Motor Programs Research Articles

Enriched music-supported therapy for individuals with chronic stroke: a randomized controlled trial.

Many stroke survivors still present with upper-limb paresis six months post-stroke, impacting their autonomy and quality of life (QoL). We designed an enriched Music-supported Therapy (eMST) program to reduce disability in this population. We evaluated the eMST's effectiveness in improving functional abilities and QoL in chronic stroke individuals compared to the conventional motor program Graded Repetitive Arm Supplementary Program (GRASP). We conducted a pragmatic two-arm parallel-group randomized controlled trial with a 3-month follow-up and masked assessment. The eMST involved playing instruments during individual self-administered and group music therapy sessions. The GRASP consisted of self-administered motor exercises using daily objects. Both interventions were completed at home with telemonitoring and involved four one-hour weekly sessions for 10weeks. The primary outcome was upper-limb motor function measured with the Action Research Arm Test. Secondary outcomes included motor impairment, daily life motor performance, cognitive functions, emotional well-being, QoL, self-regulation, and self-efficacy. Intention-to-treat (ITT)and per-protocol(PP) analyses were conducted including participants who discontinued the intervention and those who completed it entirely, respectively. Fifty-eight chronic stroke patients were randomized to the eMST-group (n = 26; age: 64.2 ± 12.5; 6[23.1%] females; 2.8 ± 2.9years post-stroke), and the control group (n = 32; age: 62.2 ± 12; 8[25%] females; 1.8 ± 6.2years post-stroke). The eMST-group had more participants achieving a clinically relevant improvement in motor impairment post-intervention than the control group for the ITT (55% vs 21.6%; OR = 4.5 (95% CI 1.4-14); p = .019) and PP analyses (60% vs 20%; OR = 6 (95% CI 1.5-24.7); p = .024), sustained at follow-up. The eMST-group reported greater improvements in emotion (difference = 11.1 (95% CI 0.8-21.5; p = 0.36) and participation (difference = 10.3 (95% CI 0.6-25.9); p = 0.41) subscales of QoL, and higher enjoyment during the sessions (difference = 1 (95% CI 0.3-1.5); p = 0.12). No changes were found in other outcomes. eMST demonstrated superiority over conventional motor rehabilitation program in enhancing upper-limb functions and QoL in chronic stroke individuals. ClinicalTrials.gov (ID: NCT04507542).

Motor and Respiratory Tele-Rehabilitation in Patients with Long COVID-19 after Hospital Discharge: An Interventional Study.

The persistence of symptoms following COVID-19 infection represents a significant challenge in healthcare management. During the outbreak, tele-rehabilitation emerged as a new tool to support healthcare structures in providing rehabilitation services. This study assessed the effectiveness and the feasibility of a 3-week home-based motor and respiratory rehabilitation program for individuals with long COVID-19 after traditional rehabilitation. Twenty-three patients completed the program and underwent functional tests at different time points (i.e., baseline, at discharge from in-hospital rehabilitation and after tele-rehabilitation). Motor function was evaluated using the instrumented Six-Minutes Walking Test (i6MWT), with monitored heart rate and oxygen saturation. Additionally, respiratory function was measured via forced vital capacity (FVC) and maximal voluntary ventilation (MVV) tests. Significant improvements (p < 0.05) in motor and respiratory function were observed throughout the intervention, including an 18.3% increase in walked distance from the baseline. The findings suggest that the proposed home-based tele-rehabilitation shows potential in enhancing motor and respiratory function in patients with long COVID. Despite limitations such as the small sample size, lack of control group and the preliminary nature of the outcomes observed, the overall findings seem to support the feasibility of the proposed tele-rehabilitation program in managing long COVID symptoms and promoting functional recovery. Nevertheless, further research is needed to validate these findings and explore tele-rehabilitation's potential in broader and different patient populations.

Proprioceptive Training Study for the Optimization of the 110 M. Hurdles Technique

Proprioceptive training represents a contemporary dimension in athletic preparation, yielding significant performance enhancements for athletes around the globe. Our study aims to quantify the technical performance of the hurdle step via biomechanical analysis. This involves measuring kinematic parameters and their association with the enhancement of coordination abilities, derived from tailored proprioceptive training. By analyzing kinematic parameters and implementing a specialized motor program, we can enhance coordination abilities and rectify technical mistakes. This leads to improved grouping of the lower limbs, quicker transitions, as well as more stable and effective landings. Such improvements optimize the movement path of the body’s center of gravity towards the hurdle plane and ensure optimal spatial-temporal alignment for subsequent strides between hurdles.

Concurrent optogenetic motor mapping of multiple limbs in awake mice reveals cortical organization of coordinated movements.

Motor mapping allows for determining the macroscopic organization of motor circuits and corresponding motor movement representations on the cortex. Techniques such as intracortical microstimulation (ICMS) are robust, but can be time consuming and invasive, making them non-ideal for cortex-wide mapping or longitudinal studies. In contrast, optogenetic motor mapping offers a rapid and minimally invasive technique, enabling mapping with high spatiotemporal resolution. However, motor mapping has seen limited use in tracking 3-dimensonal, multi-limb movements in awake animals. This gap has left open questions regarding the underlying organizational principles of motor control of coordinated, ethologically relevant movements involving multiple limbs. Our first objective was to develop Multi-limb Optogenetic Motor Mapping (MOMM) to concurrently map motor movement representations of multiple limbs with high fidelity in awake mice. Having established MOMM, our next objective was determine whether maps of coordinated and ethologically relevant motor output were topographically organized on the cortex. We combine optogenetic stimulation with a deep learning driven pose-estimation toolbox, DeepLabCut (DLC), and 3-dimentional triangulation to concurrently map motor movements of multiple limbs in awake mice. MOMM consistently revealed cortical topographies for all mapped features within and across mice. Many motor maps overlapped and were topographically similar. Several motor movement representations extended beyond cytoarchitecturally defined somatomotor cortex. Finer articulations of the forepaw resided within gross motor movement representations of the forelimb. Moreover, many cortical sites exhibited concurrent limb coactivation when photostimulated, prompting the identification of several cortical regions harboring coordinated and ethologically relevant movements. The cortex appears to be topographically organized by motor programs, which are responsible for coordinated, multi-limbed, and behavioral-like movements.

Behavioral events and functional analysis of bursicon signal during adult eclosion in the 28-spotted larger potato ladybird

To accommodate growth, insects must periodically shed their exoskeletons. In Manduca sexta, Drosophila melanogaster and Tribolium castaneum, Bursicon (Burs)/ Partner of bursicon (Pburs)-LGR2 signal is an indispensable component for the proper execution of ecdysis behavior during adult eclosion. Nevertheless, the behavioral events and the roles of bursicon signaling in other insects deserve further exploration. In the current paper, we found that the pupal-adult ecdysis in Henosepilachna vigintioctomaculata could be divided into three distinct stages, preecdysis, ecdysis and postecdysis. Preecdysis behavioral sequences included abdomen twitches, dorsal-ventral contractions and air filling that function to loosen the old cuticle. Ecdysis events began with anterior-posterior contractions that gradually split the old integument along the dorsal body midline, followed by freeing of legs and mouthparts, and culminated in detachment from pupal cuticle. Postecdysis behavioral processes contained three actions: perch selection and stretching of elytra and hindwings. RNA interference for HvBurs, HvPburs or Hvrk (encoding LGR2) strongly impaired wing expansion actions, and slightly influenced preecdysis and ecdysis behaviors. The RNAi beetles failed to extend their elytra and hindwings. In addition, injected with dsrk also caused kinked femurs and tibia. Our findings establish that bursicon pathway is involved in regulation of adult eclosion behavior, especially wing expansion motor programs. Given that wings facilitate food foraging, courtship, predator avoidance, dispersal and migration, our results provide a potential target for controlling H. vigintioctomaculata.

Learning to imitate facial expressions through sound

The question of how young infants learn to imitate others’ facial expressions has been central in developmental psychology for decades. Facial imitation has been argued to constitute a particularly challenging learning task for infants because facial expressions are perceptually opaque: infants cannot see changes in their own facial configuration when they execute a motor program, so how do they learn to match these gestures with those of their interacting partners? Here we argue that this apparent paradox mainly appears if one focuses only on the visual modality, as most existing work in this field has done so far. When considering other modalities, in particular the auditory modality, many facial expressions are not actually perceptually opaque. In fact, every orolabial expression that is accompanied by vocalisations has specific acoustic consequences, which means that it is relatively transparent in the auditory modality. Here, we describe how this relative perceptual transparency can allow infants to accrue experience relevant for orolabial, facial imitation every time they vocalise. We then detail two specific mechanisms that could support facial imitation learning through the auditory modality. First, we review evidence showing that experiencing correlated proprioceptive and auditory feedback when they vocalise – even when they are alone – enables infants to build audio-motor maps that could later support facial imitation of orolabial actions. Second, we show how these maps could also be used by infants to support imitation even for silent, orolabial facial expressions at a later stage. By considering non-visual perceptual domains, this paper expands our understanding of the ontogeny of facial imitation and offers new directions for future investigations.

STEERING FROM THE REAR: COORDINATION OF CENTRAL PATTERN GENERATORS UNDERLYING NAVIGATION BY ASCENDING INTERNEURONS.

Understanding how animals coordinate movements to achieve goals is a fundamental pursuit in neuroscience. Here we explore how neurons that reside in posterior lower-order regions of a locomotor system project to anterior higher-order regions to influence steering and navigation. We characterized the anatomy and functional role of a population of ascending interneurons in the ventral nerve cord of Drosophila larvae. Through electron microscopy reconstructions and light microscopy, we determined that the cholinergic 19f cells receive input primarily from premotor interneurons and synapse upon a diverse array of postsynaptic targets within the anterior segments including other 19f cells. Calcium imaging of 19f activity in isolated central nervous system (CNS) preparations in relation to motor neurons revealed that 19f neurons are recruited into most larval motor programmes. 19f activity lags behind motor neuron activity and as a population, the cells encode spatio-temporal patterns of locomotor activity in the larval CNS. Optogenetic manipulations of 19f cell activity in isolated CNS preparations revealed that they coordinate the activity of central pattern generators underlying exploratory headsweeps and forward locomotion in a context and location specific manner. In behaving animals, activating 19f cells suppressed exploratory headsweeps and slowed forward locomotion, while inhibition of 19f activity potentiated headsweeps, slowing forward movement. Inhibiting activity in 19f cells ultimately affected the ability of larvae to remain in the vicinity of an odor source during an olfactory navigation task. Overall, our findings provide insights into how ascending interneurons monitor motor activity and shape interactions amongst rhythm generators underlying complex navigational tasks.

A leak K+ channel TWK-40 sustains the rhythmic motor program.

Leak potassium (K+) currents, conducted by two-pore domain K+ (K2P) channels, are critical for the stabilization of the membrane potential. The effect of K2P channels on motor rhythm remains enigmatic. We show here that the K2P TWK-40 contributes to the rhythmic defecation motor program (DMP) in Caenorhabditis elegans. Disrupting TWK-40 suppresses the expulsion defects of nlp-40 and aex-2 mutants. By contrast, a gain-of-function (gf) mutant of twk-40 significantly reduces the expulsion frequency per DMP cycle. In situ whole-cell patch clamping demonstrates that TWK-40 forms an outward current that hyperpolarize the resting membrane potential of dorsorectal ganglion ventral process B (DVB), an excitatory GABAergic motor neuron that activates expulsion muscle contraction. In addition, TWK-40 substantially contributes to the rhythmic activity of DVB. Specifically, DVB Ca2+ oscillations exhibit obvious defects in loss-of-function (lf) mutant of twk-40. Expression of TWK-40(gf) in DVB recapitulates the expulsion deficiency of the twk-40(gf) mutant, and inhibits DVB Ca2+ oscillations in both wild-type and twk-40(lf) animals. Moreover, DVB innervated enteric muscles also exhibit rhythmic Ca2+ defects in twk-40 mutants. In summary, these findings establish TWK-40 as a crucial neuronal stabilizer of DMP, linking leak K2P channels with rhythmic motor activity.

Effects of Single-Session Practice Structure on Motor Skill Acquisition and Alpha and Beta EEG Oscillations

Background: Although it is known that practicing a motor skill updates the associated internal model, it is still unclear as to how cortical oscillations linked with the motor skill change under differing practice schedules. The current study investigated α- and β-power changes associated with motor skill acquisition. Objectives: Firstly, we investigated the behavioral effects of practice on motor learning and retention during repetitive (RP) and variable (VP) practice schedules on an anticipation timing task. Secondly, we investigated changes in cortical α (10 - 13 Hz) and β (15 - 30 Hz) event-related synchronization and desynchronization (ERS/ERD) under RP and VP during early (EP) and late (LP) stages of practice. Methods: To investigate the behavioral effects of practice on learning and retention, participants were pretested, post-tested at 5 min (retention), and tested twice at 30 min (one for longer retention, one for transfer to a novel velocity). To investigate electroencephalography (EEG) α and β power changes, data were collected from electrode sites T7, T8, C3, C4, CP3, CP4, FCz, AFz, and Pz. Results: Based on a 2 × 4 (practice group × test block) ANOVA, results indicated a significant learning effect for both group participants, with VP participants performing better on the 30-min transfer test. To investigate EEG α and β power changes, data were analyzed using separate, 2 × 2 repeated measures ANOVA (group [RP and VP] × practice trial blocks [EP and LP]). Power analyses revealed (1) attenuated α ERD at T7 (cognitive/verbal rehearsal), C3 (motor cortex), CP3, CP4, and FCz (pooled data representing premotor cortices), and AFz (frontal cortex and attentional processes) during LP, with greater changes observed in premotor activity (PMA), T7, and AFz electrode sites in RP participants. β frequency analysis, using beta modulation depth (BMD), revealed that participants in both groups had increased BMD at premotor, motor, and frontal electrode sites at LP, with RP participants exhibiting greater changes. Conclusions: Results are in accordance with previous research indicating that practicing under a VP schedule leads to superior motor skill transfer than practicing under an RP schedule. Moreover, lesser changes in α ERD along and lower BMD observed in VP participants might be responsible for a more adaptable and flexible motor program, allowing for greater skill retention and transfer in individuals practicing under VP conditions.

Decision uncertainty as a context for motor memory

The current view of perceptual decision-making suggests that once a decision is made, only a single motor programme associated with the decision is carried out, irrespective of the uncertainty involved in decision making. In contrast, we show that multiple motor programmes can be acquired on the basis of the preceding uncertainty of the decision, indicating that decision uncertainty functions as a contextual cue for motor memory. The actions learned after making certain (uncertain) decisions are only partially transferred to uncertain (certain) decisions. Participants were able to form distinct motor memories for the same movement on the basis of the preceding decision uncertainty. Crucially, this contextual effect generalizes to novel stimuli with matched uncertainty levels, demonstrating that decision uncertainty is itself a contextual cue. These findings broaden the understanding of contextual inference in motor memory, emphasizing that it extends beyond direct motor control cues to encompass the decision-making process.

THE RELATIONSHIP OF MORPHOLOGICAL CHARACTERISTICS WITH THE PERFORMANCE OF THE TECHNIQUE OF THROWING WITH THE STANDING LEG LEFT FROM THE BACK

Abstract The aim of the work was to determine the connection between morphological characteristics and the effectiveness of the throwing technique by kicking the legs from behind from the program of Special Physical Education (SPE). The sample of respondents consisted of 84 students (male), first year of the Faculty of Security Sciences from Banja Luka. The variable sample was composed of 17 tests for the evaluation of morphological characteristics, which were the independent variables and the dependent variable OSOTOG, which was the average grade of the performance of the kicking technique from the SPE program. The regression analysis did not establish a statistically significant connection between the efficiency of performing the throwing technique by striking the landing leg from behind and the selected set of predictor variables for the assessment of morphological characteristics. Only the elbow diameter variable (ADIJLA) gave a statistically significant contribution to the explanation of the criteria variable OSOTOG. Based on the value of the Beta coefficients, we can see that the variables: body weight (ATETJ) and leg length (ADUZNO) have significant positive partial correlations with the criterion variable, while negative correlations were achieved by the variables: elbow diameter (ADIJLA), body height (AVISTJ) and length hands (ADUZRU). The obtained results could be used in terms of improving the quality of the performance of certain program contents of the SPE, when choosing the appropriate technique within the motor program when solving certain problem situations from the SPE program. Keywords: students, interconnection, morphological characteristics, throwing by kicking out the leg from behind

Impact of Sensory and Motor Complementary Program on Severity of Symptoms among Children with Attention Deficit Hyperactivity Disorder

Impact of Sensory and Motor Complementary Program on Severity of Symptoms among Children with Attention Deficit Hyperactivity Disorder

GLUT1DS focus on dysarthria

Research purposeGLUT1 deficiency syndrome (GLUT1DS) is a rare genetic disorder caused by a mutation in the SLC2A1 gene that limits the transport of glucose across the blood-brain barrier. Speech disorders and dysarthria are typical findings in patients with GLUT1DS, but have never been deeply phenotyped. The aim of the present study was to characterize speech abilities in a sample of patients with GLUT1DS. Results30 patients with GLUT1DS were recruited. We reported impairments in different speech and oromotor domains: the speech was characterized by dysarthria, inaccurate articulation of consonants, abnormal nasal resonance, errors in intonation and prosody and low intelligibility. We observed difficulties in motor planning and programming. Moreover, we observed a significant difference between the dysarthric level of impairment with genotype groups. ConclusionsThe presence of a speech disorder in patients with GLUT1DS represents a core feature of the syndrome. Our findings suggest that patients with GLUT1DS would benefit from a comprehensive neurocognitive assessment to detect strengths and weaknesses of the speech profile. Understanding the speech and language phenotype in GLUT1DS is critical for planning early intervention to positively influence the global development of patients with GLUT1DS.

Способы действия с объектом как часть его репрезентации

&lt;p&gt;Goal. A representation is a multisensory model of an object that may or may not be represented in direct perceptual experience. In this regard, the question arises about the possibility of including in the representation information about the way of action with an object (motor programs). The purpose of this work is to analyze the existing theoretical concepts and empirical studies of the thesis about the inclusion of motor knowledge in the representation of an object and the influence of this knowledge on other cognitive processes. Methods. The work examines such theoretical approaches as the theory of the dual visual system, the model of embedded representation, as well as approaches based on manipulation and intention. In particular, the effect of compatibility is analyzed, which consists in reaction time reduction in the case of a congruence of the executed motor program and the perceived object. Results. The compatibility effect can be found in naming, categorization, and visual search tasks. The conditions for the occurrence of the compatibility effect in visual search are considered. Conclusions. It is assumed that there are two alternative explanations for the compatibility effect in the visual search &amp;mdash; the conflict resolution in working memory or the inhibition of affordances hypothesis.&lt;/p&gt;

The emergence of identity, agency and consciousness from the temporal dynamics of neural elaboration.

Identity-differentiating self from external reality-and agency-being the author of one's acts-are generally considered intrinsic properties of awareness and looked at as mental constructs generated by consciousness. Here a different view is proposed. All physiological systems display complex time-dependent regulations to adapt or anticipate external changes. To interact with rapid changes, an animal needs a nervous system capable of modelling and predicting (not simply representing) it. Different algorithms must be employed to predict the momentary location of an object based on sensory information (received with a delay), or to design in advance and direct the trajectory of movement. Thus, the temporal dynamics of external events and action must be handled in differential ways, thereby generating the distinction between self and non-self ("identity") as an intrinsic computational construct in neuronal elaboration. Handling time is not what neurons are designed for. Neuronal circuits are based on parallel processing: each bit of information diverges on many neurons, each of which combines it with many other data. Spike firing reports the likelihood that the specific pattern the neuron is designed to respond to is present in the incoming data. This organization seems designed to process synchronous datasets. However, since neural networks can introduce delays in processing, time sequences can be transformed into simultaneous patterns and analysed as such. This way predictive algorithms can be implemented, and continually improved through neuronal plasticity. To successfully interact with the external reality, the nervous system must model and predict, but also differentially handle perceptual functions or motor activity, by putting in register information that becomes available at different time moments. Also, to learn through positive/negative reinforcement, modelling must establish a causal relation between motor control and its consequences: the contrast between phase lag in perception and phase lead (and control) in motor programming produces the emergence of identity (discerning self from surrounding) and agency (control on actions) as necessary computational constructs to model reality. This does not require any form of awareness. In a brain, capable of producing awareness, these constructs may evolve from mere computational requirements into mental (conscious) constructs.

Developmental organization of the graphic gesture with a pre-scruptural task to assess handwriting

IntroductionThe literature mainly focused on spatio-temporal and kinematics parameters of tracing letters or words using digitizing tablets, no recent research has previously studied the developmental prerequisites of the organization of handwriting.ObjectivesWe aimed to aimed to investigate and validate the developmental organization of the graphic gesture with a pre-scruptural task.Methods122 typically developing right-handed elementary school children (grades 1st to 5th) aged from 6 to 11;3 years old were recruited. The axe postural and arm gestural features were video-recorded with analysis in 2D reconstruction. Spatial (length, size, regularity, slope of the line…), temporal (drawing time, pause time) and kinematic measures (velocity, peak velocity) were collected with a digital pen independent connected to an analysis software tool. External validity was studied in relation with the standardized handwriting scale BHK. The child has to draw a line of cycloid loops (from left to right drawn in an anti-clockwise direction) across the width of an A4 size unlined half sheet of white paper (containing non-visible watermarks to provide the location of the pen) free to move on the table, after observing the dynamic model on the iPad placed in front of him.ResultsFive main patterns of inter-segmental displacement gestures were found for the production of the line of loops with a significant developmental progress from grades 1st to 5th. Findings showed significant economic rotation movement with forearm rotation around the elbow in 4th and 5th grade, with the elbow tending significantly to be static on the table (p = 2.43e-16), wrist on the table and (p =0.02) and in half-supine position (p =0·001), tri-digital grasp of the pen (p =3.81e-08). Moreover, the mean pressure applied on the pen decrease at 4 and 5th grades and it is correlated to deleterious spatial-temporal and kinematic parameters.ConclusionsThe results of our study provide the first developmental grade and age-related normative data in the developmental genesis of the graphomotor gesture and with the spatio-temporal /kinematic measures. The more mature the gesture, the more there is a decrease in degrees of freedom of movement and stabilization of the joints that is fixed, as well as the presence of a distal flexion movement extending fingers in synergy with the rotation of the arm around the elbow. Furthermore, the task of copying of loops in ecological settings appears to be a good predictor for legibility and writing speed. Those data can account for the mechanisms of motor programming necessary to the automatization of the future gesture of handwriting.Disclosure of InterestNone Declared

Sense of Agency and Skills Learning in Virtual-Mediated Environment: A Systematic Review.

Agency is central to remote actions, and it may enhance skills learning due to a partial overlap between brain structures and networks, the promotion of confidence towards a telemanipulator, and the feeling of congruence of the motor choice to the motor plan. We systematically reviewed studies aiming to verify the role of agency in improving learning. Fifteen studies were selected from MEDLINE and Scopus®. When a mismatch is introduced between observed and performed actions, the decrease in agency and learning is proportional to the intensity of the mismatch, which is due to greater interference with the motor programming. Thanks to multisensory integration, agency and learning benefit both from sensory and performance feedback and from the timing of feedback based on control at the goal level or the perceptual-motor level. This work constitutes a bedrock for professional teleoperation settings (e.g., robotic surgery), with particular reference to the role of agency in performing complex tasks with remote control.

Saccades to partially occluded objects: Perceptual completion mediates oculomotor control.

Oculomotor behavior typically consists of directing gaze to objects in complex scenes for the purpose of extracting detailed perceptual information. Here, we probed the nature of the visual representations over which saccades to objects are computed. We contrasted an image-based oculomotor control hypothesis, holding that saccades are computed solely over information explicit in the retinal image, and an object-based oculomotor control hypothesis, holding that saccades are computed over object representations reflecting the three-dimensional structure of the scene. We recorded saccade landing positions to partially occluded objects in a naturalistic search task. In Experiment 1, saccade landing positions were biased toward the center of the perceptually completed object. Experiment 2 demonstrated that the bias held even when it would have been strategically advantageous to avoid it. Experiment 3 demonstrated that the bias was not due to image-level differences generated by the presence of occluders. The results indicate that saccade motor programs are computed, at least in part, over object-level representations reflecting the completion of occluded surfaces.

Effects of caudal fin stiffness on optimized forward swimming and turning maneuver in a robotic swimmer

In animal and robot swimmers of body and caudal fin (BCF) form, hydrodynamic thrust is mainly produced by their caudal fins, the stiffness of which has profound effects on both thrust and efficiency of swimming. Caudal fin stiffness also affects the motor control and resulting swimming gaits that correspond to optimal swimming performance; however, their relationship remains scarcely explored. Here using magnetic, modular, undulatory robots (μBots), we tested the effects of caudal fin stiffness on both forward swimming and turning maneuver. We developed six caudal fins with stiffness of more than three orders of difference. For a μBot equipped with each caudal fin (and μBot absent of caudal fin), we applied reinforcement learning in experiments to optimize the motor control for maximizing forward swimming speed or final heading change. The motor control of μBot was generated by a central pattern generator for forward swimming or by a series of parameterized square waves for turning maneuver. In forward swimming, the variations in caudal fin stiffness gave rise to three modes of optimized motor frequencies and swimming gaits including no caudal fin (4.6 Hz), stiffness <10−4 Pa m4 (∼10.6 Hz) and stiffness >10−4 Pa m4 (∼8.4 Hz). Swimming speed, however, varied independently with the modes of swimming gaits, and reached maximal at stiffness of 0.23 × 10−4 Pa m4, with the μBot without caudal fin achieving the lowest speed. In turning maneuver, caudal fin stiffness had considerable effects on the amplitudes of both initial head steering and subsequent recoil, as well as the final heading change. It had relatively minor effect on the turning motor program except for the μBots without caudal fin. Optimized forward swimming and turning maneuver shared an identical caudal fin stiffness and similar patterns of peduncle and caudal fin motion, suggesting simplicity in the form and function relationship in μBot swimming.

Neuromuscular Anatomy and Motor Patterns at the Base of Calling Behaviour in the Female Spongy Moth Lymantria dispar.

"Calling behaviour" is a stereotyped rhythmic motor pattern displayed by female moths, by which they emit the sex pheromone to attract of conspecific males. Calling occurs through a squeezing mechanism based on the turtleneck-like folding and unfolding of the ovipositor cuticle during its telescopic extensions and retractions. This mechanism is under the control of the terminal abdominal ganglion (TAG). By combining anatomical and electrophysiological approaches, here we studied the morpho-functional organisation of the abdominal muscles and the activity of motoneurons from TAG nerve N4-N6 as correlated to the ovipositor movements during calling in the female spongy moth Lymantria dispar. Our results show that the three abdominal segments S7, S8 and S9 (ovipositor) are highly specialized structures containing cuticular appendages, hinges, apodemes and several large muscles, innervated by N4 and especially by N5. N6 mainly innervates the oviductal tract. We also identified a number of motor units from N4 and N5, the spike activity of which is correlated with the ovipositor movements during calling. In conclusion, the release of sex pheromones in the female spongy moth is obtained by extensions and retractions of the ovipositor operated by a coordinated motor program, which is mainly sustained by the activity of a few motor units under the control of TAG nerves N4 and N5.