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Occlusion of LTP-like plasticity in human primary motor cortex by action observation.

Lepage JF, Morin-Moncet O, Beaulé V, de Beaumont L, Champoux F, Théoret H - PLoS ONE (2012)

Bottom Line: Before undergoing PAS, participants were asked to either 1) perform abductions of the right thumb as fast as possible; 2) passively observe someone else perform thumb abductions; or 3) passively observe a moving dot mimicking thumb movements.Results show that, similarly to participants in the motor practice group, individuals observing repeated motor actions showed marked inhibition of PAS-induced LTP, while the "moving dot" group displayed the expected increase in MEP amplitude, despite differences in baseline excitability.These results suggest that mere observation of repeated hand actions is sufficient to induce LTP, despite the absence of motor learning.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Université de Montréal, Montréal, Canada.

ABSTRACT
Passive observation of motor actions induces cortical activity in the primary motor cortex (M1) of the onlooker, which could potentially contribute to motor learning. While recent studies report modulation of motor performance following action observation, the neurophysiological mechanism supporting these behavioral changes remains to be specifically defined. Here, we assessed whether the observation of a repetitive thumb movement--similarly to active motor practice--would inhibit subsequent long-term potentiation-like (LTP) plasticity induced by paired-associative stimulation (PAS). Before undergoing PAS, participants were asked to either 1) perform abductions of the right thumb as fast as possible; 2) passively observe someone else perform thumb abductions; or 3) passively observe a moving dot mimicking thumb movements. Motor evoked potentials (MEP) were used to assess cortical excitability before and after motor practice (or observation) and at two time points following PAS. Results show that, similarly to participants in the motor practice group, individuals observing repeated motor actions showed marked inhibition of PAS-induced LTP, while the "moving dot" group displayed the expected increase in MEP amplitude, despite differences in baseline excitability. Interestingly, LTP occlusion in the action-observation group was present even if no increase in cortical excitability or movement speed was observed following observation. These results suggest that mere observation of repeated hand actions is sufficient to induce LTP, despite the absence of motor learning.

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Interaction between observation of moving dots, observation of thumb movements and execution of thumb movements with PAS.Data are expressed as a percent change from pre-PAS values (T2) immediately (T3) and ten minutes (T4) after the end of PAS. Bars indicate standard error of the mean. * p<0.01.
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pone-0038754-g003: Interaction between observation of moving dots, observation of thumb movements and execution of thumb movements with PAS.Data are expressed as a percent change from pre-PAS values (T2) immediately (T3) and ten minutes (T4) after the end of PAS. Bars indicate standard error of the mean. * p<0.01.

Mentions: As commonly used in similar protocols [11], a mixed ANOVA was conducted with MEP amplitudes following PAS intervention normalized to the time point immediately preceding it (T3/T2, T4/T2). This revealed a significant main effect of Group (F = 8.303; df = 2,30; p = 0.001), no main effect of Time (F = 3.170; df = 1,30; p = .085) and no interaction between factors (F = 0.666; df = 2,30; p = .521). Post-hoc analysis revealed that PAS induced greater increases in MEP size in the dot observation group than in both the action observation (p  = .002) and motor practice (p  = .006) groups, with no significant difference between action observation and motor practice (p  = .938) (Figure 3, Table 1).


Occlusion of LTP-like plasticity in human primary motor cortex by action observation.

Lepage JF, Morin-Moncet O, Beaulé V, de Beaumont L, Champoux F, Théoret H - PLoS ONE (2012)

Interaction between observation of moving dots, observation of thumb movements and execution of thumb movements with PAS.Data are expressed as a percent change from pre-PAS values (T2) immediately (T3) and ten minutes (T4) after the end of PAS. Bars indicate standard error of the mean. * p<0.01.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3368919&req=5

pone-0038754-g003: Interaction between observation of moving dots, observation of thumb movements and execution of thumb movements with PAS.Data are expressed as a percent change from pre-PAS values (T2) immediately (T3) and ten minutes (T4) after the end of PAS. Bars indicate standard error of the mean. * p<0.01.
Mentions: As commonly used in similar protocols [11], a mixed ANOVA was conducted with MEP amplitudes following PAS intervention normalized to the time point immediately preceding it (T3/T2, T4/T2). This revealed a significant main effect of Group (F = 8.303; df = 2,30; p = 0.001), no main effect of Time (F = 3.170; df = 1,30; p = .085) and no interaction between factors (F = 0.666; df = 2,30; p = .521). Post-hoc analysis revealed that PAS induced greater increases in MEP size in the dot observation group than in both the action observation (p  = .002) and motor practice (p  = .006) groups, with no significant difference between action observation and motor practice (p  = .938) (Figure 3, Table 1).

Bottom Line: Before undergoing PAS, participants were asked to either 1) perform abductions of the right thumb as fast as possible; 2) passively observe someone else perform thumb abductions; or 3) passively observe a moving dot mimicking thumb movements.Results show that, similarly to participants in the motor practice group, individuals observing repeated motor actions showed marked inhibition of PAS-induced LTP, while the "moving dot" group displayed the expected increase in MEP amplitude, despite differences in baseline excitability.These results suggest that mere observation of repeated hand actions is sufficient to induce LTP, despite the absence of motor learning.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Université de Montréal, Montréal, Canada.

ABSTRACT
Passive observation of motor actions induces cortical activity in the primary motor cortex (M1) of the onlooker, which could potentially contribute to motor learning. While recent studies report modulation of motor performance following action observation, the neurophysiological mechanism supporting these behavioral changes remains to be specifically defined. Here, we assessed whether the observation of a repetitive thumb movement--similarly to active motor practice--would inhibit subsequent long-term potentiation-like (LTP) plasticity induced by paired-associative stimulation (PAS). Before undergoing PAS, participants were asked to either 1) perform abductions of the right thumb as fast as possible; 2) passively observe someone else perform thumb abductions; or 3) passively observe a moving dot mimicking thumb movements. Motor evoked potentials (MEP) were used to assess cortical excitability before and after motor practice (or observation) and at two time points following PAS. Results show that, similarly to participants in the motor practice group, individuals observing repeated motor actions showed marked inhibition of PAS-induced LTP, while the "moving dot" group displayed the expected increase in MEP amplitude, despite differences in baseline excitability. Interestingly, LTP occlusion in the action-observation group was present even if no increase in cortical excitability or movement speed was observed following observation. These results suggest that mere observation of repeated hand actions is sufficient to induce LTP, despite the absence of motor learning.

Show MeSH
Related in: MedlinePlus