Placebo-Induced Changes in Excitatory and Inhibitory Corticospinal Circuits during Motor Performance (original) (raw)
Related papers
Scientific Reports
Among the cognitive strategies that can facilitate motor performance in sport and physical practice, a prominent role is played by the direction of the focus of attention and the placebo effect. Consistent evidence converges in indicating that these two cognitive functions can influence the motor outcome, although no study up-to-now tried to study them together in the motor domain. In this explorative study, we combine for the first time these approaches, by applying a placebo procedure to increase force and by manipulating the focus of attention with explicit verbal instructions. Sixty healthy volunteers were asked to perform abduction movements with the index finger as strongly as possible against a piston and attention could be directed either toward the movements of the finger (internal focus, IF) or toward the movements of the piston (external focus, EF). Participants were randomized in 4 groups: two groups underwent a placebo procedure (Placebo-IF and Placebo-EF), in which an inert treatment was applied on the finger with verbal information on its positive effects on force; two groups underwent a control procedure (Control-IF and Control-EF), in which the same treatment was applied with overt information about its inefficacy. The placebo groups were conditioned about the effects of the treatment with a surreptitious amplification of a visual feedback signalling the level of force. During the whole procedure, we recorded actual force, subjective variables and electromyography from the hand muscles. The Placebo-IF group had higher force levels after the procedure than before, whereas the Placebo-EF group had a decrease of force. Electromyography showed that the Placebo-IF group increased the muscle units recruitment without changing the firing rate. These findings show for the first time that the placebo effect in motor performance can be influenced by the subject's attentional focus, being enhanced with the internal focus of attention. Motor performance can be enhanced in athletes and non-athletes by mean of placebo procedures 1-6 , in which inert treatments or substances are administered together with verbal information about their powerful effects on the motor outcome. Strong placebo effects have been described in several sport disciplines, such as cycling 7,8 , running 9 , sprint 10 and weight lifting 11,12. For instance, well-trained cyclists, who thought to have ingested caffeine, showed improved performance, even if they received a placebo 8. Placebo procedures work even in non-athletes, as shown with different motor tasks, such as leg-extension 13 , simulation of a sport competition 14 , finger movements 15,16 , arm movements 17. More recently, the neurophysiological correlates of these effects have been uncovered by applying transcranial magnetic stimulation over the primary motor cortex of healthy non-athletes engaged in a force task 16. This study showed that after a placebo procedure there was an increased excitability of the corticospinal system, as demonstrated by the enhanced amplitude of the motor evoked potentials and reduced duration of the cortical silent period 16. Hence, the placebo procedure seems to boost the activity of the motor system and this could in turn favour motor performance.
Modulation of Inhibitory Corticospinal Circuits Induced by a Nocebo Procedure in Motor Performance
PLOS ONE, 2015
As recently demonstrated, a placebo procedure in motor performance increases force production and changes the excitability of the corticospinal system, by enhancing the amplitude of the motor evoked potentials (MEP) and reducing the duration of the cortical silent period (CSP). However, it is not clear whether these neurophysiological changes are related to the behavioural outcome (increased force) or to a general effect of expectation. To clarify this, we investigated the nocebo effect, in which the induced expectation decreases force production. Two groups of healthy volunteers (experimental and control) performed a motor task by pressing a piston with the right index finger. To induce a nocebo effect in the experimental group, low frequency transcutaneous electrical nerve stimulation (TENS) was applied over the index finger with instructions of its detrimental effects on force. To condition the subjects, the visual feedback on their force level was surreptitiously reduced after TENS. Results showed that the experimental group reduced the force, felt weaker and expected a worse performance than the control group, who was not suggested about TENS. By applying transcranial magnetic stimulation over the primary motor cortex, we found that while MEP amplitude remained stable throughout the procedure in both groups, the CSP duration was shorter in the experimental group after the nocebo procedure. The CSP reduction resembled previous findings on the placebo effect, suggesting that expectation of change in performance diminishes the inhibitory activation of the primary motor cortex, independently of the behavioural outcome.
2016
As recently demonstrated, a placebo procedure in motor performance increases force pro-duction and changes the excitability of the corticospinal system, by enhancing the amplitude of the motor evoked potentials (MEP) and reducing the duration of the cortical silent period (CSP). However, it is not clear whether these neurophysiological changes are related to the behavioural outcome (increased force) or to a general effect of expectation. To clarify this, we investigated the nocebo effect, in which the induced expectation decreases force pro-duction. Two groups of healthy volunteers (experimental and control) performed a motor task by pressing a piston with the right index finger. To induce a nocebo effect in the experi-mental group, low frequency transcutaneous electrical nerve stimulation (TENS) was ap-plied over the index finger with instructions of its detrimental effects on force. To condition the subjects, the visual feedback on their force level was surreptitiously reduced aft...
2019
Response inhibition—the suppression of prepotent behaviours when they are inappropriate— has been thought to rely on executive control. Against this received wisdom, it has been argued that external cues repeatedly associated with response inhibition can come to trigger response inhibition automatically without top-down command. The current project endeavoured to provide evidence for associatively-mediated motor inhibition. We tested the hypothesis that stop-associated stimuli can, in a bottom-up fashion, directly activate inhibitory mechanisms in the motor cortex. Human subjects were first trained on a stop-signal task. Once trained, the subjects received transcranial magnetic stimulation applied over their primary motor cortex during passive observation of either the stop signal (i.e. without any need to stop a response) or an equally familiar control stimulus never associated with stopping. Analysis of motor-evoked potentials showed that corticospinal excitability was reduced dur...
Journal of neuroengineering and rehabilitation, 2014
The combination of voluntary effort and functional electrical stimulation (ES) appears to have a greater potential to induce plasticity in the motor cortex than either electrical stimulation or voluntary training alone. However, it is not clear whether the motor commands from the central nervous system, the afferent input from peripheral organs, or both, are indispensable to induce the facilitative effects on cortical excitability. To clarify whether voluntary motor commands enhance corticospinal tract (CoST) excitability during neuromuscular ES, without producing voluntary muscular contraction (VMC), we examined the effect of a combination of motor imagery (MI) and electrical muscular stimulation on CoST excitability using transcranial magnetic stimulation (TMS). Eight neurologically healthy male subjects participated in this study. Five conditions (resting, MI, ES, ES + MI [ESMI], and VMC) were established. In the ES condition, a 50-Hz stimulus was applied for 3 to 5 s to the firs...
Pairing Voluntary Movement and Muscle-Located Electrical Stimulation Increases Cortical Excitability
Frontiers in Human Neuroscience, 2016
Learning new motor skills has been correlated with increased cortical excitability. In this study, different location of electrical stimulation (ES), nerve, or muscle, was paired with voluntary movement to investigate if ES paired with voluntary movement (a) would increase the excitability of cortical projections to tibialis anterior and (b) if stimulation location mattered. Cortical excitability changes were quantified using motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) at varying intensities during four conditions. Twelve healthy subjects performed 50 dorsiflexions at the ankle during nerve or muscle ES at motor threshold (MTh). ES alone was delivered 50 times and the movement was performed 50 times. A significant increase in the excitability from pre-to post-intervention (P = 0.0061) and pre-to 30 min post-intervention (P = 0.017) measurements was observed when voluntary movement was paired with muscle ES located at tibialis anterior. An increase of 50 ± 57 and 28 ± 54% in the maximum MEPs was obtained for voluntary movement paired with muscle-located and nerve-located ES, respectively. The maximum MEPs for voluntary movement alone and muscle-located ES alone were −5 ± 28 and 2 ± 42%, respectively. Pairing voluntary movement with muscle-located ES increases excitability of corticospinal projections of tibialis anterior in healthy participants. This finding suggests that active participation during muscle-located ES protocols increases cortical excitability to a greater extent than stimulation alone. The next stage of this research is to investigate the effect in people with stroke. The results may have implications for motor recovery in patients with motor impairments following neurological injury.
Corticospinal excitability is specifically modulated by motor imagery: a magnetic stimulation study
Neuropsychologia, 1998
Transcranial magnetic stimulation "TMS# was used to investigate whether the excitability of the corticospinal system is selectively a}ected by motor imagery[ To this purpose\ we performed two experiments[ In the _rst one we recorded motor evoked potentials from right hand and arm muscles during mental simulation of~exion:extension movements of both distal and proximal joints[ In the second experiment we applied magnetic stimulation to the right and the left motor cortex of subjects while they were imagining opening or closing their right or their left hand[ Motor evoked potentials "MEPs# were recorded from a hand muscle contralateral to the stimulated cortex [ The results demonstrated that the excitability pattern during motor imagery dynamically mimics that occurring during movement execution[ In addition\ while magnetic stimulation of the left motor cortex revealed increased corticospinal excitability when subjects imagined ipsilateral as well as contralateral hand movements\ the stimulation of the right motor cortex revealed a facilitatory e}ect induced by imagery of contralateral hand movements only[ In conclusion\ motor imagery is a high level process\ which\ however\ manifests itself in the activation of those same cortical circuits that are normally involved in movement execution [ Þ 0888 Elsevier Science Ltd[ All rights reserved[ Keywords] Motor system^Transcranial magnetic stimulation "TMS#^Motor evoked potentials "MEPs#^Motor imagery^Hand movement^Hemispheric asymmetry Corresponding author[ Tel[] 9928 410 189279^fax] 9928 410 180293ê !mail] _sioumÝsymbolic[parma[it[