Motor imagery during action observation modulates automatic imitation effects in rhythmical actions

We have previously shown that passively observing a task-irrelevant rhythmical action can bias the cycle time of a subsequently executed rhythmical action. Here we use the same paradigm to investigate the impact of different forms of motor imagery (MI) during action observation (AO) on this automatic imitation (AI) effect. Participants saw a picture of the instructed action followed by a rhythmical distractor movie, wherein cycle time was subtly manipulated across trials. They then executed the instructed rhythmical action. When participants imagined performing the instructed action in synchrony with the distractor action (AO + MI), a strong imitation bias was found that was significantly greater than in our previous study. The bias was pronounced equally for compatible and incompatible trials, wherein observed and imagined actions were different in type (e.g., face washing vs. painting) or plane of movement, or both. In contrast, no imitation bias was observed when MI conflicted with AO. In Experiment 2, motor execution synchronised with AO produced a stronger imitation bias compared to AO + MI, showing an advantage in synchronisation for overt execution over MI. Furthermore, the bias was stronger when participants synchronised the instructed action with the distractor movie, compared to when they synchronised the distractor action with the distractor movie. Although we still observed a significant bias in the latter condition, this finding indicates a degree of specificity in AI effects for the identity of the synchronised action. Overall, our data show that MI can substantially modulate the effects of AO on subsequent execution, wherein: (1) combined AO + MI can enhance AI effects relative to passive AO; (2) observed and imagined actions can be flexibly coordinated across different action types and planes; and (3) conflicting AO + MI can abolish AI effects. Therefore, combined AO + MI instructions should be considered in motor training and rehabilitation

EEG and behavioural correlates of different forms of motor imagery during action observation in rhythmical actions

Recent studies show that participants can engage in motor imagery (MI) and action observation (AO) simultaneously (AO + MI), indicating a capacity for dual action simulation. Here we studied the electrophysiological correlates and behavioural outcomes of two forms of AO + MI, along with pure MI and pure AO control conditions. In synchronised AO + MI, participants imagined performing a rhythmical action in synchrony with an observed distractor action. In contrast in static AO + MI, where the imagery served to conflict with AO, participants imagined holding a static hand posture during AO. Following synchronised AO + MI, rhythmical execution was strongly biased toward the cycle time of the previously observed rhythm (‘imitation bias’), whereas a weaker bias was found following pure MI, and particularly for static AO + MI. In line with these findings, event-related desynchronisation (ERD) in primary sensorimotor and parietal regions was more pronounced in synchronised AO + MI compared to both pure AO and pure MI. These ERD amplitudes were, however, highly similar for static and synchronised AO + MI; suggesting that, regardless of co-represented content, both AO + MI states produced stronger motor activations than single action simulation. In contrast, synchronised AO + MI produced significantly stronger ERD in rostral prefrontal cortex compared to the other three conditions. This specific rostral prefrontal involvement most likely reflected additional cognitive processing for aligning dual action simulations. Together these results provide an important empirical validation of different AO + MI states, in that the imitation bias was strongly modulated by the content of the AO + MI instructions, and that synchronised AO + MI produced stronger behavioural and neurophysiological effects compared to pure AO or MI

Seeing a drummer’s performance modulates the subjective experience of groove when listening to popular music drum patterns

Spontaneous rhythmical movements, like foot-tapping and head-bobbing, often emerge when people listen to music, promoting the sensation of being in the ‘groove’: a psychological construct that additionally incorporates positive affect. Here we report the first study to investigate if seeing the music maker modulates this subjective experience of groove. Across trials participants (n = 36) listened to high and low groove drum beats, while concurrently observing a task-irrelevant point-light display (PLD) of the drummer. The PLD was either fully-corresponding with the audio or was incompatible across three other visual display conditions: a static PLD, a corresponding but asynchronous PLD (0.5s time shifted); or a non-corresponding PLD (e.g. low groove audio paired with high groove PLD). Participants rated: (a) their desire to move; and (b) the perceived groove in response to the auditory beats only, using 8-point Likert scales. In both measurements there were significant main effects of groove level and of visual display. Ratings were higher for high compared to low groove audio, and for the fully-corresponding condition compared to the other three visual conditions. The participants’ desire to move was also rated higher in the static condition compared to the non-corresponding condition, while the two-way interaction was also significant: ratings were higher for the high compared to low groove audio in the fully-corresponding, static and asynchronous conditions, but not in the non-corresponding condition. These findings identify the importance of seeing as well as hearing the musician for an enhanced listening experience, which necessitates a multimodal account of music perception

Motor imagery during action observation enhances automatic imitation in children with and without developmental coordination disorder

Developmental coordination disorder (DCD) is a neurodevelopmental condition characterized by uncoordinated movement relative to age. While action observation (AO) and motor imagery (MI) can both independently enhance movement skills in children, we report the first study to assess the effects of combined action observation and motor imagery (AO + MI) on automatic imitation in children aged 7–12 years both with DCD (n = 12) and without DCD (n = 12). On each trial, participants planned to execute an instructed rhythmical action (face washing or paint brushing). Before responding, participants observed a rhythmical distractor showing the same or a different action with a subtle speed manipulation across trials (fast vs. slow). Automatic imitation was quantified as an imitation bias in subsequent response cycle times. Across blocks of trials, participants engaged in AO, MI, or combined AO + MI during the distractor phase or intentionally imitated the distractor speeds. Although there were no between groups differences, combined AO + MI instructions produced a significantly greater imitation bias (115%) than both AO (109%) and MI (109%), with intentional imitation yielding the strongest effects overall (128%). Within groups analyses revealed a significant bias for AO and MI in both groups. Combined AO + MI effects were significantly greater than AO in typically developing children and were greater than both AO and MI in children with DCD. These results demonstrate a clear capacity for different forms of motor simulation in children both with and without DCD. Moreover, combined AO + MI instructions represent an advantageous method for training movements in children with different motor abilities compared with separate AO and MI instructions.</p

Motor imagery during action observation increases eccentric hamstring force: An acute non-physical intervention

Purpose: Rehabilitation professionals typically use motor imagery (MI) or action observation (AO) to increase physical strength for injury prevention and recovery. Here we compared hamstring force gains for MI during AO (AO + MI) against two pure MI training groups. Materials and methods: Over a 3-week intervention physically fit adults imagined Nordic hamstring exercises in both legs and synchronized this with a demonstration of the same action (AO + MI), or they purely imagined this action (pure MI), or imagined upper-limb actions (pure MI-control). Eccentric hamstring strength gains were assessed using ANOVAs, and magnitude-based inference (MBI) analyses determined the likelihood of clinical/practical benefits for the interventions. Results: Hamstring strength only increased significantly following AO + MI training. This effect was lateralized to the right leg, potentially reflecting a left-hemispheric dominance in motor simulation. MBIs: The right leg within-group treatment effect size for AO + MI was moderate and likely beneficial (d = 0.36), and only small and possibly beneficial for pure MI (0.23). Relative to pure MI-control, effects were possibly beneficial and moderate for AO + MI (0.72), although small for pure MI (0.39). Conclusions: Since hamstring strength predicts injury prevalence, our findings point to the advantage of combined AO + MI interventions, over and above pure MI, for injury prevention and rehabilitation. Implications for rehabilitation While hamstring strains are the most common injury across the many sports involving sprinting and jumping, Nordic hamstring exercises are among the most effective methods for building eccentric hamstring strength, for injury prevention and rehabilitation. In the acute injury phase it is crucial not to overload damaged soft tissues, and so non-physical rehabilitation techniques are well suited to this phase. Rehabilitation professionals typically use either motor imagery or action observation techniques to safely improve physical strength, but our study shows that motor imagery during observation of Nordic hamstring exercises offers a safe, affordable and more effective way to facilitate eccentric hamstring strength gains, compared with pure motor imagery. Despite using bilateral imagery and observation training conditions in the present study, strength gains were restricted to the right leg, potentially due to a left hemispheric dominance in motor simulation

Combined action observation and motor imagery therapy: a novel method for post-stroke motor rehabilitation

Cerebral vascular accidents (strokes) are a leading cause of motor deficiency in millions of people worldwide. While a complex range of biological systems is affected following a stroke, in this paper we focus primarily on impairments of the motor system and the recovery of motor skills. We briefly review research that has assessed two types of mental practice, which are currently recommended in stroke rehabilitation. Namely, action observation (AO) therapy and motor imagery (MI) training. We highlight the strengths and limitations in both techniques, before making the case for combined action observation and motor imagery (AO + MI) therapy as a potentially more effective method. This is based on a growing body of multimodal brain imaging research showing advantages for combined AO + MI instructions over the two separate methods of AO and MI. Finally, we offer a series of suggestions and considerations for how combined AO + MI therapy could be employed in neurorehabilitation

The effects of textured insoles on quiet standing balance in four stance types with and without vision

Background: Wearing a textured shoe insole can decrease postural sway during static balance. Previous studies assessed bipedal and/or unipedal standing. In contrast, we aimed to investigate if textured insoles modulated postural sway during four stance types (bipedal, standard Romberg, tandem Romberg, and unipedal), with and without vision.Methods: The repeated measures design involved 28 healthy young adults (13 females; mean age = 26.86 +/- 6.6 yrs) performing quiet standing in the four stance types on a force platform, under two different insole conditions (textured insole; TI vs. smooth insole; SI), with eyes open and eyes closed. Postural sway was assessed via the range and standard deviation of the COP excursions in the anterior-posterior and medial-lateral sway, and overall mean velocity.Results: The main effect of insole type was statistically significant at the alpha p = 0.05 level (p = 0.045). Compared to smooth insoles, textured insoles reduced the standard deviation of anterior-posterior excursions (APSD). While simple main effect analyses revealed this was most pronounced during eyes closed bipedal standing, insole type did not provide a statistically significant interaction with either stance or vision in this measure, or any other. Postural sway showed statistically significant increases across both stance type (bipedal < standard Romberg < tandem Romberg < unipedal), and vision (eyes closed < eyes open), in almost all measures. Stance and vision did have a statistically significant interaction in each measure, reflecting greater postural disturbances with eyes closed when stance stability decreased.Conclusions: Overall, these results support textured insole use in healthy young adults to reduce postural sway measures. This is because APSD is an index of spatial variability, where a decrease is associated with improved balance and possibly translates to reduced falls risk. Placing a novel texture in the shoe presumably modulated somatosensory inputs. It is important to understand the underlying mechanisms by which textured insoles influence postural sway. As such, utilising a healthy adult group allows us to investigate possible mechanisms of textured insoles. Future research could investigate the potential underlying mechanisms of textured insole effects at a neuromuscular and cortical level, in healthy young adults

The effects of biofeedback on performance and technique variables during the boxing jab

A growing body of research has addressed the application of movement-based biofeedback techniques for improving sports performers’ gross motor skills. Unlike in previous research, we aimed in this study to quantify the effects of this “external” biofeedback on selected performance and technique variables for the boxing jab among both novices and experts. The technical setup included two inertial measurement units linked wirelessly to a video game system with audio output. The units were configured to provide auditory external biofeedback, based on the peak acceleration of the bag (i.e., biofeedback with an external attentional focus). Sixteen participants (8 novices and 8 experts) performed boxing jabs against the bag in blocked phases of biofeedback. When compared to baseline, the acute effects of externally focused biofeedback on peak bag acceleration were possibly positive in both retention phases for novices (d = 0.29; d = 0.41) and likely positive for experts (d = 0.41; d = 0.30), respectively. The experts’ performance improvements were accompanied by substantive increases in trunk rotation, though this was not true for the novices. Thus, technique improvements can be promoted indirectly via externally focused biofeedback, but only when these actions are within the performers’ motor repertoire. Overall, biofeedback via inertial sensors appears to be a potent technique for modifying human movement patterns in both experts and novices. This low-cost technology could be used to support training across sports, rehabilitation and human-computer interactions