Electromyographic analysis of rectus femoris activity during seated to standing position and walking in water and on dry land in healthy children and children with cerebral palsy

Purpose: To analyze rectus femoris activity during seated to standing position and walking in water and on dry land comparing a group of children with the spastic diparesis type of cerebral palsy (CP) and a group of children without neurological disorders. Methods: This study included a group of nine children with CP and a control group of 11 children. The study compared the electromyographic activity of the rectus femoris during seated to standing position and walking, in water and on land. Results: A greater activation of the rectus femoris was observed in the group of children with CP compared with the control group when moving from a seated position to a standing position in water (p = 0.0039) and while walking on land (p = 0.0014) or in the pool (p = 0.007). Conclusion: This study demonstrated the activation of the rectus femoris while walking or standing up from a seated position in water was greater in the group of children with CP. Further studies should be performed to better understand the extent of muscular activation during body immersion in individuals with neurological disorders.     

Electromyographic responses of erector spinae and lower limb’s muscles to dynamic postural perturbations in patients with adolescent idiopathic scoliosis

The aim of this study was to evaluate electromyographic (EMG) responses of erector spinae (ES) and lower limbs’ muscles to dynamic forward postural perturbation (FPP) and backward postural perturbation (BPP) in patients with adolescent idiopathic scoliosis (AIS) and in a healthy control group. Ten right thoracic AIS patients (Cobb = 21.6 ± 4.4°) and 10 control adolescents were studied. Using bipolar surface electrodes, EMG activities of ES muscle at T10 (ES_T10) and L3 (ES_L3) levels, biceps femoris (BF), gastrocnemius lateralis (G) and rectus femoris (RF) muscles in the right and the left sides during FPP and BPP were evaluated. Muscle responses were measured over a 1s time window after the onset of perturbation. In FPP test, the EMG responses of right ES_T10, ES_L3 and BF muscles in the scoliosis group were respectively about 1.40 (p = 0.035), 1.43 (p = 0.07) and 1.45 (p = 0.01) times greater than those in control group. Also, in BPP test, at right ES_L3 muscle of the scoliosis group the EMG activity was 1.64 times higher than that in the control group (p = 0.01). The scoliosis group during FPP displayed asymmetrical muscle responses in ES_T10 and BF muscles. This asymmetrical muscle activity in response to FPP is hypothesized to be a possible compensatory strategy rather than an inherent characteristic of scoliosis.     

Kinematic chain reactions on trunk and dynamic postural steadiness in subjects with recurrent low back pain

Although subjects with recurrent low back pain (LBP) demonstrate altered trunk control, the kinematic and kinetic responses of the trunk have not been carefully investigated. This study was conducted to compare the standing time, spine range of motion (ROM), and dynamic postural steadiness index (DPSI) based on visual condition between subjects with and without recurrent LBP during upright one leg standing. Sixty-three individuals participated in the study, including 34 control subjects and 29 subjects with recurrent LBP. The DPSI was a composite of the medio-lateral (MLSI), anterior-posterior (APSI), and vertical steadiness indices (VSI) on a force platform. The control group demonstrated longer standing time (s) during the eyes-open condition than the LBP group (26.82 ± 6.03 vs. 19.87 ± 9.36; t = 2.96, p = 0.01). Regarding spine ROM, visual condition was significantly different between groups (F = 7.09, p = 0.01) and demonstrated interactions with spine region and group (F = 5.53, p = 0.02). For the kinetic measures, there was a significant interaction between visual conditions and indices (F = 25.30, p = 0.001). In the LBP group, the DPSI was significantly correlated with the MLSI (r = 0.59, p = 0.002), APSI (r = 0.44, p = 0.03), and VSI (r = 0.98, p = 0.01) in the eyes-closed condition. Overall, the results of this study indicated that the LBP group decreased thorax and lumbar spine rotations during the eyes-closed condition. The LBP group also demonstrated positive correlations with the kinetic indices, enhancing dynamic postural steadiness in the eyes-closed condition in order to possibly avoid pain or further injury. This dynamic postural steadiness strategy is necessary to improve kinetic and kinematic chain reactions in the LBP group. This compensatory pattern supports the development of optimal postural correction strategies to prevent LBP recurrence and might represent a chain reaction to protect trunk control without visual input.     

The effects of early stages of aging on postural sway: A multiple domain balance assessment using a force platform

Technical advancements in instrumentation and analytical methods have improved the ability of assessing balance control. This study investigated the effects of early stages of aging on postural sway using traditional and contemporary postural indices from different domains. Eleven healthy young adults and fourteen healthy non-faller older adults performed two postural tasks: (a) functional limits of stability and (b) unperturbed bipedal stance for 120 s. Postural indices from spatial, temporal, frequency, and structural domains were extracted from the body’s center of pressure (COP) signals and its Rambling and Trembling components. Results revealed a preservation of functional limits of upright stability in older adults accompanied by larger, faster, and shakier body sway in both anterior-posterior and medio-lateral directions; increased medio-lateral sway frequency; increased irregularity of body sway pattern in time in both directions; and increased area, variability, velocity, and jerkiness of both rambling and trembling components of the COP displacement in the anterior-posterior direction (p < 0.02). Such changes might be interpreted as compensatory adjustments to the age-related decline of sensory, neural, and motor functions. In conclusion, balance assessment using postural indices from different domains extracted from the COP displacement was able to capture subtle effects of the natural process of aging on the mechanisms of postural control. Our findings suggest the use of such indices as potential markers for postural instability and fall risk in older adults.     

Effect of haptic supplementation on postural control of younger and older adults in an unstable sitting task

Standing postural control is known to be altered during aging, but age-related changes in sitting postural control have scarcely been explored. The present experiment studied the roles of visual and haptic information in a sitting task in both young and older adults. Fifteen young and fifteen older adults participated in this study. Six experimental conditions were performed with eyes open and eyes closed: quiet sitting, rocker-board sitting, and 4 conditions of haptic supplementation, provided by a hand-held pen, during rocker-board sitting. Classical variables were extracted from the center of pressure (COP) and pen trajectories, and the stabilogram diffusion analysis was performed on the COP data. Three-way ANOVAs (Group × Vision × Condition) were carried out.Postural instability was strongly attenuated by haptic supplementation in both age groups. Furthermore, instability due to visual deprivation was compensated by haptic supplementation. Long- and short-term diffusion coefficients were smaller in conditions of haptic supplementation. The present study confirmed the effect of haptic supplementation on both open-loop and closed-loop mechanisms of postural control and extended it to unstable sitting in young and older adults despite the complex biomechanical systems involved in sitting postural tasks.     

Loading and knee flexion after stroke: Less does not equal more

It is believed that force feedback can modulate lower extremity extensor activity during gait. The purpose of this research was to determine the role of limb loading on knee extensor excitability during the late stance/early swing phase of gait in persons post-stroke. Ten subjects with chronic hemiparesis post-stroke participated in (1) seated isolated quadriceps reflex testing with ankle loads of 0–0.4N m/kg and (2) gait analysis on a treadmill with 0%, 20% or 40% body weight support. Muscle reflex responses were recorded from vastus lateralis (VL), rectus femoris (RF), and vastus medialis (VM) during seated testing. Knee kinematics and quadriceps activity during late stance/early swing phase of gait were compared across loading conditions. Although isolated loading of the ankle plantarflexors at 0.2 N m/kg reduced VM prolonged response (p = 0.04), loading did not alter any other measure of quadriceps excitability (all p > 0.08). During gait, the use of BWS did not influence knee kinematics (p = 0.18) or muscle activity (all p > 0.17) during late stance/early swing phase. This information suggests that load sensed at the ankle has minimal effect on the ipsilateral quadriceps of individuals post-stroke during late stance. It appears that adjusting limb loading during rehabilitation may not be an effective tool to address stiff-knee gait following stroke.     

Modulation of soleus H reflex due to stance pattern and haptic stabilization of posture

The quiet stance is a complicated motor act requiring sophisticated sensorimotor integration to balance an artificial inverted pendulum with the ankle musculature. The objective of this study was to characterize the effects of stance pattern (bilateral stance vs. unilateral stance) and directional influence of light finger touch (medial–lateral vs. anterior–posterior) in unilateral stance upon responsiveness of the soleus H reflex. Sixteen healthy volunteers (mean age, 24.25 ± 1.77 years) participated in four postural tasks with the eyes open, including the bilateral stance (BS), the unilateral stance without finger touch (USNT), and with finger touch in the medial–lateral direction (USML) and anterior–posterior direction (USAP). Meanwhile, the soleus H reflex, the pre-stimulus background activity of ankle antagonist pairs, and center of pressure (CoP) sway were measured. In reference to the BS, the USNT resulted in a significant stance effect on suppression of the soleus H reflex (H/M_max) associated with enhancement of CoP sway. Among the conditions of unilateral stance, there was a marked directional effect of finger touch on modulation of the H/M_max. A greater disinhibition of the H/M_max in consequence to light touch in the ML direction than in the AP direction was noted (H/M_max: USML > USAP > USNT). This directional modulation of the soleus H reflex concurred with haptic stabilization of posture in unilateral stance, showing a more pronounced reduction in CoP sway in the USML condition than in the USAP condition. However, alteration in postural sway and modulation of the soleus H reflex were not mutually correlated when stance pattern or touch vector varied. In conclusion, gating of the soleus H reflex indicated adaptation of an ankle strategy to stance pattern and haptic stabilization of posture. Relative to bilateral stance, postural maintenance in unilateral stance relied less on reflexive correction of the soleus. When finger touch was provided in line with prevailing postural threat in the lateral direction, postural stability in unilateral stance was better secured than finger touch in anterior–posterior direction, resulting in more pronounced disinhibition of the monosynaptic reflex pathway.     

Corrélations entre l'évolution morphologique des membres inférieurs et la récupération fonctionnelle de sujets hémiplégiques

ObjectiveThe aim is to quantify the help provided by recent morphological indicators for hemiplegics patients, after a cerebral vascular accident, during functional rehabilitation. The correlations between functional recovery and the morphological evolution of the muscles and the segments of the lower limb are studied using a MRI system.Material and methodTen adult subjects suffering from vascular hemiplegia have been studied at the ELAN rehabilitation center in Wattrelos. Bobath rehabilitation technique was used to treat patients. Muscular and external volumes of the lower limbs segments, obtained through medical imagery, as well as functional tests (Functional Independence Measure (FIM), Bourges's score and indices of motricity of the pathological limb), were assessed when patients were admitted in and as they left from the rehabilitation centre. Spearman's rho coefficient was used in this study.ResultsThis non-parametric test was considered significant when P < 0.05. It demonstrated a relationship between the evolution of thigh's external and muscular volumes and changes in Bourges's score in seated position (r_s = 0.730 and r_s = 0.764, respectively). It also showed a relationship between pathologic knee motricity index and pathologic leg segment volume evolution (r_s = 0.675).Discussion–conclusionStatistical analysis demonstrated that pathologic thigh volume changes is beneficial to balance during seating as no volume evolution seems to influence balance during standing.     

Age-related differences in time-limit performance and force platform-based balance measures during one-leg stance

Poor posture control has been associated with an increased risk of falls and mobility disability among older adults. This study was conducted to assess the test–retest reliability and sensitivity to group differences regarding the time-limit (T_Limit) of one-leg standing and selected balance parameters obtained with a force platform in older and young adults. A secondary purpose was to assess the relationship between T_Limit and these balance parameters. Twenty-eight healthy older adults (age: 69 ± 5 years) and thirty young adults (age: 21 ± 4 years) participated in this study. Two one-leg stance tasks were performed: (1) three trials of 30 s maximum and (2) one T_Limit trial. The following balance parameters were computed: center of pressure area, RMS sway amplitude, and mean velocity and mean frequency in both the anterio-posterior and medio-lateral directions. All balance parameters obtained with the force platform as well as the T_Limit variable were sensitive to differences in balance performance between older and young adults. The test–retest reliability of these measures was found to be acceptable (ICC: 0.40–0.85), with better ICC scores observed for mean velocity and mean frequency in the older group. Pearson correlations coefficients (r) between balance parameters and T_Limit ranged from ?0.16 to ?0.54. These results add to the current literature that can be used in the development of measurement tools for evaluating balance in older and young adults.     

Effects of short- and long-term changes in spatial density on the social behavior of captive chimpanzees (Pan troglodytes)

The constraints of captivity may often require non-human primates to experience restrictions in space for both long- and short-term periods of time. The tension-reduction model predicts that great apes should increase affiliative behaviors and decrease aggressive behaviors as a coping strategy. The conflict avoidance model, however, predicts that great apes should decrease all social interactions (affiliative and aggressive) as a coping strategy. The purpose of this study was to test the conflict-avoidance and tension-reduction models by examining the effects of both short-term (1–2 days) and long-term (6 months) changes in spatial density on social behavior in 23 adult captive chimpanzees (6 males, 17 females) housed at the Primate Foundation of Arizona. Affiliative (i.e., social groom, social play) and agonistic (i.e., charging display, attack) were assessed using scan-sampling techniques while subjects were rotated from high-density to low-density conditions for varying lengths of time. Results of short-term increases in spatial density (crowding) supported the conflict-avoidance strategy for females, through reduced levels of aggressive (F_1,16 = 17.11, p = 0.001) and affiliative (F_1,16 = 21.13, p < 0.001) behaviors. Males, however, supported the tension-reduction model during short-term high-density by decreasing aggression (F_1,5 = 10.53, p = 0.02) while increasing affiliation (F_1,5 = 9.10, p = 0.03). Females partially supported the tension-reduction model during long-term high-density by increasing affiliative behaviors (F_1,16 = 14.19, p = 0.002) compared to short-term high-density levels, while rates of aggression remained low. Finally, males supported the tension-reduction by reducing aggression (F_1,5 = 7.668, p = 0.04) and increasing affiliation (F_1,5 = 6.08, p = 0.05) during long-term high-density. Results confirm that chimpanzees use different strategies during short-term versus long-term increases in spatial density and that these strategies may be influenced by individual sex. However, sample sizes are small and additional research on male chimpanzees is needed.     

Postural stability in young healthy subjects – Impact of reduced base of support,visual deprivation,dual tasking

ObjectiveTo provide normative postural stability data in young subjects.MethodsNinety-six healthy participants (58 W, 28 ± 6y) stood on a force plate during 60 s. We measured effects of support width (feet apart, FA; feet together, FT), vision (eyes open, EO; closed, EC), and cognitive load (single task, ST; dual tasking, DT) on anteroposterior (AP) and medio-lateral (ML) ranges, area and planar velocity of center of pressure (COP) trajectory.ResultsAll variables increased with FT (AP range, +15%; ML, +185%; area, +242%; velocity, +50%, p < 0.0002 for all, MANOVA). Visual deprivation increased COP ranges with added constraints (FT or DT, p = 0.002) and increased velocity in all conditions (FA/ST, +16%; DT, +18%; FT/ST, +29%; DT, +23%, p < 0.0002 for all). Dual tasking reduced COP displacements with FT (AP range, EO, −15%; EC, −11%; ML range, EO, −19%; EC, −13%; area, EO, −40%; EC, −28%, p < 0.0002 for all) and increased velocity in most conditions (FA/EO, +15%; FA/EC, +16%; FT/EO, +7%, p < 0.0002 for all).ConclusionIn young healthy adults, base of support reduction increases COP displacements. Vision particularly affects postural stability with feet together or dual tasking. Dual tasking increases velocity but decreases COP displacements in challenging postural tasks, potentially by enhanced lower limb stiffness.     

Electromyographic latency of postural evoked responses from the leg muscles during EquiTest Computerised Dynamic Posturography: Reference data on healthy subjects

No normative data are available for the latencies of the EMG signals from the ankle muscles in response to sudden sagittal tilt (toes-UP or toes-DOWN) or shift (shift-FOR or shift-BACK) of the support surface during standing. In this study the postural evoked response (PER) paradigm on the EquiTest™ force platform was applied to 31 healthy adults (18 women and 13 men; mean age 29 years). The EMG latencies (PEREMG) were computed both through the standard manual procedure and through a specially designed automated algorithm. The manually computed PEREMG onset yielded a 95% tolerance interval between 82 ms and 148 ms after toes-UP perturbation, between 93 ms and 182 ms after toes-DOWN perturbation, between 67 ms and 107 ms after shift-BACK perturbation, and between 73 ms and 113 ms after shift-FOR perturbation. When comparing the two methods, paired t-tests showed no significant mean difference (Bonferroni-adjusted p-values ranged from 0.440 to 1.000) and all Bland–Altman plots included zero difference within the limits of agreement. Therefore, the manual and the automated methods appear to be sufficiently consistent. These results foster the clinical application of PEREMG testing on the EquiTest platform.     

Plasma nitrate/nitrite levels are unchanged after long-term aerobic exercise training in older adults

Reduced nitric oxide (NO) production and bioactivity is a major contributor to endothelial dysfunction. Animal data suggest that improvements in endothelial function in response to aerobic exercise training may depend on the duration of the training program. However, no studies have examined changes in NO (as assessed by the major NO metabolites, nitrate and nitrite, NO_x) after long-term training in humans. In addition, aging may impair the ability of the vasculature to increase NO with exercise. Thus, we determined whether 24 weeks of aerobic exercise training increases plasma NO_x levels in sedentary older adults. We also examined changes in forearm blood flow (FBF) at rest and during reactive hyperemia as a measure of vasomotor function. Plasma NO_x levels were measured in 82 men and women using a modified Griess assay. FBF was assessed in a subset of individuals (n = 15) using venous occlusion plethysmography. After 24 weeks of exercise training, there were significant improvements in maximum oxygen consumption, HDL cholesterol, triglycerides, and body fat. Changes in plasma NO_x levels ranged from ?14.83 to +16.69 μmol/L; however, the mean change overall was not significant (?0.33 ± 6.30 μmol/L, p = 0.64). Changes in plasma NO_x levels were not associated with age, gender, race, HDL cholesterol, triglycerides, body weight, body fat, or maximal oxygen consumption. There were also no significant changes in basal FBF, peak FBF, hyperemic response, total hyperemic flow, or minimum forearm vascular resistance with exercise training. In conclusion, improvements in plasma NO_x levels and FBF are not evident after long-term training in older adults.     

Insecticide susceptibility of Ephemera orientalis (Ephemeroptera: Ephemeridae) and two mosquito species,Anopheles sinensis and Culex pipiens in the Republic of Korea

Field-collected populations of mayflies, Ephemera orientalis were tested for susceptibility to 10 different insecticides using a direct-contact mortality bioassay. Ephemera orientalis subimagoes were susceptible to the insecticides chlorpyrifos, fenitrothion and chlorfenapyr with LD₅₀ values of 69.7, 78.8 and 81.9 μg/♀, and adults had LD₅₀ values of 71.9, 78.8 and 85.4 μg/♀, respectively. Susceptibility ratios (SRs) of subimagoes and adults of E. orientalis to the 10 insecticides were 1.0 to1.2 folds. The mayflies showed higher susceptibility to organophosphates than to pyrethroids. The SRs of Anopheles sinensis to E. orientalis were 514 to 1438 folds higher for organophosphates (LD₅₀ values of 0.05 to 0.23 μg/♀) and 62 to 1155 folds higher for pyrethroids (LD₅₀ values of 0.13 to 2.41 μg/♀). The SRs of Culex pipiens to E. orientalis were 606 to 3595 folds higher for organophosphates with LD₅₀ values of 0.02–0.17 μg/♀ and 81 to 1365 folds higher for pyrethroids with LD₅₀ values of 0.11–1.83 μg/♀. These results indicate that the use of ineffective insecticides will result in unsatisfactory control against field populations of the subimagoes and adults of E. orientalis.     

Toxicity of basil and orange essential oils and their components against two coleopteran stored products insect pests

Two commercialized essential oils and their constituent compounds were investigated for fumigant and contact activities against two grain storage insects, adults of the maize weevil (Sitophilus zeamais) and the red flour beetle (Tribolium castaneum). The two commercialized basil and orange oils showed strong fumigant and contact activities against S. zeamais and T. castaneum. The constituents of the basil oil were linalool (21.83%), estragole (74.29%), and α-humulene (2.17%), and those of the orange oil were α-pinene (0.54%), sabinene (0.38%), β-myrcene (1.98%), limonene (96.5%), and linalool (0.6%). As a toxic fumigant, the basil oil was more effective (24-h LC₅₀ = 0.014 and 0.020 mg cm^− 3) than the orange oil (24-h LC₅₀ = 0.106 and 0.130 mg cm^− 3) against S. zeamais and T. castaneum adults, respectively. Among the constituents of the two essential oils, the toxicity of estragole was the highest (0.004 and 0.013), followed by linalool (0.016 and 0.023), limonene (0.122 and 0.171), α-pinene (0.264 and 0.273), and β-myrcene (0.274 and 0.275) based on 24-h LC₅₀ values (mg cm^− 3). Similar results were obtained in a contact toxicity test. The contact activity of basil oil was more toxic than orange oil, and estragole and linalool showed pronounced contact toxicity against S. zeamais and T. castaneum adults. Alpha-humulene had no activity as a fumigant at the tested doses, but it did have an effect as a contact poison, having 24-h LD₅₀ values of 0.040 and 0.045 mg adult^− 1 to S. zeamais and T. castaneum, respectively. Although basil oil, orange oil, and their components displayed both contact and fumigant toxicities, their effects were mainly exerted by fumigant action via the vapor phase. Thus, basil oil, orange oil, and their components could be potential candidates as new fumigants for the control of S. zeamais and T. castaneum adults.     

The effects of feeding on the swimming performance and metabolic response of juvenile southern catfish,Silurus meridionalis,acclimated at different temperatures

To test whether the effects of feeding on swimming performance vary with acclimation temperature in juvenile southern catfish (Silurus meridionalis), we investigated the specific dynamic action (SDA) and swimming performance of fasting and feeding fish at acclimation temperatures of 15, 21, 27, and 33 °C. Feeding had no effect on the critical swimming speeding (U_crit) of fish acclimated at 15 °C (p = 0.66), whereas it elicited a 12.04, 18.70, and 20.98% decrease in U_crit for fish acclimated at 21, 27 and 33 °C, respectively (p < 0.05). Both the maximal postprandial oxygen consumption rate (VO_2peak) and the active metabolic rate (VO_2active, maximal aerobic sustainable metabolic rate of fasting fish) increased significantly with temperature (p < 0.05). The postprandial maximum oxygen consumption rates during swimming (VO_2max) were higher than the VO_2active of fasting fish at all temperature groups (p < 0.05). The VO_2max increased with increasing temperature, but the relative residual metabolic scope (VO_2max? VO_2peak) during swimming decreased with increasing in temperature. The present study showed that the impairment of postprandial swimming performance increased with increasing temperature due to the unparalleled changes in the catfish's central cardio-respiratory, peripheral digestive and locomotory capacities. The different metabolic strategies of juvenile southern catfish at different temperatures may relate to changes in oxygen demand, imbalances in ion fluxes and dissolved oxygen levels with changes in temperature.     

Can acclimation of thermal tolerance,in adults and across generations,act as a buffer against climate change in tropical marine ectotherms?

Thermal acclimation capacity was investigated in adults of three tropical marine invertebrates, the subtidal barnacle Striatobalanus amaryllis, the intertidal gastropod Volegalea cochlidium and the intertidal barnacle Amphibalanus amphitrite. To test the relative importance of transgenerational acclimation, the developmental acclimation capacity of A. amphitrite was investigated in F₁ and F₂ generations reared at a subset of the same incubation temperatures. The increase in CT_max (measured through loss of key behavioural metrics) of F₀ adults across the incubation temperature range 25.4–33.4 °C was low: 0.00 °C (V. cochlidium), 0.05 °C (S. amaryllis) and 0.06 °C (A. amphitrite) per 1 °C increase in incubation temperature (the acclimation response ratio; ARR). Although the effect of generation was not significant, across the incubation temperature range of 29.4–33.4 °C, the increase in CT_max in the F₁ (0.30 °C) and F₂ (0.15 °C) generations of A. amphitrite was greater than in the F₀ (0.10 °C). These correspond to ARR's of 0.03 °C (F₀), 0.08 °C (F₁) and 0.04 °C (F₂), respectively. The variability in CT_max between individuals in each treatment was maintained across generations, despite the high mortality of progeny. Further research is required to investigate the potential for transgenerational acclimation to provide an extra buffer for tropical marine species facing climate warming.     

Reciprocal influences on performances of a postural–suprapostural task by manipulating the level of task-load

The objective of this study was to investigate the reciprocal influences of stance pattern (bilateral stance vs. unilateral stance) and thumb-index precision grip task (static target vs. dynamic target) on postural–suprapostural tasks by manipulating task-load. Fifteen healthy volunteers participated in four postural–suprapostural tasks, including static force-matching in bilateral/unilateral stance (BS_static; US_static), dynamic force-matching in bilateral/unilateral stance (BS_dynamic; US_dynamic), and two control tasks in bilateral and unilateral stances without a finger task. The normalized force error (NFE), reaction time (RT) of the finger tasks, and normalized change in center of pressure sway (ΔNCoP) were measured. For suprapostural task performance, a significant interaction effect between postural and suprapostural tasks on NFE of the finger tasks was noted (static: BS < US; dynamic: BS > US), but RT was not different among the four tasks. For postural task performance, negative ΔNCoP during unilateral stance indicated a spontaneous reduction in postural sway due to added force-matching. In contrast, addition of force-matching tended to increase postural sway during bilateral stance, but postural fluctuations decreased as task-load of suprapostural task increased (BS_dynamic < BS_static). In conclusion, performance of postural–suprapostural tasks was differently modulated by task-load increment. Our observations favored adaptive resource-sharing and implicit expansion of resource capacity for a postural task with a motor suprapostural goal.     

Enhancing bio-suppression of Parthenium hysterophorus L.: Diapause in Zygogramma bicolorata Pallister and its manipulation through insulin-like peptides (ILPs)

In-depth investigations on diapause behaviour of Z. bicolorata revealed that the adults entered diapause at any time from August to December and that the number peaked (42.00%) during the last half of November. The percentage of adults entering diapause increased with a decrease in day length. Weight of diapausing adults was significantly higher than weight of non-diapausing adults. The percentage of adults undergoing diapause at 30 °C was significantly lower than those undergoing diapause at 15 and 25 °C. The percentage of adults burrowing increased with increasing moisture. In silty soil and soil with high organic matter, 46.7% and 49.2% of adults entered diapause, respectively, whereas in sandy soil, only 23.5% of adults entered diapause. When newly emerged beetles were exposed to 5 μg of human insulin 30/70, a significantly lower percentage of treated adults underwent diapause compared to untreated adults under both feeding and no feeding conditions. Insulin treatment also influenced the emergence period from diapause (93.92 ± 1.73 days), percent emergence (81 ± 1.54%) and fecundity/month (512.7 ± 25.38 eggs) of Z. bicolorata in treated adults as compared to untreated adults (109.05 ± 2.2, 74.00 ± 1.82 and 438.3 ± 19.33 eggs, respectively). However, there was no significant impact of insulin on adult longevity. These findings are of great utility in the biological suppression of Parthenium as it will enhance the effectiveness of this beetle through manipulation of diapause.     

Role of vision and task complexity on soleus H-reflex gain

There exists extensive evidence supporting the presence of reflex modulation in humans during a variety of motor tasks. The soleus H-reflex has been shown to be modulated during static and dynamic balance conditions as well as during various motor tasks. The purpose of this study was to examine the effects of two different stance positions and visual conditions on soleus H-reflex gain in 15 apparently healthy adults (mean age = 30.27 ± 6.92 yrs). The soleus H-reflexes were examined in two experimental stance conditions: two-legged (stable) and one-leg (unstable), and two visual conditions: eyes open and eyes closed. To assess the reflex gain, subjects performed ten trials under each of the four conditions and a soleus H-reflex was elicited during the performance of each trial. For each condition the peak-to-peak amplitude of the H-reflex and the EMG activity 50 ms prior to the stimulus was recorded. Differences in the peak-to-peak amplitudes of the soleus H-reflex for the experimental conditions were compared with a 2 × 2 (Stance × Vision) repeated measures ANOVA. The level of significance was p < 0.05. Results demonstrated significant differences in reflex gain for both the vision (F_l,15 = 4.87, p < 0.05) and the stance condition (F_l,15 = 14.86, p < 0.05). Although both the stance condition and vision significantly affected the H-reflex gain, there was no interaction between these two variables (F_l,15 = 0.17). From these results, we conclude that H-reflex gain was decreased both as stance complexity increased and as visual inputs were removed. Consistent with previous reports, it may be speculated that changes in presynaptic inhibition to the soleus Ia fibers regulate these gain changes. We propose that vision and stability of stance affect soleus H-reflex gain, but do so without any interactive effects.