Search results for " latency"
showing 10 items of 65 documents
Diversity of foraging strategies and responses to predator interference in seed-eating carabid beetles
2019
12 pages; International audience; The prediction of pest regulation by multi-predator communities often remains challenging because of variable and opposite effects of niche complementarity and predator interference. Carabid communities are regulating weeds in arable fields and include a mix of species ranging from granivores to predators that are obligate omnivores. It is not clear from field studies whether granivore and obligate omnivore species either contribute equally or are complementary in the process of weed suppression, and little is known about the impact of potential predator interference within carabid communities on weed suppression. We compared the weed seed foraging strategy…
Detecting differences with magnetoencephalography of somatosensory processing after tactile and electrical stimuli.
2018
Abstract Background Deviant stimuli within a standard, frequent stimulus train induce a cortical somatosensory mismatch response (SMMR). The SMMR reflects the brain’s automatic mechanism for the detection of change in a somatosensory domain. It is usually elicited by electrical stimulation, which activates nerve fibers and receptors in superficial and deep skin layers, whereas tactile stimulation is closer to natural stimulation and activates uniform fiber types. We recorded SMMRs after electrical and tactile stimuli. Method 306-channel magnetoencephalography recordings were made with 16 healthy adults under two conditions: electrical (eSMMR) and tactile (tSMMR) stimulations. The SMMR proto…
Murine cytomegalovirus (CMV) infection via the intranasal route offers a robust model of immunity upon mucosal CMV infection
2016
Cytomegalovirus (CMV) is a ubiquitous virus, causing the most common congenital infection in humans, yet a vaccine against this virus is not available. Experimental studies of immunity against CMV in animal models of infection, such as the infection of mice with mouse CMV (MCMV), have relied mainly on parenteral infection protocols, although the virus naturally transmits by mucosal routes via body fluids. To characterize the biology of infections by mucosal routes, we compared the kinetics of virus replication, latent viral load and CD8 T-cell responses in lymphoid organs upon experimental intranasal (targeting the respiratory tract) and intragastric (targeting the digestive tract) infectio…
Gamma interferon blocks gammaherpesvirus reactivation from latency in a cell type-specific manner
2007
Gammaherpesviruses are important pathogens whose lifelong survival in the host depends critically on their capacity to establish and reactivate from latency, processes regulated by both viral genes and the host immune response. Previous work has demonstrated that gamma interferon (IFN-gamma) is a key regulator of chronic infection with murine gammaherpesvirus 68 (gammaHV68), a virus that establishes latent infection in B lymphocytes, macrophages, and dendritic cells. In mice deficient in IFN-gamma or the IFN-gamma receptor, gammaHV68 gene expression is altered during chronic infection, and peritoneal cells explanted from these mice reactivate more efficiently ex vivo than cells derived from…
Short and long latency reflex responses elicited by electrical and mechanical stimulation in human hand muscle
1986
The relationship between electrically and mechanically induced reflex responses in the rectified, averaged surface electromyogram of the first interosseus dorsalis muscle was examined in 18 healthy human subjects. Both methods evoked identifiable short and long latency reflex responses. The onset latencies for short latency reflexes with electrical and mechanical stimulations were 30.6 ms (+/- 2.2 ms) and 28.9 ms (+/- 2.2 ms) and for long latency reflexes 50.0 ms (+/- 2.8 ms) and 51.2 ms (+/- 5.2 ms), respectively. The correlation of the onset latencies of the reflexes revealed significant correspondence between the electrical and mechanical methods implying at least partly mutual mechanism…
Effects of Pulsed High-Frequency Electromagnetic Fields on Human Sleep
1996
In the present study we investigated the influence of pulsed high-frequency electromagnetic fields of digital mobile radio telephones on sleep in healthy humans. Besides a hypnotic effect with shortening of sleep onset latency, a REM suppressive effect with reduction of duration and percentage of REM sleep was found. Moreover, spectral analysis revealed qualitative alterations of the EEG signal during REM sleep with an increased spectral power density. Knowing the relevance of REM sleep for adequate information processing in the brain, especially concerning mnestic functions and learning processes, the results emphasize the necessity to carry out further investigations on the interaction of…
Short-latency stretch reflex modulation in response to varying soleus muscle activities.
2002
The current investigation examined the effect of various types of background muscle contractions on the short-latency stretch reflex (SLR) elicited from the soleus muscle while subjects were in a sitting position. A stretch was applied to the calf muscles while they performed an isometric (pre-ISO), shortening (pre-SHO) and lengthening contraction (pre-LEN) with several pre-contraction levels. The ankle was at a 90 degrees tibio-tarsal joint angle when the perturbation was applied. Subjects developed and maintained a given pre-load level, which was maintained at various percentages of the maximum voluntary isometric plantar flexion torque. This was performed at 80 degrees in pre-SHO, 90 deg…
The effects of muscle history on short latency stretch reflex response of soleus muscle
2003
Abstract The purpose of the present study was to investigate the combined effects of muscle history, activation and stretching velocity on short latency stretch response (SLR). Stretches (70, 120 and 200 deg s-1) were elicited to both passive and active (10–25% MVC) triceps surae muscle with constant (ISO), lengthened (LEN) or shortened (SHO) muscle length. Under the passive SHO pre-condition both SLR amplitude and reflex torque (RT) decreased where as latency increased compared with the passive ISO pre-condition. Such observations were absent in active trials. Stretches applied to a lengthening passive muscle (LEN) resulted in smaller SLR amplitude and RT compared with passive ISO. In acti…
Neuromuscular control in landing from supra-maximal dropping height.
2009
International audience; The present study utilized high-impact supra-maximal landings to examine the influence of the pre-impact force level on the post-impact electromyographic (EMG) activity and, in particular, on the short latency EMG reflex (SLR) component. Unilateral-leg landings were performed in a sitting position on a sledge apparatus after release from high, but individually constant dropping height. A lower limb guiding device fixed to the front of the sledge seat allowed the subjects to sustain a given pre-set force level up to impact. This force level was either freely chosen or set at 20, 35, and 50% of maximal isometric plantarflexion force. EMG activity was recorded from eigh…
Conventional and spectral power analysis of all-night sleep EEG after subchronic treatment with paroxetine in healthy male volunteers.
1998
Paroxetine is a selective and potent serotonin reuptake inhibitor with reported antidepressant properties. Since changes in the regular sleeping pattern were described as side effects under treatment with paroxetine, the impact of the drug on the sleep architecture is of major interest. The present study addressed the question of subchronic effects of paroxetine medication (30 mg/day) in eight healthy male volunteers in a double blind, placebo-controlled crossover-design. Conventional sleep EEG parameters and additionally computed spectral power analysis based on FFT of 20-s time epochs in the delta, theta, alpha, beta and gamma frequency range for different sleep stages after 4 weeks of tr…