Swimming Control Research Articles

Occlusion of Low-Frequency-Induced, Heterosynaptic Long-Term Potentiation in the Rat Hippocampus In Vivo Following Spatial Training

Recent work has shown that some low-frequency stimulation (LFS) protocols can induce long-term potentiation (LTP) at hippocampal synapses. As LFS mimics certain aspects of low-frequency oscillations during slow-wave sleep, LFS-LTP may be relevant to processes of sleep-dependent consolidation. Here, alternating LFS (1 Hz) of heterosynaptic inputs arising in the medial septum and area CA3 induced LTP at hippocampal CA1 synapses of anesthetized rats. Remarkably, this LTP was absent when delivered 3 h, but not 8 or 24 h, after training in the hidden platform version of the Morris water maze, suggesting a time-specific occlusion of LFS-LTP following spatial learning. LTP assessed 3 h after training was intact in yoked swim controls and rats trained in darkness. Visible platform training resulted in heterogeneous effects, with about half of the animals showing LTP occlusion. Pharmacological experiments revealed that N-methyl-d-aspartate (NMDA)-receptor activation was required for both LFS-LTP and the retention of spatial learning. To test whether a learning-related, NMDA-dependent potentiation accounted for the occlusion effect, we blocked NMDA receptors immediately following spatial training. This manipulation reversed LTP occlusion 3 h after training. Together, these experiments indicate a mechanistic overlap between heterosynaptically induced LFS-LTP and processes mediating the consolidation of spatial information at hippocampal synapses.

3D geometric morphometric analysis of phenotypic plasticity in the pectoral girdle of a basal actinopterygiian fish

Polypterids are a basal group of actinopterygian fishes that represent a possible living analogue for the evolutionary transition from fish to tetrapods for number of reasons, including their ability to walk on land using robustly, muscled pectoral fins. We examined the phenotypic plasticity in the pectoral anatomy of Polypterus senegalus induced by habitual terrestrial locomotion. Fish were reared in a fully terrestrial environment where they were forced to live and locomote over land for up to two years. MicroCT scans were taken of the experimental walking group and a swimming control group. 3D reconstructions of the pectoral anatomy were described using spherical harmonics, a 3D extension of elliptic Fourier analysis. Here we present a geometric morphometric analysis of morphological differences in the pectoral anatomy between swimming and walking fish, and discuss potential small‐scale morphological changes in response to the functional demands of terrestrial locomotion during the fin‐to‐limb transition.Grant Funding Source: NSERC, Canada Research Chair, Tomlinson Postdoctoral Fellowship

Modelling and Fuzzy Control of an Efficient Swimming Ionic Polymer-Metal Composite Actuated Robot

In this study, analytical techniques and fuzzy logic methods are applied to the dynamic modelling and efficient swimming control of a biomimetic robotic fish, which is actuated by an ionic polymer-metal composite (IPMC). A physical-based model for the biomimetic robotic fish is proposed. The model incorporates both the hydrodynamics of the IPMC tail and the actuation dynamics of the IPMC. The comparison of the results of the simulations and experiments shows the feasibility of the dynamic model. By using this model, we found that the harmonic control of the actuation frequency and voltage amplitude of the IPMC is a principal mechanism through which the robotic fish can obtain high thrust efficiency while swimming. The fuzzy control method, which is based on the knowledge of the IPMC fish's dynamic behaviour, successfully utilized this principal mechanism. By comparing the thrust performance of the robotic fish with other control methods via simulation, we established that the fuzzy controller was able to achieve faster acceleration compared with what could be achieved with a conventional PID controller. The thrust efficiency during a steady state was superior to that with conventional control methods. We also found that when using the fuzzy control method the robotic fish can always swim near a higher actuation frequency, which could obtain both the desired speed and high thrust efficiency.

Novel Method for the Modeling and Control Investigation of Efficient Swimming for Robotic Fish

In this paper, analytical techniques and fuzzy logic method are applied to the dynamic modeling and efficient swimming control of a robotic fish. The bioinspired robotic fish, which follows an exact replica of a live mackerel (Scomber scombrus), is modeled by treating the undulating body and flapping tail independently using analytical methods. Comparing the results of simulations and experiments shows the feasibility of the dynamic model. Using this model, we found that the harmonic control of the Strouhal number and caudal fin angle of attack is a principal mechanism through which the robotic fish can obtain high thrust efficiency while swimming. The fuzzy control method, which is based on the knowledge of the robotic fish's dynamic behavior, has successfully utilized this principal mechanism. By comparing the thrust performance of the robotic fish with different control methods via simulation, we established that the fuzzy controller was able to achieve faster acceleration and smaller steady-state error than what could be achieved from an open-loop and conventional proportional-integral-derivative controller. The thrust efficiency during steady state was superior to that with conventional control methods. We also found that, when using the fuzzy control method, robotic fish can always swim near a “universal” Strouhal number that approximates to the swimming of live fish.

A role for dorsal and ventral hippocampus in response learning

The hippocampus and the striatum have been traditionally considered as part of different and independent memory systems despite growing evidence supporting that both brain regions may even compete for behavioral control in particular learning tasks. In this regard, it has been reported that the hippocampus could be necessary for the use of idiothetic cues in several types of spatial learning tasks. Accordingly, the ventral striatum receives strong anatomical projections from the hippocampus, suggesting a participation of both regions in goal-directed behavior. Our work examined the role of the dorsal and ventral hippocampus on a response learning task. Cytochrome c oxidase (C.O.) quantitative histochemistry was used as an index of brain oxidative metabolism. In addition, determination of C.O. subunit I levels in the hippocampus by western blot analysis was performed to assess the contribution of this subunit to overall C.O. activity. Increased brain oxidative metabolism was found in most of the studied hippocampal subregions when experimental group was compared with a swim control group. However, no differences were found in the amount of C.O. subunit I expressed in the hippocampus by western blot analysis. Our results support that both the dorsal and ventral hippocampus are associated with the use of response strategies during response learning.

Multimodal swimming control of a robotic fish with pectoral fins using a CPG network

The neural-based approaches inspired by biological neural mechanisms of locomotion are becoming increasingly popular in robot control. This paper investigates a systematic method to formulate a Central Pattern Generator (CPG) based control model for multimodal swimming of a multi-articulated robotic fish with flexible pectoral fins. A CPG network is created to yield diverse swimming in three dimensions by coupling a set of nonlinear neural oscillators using nearest-neighbor interactions. In particular, a sensitivity analysis of characteristic parameters and a stability proof of the CPG network are given. Through the coordinated control of the joint CPG, caudal fin CPG, and pectoral fin CPG, a diversity of swimming modes are defined and successfully implemented. The latest results obtained demonstrate the effectiveness of the proposed method. It is also confirmed that the CPG-based swimming control exhibits better dynamic invariability in preserving rhythm than the conventional body wave method.

Numerical simulations and vorticity dynamics of self-propelled swimming of 3D bionic fish

Numerical simulations and the control of self-propelled swimming of three-dimensional bionic fish in a viscous flow and the mechanism of fish swimming are carried out in this study, with a 3D computational fluid dynamics package, which includes the immersed boundary method and the volume of fluid method, the adaptive multi-grid finite volume method, and the control strategy of fish swimming. Firstly, the mechanism of 3D fish swimming was studied and the vorticity dynamics root was traced to the moving body surface by using the boundary vorticity-flux theory. With the change of swimming speed, the contributions of the fish body and caudal fin to thrust are analyzed quantitatively. The relationship between vortex structures of fish swimming and the forces exerted on the fish body are also given in this paper. Finally, the 3D wake structure of self-propelled swimming of 3D bionic fish is presented. The in-depth analysis of the 3D vortex structure in the role of 3D biomimetic fish swimming is also performed.

Diyabetin ve Zorlu Yüzme Egzersizinin Sıçan Beyin Dokusunda Yol Açtığı Oksidan Hasar Üzerine Melatoninin Koruyucu Etkisi

Objective: The objective of the present study is to examine how melatonin supplementation affects lipid peroxidation in the brain tissue of diabetic rats subjected to acute swimming exercise. Material and Methods: The study was carried out on 80 Spraque-Dawley type adult male rats, which were equally allocated to 8 groups: Group 1, general control; Group 2, melatonin-supplemented control; Group 3, melatonin-supplemented diabetic control; Group 4, swimming control; Group 5, melatonin-supplemented swimming; Group 6, melatonin-supplemented diabetic swimming; Group 7, diabetic swimming; and Group 8, diabetic control. The animals were injected with 40 mg/kg subcutaneous streptozotocin (STZ). The same dose was repeated after 24 hours. The rats were supplemented with 3 mg/kg/day intraperitoneal (ip) melatonin for 4 weeks. Brain tissue samples were collected from the animals, which were decapitated at the end of the study, to determine malondialdehyde (MDA) (nmol/gram/protein) and glutathione (GSH) (mg/dL/gram protein) levels. Results: The highest MDA values in brain tissue were in Group 7 and 8. Groups 3 and 6 had the highest brain GSH values. Brain GSH values in Group 2 were lower than the values in Groups 3 and 6, but higher than those in all other groups. The lowest GSH values in brain tissue were established in Groups 7 and 8. Conclusion: Results of the present study indicate that the oxidative stress caused by diabetes and acute swimming exercise in rat brain tissue can be offset by melatonin supplementation.

Protective effect of melatonin on lipid peroxidation in various tissues of diabetic rats subjected to an acute swimming exercise

The present study aimed to explore the effect of melatonin administration on lipid peroxidation in various tissues of rats with streptozocin induced diabetes and subjected to an acute swimming exercise. The study used 80 adult male rats, which were equally allocated to 8 groups: Group 1, general control; Group 2, melatonin-administered control; Group 3, melatonin-administered diabetic control; Group 4, swimming control; Group 5, melatonin-administered swimming; Group 6, melatonin-administered diabetic swimming; Group 7, diabetic swimming; Group 8, diabetic control. Diabetic rats were administered 3 mg/kg/day ip melatonin for 4 weeks. At the end of the study, the animals were decapitated to collect samples from liver, lung and spleen tissues, which were then analyzed to determine levels of liver MDA (nmol/gram/protein) and GSH (mg/g/protein). The highest MDA values in liver, lung and spleen tissues were obtained in the Group 7. The values in the Group 8 were lower than those in the Group 7, but higher than in all other groups. The Group 5 and 6 had the highest liver, lung and spleen GSH values. Results obtained from the study indicate that the increase in free radical production and the inhibition of antioxidant activity in diabetes and acute exercise are both prevented by melatonin administration (Tab. 2, Ref. 30).

Effect of zinc supplementation on lipid peroxidation and lactate levels in rats with diabetes induced by streptozotocin and subjected to acute swimming exercise

The present study aims to explore the effect of zinc supplementation on lipid peroxidation and lactate levels in rats having diabetes induced by streptozotocin and subjected to acute swimming exercise. A total of 80 adult male rats of Sprague-Dawley type were equally allocated to 8 groups: Group 1, general control. Group 2, zinc-supplemented group. Group 3, zinc-supplemented, diabetic group. Group 4, swimming control group. Group 5, zinc-supplemented swimming group. Group 6, zinc-supplemented diabetic swimming group. Group 7, diabetic swimming group. Group 8, diabetic group. At the end of the 4-week study, blood samples were collected to determine MDA, GSH, GPx, SOD, lactate and zinc levels. The highest MDA values were found in group 7 and 8 (p<0.001). GSH values in groups 5 and 6 were higher (p<0.001). The highest GPx values were established in groups 2, 5 and 6 (p<0.001). SOD values were the highest in groups 5 and 6 (p<0.001) and lowest in groups 2, 3 and 8 (p<0.001). The highest plasma lactate levels were found in group 7 (p<0.001). The highest zinc levels were obtained in groups 1, 2 and 5 (p<0.001), and the lowest zinc levels were found in groups 7 and 8 (p<0.001). Results of the study reveal that zinc supplementation prevents the increase of free radical formation, suppression of antioxidant activity and muscle exhaustion, all of which result from diabetes and acute exercise. Zinc supplementation may contribute to health performance in diabetes and acute exercise (Tab. 2, Fig. 1 Ref. 47). Full Text in PDF www.elis.sk.

Effect of Conclevan on Endurance Capacity in Mice

The purpose of this study was to clarify the anti-fatigue effect of Conclevan, which is mainly composed of liver hydrolysate, via a forced swimming test using mice. Conclevan was administered to mice for 6 weeks, and a forced swimming test was conducted to measure swimming time. After six weeks, the blood ammonia and glutamine concentrations were measured. In the Conclevan administration group, swimming time increased significantly compared to the swimming control group. In the swimming control group, an increase in blood ammonia and a decrease in blood glutamine were observed, relative to the non-swimming control group. In the Conclevan administration group, the increased blood ammonia and decreased blood glutamine induced by swimming were significantly reduced, compared to the swimming control group. The mRNA expression levels of the hepatic enzymes of the urea cycle (carbamoyl-phosphate synthetase, argininosuccinate synthetase, and arginase) and glutamine synthesis (glutamate dehydrogenase and glutamine synthetase) were significantly increased in the Conclevan administration group, compared to the swimming control group. The results of this study demonstrated the anti-fatigue effects of Conclevan. This product may inhibit an increase in the fatigue-inducing ammonia concentration in the blood by increasing the expression of hepatic enzymes, which convert ammonia to urea, leading to increased swimming time. In addition, Conclevan may prolong swimming time by increasing the hepatic synthesis of glutamine, which is an important amino acid for supplying energy in muscles.

Changes in wingstroke kinematics associated with a change in swimming speed in a pteropod mollusk,Clione limacina

In pteropod mollusks, the gastropod foot has evolved into two broad, wing-like structures that are rhythmically waved through the water for propulsion. The flexibility of the wings lends a tremendous range of motion, an advantage that could be exploited when changing locomotory speed. Here, we investigated the kinematic changes that take place during an increase in swimming speed in the pteropod mollusk Clione limacina. Clione demonstrates two distinct swim speeds: a nearly constant slow swimming behavior and a fast swimming behavior used for escape and hunting. The neural control of Clione's swimming is well documented, as are the neuromuscular changes that bring about Clione's fast swimming. This study examined the kinematics of this swimming behavior at the two speeds. High speed filming was used to obtain 3D data from individuals during both slow and fast swimming. Clione's swimming operates at a low Reynolds number, typically under 200. Within a given swimming speed, we found that wing kinematics are highly consistent from wingbeat to wingbeat, but differ between speeds. The transition to fast swimming sees a significant increase in wing velocity and angle of attack, and range of motion increases as the wings bend more during fast swimming. Clione likely uses a combination of drag-based and unsteady mechanisms for force production at both speeds. The neuromuscular control of Clione's speed change points to a two-gaited swimming behavior, and we consider the kinematic evidence for Clione's swim speeds being discrete gaits.

수영부하 피로에 대한 마늘추출물 및 비타민 B군 강화 급이의 회복 효과

The purpose of this study was to investigate the effects of a diet supplemented with garlic extract and vitamin B complex on fatigue recovery from swimming load test in rats. Sprague-Dawley rats were divided into a non-swimming control group (Normal) and swimming load test groups. Swimming load test groups were re-divided into swimming control group (Control), 1% of 60 brix garlic extract fed group (SG), vitamin B complex twice mixture fed group (SV) and 1% of 60 brix garlic extract and vitamin B group twice mixture fed group (SGV). Concentration of plasma lipids and glucose were determined in the rats post-swimming. Concentration of plasma glucose, total lipid, total cholesterol and triglyceride were significantly increased in the control group compared to the non-swimming control group (p mg/dl) group. LDL-cholesterol concentration was the highest in the control group, but it was decreased significantly in the SGV group. In conclusion, this study demonstrates that a diet supplemented with 1% 60 brix garlic extract and vitamin B group twice mixture has beneficial effects on fatigue recovery in swimming load tests.

The Effect of Exercise Training on the Responsiveness of Renal Resistance Arteries in Rats

Blood flow to several tissues changes during an acute bout of exercise. The kidney is one of the organs that are most affected by exercise-induced blood redistribution. The aim of the present study was to investigate possible exercise-induced vascular reactivity changes in renal resistance arteries in rats. Renal resistance arteries were isolated from rats that underwent 8 weeks of swimming and sedentary control rats, and the arteries were evaluated using wire myography. Similar dilation responses to acetylcholine, bradykinin, adenosine, isoproterenol, and sodium nitroprusside were observed in both groups. The vasoconstrictive agents vasopressin, endothelin-1, potassium chloride, and thromboxane A2 also induced similar responses in both groups; however, the trained group had an increased constrictive response to norepinephrine compared to the control rats. The results of our study show that renal resistance arteries of trained rats behave differently than conduit-type renal arteries and exhibit an increased contractile response to sympathetic agonists. This finding provides supporting evidence that renal blood flow markedly decreases during exercise in trained individuals.

Effect of zinc supplementation on the distribution of various elements in the serum of diabetic rats subjected to an acute swimming exercise

The present study aims to examine the effect of supplementation of zinc on the distribution of various elements in the sera of diabetic rats subjected to an acute swimming exercise. A total of 80 Sprague-Dawley-type adult male rats were equally allocated to one of eight groups: Group 1, general; Group 2, zinc-supplemented; Group 3, zinc-supplemented diabetic; Group 4, swimming control; Group 5, zinc-supplemented swimming; Group 6, zinc-supplemented diabetic swimming; Group 7, diabetic swimming; and Group 8, diabetes. The rats were injected with 40mg/kg/day subcutaneous streptozotocin (STZ) twice, with a 24-h interval between two injections. Zinc was supplemented at a dose of 6mg/kg/day (ip) for 4weeks. Blood samples were collected at the end of the 4-week study, and serum levels of lead, cobalt, molybdenum, chrome, sulfur, magnesium, manganese, sodium, potassium, phosphorus, copper, iron, calcium, zinc, and selenium (mg/L) were determined with atomic emission. The lowest molybdenum, chrome, copper, iron, potassium, magnesium, sodium, phosphorus, lead, selenium, and zinc values were obtained in Group 7 and 8. These same parameters were higher in the swimming exercise group (Group 4), relative to all other groups. The values in zinc-supplemented groups were found lower than the values in Group 4, but higher than those in Group 6 and 7. The results obtained from the study demonstrate that acute swimming exercise and diabetes affect the distribution of various elements in the serum, while zinc supplementation can prevent the negative conditions associated with both exercise and diabetes.

Modelling the fate of marine turtle hatchlings

The SLIM oceanographic model was used to examine the fate of hatchling flatback turtles ( Natator depressus) in the first two weeks of their dispersal starting at Wild Duck Island, a major turtle-nesting site in the central Great Barrier Reef region of Australia. We ran simulations to investigate the effects of spring versus neap tides, hatchling's swimming behaviour during their first three days at sea, and the location of nesting beaches. The model predicted that up to 50% of the turtle hatchlings entering the sea from the windward, southern beach remained after 14 days in shallow, nearshore waters, irrespective of tides and swimming. These waters are turbid and may be inhospitable to hatchlings. In contrast >80% of hatchlings dispersing from the leeward, northern beach were dispersed to deeper water (10–40 m) in a quasi-stationary dispersion core centred around 10 km north of the nesting beach after 14 days and the offshore spread of the turtle plume was enhanced by the hatchling's seaward swimming during the first three days. This was due to the presence of a coastal boundary layer and a stagnation zone around the northern side of island, but not the southern side. The model confirmed that dispersal from eastern Queensland flatback turtle rookeries is restricted to the lagoons and coastal waters, and that water circulation and hatchling's swimming control dispersion. The model explains why more turtles nest on the northern than the southern side. This study highlights the usefulness of oceanographic models to increase knowledge about a cryptic life stage of marine turtles.

Alpha-conotoxin ImI disrupts central control of swimming in the medicinal leech

Medicinal leeches ( Hirudo spp.) swim using a metachronal, front-to-back undulation. The behavior is generated by central pattern generators (CPGs) distributed along the animal's midbody ganglia and is coordinated by both central and peripheral mechanisms. Here we report that a component of the venom of Conus imperialis, α-conotoxin ImI, known to block nicotinic acetyl-choline receptors in other species, disrupts swimming. Leeches injected with the toxin swam in circles with exaggerated dorsoventral bends and reduced forward velocity. Fictive swimming in isolated nerve cords was even more strongly disrupted, indicating that the toxin targets the CPGs and central coordination, while peripheral coordination partially rescues the behavior in intact animals.

Effect of Selenium Supplementation on Lipid Peroxidation, Antioxidant Enzymes, and Lactate Levels in Rats Immediately After Acute Swimming Exercise

The present study aims to evaluate the effect of selenium supplementation on lipid peroxidation and lactate levels in rats subjected to acute swimming exercise. Thirty-two adult male rats of Sprague-Dawley type were divided into four groups. Group 1, control; group 2, selenium-supplemented; group 3, swimming control; group 4, selenium-supplemented swimming group. The animals in groups 2 and 4 were supplemented with (i.p.) 6mg/kg/day sodium selenite for 4weeks. The blood samples taken from the animals by decapitation method were analyzed in terms of erythrocyte-reduced glutathione (GSH), serum glutathione peroxidase (GPx) and superoxide dismutase (SOD), and plasma malondialdehyde (MDA) and lactate using the colorimetric method, and serum selenium values using an atomic emission device. In the study, the highest MDA and lactate values were found in group 3, while the highest GSH, GPx and SOD values were obtained in group 4 (p < 0,001). Group 2 had the highest and group 3 had the lowest selenium levels (p < 0,001). Results of the study indicate that the increase in free radical production and lactate levels due to acute swimming exercise in rats might be offset by selenium supplementation. Selenium supplementation may be important in that it supports the antioxidant system in physical activity.

Recent and remote memory recalls modulate different sets of stereotypical interlaminar correlations in Arc/Arg3.1 mRNA expression in cortical areas

Detailed organization of interlaminar relations in neuronal activity underlying recent and remote memory recall is unknown but essential for deciphering interlaminar connections involved in systems-level memory consolidation and permanent information storage. We mapped Arc/Arg3.1 (Arc) mRNA expression, a neuronal activity marker, at multiple rostro-caudal levels of the brain in Wistar rats following a platform search in a water-maze task. Strength of interlaminar correlations in Arc expression and modulation of the strength by memory recall in sensory, motor and association cortical areas were measured at 24 h and 1 month in memory retention. In order to estimate the extent of modular organization in neocortical function underlying memory recall, we studied multiple profiles of interlaminar coupling. At the level of cortical areas, we captured two robust stereotypical laminar patterns for distribution of strong and weak interlaminar correlations. These patterns emerged during both control swimming and navigation, at both retention delays. Within limits of these patterns, we established task-, time- and area-dependent modulations of the Arc correlations. Relative to swimming control, during memory recall, changes in strength of analogous interlaminar relations occurred largely in parallel but recent and remote recall modulated mostly distinct correlations. An effective remote memory recall was accompanied by fewer strengthened correlations as compared to recent recall. Thus, a behavioral experience is accompanied by a well-ordered or stereotypical spatial organization of interlaminar relations in neuronal activity distribution. Interlaminar correlations in Arc expression modulated by recent and remote memory recall could guide future inactivation and detection studies necessary to decipher interlaminar connections involved in systems-level consolidation and to reveal mnemonic plasticity specific to spatial memory.

Effect of Intraperitoneal Selenium Administration on Liver Glycogen Levels in Rats Subjected to Acute Forced Swimming

There are a few of studies examining how selenium, which is known to reduce oxidative damage in exercise, influences glucose metabolism and exhaustion in physical activity. The present study aims to examine how selenium administration affects liver glycogen levels in rats subjected to acute swimming exercise. The study included 32 Sprague-Dawley type male rats, which were equally allocated to four groups: Group 1, general control; Group 2; selenium-supplemented control (6 mg/kg/day sodium selenite); Group 3, swimming control; Group 4, selenium-supplemented swimming (6 mg/kg/day sodium selenite). Liver tissue samples collected from the animals at the end of the study were fixed in 95% ethyl alcohol. From the tissue samples buried into paraffin, 5-µm cross-sections were obtained using a microtome, put on a microscope slide, and stained with PAS. Stained preparations were assessed using a Nikon Eclipse E400 light microscope. All images obtained with the light microscope were transferred to a PC and evaluated using Clemex PE 3.5 image analysis software. The highest liver glycogen levels were found in groups 1 and 2 (p < 0.05). The levels in group 4 were lower than those in groups 1 and 2 but higher than the levels in group 3 (p < 0.05). The lowest liver glycogen levels were obtained in group 3 (p < 0.05). Results of the study indicate that liver glycogen levels that decrease in acute swimming exercise can be restored by selenium administration. It can be argued that physiological doses of selenium administration can contribute to performance.