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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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Corticospinal excitability before (black) and after (white) observation of moving dots, observation of thumb movements, or execution of thumb movements.Bars indicate standard error of the mean.
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pone-0038754-g001: Corticospinal excitability before (black) and after (white) observation of moving dots, observation of thumb movements, or execution of thumb movements.Bars indicate standard error of the mean.

Mentions: ANOVA with Group and Time (T1, T2) revealed a significant main effect of Group (F = 3.653; p = .038), no main effect of Time (F = 0.227; p = .637), and a trend towards significance for the interaction (F = 2.518; p = .097). This trend was manly driven by the presence of an increase in MEP size from T1 and T2 limited to the motor practice group (dot observation: 0.94±0.34mV → 0.81±0.30mV; action observation: 0.95±.30mV → 0.92±0.45mV; motor practice: 1.08±0.26mV → 1.34±0.51mV) (Figure 1, 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)

Corticospinal excitability before (black) and after (white) observation of moving dots, observation of thumb movements, or execution of thumb movements.Bars indicate standard error of the mean.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0038754-g001: Corticospinal excitability before (black) and after (white) observation of moving dots, observation of thumb movements, or execution of thumb movements.Bars indicate standard error of the mean.
Mentions: ANOVA with Group and Time (T1, T2) revealed a significant main effect of Group (F = 3.653; p = .038), no main effect of Time (F = 0.227; p = .637), and a trend towards significance for the interaction (F = 2.518; p = .097). This trend was manly driven by the presence of an increase in MEP size from T1 and T2 limited to the motor practice group (dot observation: 0.94±0.34mV → 0.81±0.30mV; action observation: 0.95±.30mV → 0.92±0.45mV; motor practice: 1.08±0.26mV → 1.34±0.51mV) (Figure 1, 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