The Experts below are selected from a list of 58470 Experts worldwide ranked by ideXlab platform
Michel Petitjean - One of the best experts on this subject based on the ideXlab platform.
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Modulation of soleus corticospinal excitability during Achilles tendon vibration
Experimental Brain Research, 2015Co-Authors: Thomas Lapole, Pierrick J. Arnal, Philippe Gimenez, Michel Petitjean, John Temesi, Guillaume Y. MilletAbstract:Soleus (SOL) corticospinal excitability has been reported to increase during Achilles tendon vibration. The aim of the present study was to further investigate SOL corticospinal excitability and elucidate the changes to intraCortical mechanisms during Achilles tendon vibration. Motor-evoked potentials (MEPs) were elicited in the SOL by transcranial magnetic stimulation (TMS) of the corresponding motor Cortical Area of the leg with and without 50-Hz Achilles tendon vibration. SOL input–output curves were determined. Paired-pulse protocols were also performed to investigate short-interval intraCortical inhibition (SICI) and intraCortical facilitation (ICF) by conditioning test TMS pulses with sub-threshold TMS pulses at inter-stimulus intervals of 3 and 13 ms, respectively. During Achilles tendon vibration, motor threshold was lower than in the control condition (43 ± 13 vs. 49 ± 11 % of maximal stimulator output; p = 0.008). Input–output curves were also influenced by vibration, i.e. there was increased maximal MEP amplitude (0.694 ± 0.347 vs. 0.268 ± 0.167 mV; p
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Achilles tendon vibration-induced changes in plantar flexor corticospinal excitability
Experimental Brain Research, 2014Co-Authors: Thomas Lapole, Pierrick J. Arnal, Philippe Gimenez, John Temesi, Guillaume Y. Millet, Michel PetitjeanAbstract:Daily Achilles tendon vibration has been shown to increase muscle force, likely via corticospinal neural adaptations. The aim of the present study was to determine the extent by which corticospinal excitability is influenced during direct Achilles tendon vibration. Motor-evoked potentials (MEPs) were elicited in the soleus (SOL), gastrocnemius medialis (GM) and tibialis anterior (TA) by transcranial magnetic stimulation of the motor Cortical Area of the leg with and without Achilles tendon vibration at various frequencies (50, 80 and 110 Hz). Contralateral homologues were also investigated. SOL and GM MEP amplitude significantly increased by 226 ± 188 and 66 ± 39 %, respectively, during Achilles tendon vibration, without any difference between the tested frequencies. No MEP changes were reported for TA or contralateral homologues. Increased SOL and GM MEP amplitude suggests increased vibration-induced corticospinal excitability independent of vibration frequency.
Guillaume Y. Millet - One of the best experts on this subject based on the ideXlab platform.
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Modulation of soleus corticospinal excitability during Achilles tendon vibration
Experimental Brain Research, 2015Co-Authors: Thomas Lapole, Pierrick J. Arnal, Philippe Gimenez, Michel Petitjean, John Temesi, Guillaume Y. MilletAbstract:Soleus (SOL) corticospinal excitability has been reported to increase during Achilles tendon vibration. The aim of the present study was to further investigate SOL corticospinal excitability and elucidate the changes to intraCortical mechanisms during Achilles tendon vibration. Motor-evoked potentials (MEPs) were elicited in the SOL by transcranial magnetic stimulation (TMS) of the corresponding motor Cortical Area of the leg with and without 50-Hz Achilles tendon vibration. SOL input–output curves were determined. Paired-pulse protocols were also performed to investigate short-interval intraCortical inhibition (SICI) and intraCortical facilitation (ICF) by conditioning test TMS pulses with sub-threshold TMS pulses at inter-stimulus intervals of 3 and 13 ms, respectively. During Achilles tendon vibration, motor threshold was lower than in the control condition (43 ± 13 vs. 49 ± 11 % of maximal stimulator output; p = 0.008). Input–output curves were also influenced by vibration, i.e. there was increased maximal MEP amplitude (0.694 ± 0.347 vs. 0.268 ± 0.167 mV; p
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Achilles tendon vibration-induced changes in plantar flexor corticospinal excitability
Experimental Brain Research, 2014Co-Authors: Thomas Lapole, Pierrick J. Arnal, Philippe Gimenez, John Temesi, Guillaume Y. Millet, Michel PetitjeanAbstract:Daily Achilles tendon vibration has been shown to increase muscle force, likely via corticospinal neural adaptations. The aim of the present study was to determine the extent by which corticospinal excitability is influenced during direct Achilles tendon vibration. Motor-evoked potentials (MEPs) were elicited in the soleus (SOL), gastrocnemius medialis (GM) and tibialis anterior (TA) by transcranial magnetic stimulation of the motor Cortical Area of the leg with and without Achilles tendon vibration at various frequencies (50, 80 and 110 Hz). Contralateral homologues were also investigated. SOL and GM MEP amplitude significantly increased by 226 ± 188 and 66 ± 39 %, respectively, during Achilles tendon vibration, without any difference between the tested frequencies. No MEP changes were reported for TA or contralateral homologues. Increased SOL and GM MEP amplitude suggests increased vibration-induced corticospinal excitability independent of vibration frequency.
Thomas Lapole - One of the best experts on this subject based on the ideXlab platform.
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Modulation of soleus corticospinal excitability during Achilles tendon vibration
Experimental Brain Research, 2015Co-Authors: Thomas Lapole, Pierrick J. Arnal, Philippe Gimenez, Michel Petitjean, John Temesi, Guillaume Y. MilletAbstract:Soleus (SOL) corticospinal excitability has been reported to increase during Achilles tendon vibration. The aim of the present study was to further investigate SOL corticospinal excitability and elucidate the changes to intraCortical mechanisms during Achilles tendon vibration. Motor-evoked potentials (MEPs) were elicited in the SOL by transcranial magnetic stimulation (TMS) of the corresponding motor Cortical Area of the leg with and without 50-Hz Achilles tendon vibration. SOL input–output curves were determined. Paired-pulse protocols were also performed to investigate short-interval intraCortical inhibition (SICI) and intraCortical facilitation (ICF) by conditioning test TMS pulses with sub-threshold TMS pulses at inter-stimulus intervals of 3 and 13 ms, respectively. During Achilles tendon vibration, motor threshold was lower than in the control condition (43 ± 13 vs. 49 ± 11 % of maximal stimulator output; p = 0.008). Input–output curves were also influenced by vibration, i.e. there was increased maximal MEP amplitude (0.694 ± 0.347 vs. 0.268 ± 0.167 mV; p
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Achilles tendon vibration-induced changes in plantar flexor corticospinal excitability
Experimental Brain Research, 2014Co-Authors: Thomas Lapole, Pierrick J. Arnal, Philippe Gimenez, John Temesi, Guillaume Y. Millet, Michel PetitjeanAbstract:Daily Achilles tendon vibration has been shown to increase muscle force, likely via corticospinal neural adaptations. The aim of the present study was to determine the extent by which corticospinal excitability is influenced during direct Achilles tendon vibration. Motor-evoked potentials (MEPs) were elicited in the soleus (SOL), gastrocnemius medialis (GM) and tibialis anterior (TA) by transcranial magnetic stimulation of the motor Cortical Area of the leg with and without Achilles tendon vibration at various frequencies (50, 80 and 110 Hz). Contralateral homologues were also investigated. SOL and GM MEP amplitude significantly increased by 226 ± 188 and 66 ± 39 %, respectively, during Achilles tendon vibration, without any difference between the tested frequencies. No MEP changes were reported for TA or contralateral homologues. Increased SOL and GM MEP amplitude suggests increased vibration-induced corticospinal excitability independent of vibration frequency.
Stefan Treue - One of the best experts on this subject based on the ideXlab platform.
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dynamic shifts of visual receptive fields in Cortical Area mt by spatial attention
Nature Neuroscience, 2006Co-Authors: Katharina Antonerxleben, Thilo Womelsdorf, Florian Pieper, Stefan TreueAbstract:Voluntary attention is the top-down selection process that focuses Cortical processing resources on the most relevant sensory information. Spatial attention—that is, selection based on stimulus position—alters neuronal responsiveness throughout primate visual cortex. It has been hypothesized that it also changes receptive field profiles by shifting their centers toward attended locations and by shrinking them around attended stimuli. Here we examined, at high resolution, receptive fields in Cortical Area MT of rhesus macaque monkeys when their attention was directed to different locations within and outside these receptive fields. We found a shift of receptive fields, even far from the current location of attention, accompanied by a small amount of shrinkage. Thus, already in early extrastriate cortex, receptive fields are not static entities but are highly modifiable, enabling the dynamic allocation of processing resources to attended locations and supporting enhanced perception within the focus of attention by effectively increasing the local Cortical magnification.
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attentional modulation strength in Cortical Area mt depends on stimulus contrast
Neuron, 2002Co-Authors: Julio C Martineztrujillo, Stefan TreueAbstract:The attentional modulation of sensory information processing in the visual system is the result of top-down influences, which can cause a multiplicative modulation of the firing rate of sensory neurons in extrastriate visual cortex, an effect reminiscent of the bottom-up effect of changes in stimulus contrast. This similarity could simply reflect the multiplicity of both effects. But, here we show that in direction-selective neurons in monkey visual Cortical Area MT, stimulus and attentional effects share a nonlinearity. These neurons show higher response gain for both contrast and attentional changes for intermediate contrast stimuli and smaller gain for low- and high-contrast stimuli. This finding suggests a close relationship between the neural encoding of stimulus contrast and the modulating effect of the behavioral relevance of stimuli.
Christopher C Pack - One of the best experts on this subject based on the ideXlab platform.
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two distinct types of remapping in primate Cortical Area v4
Nature Communications, 2016Co-Authors: Sujaya Neupane, Daniel Guitton, Christopher C PackAbstract:Visual neurons typically receive information from a limited portion of the retina, and such receptive fields are a key organizing principle for much of visual cortex. At the same time, there is strong evidence that receptive fields transiently shift around the time of saccades. The nature of the shift is controversial: Previous studies have found shifts consistent with a role for perceptual constancy; other studies suggest a role in the allocation of spatial attention. Here we present evidence that both the previously documented functions exist in individual neurons in primate Cortical Area V4. Remapping associated with perceptual constancy occurs for saccades in all directions, while attentional shifts mainly occur for neurons with receptive fields in the same hemifield as the saccade end point. The latter are relatively sluggish and can be observed even during saccade planning. Overall these results suggest a complex interplay of visual and extraretinal influences during the execution of saccades.
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contrast dependence of suppressive influences in Cortical Area mt of alert macaque
Journal of Neurophysiology, 2005Co-Authors: Christopher C Pack, Nicholas J Hunter, Richard T BornAbstract:Visual neurons are often characterized in terms of their tuning for various stimulus properties, such as shape, color, and velocity. Generally, these tuning curves are further modulated by the over...
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dynamic properties of neurons in Cortical Area mt in alert and anaesthetized macaque monkeys
Nature, 2001Co-Authors: Christopher C Pack, Vladimir K Berezovskii, Richard T BornAbstract:In order to see the world with high spatial acuity, an animal must sample the visual image with many detectors that restrict their analyses to extremely small regions of space. The visual cortex must then integrate the information from these localized receptive fields to obtain a more global picture of the surrounding environment. We studied this process in single neurons within the middle temporal visual Area (MT) of macaques using stimuli that produced conflicting local and global information about stimulus motion. Neuronal responses in alert animals initially reflected predominantly the ambiguous local motion features, but gradually converged to an unambiguous global representation. When the same animals were anaesthetized, the integration of local motion signals was markedly impaired even though neuronal responses remained vigorous and directional tuning characteristics were intact. Our results suggest that anaesthesia preferentially affects the visual processing responsible for integrating local signals into a global visual representation.
