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Cortical output to fast and slow muscles of the ankle in the rhesus macaque.

Hudson HM, Griffin DM, Belhaj-Saïf A, Cheney PD - Front Neural Circuits (2013)

Bottom Line: Although it is generally agreed that cortical stimulation yields short latency facilitation of fast muscles, the effects on the slow muscle, soleus, remain controversial.However, while poststimulus suppression (PStS) was observed in all muscles, it was more common in the slow muscle compared to the fast muscles and was as common as facilitation at low stimulus intensities.Overall, our results demonstrate that cortical facilitation of soleus has an organization that is very similar to that of the fast ankle muscles.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City KS, USA.

ABSTRACT
The cortical control of fast and slow muscles of the ankle has been the subject of numerous reports yielding conflicting results. Although it is generally agreed that cortical stimulation yields short latency facilitation of fast muscles, the effects on the slow muscle, soleus, remain controversial. Some studies have shown predominant facilitation of soleus from the cortex while others have provided evidence of differential control in which soleus is predominantly inhibited from the cortex. The objective of this study was to investigate the cortical control of fast and slow muscles of the ankle using stimulus triggered averaging (StTA) of EMG activity, which is a sensitive method of detecting output effects on muscle activity. This method also has relatively high spatial resolution and can be applied in awake, behaving subjects. Two rhesus macaques were trained to perform a hindlimb push-pull task. Stimulus triggered averages (StTAs) of EMG activity (15, 30, and 60 μA at 15 Hz) were computed for four muscles of the ankle [tibialis anterior (TA), medial gastrocnemius (MG), lateral gastrocnemius (LG), and soleus] as the monkeys performed the task. Poststimulus facilitation (PStF) was observed in both the fast muscles (TA, MG, and LG) as well as the slow muscle (soleus) and was as common and as strong in soleus as in the fast muscles. However, while poststimulus suppression (PStS) was observed in all muscles, it was more common in the slow muscle compared to the fast muscles and was as common as facilitation at low stimulus intensities. Overall, our results demonstrate that cortical facilitation of soleus has an organization that is very similar to that of the fast ankle muscles. However, cortical inhibition is organized differently allowing for more prominent suppression of soleus motoneurons.

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(A) Hindlimb push-pull task. The monkey is seated in a custom-built primate chair with both arms and the left leg restrained. The monkey gripped the push-pull device's manipulandum (horizontal post) with the right foot and pushed it to a target zone. After a hold period of 500 ms in the target zone, the monkey pulled the manipulandum to a second target zone and held for 500 ms. Upon successful completion of each push-pull trial, the monkey was given an applesauce reward. The behavioral task was guided by visual and auditory cues. (B) EMG records of ankle muscles during two cycles of the hindlimb push-pull task. TA, tibialis anterior; MG, medial gastrocnemius; LG, lateral gastrocnemius; SOL, soleus. Figure adapted from Hudson et al. (2010).
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Figure 1: (A) Hindlimb push-pull task. The monkey is seated in a custom-built primate chair with both arms and the left leg restrained. The monkey gripped the push-pull device's manipulandum (horizontal post) with the right foot and pushed it to a target zone. After a hold period of 500 ms in the target zone, the monkey pulled the manipulandum to a second target zone and held for 500 ms. Upon successful completion of each push-pull trial, the monkey was given an applesauce reward. The behavioral task was guided by visual and auditory cues. (B) EMG records of ankle muscles during two cycles of the hindlimb push-pull task. TA, tibialis anterior; MG, medial gastrocnemius; LG, lateral gastrocnemius; SOL, soleus. Figure adapted from Hudson et al. (2010).

Mentions: Data were collected from the left primary motor cortex (M1) of two male rhesus macaques (Macaca mulatta, ~10 kg, 6–7 years old). The monkeys were trained to perform a hindlimb push-pull task (Figure 1A) engaging both proximal and distal muscles in reliable and stereotyped patterns of activation (Hudson et al., 2010). Seated in a custom primate chair within a sound-attenuating chamber, both arms and the left leg were restrained. With the right foot, the monkey gripped the manipulandum (horizontal post) and extended the leg until the target zone was achieved. After a hold period of 500 ms in the target zone, the monkey flexed the leg pulling the manipulandum to a second target zone. Following a second hold period of 500 ms, the monkey was given an applesauce reward. The behavioral task was guided by visual and auditory cues.


Cortical output to fast and slow muscles of the ankle in the rhesus macaque.

Hudson HM, Griffin DM, Belhaj-Saïf A, Cheney PD - Front Neural Circuits (2013)

(A) Hindlimb push-pull task. The monkey is seated in a custom-built primate chair with both arms and the left leg restrained. The monkey gripped the push-pull device's manipulandum (horizontal post) with the right foot and pushed it to a target zone. After a hold period of 500 ms in the target zone, the monkey pulled the manipulandum to a second target zone and held for 500 ms. Upon successful completion of each push-pull trial, the monkey was given an applesauce reward. The behavioral task was guided by visual and auditory cues. (B) EMG records of ankle muscles during two cycles of the hindlimb push-pull task. TA, tibialis anterior; MG, medial gastrocnemius; LG, lateral gastrocnemius; SOL, soleus. Figure adapted from Hudson et al. (2010).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3585439&req=5

Figure 1: (A) Hindlimb push-pull task. The monkey is seated in a custom-built primate chair with both arms and the left leg restrained. The monkey gripped the push-pull device's manipulandum (horizontal post) with the right foot and pushed it to a target zone. After a hold period of 500 ms in the target zone, the monkey pulled the manipulandum to a second target zone and held for 500 ms. Upon successful completion of each push-pull trial, the monkey was given an applesauce reward. The behavioral task was guided by visual and auditory cues. (B) EMG records of ankle muscles during two cycles of the hindlimb push-pull task. TA, tibialis anterior; MG, medial gastrocnemius; LG, lateral gastrocnemius; SOL, soleus. Figure adapted from Hudson et al. (2010).
Mentions: Data were collected from the left primary motor cortex (M1) of two male rhesus macaques (Macaca mulatta, ~10 kg, 6–7 years old). The monkeys were trained to perform a hindlimb push-pull task (Figure 1A) engaging both proximal and distal muscles in reliable and stereotyped patterns of activation (Hudson et al., 2010). Seated in a custom primate chair within a sound-attenuating chamber, both arms and the left leg were restrained. With the right foot, the monkey gripped the manipulandum (horizontal post) and extended the leg until the target zone was achieved. After a hold period of 500 ms in the target zone, the monkey flexed the leg pulling the manipulandum to a second target zone. Following a second hold period of 500 ms, the monkey was given an applesauce reward. The behavioral task was guided by visual and auditory cues.

Bottom Line: Although it is generally agreed that cortical stimulation yields short latency facilitation of fast muscles, the effects on the slow muscle, soleus, remain controversial.However, while poststimulus suppression (PStS) was observed in all muscles, it was more common in the slow muscle compared to the fast muscles and was as common as facilitation at low stimulus intensities.Overall, our results demonstrate that cortical facilitation of soleus has an organization that is very similar to that of the fast ankle muscles.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City KS, USA.

ABSTRACT
The cortical control of fast and slow muscles of the ankle has been the subject of numerous reports yielding conflicting results. Although it is generally agreed that cortical stimulation yields short latency facilitation of fast muscles, the effects on the slow muscle, soleus, remain controversial. Some studies have shown predominant facilitation of soleus from the cortex while others have provided evidence of differential control in which soleus is predominantly inhibited from the cortex. The objective of this study was to investigate the cortical control of fast and slow muscles of the ankle using stimulus triggered averaging (StTA) of EMG activity, which is a sensitive method of detecting output effects on muscle activity. This method also has relatively high spatial resolution and can be applied in awake, behaving subjects. Two rhesus macaques were trained to perform a hindlimb push-pull task. Stimulus triggered averages (StTAs) of EMG activity (15, 30, and 60 μA at 15 Hz) were computed for four muscles of the ankle [tibialis anterior (TA), medial gastrocnemius (MG), lateral gastrocnemius (LG), and soleus] as the monkeys performed the task. Poststimulus facilitation (PStF) was observed in both the fast muscles (TA, MG, and LG) as well as the slow muscle (soleus) and was as common and as strong in soleus as in the fast muscles. However, while poststimulus suppression (PStS) was observed in all muscles, it was more common in the slow muscle compared to the fast muscles and was as common as facilitation at low stimulus intensities. Overall, our results demonstrate that cortical facilitation of soleus has an organization that is very similar to that of the fast ankle muscles. However, cortical inhibition is organized differently allowing for more prominent suppression of soleus motoneurons.

Show MeSH
Related in: MedlinePlus