► The mirror neuron system sub-serves both motor imagery and action observation. ► Both motor imagery and action observation play a role in motor learning. ► In this study we compared these ...strategies in learning a novel complex motor task. ► Action observation revealed better than motor imagery as a motor learning strategy. ► This is relevant in educational activities, sport training and neurorehabilitation.
Both motor imagery and action observation have been shown to play a role in learning or re-learning complex motor tasks. According to a well accepted view they share a common neurophysiological basis in the mirror neuron system. Neurons within this system discharge when individuals perform a specific action and when they look at another individual performing the same or a motorically related action. In the present paper, after a short review of literature on the role of action observation and motor imagery in motor learning, we report the results of a kinematics study where we directly compared motor imagery and action observation in learning a novel complex motor task. This involved movement of the right hand and foot in the same angular direction (in-phase movement), while at the same time moving the left hand and foot in an opposite angular direction (anti-phase movement), all at a frequency of 1Hz. Motor learning was assessed through kinematics recording of wrists and ankles. The results showed that action observation is better than motor imagery as a strategy for learning a novel complex motor task, at least in the fast early phase of motor learning. We forward that these results may have important implications in educational activities, sport training and neurorehabilitation.
Functional magnetic resonance imaging (fMRI) was used to localize brain areas that were active during the observation of actions made by another individual. Object‐ and non‐object‐related actions ...made with different effectors (mouth, hand and foot) were presented. Observation of both object‐ and non‐object‐related actions determined a somatotopically organized activation of premotor cortex. The somatotopic pattern was similar to that of the classical motor cortex homunculus. During the observation of object‐related actions, an activation, also somatotopically organized, was additionally found in the posterior parietal lobe. Thus, when individuals observe an action, an internal replica of that action is automatically generated in their premotor cortex. In the case of object‐related actions, a further object‐related analysis is performed in the parietal lobe, as if the subjects were indeed using those objects. These results bring the previous concept of an action observation/execution matching system (mirror system) into a broader perspective: this system is not restricted to the ventral premotor cortex, but involves several somatotopically organized motor circuits.
Transcranial magnetic stimulation (TMS) and a behavioral paradigm were used to assess whether listening to action-related sentences modulates the activity of the motor system. By means of ...single-pulse TMS, either the hand or the foot/leg motor area in the left hemisphere was stimulated in distinct experimental sessions, while participants were listening to sentences expressing hand and foot actions. Listening to abstract content sentences served as a control. Motor evoked potentials (MEPs) were recorded from hand and foot muscles. Results showed that MEPs recorded from hand muscles were specifically modulated by listening to hand-action-related sentences, as were MEPs recorded from foot muscles by listening to foot-action-related sentences. This modulation consisted of an amplitude decrease of the recorded MEPs. In the behavioral task, participants had to respond with the hand or the foot while listening to actions expressing hand and foot actions, as compared to abstract sentences. Coherently with the results obtained with TMS, when the response was given with the hand, reaction times were slower during listening to hand-action-related sentences, while when the response was given with the foot, reaction times were slower during listening to foot-action-related sentences. The present data show that processing verbally presented actions activates different sectors of the motor system, depending on the effector used in the listened-to action.
Previous reports suggest that the internal organization of semantic memory is in terms of different “types of knowledge,” including “sensory” (information about perceptual features), “action” ...(motor-based knowledge of object utilization), and “functional” (abstract properties, as function and context of use). Consistent with this view, a specific loss of action knowledge, with preserved functional knowledge, has been recently observed in patients with left frontoparietal lesions. The opposite pattern (impaired functional knowledge with preserved action knowledge) was reported in association with anterior inferotemporal lesions. In the present study, the cerebral representation of action and functional knowledge was investigated using event-related analysis of functional magnetic resonance imaging data. Fifteen subjects were presented with pictures showing pairs of manipulable objects and asked whether the objects within each pair were used with the same manipulation pattern (“action knowledge” condition) or in the same context (“functional knowledge” condition). Direct comparisons showed action knowledge, relative to functional knowledge, to activate a left frontoparietal network, comprising the intraparietal sulcus, the inferior parietal lobule, and the dorsal premotor cortex. The reverse comparison yielded activations in the retrosplenial and the lateral anterior inferotemporal cortex. These results confirm and extend previous neuropsychological data and support the hypothesis of the existence of different types of information processing in the internal organization of semantic memory.
The observation of actions performed by others activate in an observer the same neural structures (including mirror neurons) as when he/she actually performs the same actions.
The aim of the present ...study was to assess whether action observation treatment may improve upper limb motor impairment in chronic stroke patients.
This was an observational study.
Patients were recruited by three Italian Centres for Neurorehabilitation between 2006 and 2008.
Twenty-eight chronic stroke patients with upper limb impairment have undergone for four weeks, five days a week, a rehabilitation treatment based on observation of video-clips presenting hand daily actions, followed by the imitation of those same actions with the affected limb.
Functional evaluation by means of Modified Barthel Index (MBI), Frenchay Arm Test (FAT) and Fugl Meyer (FM) was carried out twice before treatment (BT1 and BT2), at an interval of 15 days, then after treatment (AT1) and finally at a two-month follow-up (AT2). Wilcoxon Signed Rank test was applied to test differences between scores obtained from functional scales before and after treatment (BT1 vs. BT2; BT2 vs. AT1; AT1 vs. AT2).
In all scales, scores did not differ when comparing BT1 with BT2. Scores improved significantly in all scales at AT1 as compared to BT2 (MBI, P=0.026; FAT, P=0.005; FM, P=0.001). This improvement was still present at the two-month follow-up as testified by no score difference between AT1 and AT2.
Action Observation Treatment may become a useful strategy in the rehabilitation of stroke patients.
The present preliminary study suggests that stimulation of neural structures (including mirror neurons), activated when the patients actually perform the same actions as those observed could constitute a good alternative rehabilitative approach in chronic stroke patients.
Functional magnetic resonance imaging (fMRI) was used to localize brain areas active during manipulation of complex objects. In one experiment subjects were required to manipulate complex objects for ...exploring their macrogeometric features as compared to manipulation of a simple smooth object (a sphere). In a second experiment subjects were asked to manipulate complex objects and to silently name them upon recognition as compared to manipulation of complex not recognizable objects without covert naming. Manipulation of complex objects resulted in an activation of ventral premotor cortex Brodmann's area (BA) 44, of a region in the intraparietal sulcus (most probably corresponding to the anterior intraparietal area in the monkey), of area SII and of a sector of the superior parietal lobule. When the objects were covertly named additional activations were found in the opercular part of BA 44 and in the pars triangularis of the inferior frontal gyrus (BA 45). We suggest that a fronto‐parietal circuit for manipulation of objects exists in humans and involves basically the same areas as in the monkey. It is proposed that area SII analyses the intrinsic object characteristics whilst the superior parietal lobule is related to kinaesthesia.
► There are no experimental evidence on how the brain processes adjectives. ► We applied TMS while subjects were reading adjectives, expressing negative or positive features. ► We recorded MEPs from ...two antagonist muscles, one involved in grasping, the other in releasing. ► Depending on their function, muscle activity was differently modulated by the used adjectives. ► These results are well explained by an embodied approach to language processing.
Using transcranial magnetic stimulation (TMS), motor evoked potentials (MEPs) were recorded from two antagonistic muscles, the first dorsal interosseus (FDI) of the hand and the extensor communis digitorum (EC) of the forearm. FDI is involved in grasping actions and EC in releasing. TMS pulses were delivered while participants were reading adjectives expressing either negative or positive pragmatic properties, at 150ms after presentation of language material. Overall findings showed an interaction of adjective type (positive, negative) and muscle (FDI, EC), the effect being driven by a significant difference for negative adjectives. Further analysis aimed at investigating the effectiveness of positive adjectives showed a similar, but opposite, pattern of effects for the positive words in the initial two blocks. The present results indicate that, as for verbs and nouns, adjectives recruit the sensorimotor system, and their processing is best explained by an embodiment rather than an amodal approach to language.
Functional magnetic resonance imaging (fMRI) was used to assess cerebral activation during manipulation of various complex meaningless objects as compared to manipulation of a single simple object (a ...sphere). Significant activation was found bilaterally in the ventral premotor cortex (Brodmann's area 44), in the cortex lining the anterior part of the intraparietal sulcus (most probably corresponding to monkey anterior intraparietal area, AIP), in the superior parietal lobule and in the opercular parietal cortex including the secondary somatosensory area (SII). We suggest that the cortex lining the anterior part of the intraparietal sulcus and area 44 are functionally connected and mediate object manipulation in humans.
Background Recent studies show that limb apraxia is often not recognized as a higher motor impairment in patients suffering from a stroke. Because it is adversely affecting every-day life and ...personal independence, a successful rehabilitation of apraxia is critical for personal well-being ( Cappa et al., 2005; Dovern et al., 2012 ). Yet, evidence of an effective treatment approach with long-lasting effects and generalization to untrained actions is still missing ( Binkofski and Klann, 2013; Dovern et al., 2011 ). One possible reason for the treatment-resistance of this neurological disorder may be a deficit in motor memory storage of (re-) learned motor acts. So far, however, such a hypothesis has not been tested. Objective The present study aimed at assessing the ability of apractic stroke patients to acquire and retain a new motor sequence skill. Methods Eleven stroke patients suffering from chronic upper limb apraxia participated in a four-weeks multiple session training program using a motor sequence learning paradigm. Patients were required to perform a standardized finger sequence movement task, which is a well-established paradigm to explore motor learning and procedural memory abilities (e.g. Doyon et al., 2009 ). Motor performance was recorded with a modified four-button PC gaming keypad (Belkin Razer Nostromo, Belkin, Playa Vista, USA) and analyzed using customized Matlab (MathWorks, Natick, USA) scripts. Motor sequence learning was measured in terms of speed and accuracy. According to the hypothesis of disturbed motor memory abilities, no training induced simultaneous improvement in both, speed and accuracy, was expected. Results All patients improved in terms of speed in producing the learned finger sequence. While patients were slow at the beginning of the training program, nearly all ended up with performance within age related norms. In contrast, accuracy varied across sessions. The latter finding can be explained through the notion of stroke-specific capacity problems (improving one capacity at cost of another). Moreover and unexpectedly, most of patients showed clinical improvement of their apraxia symptoms. Conclusions All of our patients with limb apraxia were able to improve the speed of producing novel motor sequences, while accuracy remained variable. Thus, the present findings did not unequivocally reveal that the ability to acquire a new motor skill was retained. Further studies must determine whether the unexpected improvement of apraxia in patients with stable deficits is causally and specifically related to motor sequence training.
The mechanisms underlying attention to action are poorly understood. Although distracted by something else, we often maintain the accuracy of a movement, which suggests that differential neural ...mechanisms for the control of attended and nonattended action exist. Using functional magnetic resonance imaging (fMRI) in normal volunteers and probabilistic cytoarchitectonic maps, we observed that neural activity in subarea 4p (posterior) within the primary motor cortex was modulated by attention to action, while neural activity in subarea 4a (anterior) was not. The data provide the direct evidence for differential neural mechanisms during attended and unattended action in human primary motor cortex.
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