Effects Of Different Frequencies Research Articles

Modulation of spinal inhibitory reflexes depends on the frequency of transcutaneous electrical nerve stimulation in spastic stroke survivors

Neurophysiological studies in healthy subjects suggest that increased spinal inhibitory reflexes from the tibialis anterior (TA) muscle to the soleus (SOL) muscle might contribute to decreased spasticity. While 50 Hz is an effective frequency for transcutaneous electrical nerve stimulation (TENS) in healthy subjects, in stroke survivors, the effects of TENS on spinal reflex circuits and its appropriate frequency are not well known. We examined the effects of different frequencies of TENS on spinal inhibitory reflexes from the TA to SOL muscle in stroke survivors. Twenty chronic stroke survivors with ankle plantar flexor spasticity received 50-, 100-, or 200-Hz TENS over the deep peroneal nerve (DPN) of the affected lower limb for 30 min. Before and immediately after TENS, reciprocal Ia inhibition (RI) and presynaptic inhibition of the SOL alpha motor neuron (D1 inhibition) were assessed by adjusting the unconditioned H-reflex amplitude. Furthermore, during TENS, the time courses of spinal excitability and spinal inhibitory reflexes were assessed via the H-reflex, RI, and D1 inhibition. None of the TENS protocols affected mean RI, whereas D1 inhibition improved significantly following 200-Hz TENS. In a time-series comparison during TENS, repeated stimulation did not produce significant changes in the H-reflex, RI, or D1 inhibition regardless of frequency. These results suggest that the frequency-dependent effect of TENS on spinal reflexes only becomes apparent when RI and D1 inhibition are measured by adjusting the amplitude of the unconditioned H-reflex. However, 200-Hz TENS led to plasticity of synaptic transmission from the antagonist to spastic muscles in stroke survivors.

Immediate effects of different frequencies of auditory stimulation on lower limb motor function of healthy people

[Purpose] The purpose of this study was to explore the immediate effects of different frequencies of auditory stimulation on the lower limb motor function of healthy people. [Subjects and Methods] The subjects were 7 healthy people (5 males and 2 females). The subjects’ lower limb function was measured without auditory stimulation (control), and with auditory stimulation of 500, 1,000, 1,500, and 2,000 Hz. The measured parameters were maximum knee extension torque, average knee extension torque, the Timed Up and Go test (TUG) time, Functional Reach (FR), and the 10-meter walking time. [Results] The TUG times of 500, 1,500, and 2,000 Hz auditory stimulation showed significant decreases compared to the control. The 10-m walking times of 1,000 and 2,000 Hz auditory stimulation showed significant decreases compared to the control. [Conclusion] The results show that auditory stimulation improved the TUG and 10-meter walking times of healthy people and that different frequencies of auditory stimulation had different effects on lower limb motor function.

Effect of Frequency and Migration Aperture on Seismic Diffraction Imaging

Conventional processing and migration frequently give successful results in using specular reflections to estimate the subsurface geometry and strength of continuous reflector geology. However, the correct interpretation of the true geological gaps, such as fault, fracture, karsts and pinch-outs, is one of the main objectives in seismic data processing and interpretation. In regular processing/migration sequence the diffraction response is suppressed because of the lack of choosing the right migration aperture. Kirchhoff migration is a tool to represent the seismic data as a summation of diffraction hyperbolas governed by the velocities at their apex. In this paper, we have investigated two different velocity models to show the effects of different frequencies and aperture size. We used the diffraction-based and data oriented approach that is dependent on the migration aperture from a low to high aperture to properly image the section. We have done the error analysis between the un-imaged and imaged section after processing and observed that the low aperture can give the undesired result for sharp edges. For the same model, we have applied different frequencies to show the effect of frequencies on seismic Imaging and migration.

Effects of different frequencies of repetitive transcranial magnetic stimulation on the recovery of upper limb motor dysfunction in patients with subacute cerebral infarction.

Studies have confirmed that low-frequency repetitive transcranial magnetic stimulation can decrease the activity of cortical neurons, and high-frequency repetitive transcranial magnetic stimulation can increase the excitability of cortical neurons. However, there are few studies concerning the use of different frequencies of repetitive transcranial magnetic stimulation on the recovery of upper-limb motor function after cerebral infarction. We hypothesized that different frequencies of repetitive transcranial magnetic stimulation in patients with cerebral infarction would produce different effects on the recovery of upper-limb motor function. This study enrolled 127 patients with upper-limb dysfunction during the subacute phase of cerebral infarction. These patients were randomly assigned to three groups. The low-frequency group comprised 42 patients who were treated with 1 Hz repetitive transcranial magnetic stimulation on the contralateral hemisphere primary motor cortex (M1). The high-frequency group comprised 43 patients who were treated with 10 Hz repetitive transcranial magnetic stimulation on ipsilateral M1. Finally, the sham group comprised 42 patients who were treated with 10 Hz of false stimulation on ipsilateral M1. A total of 135 seconds of stimulation was applied in the sham group and high-frequency group. At 2 weeks after treatment, cortical latency of motor-evoked potentials and central motor conduction time were significantly lower compared with before treatment. Moreover, motor function scores were significantly improved. The above indices for the low- and high-frequency groups were significantly different compared with the sham group. However, there was no significant difference between the low- and high-frequency groups. The results show that low- and high-frequency repetitive transcranial magnetic stimulation can similarly improve upper-limb motor function in patients with cerebral infarction.

Monophasic Pulsed Microcurrent of 1-8 Hz Increases the Number of Human Dermal Fibroblasts.

Pressure injuries seriously impact the quality of life of patients and increase public and private healthcare costs. Electrical stimulation therapy is recommended for wound contraction, and some clinical studies have shown that the application of a monophasic pulsed microcurrent can help to reduce the treatment period. However, the optimal stimulus conditions are unclear. The purpose of this study was to investigate the effect of different frequencies of monophasic pulsed microcurrent stimulation on the number and viability of human dermal fibroblasts. Human dermal fibroblasts were electrically stimulated in vitro (intensity: 200 μA; frequency: 1, 2, 4, 8, 16, 32, and 64 Hz; duty factor: 50%) for 1 h three times every 24 h. Controls were unstimulated. Cell numbers and cell viability were assessed after each electrical stimulation session. In the 1-, 2-, 4-, and 8-Hz groups, cell numbers were significantly higher than those in the control group, whereas electrical stimulation at 64 Hz resulted in a decrease in cell numbers at 24 h after the third treatment (p < 0.05). Cell viability was high in both the control and low-frequency stimulation groups, with no significant differences between groups. Application of 1-8 Hz monophasic pulsed microcurrent stimulation increased the number of human dermal fibroblasts in vitro, and is proposed as the optimal condition for accelerating the healing of pressure injuries.

Investigation of the Durability of a Diaphragm for a Total Artificial Heart.

One of the most critical components regarding the durability of the ReinHeart total artificial heart (TAH) is its biocompatible diaphragm, which separates the drive unit from the ventricles. Hence, a durability tester was designed to investigate its required 5-year lifetime. The aim of this study was to prove the validity of accelerated testing of the polyurethane diaphragm. The durability tester allows simultaneous testing of 12 diaphragms and mimics physiological conditions. To accelerate the time of testing, it operates with an increased speed at a frequency of 8 Hz. To prove the correctness of this acceleration, a servo-hydraulic testing machine was used to study the effect of different frequencies and their corresponding loads. Thereby the viscoelastic behavior of the polyurethane was investigated. Additionally, high-speed video measurements were performed. The force against frequency and the high-speed video measurements showed constant behavior. In the range of 1-10 Hz, the maximum resulting forces varied by 3%, and the diaphragm movement was identical. Frequencies below 10 Hz allow a valid statement of the diaphragm's mechanical durability. Viscoelasticity of the polyurethane in the considered frequency-range is negligible. The accelerated durability test is applicable to polyurethane diaphragms, and the results are applicable to TAH use. The reliability of the diaphragm for a lifetime of 5 years was found to be 80% with a confidence of 62%.

Modelling control of Schistosoma haematobium infection: predictions of the long-term impact of mass drug administration in Africa

BackgroundEffective control of schistosomiasis remains a challenging problem for endemic areas of the world. Given knowledge of the biology of transmission and past experience with mass drug administration (MDA) programs, it is important to critically evaluate the likelihood that MDA programs will achieve substantial reductions in Schistosoma prevalence. In implementing the World Health Organization Roadmap for Neglected Tropical Diseases it would useful for policymaking to model projections of the status of Schistosoma control in MDA-treated areas in the next 5–10 years.MethodsCalibrated mathematical models were used to project the effects of different frequency and coverage of MDA for schistosomiasis haematobia control in present-day endemic communities, taking into account uncertainties of parasite biology and input data. The modeling approach in this analysis was the Stratified Worm Burden model developed in our earlier works, calibrated using data from longitudinal S. haematobium control trials in Kenya.ResultsModel-based simulations of MDA control in typical low-risk and higher-risk communities indicated that infection prevalence can be substantially reduced within 10 years only when there is a high degree of community participation (>70 %) with at least annual MDA. Significant risk for re-emergence of infection remains if MDA is suspended.ConclusionsIn a stable (stationary) ecosystem, Schistosoma reproduction and transmission are sufficiently robust that the process of human infection continues, even under pressure from aggressive MDA. MDA alone is unlikely to interrupt transmission, and once mass treatment is suspended, the prevalence of human infection is likely to rebound to pre-control levels over a period of 25–30 years. MDA success in achieving very low levels of infection prevalence is highly dependent on treatment coverage and frequency within the local human population, and requires that both adults and children be included in drug delivery coverage. Ultimately, supplemental snail control and significant improvements in sanitation will be required to achieve full control of schistosomiasis by elimination of ongoing Schistosoma transmission.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-1144-3) contains supplementary material, which is available to authorized users.

Corrente interferencial no limiar de dor induzida à pressão e ao frio, nas frequências de 2 kHz, 4 kHz e 8 kHz

Introdução: A corrente interferencial é uma forma de estimulação elétrica nervosa transcutânea, com finalidades terapêuticas, a qual tem seus efeitos analgésicos avaliados por modelos experimentais para indução da dor, como a dor ao frio e à pressão. Objetivo: Verificar a eficácia das diferentes frequências (2000 Hz, 4000 Hz e 8000 Hz) na alteração do limiar de dor ao frio e à pressão. Métodos: Vinte voluntários foram divididos aleatoriamente em quatro grupos e foram estimulados por diferentes frequências. Foram avaliados os limiares da dor por pressão e ao frio, além do desconforto pela Escala Visual Analógica. As formas de avaliação ocorreram prévias à estimulação, e 20 e 60 minutos após esta. Resultados: Não houve diferenças significativas, tanto no grupo placebo quanto nos três grupos que passaram pela eletroestimulação. Conclusão: Não houve alteração no limiar de dor induzida ao frio e à pressão nas diferentes frequências da corrente interferencial.

Fatigue and post-fatigue behavior of PBO FRCM-concrete joints

Fiber-reinforced cementitious matrix (FRCM) composites may represent a valid alternative to the use of traditional techniques for strengthening and retrofitting existing reinforced concrete (RC) and masonry structures. Although FRCM composites appear to be an effective strengthening technique for RC structures, limited work is available in the literature. In this paper the behavior of FRCM-concrete joints subjected to fatigue and post-fatigue quasi-static monotonic loading is presented and discussed. The single-lap direct-shear test set-up was adopted in this study. The fatigue loading protocol was designed to investigate the effects of different frequencies and different load ranges on: (a) the interfacial slip; (b) the dissipated energy during cycles; (c) the stiffness degradation of the interface; and (d) the post-fatigue quasi-static monotonic behavior. In general, it was observed that different combination of amplitude and mean value of the load range implies different damage measured in terms of slip, energy dissipation, and stiffness degradation. A fracture mechanics approach was proposed to describe the intermediate range of the fatigue crack growth for different frequencies.

Characterization and Modulation of High Power Diode Laser Module as a Target Designator

In a laser tracking system (LTS) the objective is to track the reflected or scattered modulated laser beam. A four-quadrant is essentially required to center and align the optical axis of the quad detector (QD) with the main laser beam. This paper shows an experimental characterization of a high power diode laser module as a laser target designator source (LTD) used in the tracking system. It includes the (I-V) characteristic, output optical power verses driving electrical currents, slope efficiency, the laser beam profile and the wavelength dependence of temperature. Like all practical designation and tracking system, a modulation of a high power laser source with pulse repetition frequencies (PRF) mode of operation is required. So the effect of different frequencies on both of the pulse to pulse stability and wavelength stability are measured, analyzed and investigated.

Effects of different frequencies of rhythmic auditory cueing on the stride length, cadence, and gait speed in healthy young females.

[Purpose] The aim of this study was to explore the effects of different frequencies of rhythmic auditory cueing (RAC) on stride length, cadence, and gait speed in healthy young females. The findings of this study might be used as clinical guidance of physical therapy for choosing the suitable frequency of RAC. [Subjects] Thirteen healthy young females were recruited in this study. [Methods] Ten meters walking tests were measured in all subjects under 4 conditions with each repeated 3 times and a 3-min seated rest period between repetitions. Subjects first walked as usual and then were asked to listen carefully to the rhythm of a metronome and walk with 3 kinds of RAC (90%, 100%, and 110% of the mean cadence). The three frequencies (90%, 100%, and 110%) of RAC were randomly assigned. Gait speed, stride length, and cadence were calculated, and a statistical analysis was performed using the SPSS (version 17.0) computer package. [Results] The gait speed and cadence of 90% RAC walking showed significant decreases compared with normal walking and 100% and 110% RAC walking. The stride length, cadence, and gait speed of 110% RAC walking showed significant increases compared with normal walking and 90% and 100% RAC walking. [Conclusion] Our results showed that 110% RAC was the best of the 3 cueing frequencies for improvement of stride length, cadence, and gait speed in healthy young females.

Clinical efficacy of different frequency repetitive transcranial magnetic stimulation for tardive dyskinesia

Objective To investigate the effect of different frequency of repetitive transcranial magnetic stimulation (rTMS)on tardive dyskinesia (TD). Methods Schizophrenia combined with antipsychotic-induced TD were screened. All patients were planed to receive 1Hz or 10Hz rTMS for 4 weeks in which two weeks’ break was inserted at end of 2nd weekend. The curative effect and side effects were assessed by abnormal involuntary movement scale(AIMS) and rating scale for extrapyramidal side effects(RSESE) respectively at before and after treatment. Results In the 1Hz group, only Involuntary movements of the upper extremities were improved after rTMS treatment (before treatment 2.6±1.0, after treatment 1.8±1.1), the difference was statistically significant (P <0.05). But in 10Hz group, upper extremities(before treatment 1.9±1.2, 0.8±0.9 after treatment), mouth(before treatment 1.0±0.8, after treatment 0.3±0.5), tongue(before treatment 2.6±0.9, after treatment 1.7±0.9), and total score(before treatment 7.7±3.0, after treatment 4.2±1.7) significantly decreased after rTMS treatment(P <0.05 or <0.01). In addition, the reduction rates in both the lower extremities and the total score was statistically different between the two groups (P<0.05 ). Conclusion rTMS can reduce the symptom of involuntary movement of TD patients and 10Hz rTMS is better. Key words: Repetitive transcranial magnetic stimulation (rTMS); Schizophrenia; Tardive dyskinesia(TD); Efficacy

Acute Effects of Whole-Body Vibration on Trunk Muscle Functioning in Young Healthy Adults

The purpose of this study was to explore the immediate effects of different frequencies of whole-body vibration (WBV) on the performance of trunk muscles of healthy young adults. A group of 30 healthy subjects (15 men; 15 women; age, 26.8 ± 3.74 years; body mass index, 21.9 ± 1.802) participated in the study. Each subject received 3 sessions of vibration exercise with different exercise parameters with frequencies of 25 Hz and 40 Hz and sham stimulation in a random order on different days. Before and after each WBV exercise session, subjects were assessed for trunk muscle strength/endurance tests and trunk proprioception tests. There was a significant increase in trunk extensor strength (p ≤ 0.05) after low-frequency (25 Hz) WBV exercise, but high-frequency (40 Hz) vibration exercise had resulted in a significant decrease in trunk extensor endurance (p ≤ 0.05). Statistical gender difference (p = 0.04) was found for trunk extensor endurance with lower WBV training. No change was noted in the trunk proprioception with different frequencies of WBV. In conclusions, the immediate response of the body to WBV was different for low and high frequencies. Low-frequency vibration enhanced trunk extensor strength, but high-frequency vibration would decrease endurance of the trunk extensor muscles. Males are more sensitive than females in trunk extensor endurance for lower frequency WBV exposure. These results indicated that short-term WBV with low frequency was effective to improve trunk extensor strength in healthy adults, and that could be helpful for relevant activities of trunk extensor performing and preventing sport injury.

Influence of slope on physical soil disturbance due to farm tractor forwarding in a Hyrcanian forest of northern Iran

Tractor-based systems are the most common type of small-scale timber harvesting equipment in the Hyrcanian forest, where farm tractors equipped with a 2-wheel trailer typically perform forwarding operations for pulpwood and fuelwood. The objective of this study was to evaluate the effects of different frequencies of machine passes on soil bulk density (BD), penetration resistance (PR) and total porosity (TP) in different slope gradient and forwarding direction (i.e., uphill vs. downhill). The study, performed on a brown soil with a silt loam to loamy texture, was designed as a factorial experiment with three slope gradient/forwarding direction classes (0-10% downhill forwarding slope, 10-20% downhill forwarding slope and 0-10% uphill forwarding slope) and four traffic intensity classes (0 [undisturbed control area], 1-4, 5-10 and >10 machine passes). Responses were assessed at four soil profile depth classes (5, 10, 15 and 20 cm). BD and PR significantly increased and TP significantly decreased with increasing machine traffic, with magnitudes of change that were not consistently greater in the upper 5 cm compared to the 20 cm soil profile depth class. Whereas the majority of changes in BD and TP occurred after fewer than 5 passes, large increases in PR occurred even after 10 passes. Changes of BD, PR and TP in response to machine traffic differed significantly among slope gradient/forwarding direction classes. Increases in BD and PR and decreases in TP were largest on the 0-10% uphill forwarding slope, followed by the 10-20% downhill and 0-10% downhill forwarding slope. We conclude that the application of farm tractors in forwarding operations should be limited to gentle slopes and uphill forwarding with these machines should be avoided.

Efeitos de diferentes frequências da estimulação elétrica nervosa transcutânea em relação à acomodação e à agradabilidade

AIMS: The aim of this study was to investigate the effects of different frequencies of transcutaneous electrical nerve stimulation (TENS) regarding to accommodation and pleasantness of the different forms of application. METHODS: The sample consisted of 20 subjects randomly divided into 3 groups, in which they were submitted to 3 different frequencies of TENS: 7 Hz, 100Hz, 255Hz, pulse duration of 250 µs, for 20 minutes once a week over three weeks. The volunteers were instructed to indicate the first and subsequent accommodation moments. At the end of the period of data collection, subjects were asked about which frequency they thought most enjoyable. RESULTS: For the threshold of adaptation, considering all frequencies analyzed, it was found that there was no significant difference (p> 0.05), a fact that was also repeated for the number of adaptations in 20 minutes (p> 0.05). With regard to pleasantness, 11 subjects indicated the frequency of 7 Hz as the most enjoyable. CONCLUSIONS: There was no significant difference in threshold for adaptation and the number of adaptations between the frequencies used. The frequency of 7 Hz was identified as the most enjoyable then the frequency of 100 Hz.

Effects of different frequencies of transcutaneous electrical nerve stimulation on venous vascular reactivity.

Transcutaneous electrical nerve stimulation (TENS) is a type of therapy used primarily for analgesia, but also presents changes in the cardiovascular system responses; its effects are dependent upon application parameters. Alterations to the cardiovascular system suggest that TENS may modify venous vascular response. The objective of this study was to evaluate the effects of TENS at different frequencies (10 and 100 Hz) on venous vascular reactivity in healthy subjects. Twenty-nine healthy male volunteers were randomized into three groups: placebo (n=10), low-frequency TENS (10 Hz, n=9) and high-frequency TENS (100 Hz, n=10). TENS was applied for 30 min in the nervous plexus trajectory from the superior member (from cervical to dorsal region of the fist) at low (10 Hz/200 μs) and high frequency (100 Hz/200 μs) with its intensity adjusted below the motor threshold and intensified every 5 min, intending to avoid accommodation. Venous vascular reactivity in response to phenylephrine, acetylcholine (endothelium-dependent) and sodium nitroprusside (endothelium-independent) was assessed by the dorsal hand vein technique. The phenylephrine effective dose to achieve 70% vasoconstriction was reduced 53% (P<0.01) using low-frequency TENS (10 Hz), while in high-frequency stimulation (100 Hz), a 47% increased dose was needed (P<0.01). The endothelium-dependent (acetylcholine) and independent (sodium nitroprusside) responses were not modified by TENS, which modifies venous responsiveness, and increases the low-frequency sensitivity of α1-adrenergic receptors and shows high-frequency opposite effects. These changes represent an important vascular effect caused by TENS with implications for hemodynamics, inflammation and analgesia.

Effects of different frequencies of conventional transcutaneous electrical nerve stimulation on pressure pain threshold and tolerance

Pulse frequency is one of the key determinants of analgesic outcomes by transcutaneous electrical nerve stimulation (TENS). However, optimal settings remain unclear. To compare the effects of different frequencies of TENS, on pressure pain threshold and tolerance. Currents with pulse duration of 110 μs, and pulse frequencies of 60 pps or 150 pps were applied on the volar aspects of the dominant forearms of 20 healthy volunteers, on two consecutive days, in a randomized order. Threshold and tolerance were measured at the beginning, after the 15th and 30th minutes of the applications, and 30 minutes after the applications. Pressure pain threshold and tolerance values were higher at the 150 pps frequency, at all measurement times (p< 0.05). However, no frequencyXtime interaction and time-dependent changes were found for the outcome measures (p> 0.05). These findings established that, at 150 pps conventional TENS, threshold and tolerance values were consistently higher. These results are presented to inform future research regarding optimal conventional TENS parameters and to provide support for clinical applications.

Effect of Extremely Low-Frequency (ELF) Magnetic Fields on the Potency of Drugs in Bacterial Cells

Our previous paper showed that magnetic fields (60 Hz, 50 mT) enhance the potency of the drugs mitomycin C and cisplatin in bacterial cells and suggested that magnetic fields change the permeability of the cell membrane and increase drug uptake. The present paper demonstrates the effect of magnetic fields (60 Hz, 50 mT) on the potency of five different drugs in Escherichia coli cells and additionally assessed the effects of different frequencies of ac magnetic fields. The drugs such as mitoxantrone, daunorubicin, actinomycin D, bleomycin, and zinostatin differ from one another in certain characteristics such as molecular weight and cellular action mechanism. The results showed that the potency of mitoxantrone, daunorubicin, actinomycin D, and bleomycin enhanced approximately 1.3-fold as drug concentration on exposure to the magnetic fields for 6 h. However, in the case of zinostatin, the enhancement was only 1.03-fold. Zinostatin differs from other drugs in that it is a polymeric compound and has an average molecular weight of 15000, which is ten or more times greater than that of the other drugs. These results indicate that magnetic fields (60 Hz, 50 mT) have the ability to enhance the potency of a number of different drugs, although it was difficult to influence the potency of zinostatin. The results of different frequencies of the ac magnetic fields indicated that approximately 60 Hz is the most effective frequency for enhancing the potency of mitomycin C.

Verbal Fluency in Essential Tremor Patients: The Effects of Deep Brain Stimulation

To assess the effects of different frequencies of thalamic Deep-Brain-Stimulation (DBS) on cognitive performance of patients suffering from Essential Tremor (ET). In 17 ET-patients with thalamic-DBS, Tremor-Rating-Scale (TRS), standardized phonemic and semantic verbal fluency (VF), Stroop-Color-Word-Test and Digit-span-test were investigated in three randomized stimulation-settings: i) high-frequency stimulation (HFS), ii) low-frequency stimulation (LFS) and iii) OFF-stimulation (DBS-OFF). Paired-samples t-test for TRS and one-way repeated measures analysis of variance for cognitive performance were calculated. Tremor was reduced during HFS (MeanTRS-HFS = 12.9 ± 9.6) compared to DBS-OFF (MeanTRS-OFF = 44.4 ± 19.8, P < .001) and to LFS (MeanTRS-10 Hz = 50.0 ± 24.2; P < .001). While performance of Stroop-task and digit-span remained unaffected by stimulation-settings (P > .05), phonemic and semantic VF differed significantly between the three conditions (FPvf = 5.28, FSvf = 3.41, both P < .05). Post-hoc comparisons revealed significant differences for both phonemic and semantic VF between LFS (MeanPvf-10 Hz = 54.6 ± 9.2, MeanSvf-10 Hz = 56.4 ± 7.9) and HFS (MeanPvf-ON = 48.3 ± 11.4, MeanSvf-ON = 51.1 ± 11.0, both P < .05), while DBS-OFF (MeanPvf-OFF = 51.2 ± 9.3, MeanSvf-OFF = 53.6 ± 12.9) and HFS and DBS-OFF and LFS did not differ significantly (P > .05). HFS compared to LFS or DBS-OFF significantly reduced tremor but simultaneously worsened VF while working memory and cognitive inhibition remained unaffected. In contrast, LFS enhanced VF but did not ameliorate tremor. The data emphasize the relevance of thalamocortical loops for verbal fluency but also suggest that more sophisticated DBS-regimes in ET may improve both motor and cognitive performance.

Fitness costs associated with different frequencies and magnitudes of temperature change in the butterfly Bicyclus anynana

Plastic responses to changes in environmental conditions are ubiquitous and typically highly effective, but are predicted to incur costs. We here investigate the effects of different frequencies and magnitudes of temperature change in the tropical butterfly Bicyclus anynana, considering developmental (Experiment 1) and adult stage plasticity (Experiment 2). We predicted negative effects of more frequent temperature changes on development, immune function and/or reproduction. Results from Experiment 1 showed that repeated temperature changes during development, if involving large amplitudes, negatively affect larval time, larval growth rate and pupal mass, while adult traits remained unaffected. However, results from treatment groups with smaller temperature amplitudes yielded no clear patterns. In Experiment 2 prolonged but not repeated exposure to 39°C increased heat tolerance, potentially reflecting costs of repeatedly activating emergency responses. At the same time fecundity was more strongly reduced in the group with prolonged heat stress, suggesting a trade-off between heat tolerance and reproduction. Clear effects were restricted to conditions involving large temperature amplitudes or high temperatures.