The mirror neuron system in post-stroke rehabilitation
- Diana Carvalho1,
- Silmar Teixeira1, 2,
- Marina Lucas1,
- Ti-Fei Yuan3,
- Fernanda Chaves1,
- Caroline Peressutti2, 4,
- Sergio Machado5, 6, 7, 13,
- Juliana Bittencourt2,
- Manuel Menéndez-González8,
- Antonio Egidio Nardi5, 7,
- Bruna Velasques2, 4,
- Mauricio Cagy9,
- Roberto Piedade2,
- Pedro Ribeiro2, 4, 10 and
- Oscar Arias-Carrión11, 12Email author
© Carvalho et al.; licensee BioMed Central Ltd. 2013
Received: 3 September 2013
Accepted: 12 October 2013
Published: 17 October 2013
Different treatments for stroke patients have been proposed; among them the mirror therapy and motion imagery lead to functional recovery by providing a cortical reorganization. Up today the basic concepts of the current literature on mirror neurons and the major findings regarding the use of mirror therapy and motor imagery as potential tools to promote reorganization and functional recovery in post-stroke patients. Bibliographic research was conducted based on publications over the past thirteen years written in English in the databases Scielo, Pubmed/MEDLINE, ISI Web of Knowledge. The studies showed how the interaction among vision, proprioception and motor commands promotes the recruitment of mirror neurons, thus providing cortical reorganization and functional recovery of post-stroke patients. We conclude that the experimental advances on Mirror Neurons will bring new rational therapeutic approaches to post-stroke rehabilitation.
KeywordsImagery Imitation Mirror neurons system Mirror therapy Rehabilitation Stroke
Different approaches have been employed to investigate post-stroke rehabilitation [1, 2]. It has been shown that the human brain is capable of significant recovery after this type of injury [3, 4]. Among its sequels, hemiparesis has been treated with mirror-therapy which promotes cortical changes [5, 6]. In particular, sensorimotor disorders in post-stroke patients during the execution or observation of motor action have induced changes to the adjacent cortical penumbra area . Moreover, motion imagination studies have demonstrated efficacies in treating the post-stroke population . Th underlying hypothesis is that “mirror neurons” have been activated during such trainings. These cells were firstly discovered in the premotor cortex of rhesus monkeys by Rizzolatti and colleagues when they analyzed the monkeys observing the researchers’ act of eating up a fruit. These cells were then named because of their property to mirror the observed motor act inside the brain of monkeys [9, 10].
Further experiments have verified the existence of mirror neurons in the parietal-frontal circuit, when an animal was exposed to a task of observing a particular action or intention mad by another animal [11, 12]. Thus, researchers suggested that mirror neurons are part of a neural system where the observation of an action activates the cortical area of the observer’s brain [10, 13–15]. Therefore, the purpose of this review is to describe basic concepts about the current literature on mirror neurons and the major findings regarding the use of mirror therapy and motor imagery as potential tools to promote cortical reorganization and functional recovery in post-stroke patients. The present review is divided in four sections: i) Introduction to Mirror Neuron System: Evidences in Humans; ii) Imitation: The role played by Mirror Neurons; iii) Mirror Neuron System: The Hypothesis of Motor Imagery, and iv) Contributions of the Mirror Neuron System on Post-Stroke Rehabilitation.
Mirror neuron system: evidence in humans
The mirror neuron system is considered a major breakthrough for neuroscience and it represents one important feature during the evolution of the human brain [16, 17]. In this context, several studies analyzed areas where this system participates; in particular, the majority of the experiments in humans and monkeys found mirror neurons in frontal and parietal lobes in tasks involving manual action observation [5, 6, 18–20]. Moreover, other experiments identified the activation of mirror neurons, specifically in the inferior frontal gyrus and premotor cortex. These findings were replicated in humans during task execution and observation of motor acts with hands, feet and mouth [21–23].
Several tools for cortical stimulation and brain mapping have been employed to uncover the mechanisms behind the activity of mirror neurons. Among them, Transcranial Magnetic Stimulation (TMS) has provided relevant information about the participation of the motor cortex during simple action observation [20, 24, 25]. Hari et al., 1998, investigated the involvement of the mirror neuron system during action observation using magnetoencephalography. With this technique, subjects were instructed to observe stationary or moving stimuli. They observed a suppression of the 15 to 25 Hz activity and concluded that the human primary motor cortex is activated during observation as well as execution of motor tasks. Thus, the mirror neuron system seems to play an important role in human mimicking behavior, and it is activated when an individual observes an action performed by another person. Furthermore, its activation does not depend on memory; i.e., the mirror neuron system is able to identify action complexity, and it unconsciously imitates what we see, hear or perceive .
Clinical studies involving the mirror system
Grèzes et al.
Video recordings of objects, grasping pantomimes.
Significant activation in the left intraparietal area during object observation vs baseline.
p = 0.001
Montgomery et al.
Videos of communicative hand gestures, object-directed hand movements and word stimuli.
Activations in the inferior parietal lobe and frontal operculum.
p < 0.001
Hamilton and Grafton. 
Handed participants watched twelve sets of videos presented in a pseudorandom order and pressed a key if the film was froze in the middle of the action.
A stronger response was found in regions throughout the fronto-parietal circuits, right inferior parietal lobule and right inferior frontal gyrus extending to the inferior frontal sulcus.
p < 0.001
Gazzola et al.
Subjects watched either a human or a robot performing various actions. All visual stimuli were video clips lasting between 2.5 and 4 s.
During motor execution active areas were: motor primary in the frontal lobe; sensitive primary and secondary the parietal lobe and the middle temporal gyrus in the temporal lobe.
p < 0.001
Movement of the hands with observation of the mirror reflex.
The active regions were the precuneus and the posterior cingulate cortex.
p < 0.005
Tanaka and Inui. 
Subjects were instructed to imitate presented postures using their right hand or fingers.
Significant activation was observed in Broca’s area.
p < 0.001
Heiser et al.
Patients watched different videos showing a hand pressing a sequence of 2 (out of 4 possible keys) on a key-press box.
There was a selective deficit of the imitation task for rTMS over the left and right pars opercularis of the inferior frontal gyrus, compared to rTMS over the occipital cortex.
p < 0.005
Stefan et al.
Task that encoded an elementary motor memory.
Observation of movements led to the formation of a lasting specific memory trace in movement representations that resembled that elicited by physical training.
p < 0.005
Oberman et al.
Subjects opened and closed their right hand while watching a video of a moving hand.
Consistent pattern of suppression in the frequency band of interest.
p = 0.001
Imitation and action learning: the role played by mirror neurons
Mirror neurons have been associated with various forms of human behaviors: imitation, mind theory, new skill learning and intention reading [9, 38–40]. Studies suggested that humans have a mechanism for copying mental notes of different behaviors, which partly explains how we learn to smile, talk, walk, dance or play tennis. This means that we mentally rehearse or imitate every action observed, whether a somersault or [40, 41] a subtle smile, indicating that these cells are used to learn everything from the first basic steps to more graceful accurate movements. Therefore, imitation is involved in learning through the transformation of visual inputs encoded into action by the observer .
In this context, evidences showed that the mirror neuron system is involved in imitation as a response to the observed motor act . Further studies applying TMS found that the mirror neuron system plays a key role in imitation. The use of TMS caused a temporary depression in the caudal region of the left frontal gyrus when the volunteers pressed the keyboard as a response to a red light indicating which key should be pressed. The findings suggested that during imitation, segmentation of cortical action to be imitated occurred and organization of these movements occurred as well .
Mirror neuron system: the hypothesis of motor imagery
Mental practice (MP), or motor imagery, is the internal reproduction of a given motor act, which is repeated several times in order to promote learning or just to improve a given motor skill . Thus, MP results from the conscious access to the intention of moving, and it establishes a relationship between motor events and cognitive perceptions, specifically in post-stroke patients [47, 48]. MP can be used according to two different principles: the first consists of internal images, where the individual will perform a mental simulation, and the second applies external image, i.e. the individual watches the movement performed by another individual or by segments of his own body, and this plays an important role in the acquisition of new motor skills , improving post-stroke patients rehabilitation. Verma et al.  evaluated the effectiveness of circuit training with MP in post-stroke individuals, and observed that the gait significantly improved with this practice, i.e. the spasticity was attenuated and ambulation was improved . De Vries et al.  surveyed 12 subjects who underwent three imagery tasks, in order to examine whether MP improves the recovery of individuals 3 to 6 weeks after the stroke . Results revealed improvements in the ability of visual imagination and suggest that patients with acute stroke, who cannot perform mental practice, should use this modality during the period of rehabilitation. On the other hand, Letswaart et al.  conducted a cohort study in post-stroke patients (about three months later) with residual weakness in the upper limb . Thirty nine patients underwent four weeks of mental rehearsal of superior movements, 3 times per week, using each arm for 45 minutes. When compared to 32 patients who received normal care, the MP group did not show any significant result, suggesting that motor recovery of post-stroke individuals does not increase with MP. Despite the involvement of mirror neurons in the motor act imitation , its activation via MP in the early stages of post-stroke rehabilitation was not consistent .
Contributions of the mirror neuron system on post-stroke rehabilitation
The functional damages caused by stroke may be irreversible and compromise the physical functions: cognitive, perceptive, visual and emotional . Thus, physical therapists use many treatments on stroke patients in order to attenuate their sequels. From this point of view, the physical therapy intervention has been implemented based on the neural system. Findings that mirror neurons were activated in monkeys’ cerebral cortex were the first step to research these neurons in human brains . This fact promoted the current treatments of many diseases with the mirror therapy.
The imitation of the movement requires a complex cognitive function that is gradually constructed in several stages including motor observation [53, 54]. Considering this, therapies which activate mirror neurons have been used in studies seeking a better post-stroke rehabilitation. In particular, Burns (2008) has shown that motor acts observation in post-stroke patients rehabilitation may accelerate the return to functional activities . Within this context, researchers used fMRI to examine brain activity in post-stroke patients watching a video which contained sequences of mouth, hand and foot movements and they noted that the patients’ cortical areas were activated after observation. A simple exposure to videos showing functional task performances activated the mirror neuron system [7, 48]. In particular, the use of mirror therapy has been shown to improve movement recovery, reinforcing motor circuits responsible for the execution of observed actions . This treatment model uses a mirror in such a way that it reflects the action of the healthy limb hiding the affected one. This technique has shown that a neural network responsible for controlling the movement of a particular body region can also be used to control the movements of the contralateral body region. Thus, the idea is to retrain the brain via a simple task, where the individual can perform a series of movements with the healthy limb; this is reflected by the mirror and the brain is “tricked” thinking that the movement is performed by the affected limb .
The use of mirror therapy in post-stroke patients involves a re-assemblage of the body image in the sensorimotor cortex, which can generate movement limitations, classified as “learned paralysis”. In fact, the fibers that extend from the brain to the spinal cord are deprived of oxygen and suffer an injury, causing a real paralysis. In addition to this, in the early stages of cerebral damage, the penumbra area presents a cellular swelling, temporarily leaving neurons with little or no conduction property. Moreover, during its inactive period, the brain receives only negative visual feedback; this will possibly promote a form of learned paralysis, due to residual mirror neuron functioning. In this case, mirror therapy can potentially reactivate the cortical motor neurons . Therefore, mirror therapy has been used in many clinical instances, because it accelerates the functional recovery of a wide range of sensorimotor disorders, such as post-stroke hemiparesis . Hamzei et al.  studied the neural plasticity in the primary sensory motor cortex using mirror therapy conducting an experiment in which subjects performed hand movement tasks for 20 minutes every day during 4 days . The authors found that compared to the control group, the performance of the untrained hand improved significantly in the group that used the mirror therapy. Moreover, in the pre-training and post-training analysis, right dorsal and left ventral pre-motor cortex, primary sensorimotor cortex and supplementary motor area were activated. Thus, mirror therapy influences the neural circuitry, which reprograms the motor act by observing the hand trained by the illusory movement of the untrained hand.
In order to examine the clinical effects of mirror therapy and cortical reorganization in 40 post-stroke patients, Michielsen et al.  divided the subjects into two groups: control and mirror therapy groups; they performed a task using the upper limb one hour per day, five days per week, during six weeks. For such analysis, fMRI and Fugl-Meyer scale (FMS), which evaluates motor function, were used. The FMS results showed that the group with mirror therapy significantly improved its scores, but these changes were not sustained in the follow-up trials. On the other hand, a more balanced activity was observed in the primary motor cortex after fMRI. In another study, Michielsen et al.  used the mirror therapy in 22 post-stroke patients who performed unimanual and bimanual tasks under two conditions: hand observation (no mirror condition), and observation of the hand reflex in the mirror (mirror condition). They found a significant increase in the posterior cingulate activity and a reduction of 'learned non-use’ (loss of movement ability) patterns during of the movement with the mirror in the bimanual task. They did not find activation during the unimanual condition suggesting that it is not the illusion of a virtual moving hand that causes this activation, but the mismatch between the movement one performs and the movement that is observed [2, 23]. Franceschini et al. valuated the efficacy of the mirror therapy for upper limb motor impairment in post-stroke patients. In this study, 28 patients with chronic upper limb motor impairment underwent a treatment consisting of watching videos of hand movements for 5 days a week during 4 weeks, and the subjects performed imitation of the movement . Due to the significant findings, they concluded that the observed action can be used as an effective strategy in post-stroke rehabilitations. Thus, mirror neurons can be activated not only using mirror therapy, but also through motor imagery .
MNS and music therapy
Some of the mirror neurons could respond to sounds that are specific for actions, which were named as “audio-visual” mirror neurons . This suggests that combined therapies including both visual and auditory that activate mirror neuron system might be more effective in promoting rehabilitation, which could be, possibly, achieved by online virtual pets  or designed multi-media techniques. On the other hand, this suggested that auditory function impairment might be restored with specifically designed MNS training procedures. This idea is yet to be clinically tested.
As a unique and multi-modal stimulus, music transfers visual, auditory, somatosensory and proprioceptive information simultaneously. Interestingly, it has been suggested that music related brain activity involving imitation and synchronization overlapped with MNS brain regions [61, 62]. Additionally, the inferior frontal gyrus and the ventral premotor cortex (including Broca’s area) that belong to MNS participated in music execution and listening . For instance, Broca’s area was activated during music perception tasks, active music tasks such as singing, and imagination of playing an instrument . These evidences strongly argued for the potential function of MNS during music-relevant behaviors. It should be noted that in autism patients, individuals with normal (singing) and even superior abilities with specific aspects of music processing (pitch memory and absolute pitch, etc.) could be found as well. This dissociation between singing and speaking is similar to what was observed in Broca’s aphasia patients.
The music based activation of MNS therefore provided alternative option of brain activity manipulation beyond visual training therapy, as well as the possibility of mutli-sensory stimulation. For instance, Melodic intonation therapy (MIT) is one of music-based therapeutic interventions using hand tapping to promote engagement of the sensorimotor network in patients with aphasia [65, 66]. These available approaches are ready to be modified from a MNS based perspective for further studies. Music therapy has already been employed to treat some disorders discussed above, such as aphasia , stroke [68, 69]. It is acknowledged that the psychosomatic effects of music also contributed to the beneficial aspects of music therapy [70, 71]; whether MNS activation also mediates such effects are to be examined.
The mirror neuron system can explain many human behaviors and disorders. Mirror neurons are involved in imitative learning through interactions with neural motor areas in humans. The application of mirror therapy techniques, based on the functions of the mirror neuron system, in post-stroke patients has demonstrated good results, mainly when combined with other therapies. Moreover, the studies showed that the mirror neuron system interacts with vision, proprioception and motor commands, promoting the recruitment of mirror neurons and the cortical reorganization and functional recovery of post-stroke patients. However, many brain areas are not activated in mirror therapy and this factor may compromise the therapy. Also, patients experience fatigue and attention level decrease, which may cause a deficiency in concentration when executing mirror therapy tasks.
OAC is supported by Hospital General Dr. Manuel Gea Gonzalez and Hospital General Ajusco Medio.
- Altschuler EL, Wisdom SB, Stone L, Foster C, Galasko D, Llewellyn DM, Ramachandran VS: Rehabilitation of hemiparesis after stroke with a mirror. Lancet 1999,353(9169):2035–2036.PubMedView ArticleGoogle Scholar
- Michielsen ME, Selles RW, van der Geest JN, Eckhardt M, Yavuzer G, Stam HJ, Smits M, Ribbers GM, Bussmann JB: Motor recovery and cortical reorganization after mirror therapy in chronic stroke patients: a phase II randomized controlled trial. Neurorehabil Neural Repair 2011,25(3):223–233.PubMedView ArticleGoogle Scholar
- Broderick J, Brott T, Kothari R, Miller R, Khoury J, Pancioli A, Gebel J, Mills D, Minneci L, Shukla R: The greater cincinnati/northern kentucky stroke study: preliminary first-ever and total incidence rates of stroke among blacks. Stroke 1998,29(2):415–421.PubMedView ArticleGoogle Scholar
- Kalra L, Ratan R: Recent advances in stroke rehabilitation 2006. Stroke 2007,38(2):235–237.PubMedView ArticleGoogle Scholar
- Umilta MA, Escola L, Intskirveli I, Grammont F, Rochat M, Caruana F, Jezzini A, Gallese V, Rizzolatti G: When pliers become fingers in the monkey motor system. Proc Natl Acad Sci USA 2008,105(6):2209–2213.PubMedView ArticleGoogle Scholar
- Van Der Werf YD, Van Der Helm E, Schoonheim MM, Ridderikhoff A, Van Someren EJ: Learning by observation requires an early sleep window. Proc Natl Acad Sci USA 2009,106(45):18926–18930.PubMedView ArticleGoogle Scholar
- Cacchio A, De Blasis E, De Blasis V, Santilli V, Spacca G: Mirror therapy in complex regional pain syndrome type 1 of the upper limb in stroke patients. Neurorehabil Neural Repair 2009,23(8):792–799.PubMedView ArticleGoogle Scholar
- Garrison KA, Winstein CJ, Aziz-Zadeh L: The mirror neuron system: a neural substrate for methods in stroke rehabilitation. Neurorehabil Neural Repair 2010,24(5):404–412.PubMedView ArticleGoogle Scholar
- Rizzolatti G, Craighero L: The mirror-neuron system. Annu Rev Neurosci 2004, 27:169–192.PubMedView ArticleGoogle Scholar
- Fadiga L, Craighero L, Olivier E: Human motor cortex excitability during the perception of others’ action. Curr Opin Neurobiol 2005,15(2):213–218.PubMedView ArticleGoogle Scholar
- Gazzola V, Rizzolatti G, Wicker B, Keysers C: The anthropomorphic brain: the mirror neuron system responds to human and robotic actions. Neuroimage 2007,35(4):1674–1684.PubMedView ArticleGoogle Scholar
- Cattaneo L, Rizzolatti G: The mirror neuron system. Arch Neurol 2009,66(5):557–560.PubMedView ArticleGoogle Scholar
- Buccino G, Binkofski F, Riggio L: The mirror neuron system and action recognition. Brain Lang 2004,89(2):370–376.PubMedView ArticleGoogle Scholar
- Rizzolatti G: The mirror neuron system and its function in humans. Anat Embryol 2005,210(5–6):419–421.PubMedView ArticleGoogle Scholar
- Williams JH, Waiter GD, Gilchrist A, Perrett DI, Murray AD, Whiten A: Neural mechanisms of imitation and 'mirror neuron’ functioning in autistic spectrum disorder. Neuropsychologia 2006,44(4):610–621.PubMedView ArticleGoogle Scholar
- Stefan K, Cohen LG, Duque J, Mazzocchio R, Celnik P, Sawaki L, Ungerleider L, Classen J: Formation of a motor memory by action observation. J Neurosci 2005,25(41):9339–9346.PubMedView ArticleGoogle Scholar
- Pfeifer JH, Iacoboni M, Mazziotta JC, Dapretto M: Mirroring others’ emotions relates to empathy and interpersonal competence in children. Neuroimage 2008,39(4):2076–2085.PubMedView ArticleGoogle Scholar
- Kohler E, Keysers C, Umilta MA, Fogassi L, Gallese V, Rizzolatti G: Hearing sounds, understanding actions: action representation in mirror neurons. Science 2002,297(5582):846–848.PubMedView ArticleGoogle Scholar
- Dapretto M, Davies MS, Pfeifer JH, Scott AA, Sigman M, Bookheimer SY, Iacoboni M: Understanding emotions in others: mirror neuron dysfunction in children with autism spectrum disorders. Nat Neurosci 2006,9(1):28–30.PubMedView ArticleGoogle Scholar
- Iacoboni M, Dapretto M: The mirror neuron system and the consequences of its dysfunction. Nat Rev Neurosci 2006,7(12):942–951.PubMedView ArticleGoogle Scholar
- Gazzola V, Aziz-Zadeh L, Keysers C: Empathy and the somatotopic auditory mirror system in humans. Curr Biol 2006,16(18):1824–1829.PubMedView ArticleGoogle Scholar
- Le Bel RM, Pineda JA, Sharma A: Motor-auditory-visual integration: the role of the human mirror neuron system in communication and communication disorders. J Commun Disord 2009,42(4):299–304.PubMedView ArticleGoogle Scholar
- Michielsen ME, Smits M, Ribbers GM, Stam HJ, van der Geest JN, Bussmann JB, Selles RW: The neuronal correlates of mirror therapy: an fMRI study on mirror induced visual illusions in patients with stroke. J Neurol Neurosurg Psychiatry 2011,82(4):393–398.PubMedView ArticleGoogle Scholar
- Caggiano V, Fogassi L, Rizzolatti G, Pomper JK, Thier P, Giese MA, Casile A: View-based encoding of actions in mirror neurons of area f5 in macaque premotor cortex. Curr Biol 2011,21(2):144–148.PubMedView ArticleGoogle Scholar
- Cattaneo Z, Mattavelli G, Papagno C, Herbert A, Silvanto J: The role of the human extrastriate visual cortex in mirror symmetry discrimination: a TMS-adaptation study. Brain Cogn 2011,77(1):120–127.PubMedView ArticleGoogle Scholar
- Maeda F, Kleiner-Fisman G, Pascual-Leone A: Motor facilitation while observing hand actions: specificity of the effect and role of observer’s orientation. J Neurophysiol 2002,87(3):1329–1335.PubMedGoogle Scholar
- Giromini L, Porcelli P, Viglione DJ, Parolin L, Pineda JA: The feeling of movement: EEG evidence for mirroring activity during the observations of static, ambiguous stimuli in the Rorschach cards. Biol Psychol 2010,85(2):233–241.PubMedView ArticleGoogle Scholar
- Cooper NR, Puzzo I, Pawley AD, Bowes-Mulligan RA, Kirkpatrick EV, Antoniou PA, Kennett S: Bridging a yawning chasm: EEG investigations into the debate concerning the role of the human mirror neuron system in contagious yawning. Cogn Affect Behav Neurosci 2012,12(2):393–405.PubMedView ArticleGoogle Scholar
- Oberman LM, Hubbard EM, McCleery JP, Altschuler EL, Ramachandran VS, Pineda JA: EEG evidence for mirror neuron dysfunction in autism spectrum disorders. Brain Res Cogn Brain Res 2005,24(2):190–198.PubMedView ArticleGoogle Scholar
- Gallese V, Keysers C, Rizzolatti G: A unifying view of the basis of social cognition. Trends Cogn Sci 2004,8(9):396–403.PubMedView ArticleGoogle Scholar
- Pomeroy VM, Clark CA, Miller JS, Baron JC, Markus HS, Tallis RC: The potential for utilizing the “mirror neurone system” to enhance recovery of the severely affected upper limb early after stroke: a review and hypothesis. Neurorehabil Neural Repair 2005,19(1):4–13.PubMedView ArticleGoogle Scholar
- Grèzes J, Tucker M, Armony J, Ellis R, Passingham RE: Objects automatically potentiate action: an fMRI study of implicit processing. Eur J Neurosci 2003,17(12):2735–2740.PubMedView ArticleGoogle Scholar
- Montgomery KJ, Isenberg N, Haxby JV: Communicative hand gestures and object-directed hand movements activated the mirror neuron system. Soc Cogn Affect Neurosci 2007,2(2):114–122.PubMedView ArticleGoogle Scholar
- Hamilton AF, Grafton ST: Action outcomes are represented in human inferior frontoparietal cortex. Cereb Cortex 2008,18(5):1160–1168.PubMedView ArticleGoogle Scholar
- Tanaka S, Inui T: Cortical involvement for action imitation of hand/arm postures versus finger configurations: an fMRI study. Neuroreport 2002,13(13):1599–1602.PubMedView ArticleGoogle Scholar
- Heiser M, Iacoboni M, Maeda F, Marcus J, Mazziotta JC: The essential role of Broca’s area in imitation. Eur J Neurosci 2003,17(5):1123–1128.PubMedView ArticleGoogle Scholar
- Oberman LM, Pineda JA, Ramachandran VS: The human mirror neuron system: a link between action observation and social skills. Soc Cogn Affect Neurosci 2007,2(1):62–66.PubMedView ArticleGoogle Scholar
- Rizzolatti G, Fogassi L, Gallese V: Neurophysiological mechanisms underlying the understanding and imitation of action. Nat Rev Neurosci 2001,2(9):661–670.PubMedView ArticleGoogle Scholar
- Hickok G: Eight problems for the mirror neuron theory of action understanding in monkeys and humans. J Cogn Neurosci 2009,21(7):1229–1243.PubMedView ArticleGoogle Scholar
- Martineau J, Andersson F, Barthelemy C, Cottier JP, Destrieux C: A typical activation of the mirror neuron system during perception of hand motion in autism. Brain Res 2010, 1320:168–175.PubMedView ArticleGoogle Scholar
- Koski L, Iacoboni M, Dubeau MC, Woods RP, Mazziotta JC: Modulation of cortical activity during different imitative behaviors. J Neurophysiol 2003,89(1):460–471.PubMedView ArticleGoogle Scholar
- Gallese V, Goldman A: Mirror neurons and the simulation theory of mind-reading. Trends Cogn Sci 1998,2(12):493–501.PubMedView ArticleGoogle Scholar
- Iacoboni M, Woods RP, Brass M, Bekkering H, Mazziotta JC, Rizzolatti G: Cortical mechanisms of human imitation. Science 1999,286(5449):2526–2528.PubMedView ArticleGoogle Scholar
- Nishitani N, Hari R: Temporal dynamics of cortical representation for action. Proc Natl Acad Sci USA 2000,97(2):913–918.PubMedView ArticleGoogle Scholar
- Williams JH, Whiten A, Suddendorf T, Perrett DI: Imitation, mirror neurons and autism. Neurosci Biobehav Rev 2001,25(4):287–295.PubMedView ArticleGoogle Scholar
- Hamilton AF, Brindley RM, Frith U: Imitation and action understanding in autistic spectrum disorders: how valid is the hypothesis of a deficit in the mirror neuron system? Neuropsychologia 2007,45(8):1859–1868.PubMedView ArticleGoogle Scholar
- de Vries S, Tepper M, Otten B, Mulder T: Recovery of motor imagery ability in stroke patients. Rehabil ResPract 2011, 2011:283840.Google Scholar
- de Vries S, Mulder T: Motor imagery and stroke rehabilitation: a critical discussion. J Rehabil Med 2007,39(1):5–13.PubMedView ArticleGoogle Scholar
- Anwar MN, Tomi N, Ito K: Motor imagery facilitates force field learning. Brain Res 2011, 1395:21–29.PubMedView ArticleGoogle Scholar
- Verma R, Arya KN, Garg RK, Singh T: Task-oriented circuit class training program with motor imagery for gait rehabilitation in poststroke patients: a randomized controlled trial. Top Stroke Rehabil 2011,18(Suppl 1):620–632.PubMedView ArticleGoogle Scholar
- Ietswaart M, Johnston M, Dijkerman HC, Joice S, Scott CL, MacWalter RS, Hamilton SJ: Mental practice with motor imagery in stroke recovery: randomized controlled trial of efficacy. Brain 2011,134(Pt 5):1373–1386.PubMedView ArticleGoogle Scholar
- Wojner-Alexander AW, Garami Z, Chernyshev OY, Alexandrov AV: Heads down: flat positioning improves blood flow velocity in acute ischemic stroke. Neurology 2005,64(8):1354–1357.PubMedView ArticleGoogle Scholar
- Small SL, Buccino G, Solodkin A: The mirror neuron system and treatment of stroke. Dev Psychobiol 2012,54(3):293–310.PubMedView ArticleGoogle Scholar
- Garrison KA, Aziz-Zadeh L, Wong SW, Liew SL, Winstein CJ: Modulating the motor system by action observation after stroke. Stroke 2013,44(8):2247–2253.PubMedView ArticleGoogle Scholar
- Burns MS: Application of neuroscience to technology in stroke rehabilitation. Top Stroke Rehabil 2008,15(6):570–579.PubMedView ArticleGoogle Scholar
- Ramachandran VS, Rogers-Ramachandran D, Stewart M: Perceptual correlates of massive cortical reorganization. Science 1992,258(5085):1159–1160.PubMedView ArticleGoogle Scholar
- Sutbeyaz S, Yavuzer G, Sezer N, Koseoglu BF: Mirror therapy enhances lower-extremity motor recovery and motor functioning after stroke: a randomized controlled trial. Arch Phys Med Rehabil 2007,88(5):555–559.PubMedView ArticleGoogle Scholar
- Hamzei F, Lappchen CH, Glauche V, Mader I, Rijntjes M, Weiller C: Functional plasticity induced by mirror training: the mirror as the element connecting both hands to one hemisphere. Neurorehabil Neural Repair 2012,26(5):484–496.PubMedView ArticleGoogle Scholar
- Franceschini M, Agosti M, Cantagallo A, Sale P, Mancuso M, Buccino G: Mirror neurons: action observation treatment as a tool in stroke rehabilitation. Eur J Phys Rehabil Med 2010,46(4):517–523.PubMedGoogle Scholar
- Altschuler EL: Play with online virtual pets as a method to improve mirror neuron and real world functioning in autistic children. Med Hypotheses 2008,70(4):748–749.PubMedView ArticleGoogle Scholar
- D’Ausilio A: Mirror-like mechanisms and music. ScientificWorldJournal 2009, 9:1415–1422.PubMedView ArticleGoogle Scholar
- Molnar-Szakacs I, Overy K: Music and mirror neurons: from motion to 'e’motion. Soc Cogn Affect Neurosci 2006,1(3):235–241.PubMedView ArticleGoogle Scholar
- Fadiga L, Craighero L, D’Ausilio A: Broca’s area in language, action, and music. Ann N Y Acad Sci 2009, 1169:448–458.PubMedView ArticleGoogle Scholar
- Tillmann B, Janata P, Bharucha JJ: Activation of the inferior frontal cortex in musical priming. Brain Res Cogn Brain Res 2003,16(2):145–161.PubMedView ArticleGoogle Scholar
- Sparks R, Helm N, Albert M: Aphasia rehabilitation resulting from melodic intonation therapy. Cortex 1974,10(4):303–316.PubMedView ArticleGoogle Scholar
- Norton A, Zipse L, Marchina S, Schlaug G: Melodic intonation therapy: shared insights on how it is done and why it might help. Ann N Y Acad Sci 2009, 1169:431–436.PubMedView ArticleGoogle Scholar
- Tomaino CM: Effective music therapy techniques in the treatment of nonfluent aphasia. Ann N Y Acad Sci 2012,1252(1):312–317.PubMedView ArticleGoogle Scholar
- van Wijck F, Knox D, Dodds C, Cassidy G, Alexander G, Macdonald R: Making music after stroke: using musical activities to enhance arm function. Ann N Y Acad Sci 2012,1252(1):305–311.PubMedView ArticleGoogle Scholar
- Forsblom A, Laitinen S, Sarkamo T, Tervaniemi M: Therapeutic role of music listening in stroke rehabilitation. Ann N Y Acad Sci 2009, 1169:426–430.PubMedView ArticleGoogle Scholar
- Sarkamo T, Tervaniemi M, Laitinen S, Forsblom A, Soinila S, Mikkonen M, Autti T, Silvennoinen HM, Erkkila J, Laine M, et al.: Music listening enhances cognitive recovery and mood after middle cerebral artery stroke. Brain 2008,131(Pt 3):866–876.PubMedView ArticleGoogle Scholar
- Hari R, Forss N, Avikainen S, Kirveskarj E, Salenius S, Rizzolatti G: Activation of human primary motor cortex during action observation: a neuromagnetic study. Proc Natl Acad Sci USA 1998, 95:15061–15065.PubMedView ArticleGoogle Scholar
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