and electrophysiology of flight control. We performed microelectrode recordings of spikes in an indirect flight muscle (the dorsal longitudinal muscle, DLMa) coupled with acoustic analysis of wing beat frequency (WBF) via microphone signals. Simultaneous electrophysiological recording of direct and indirect flight muscles has been technically challenging; however, the WBF is thought to reflect in a one-to-one relationship with spiking activity in a subset of direct flight muscles, including muscle m1b. Therefore, our approach enables systematic mutational analysis for changes in temporal features of electrical activity of motor neurons innervating subsets of direct and indirect flight muscles. Here, we report the consequences of specific ion channel disruptions on the spiking activity of myogenic DLMs (firing at ∼5 Hz) and the corresponding WBF (∼200 Hz). We examined mutants of the genes enconding: 1) voltage-gated Ca(2+) channels (cacophony, cac), 2) Ca(2+)-activated K(+) channels (slowpoke, slo), and 3) voltage-gated K(+) channels (Shaker, Sh) and their auxiliary subunits (Hyperkinetic, Hk and quiver, qvr). We found flight initiation in response to an air puff was severely disrupted in both cac and slo mutants. However, once initiated, slo flight was largely unaltered, whereas cac displayed disrupted DLM firing rates and WBF. Sh, Hk, and qvr mutants were able to maintain normal DLM firing rates, despite increased WBF. Notably, defects in the auxiliary subunits encoded by Hk and qvr could lead to distinct consequences, that is, disrupted DLM firing rhythmicity, not observed in Sh. Our mutant analysis of direct and indirect flight muscle activities indicates that the two motor activity patterns may be independently modified by specific ion channel mutations, and that this approach can be extended to other dipteran species and additional motor programs, such as electroconvulsive stimulation-induced seizures.

Measuring Mouse Somatosensory Reflexive Behaviors with High-speed Videography, Statistical Modeling, and Machine Learning.

Objectively measuring and interpreting an animal's sensory experience remains a challenging task. This is particularly true when using preclinical rodent models to study pain mechanisms and screen for potential new pain treatment reagents. How to determine their pain states in a precise and unbiased manner is a hurdle that the field will need to overcome. Here, we describe our efforts to measure mouse somatosensory reflexive behaviors with greatly improved precision by high-speed video imaging. We describe how coupling sub-second ethograms of reflexive behaviors with a statistical reduction method and supervised machine learning can be used to create a more objective quantitative mouse "pain scale." Our goal is to provide the readers with a protocol of how to integrate some of the new tools described here with currently used mechanical somatosensory assays, while discussing the advantages and limitations of this new approach.

Breaking the technical barrier of microvascular anastomosis with high-speed videography: A prospective cohort study.

BACKGROUND: Microsurgical anastomosis is technically difficult especially for less-experienced surgeons. Traditionally, surgeons in training could only accomplish these surgeries under intensive guiding and supervision from senior surgeons. This study presents and characterises a new method for microsurgical trainees to objectively evaluating the quality of vascular anastomosis intraoperatively. MATERIALS AND METHODS: We conducted a prospective study to determine the utility of patency test of vascular anastomosis with assistance of high-speed video recording (PTHVR) to evaluate the quality of vascular anastomosis during microsurgery. To determine whether the use of PTHVR outperformed traditional supervision from senior surgeons (historical control), we compared the outcomes of microsurgeries including free flap transfer and replantation between the two groups. RESULTS: A total of 211 patients were enrolled, of which 98 underwent surgery under traditional supervision and 113 underwent surgery with PTHVR. Of the 211 patients, 102 underwent digit replantation (48%), 22 underwent limb replantation (10%), and 87 underwent free flap transfer (42%). There was no statistical difference between the two groups in age, gender, BMI, pre-existing comorbidities, smoking status, alcohol consumption, and duration of surgery. Use of PTHVR as an intraoperative guide significantly decreased the rate of re-exploration surgeries (PTHVR, 8.0% [9/113]; control, 23.5% [23/98]; P = 0.002) and replantation/free flap failures (PTHVR, 8.8% [10/113]; control, 19.4% [19/98]; P = 0.029) compared with historical control under traditional supervision. CONCLUSIONS: PTHVR is a useful tool for improving the success rate of microsurgery for less-experienced surgeons when compared with traditional supervision mode.

Prey Capturing Dynamics and Nanomechanically Graded Cutting Apparatus of Dragonfly Nymph.

Aquatic predatory insects, like the nymphs of a dragonfly, use rapid movements to catch their prey and it presents challenges in terms of movements due to drag forces. Dragonfly nymphs are known to be voracious predators with structures and movements that are yet to be fully understood. Thus, we examine two main mouthparts of the dragonfly nymph (Libellulidae: Insecta: Odonata) that are used in prey capturing and cutting the prey. To observe and analyze the preying mechanism under water, we used high-speed photography and, electron microscopy. The morphological details suggest that the prey-capturing labium is a complex grasping mechanism with additional sensory organs that serve some functionality. The time taken for the protraction and retraction of labium during prey capture was estimated to be 187 ± 54 ms, suggesting that these nymphs have a rapid prey mechanism. The Young's modulus and hardness of the mandibles were estimated to be 9.1 ± 1.9 GPa and 0.85 ± 0.13 GPa, respectively. Such mechanical properties of the mandibles make them hard tools that can cut into the exoskeleton of the prey and also resistant to wear. Thus, studying such mechanisms with their sensory capabilities provides a unique opportunity to design and develop bioinspired underwater deployable mechanisms.

Step by step and frame by frame - Workflow for efficient motion tracking of high-speed movements in animals.

Analysing the motion of animals, especially at high speeds, is often challenging. Motion tracking software needs to deal with a variety of visual contexts, variable lighting conditions, heterogeneous backgrounds and even background movements. Here we present motion tracking via the easy to use and constantly updated Adobe After Effects software - which is often included in software packages most researchers are already using. The provided custom-made Javascript allows for easy exporting of tracking coordinates. Furthermore, some examples for analysing the obtained data in the open source statistical software 'R' will provide reference points, even for an unexperienced user. We present a step-by-step guide of the methodology using high-speed video recordings of locust jumps and additionally validate this method by successful tracking of simulated data under defined subpar filming conditions. This simulated data allows experienced users to compare the tracking software in use with the here presented workflow to weigh the advantages and disadvantages of any motion tracking software on the market.

A machine-vision approach for automated pain measurement at millisecond timescales.

Objective and automatic measurement of pain in mice remains a barrier for discovery in neuroscience. Here, we capture paw kinematics during pain behavior in mice with high-speed videography and automated paw tracking with machine and deep learning approaches. Our statistical software platform, PAWS (Pain Assessment at Withdrawal Speeds), uses a univariate projection of paw position over time to automatically quantify seven behavioral features that are combined into a single, univariate pain score. Automated paw tracking combined with PAWS reveals a behaviorally divergent mouse strain that displays hypersensitivity to mechanical stimuli. To demonstrate the efficacy of PAWS for detecting spinally versus centrally mediated behavioral responses, we chemogenetically activated nociceptive neurons in the amygdala, which further separated the pain-related behavioral features and the resulting pain score. Taken together, this automated pain quantification approach will increase objectivity in collecting rigorous behavioral data, and it is compatible with other neural circuit dissection tools for determining the mouse pain state.

Neurophysiology of spontaneous facial expressions: II. Motor control of the right and left face is partially independent in adults.

Facial expressions are described traditionally as monolithic or unitary entities. However, humans have the capacity to produce facial blends of emotion in which the upper and lower face simultaneously display different expressions. Recent neuroanatomical studies in monkeys have demonstrated that there are separate cortical motor areas for controlling the upper and lower face in each hemisphere that, presumably, also occur in humans. Using high-speed videography, we began measuring the movement dynamics of spontaneous facial expressions, including facial blends, to develop a more complete understanding of the neurophysiology underlying facial expressions. In our part 1 publication in Cortex (2016), we found that hemispheric motor control of the upper and lower face is overwhelmingly independent; 242 (99%) of the expressions were classified as demonstrating independent hemispheric motor control whereas only 3 (1%) were classified as demonstrating dependent hemispheric motor control. In this companion paper (part 2), 251 unitary facial expressions that occurred on either the upper or lower face were analyzed. 164 (65%) expressions demonstrated dependent hemispheric motor control whereas 87 (35%) expressions demonstrated independent or dual hemispheric motor control, indicating that some expressions represent facial blends of emotion that occur across the vertical facial axis. These findings also support the concepts that 1) spontaneous facial expressions are organized predominantly across the horizontal facial axis and secondarily across the vertical facial axis and 2) facial expressions are complex, multi-component, motoric events. Based on the Emotion-type hypothesis of cerebral lateralization, we propose that facial expressions modulated by a primary-emotional response to an environmental event are initiated by the right hemisphere on the left side of the face whereas facial expressions modulated by a social-emotional response to an environmental event are initiated by the left hemisphere on the right side of the face.

Fungal artillery of zombie flies: infectious spore dispersal using a soft water cannon.

Dead sporulating female fly cadavers infected by the house fly-pathogenic fungus Entomophthora muscae are attractive to healthy male flies, which by their physical inspection may mechanically trigger spore release and by their movement create whirlwind airflows that covers them in infectious conidia. The fungal artillery of E. muscae protrudes outward from the fly cadaver, and consists of a plethora of micrometric stalks that each uses a liquid-based turgor pressure build-up to eject a jet of protoplasm and the initially attached spore. The biophysical processes that regulate the release and range of spores, however, are unknown. To study the physics of ejection, we design a biomimetic 'soft cannon' that consists of a millimetric elastomeric barrel filled with fluid and plugged with a projectile. We precisely control the maximum pressure leading up to the ejection, and study the cannon efficiency as a function of its geometry and wall elasticity. In particular, we predict that ejection velocity decreases with spore size. The calculated flight trajectories under aerodynamic drag predict that the minimum spore size required to traverse a quiescent layer of a few millimetres around the fly cadaver is approximately 10 µm. This corroborates with the natural size of E. muscae conidia (approx. 27 µm) being large enough to traverse the boundary layer but small enough (less than 40 µm) to be lifted by air currents. Based on this understanding, we show how the fungal spores are able to reach a new host.

Ultra-high-speed videography of resin-dentin interface failure dynamics under tensile load.

OBJECTIVES: Ultra-high-speed (UHS) videography was used to visualize the fracture phenomena at the resin-dentin interface during micro-tensile bond strength (µTBS) test. We also investigated whether UHS videography is applicable for failure-mode analysis. METHODS: Ten human mid-coronal dentin surfaces were bonded using Clearfil SE Bond either in self-etching (SE) or etch-and-rinse (ER) mode. After 24-h water storage, the samples were cut into beams for µTBS test and tested at a cross-head speed of 1 mm/min. The fracture phenomena at the bonded interface were captured using a complementary metal-oxide-semiconductor digital UHS camera at 299,166 frames per second. The failure modes were classified using UHS videography, followed by scanning electron microscopy (SEM) analysis. The failure-mode distributions determined by UHS videography and SEM analysis were statistically analyzed using Fisher's exact test with Bonferroni correction. RESULTS: The crack-propagation speed exceeded 1,500 km/h. No significant difference was found between the SEM and UHS videography failure-mode distributions in the SE mode. A significant difference appeared between them in the ER mode. Significant differences in the incidence of cohesive failures within the adhesive and at the adhesive-composite interface between the SE and ER modes were identified by both SEM and UHS videography. SIGNIFICANCE: UHS videography enabled visualization of the fracture dynamics at the resin- dentin interfaces under tensile load. However, the resolution at such high frame rate was insufficient to classify the failure mode as precisely as that of SEM. Nevertheless, UHS videography can provide more detailed information about the fracture origin and propagation.

Identification of a novel spinal nociceptive-motor gate control for Aδ pain stimuli in rats.

Physiological responses to nociceptive stimuli are initiated within tens of milliseconds, but the corresponding sub-second behavioral responses have not been adequately explored in awake, unrestrained animals. A detailed understanding of these responses is crucial for progress in pain neurobiology. Here, high-speed videography during nociceptive Aδ fiber stimulation demonstrated engagement of a multi-segmental motor program coincident with, or even preceding, withdrawal of the stimulated paw. The motor program included early head orientation and adjustments of the torso and un-stimulated paws. Moreover, we observed a remarkably potent gating mechanism when the animal was standing on its hindlimbs and which was partially dependent on the endogenous opioid system. These data reveal a profound, immediate and precise integration of nociceptive inputs with ongoing motor activities leading to the initiation of complex, yet behaviorally appropriate, response patterns and the mobilization of a new type of analgesic mechanism within this early temporal nociceptive window.

Neurophysiology of spontaneous facial expressions: I. Motor control of the upper and lower face is behaviorally independent in adults.

Facial expressions are described traditionally as monolithic entities. However, humans have the capacity to produce facial blends, in which the upper and lower face simultaneously display different emotional expressions. This, in turn, has led to the Component Theory of facial expressions. Recent neuroanatomical studies in monkeys have demonstrated that there are separate cortical motor areas for controlling the upper and lower face that, presumably, also occur in humans. The lower face is represented on the posterior ventrolateral surface of the frontal lobes in the primary motor and premotor cortices and the upper face is represented on the medial surface of the posterior frontal lobes in the supplementary motor and anterior cingulate cortices. Our laboratory has been engaged in a series of studies exploring the perception and production of facial blends. Using high-speed videography, we began measuring the temporal aspects of facial expressions to develop a more complete understanding of the neurophysiology underlying facial expressions and facial blends. The goal of the research presented here was to determine if spontaneous facial expressions in adults are predominantly monolithic or exhibit independent motor control of the upper and lower face. We found that spontaneous facial expressions are very complex and that the motor control of the upper and lower face is overwhelmingly independent, thus robustly supporting the Component Theory of facial expressions. Seemingly monolithic expressions, be they full facial or facial blends, are most likely the result of a timing coincident rather than a synchronous coordination between the ventrolateral and medial cortical motor areas responsible for controlling the lower and upper face, respectively. In addition, we found evidence that the right and left face may also exhibit independent motor control, thus supporting the concept that spontaneous facial expressions are organized predominantly across the horizontal facial axis and secondarily across the vertical axis.