Thursday, October 14, 2021

Plasticity in the sensorimotor cortex induced by Music-supported therapy in stroke patients: a TMS study

 Did your doctors and hospital create protocols on music therapy when this came out 8 years ago? Or are they still completely incompetent having done nothing? If they have done nothing you don't have a functioning stroke hospital.

Plasticity in the sensorimotor cortex induced by Music-supported therapy in stroke patients: a TMS study

Front. Hum. Neurosci., 03 September 2013 | https://doi.org/10.3389/fnhum.2013.00494

  • 1Cognition and Brain Plasticity Group, Bellvitge Biomedical Research Institute - IDIBELL, Barcelona, Spain
  • 2Neurology Section, Hospital Universitari de Bellvitge, Bellvitge Biomedical Research Institute - IDIBELL, Barcelona, Spain
  • 3Institute of Music Physiology and Musicians' Medicine, Hannover University of Music, Drama and Media, Hannover, Germany
  • 4Department of Neurology, University of Lübeck, Lübeck, Germany
  • 5Department of Basic Psychology, University of Barcelona, Barcelona, Spain
  • 6Catalan Institution for Research and Advanced Studies, ICREA, Barcelona, Spain

Playing a musical instrument demands the engagement of different neural systems. Recent studies about the musician's brain and musical training highlight that this activity requires the close interaction between motor and somatosensory systems. Moreover, neuroplastic changes have been reported in motor-related areas after short and long-term musical training. Because of its capacity to promote neuroplastic changes, music has been used in the context of stroke neurorehabilitation. The majority of patients suffering from a stroke have motor impairments, preventing them to live independently. Thus, there is an increasing demand for effective restorative interventions for neurological deficits. Music-supported Therapy (MST) has been recently developed to restore motor deficits. We report data of a selected sample of stroke patients who have been enrolled in a MST program (1 month intense music learning). Prior to and after the therapy, patients were evaluated with different behavioral motor tests. Transcranial Magnetic Stimulation (TMS) was applied to evaluate changes in the sensorimotor representations underlying the motor gains observed. Several parameters of excitability of the motor cortex were assessed as well as the cortical somatotopic representation of a muscle in the affected hand. Our results revealed that participants obtained significant motor improvements in the paretic hand and those changes were accompanied by changes in the excitability of the motor cortex. Thus, MST leads to neuroplastic changes in the motor cortex of stroke patients which may explain its efficacy.

Introduction

Stroke represents a major cause of death and the most important cause of acquired disability in adults of developed countries (World Health Organization, 2003). In stroke survivors, motor deficits are present in a majority of patients (Rathore et al., 2002), leading to limitations in the participation of activities of daily living and preventing patients to live independently. For this reason, restoration of motor deficits is the target of many different therapies (Langhorne et al., 2011).

Usually, the rehabilitation process of motor impairments comprises different stages. At the beginning, motor function is assessed through domain-specific measures in order to set goals with the patient. Subsequently, therapeutic interventions are provided and, finally, reassessment is performed to ensure that motor improvements have been achieved (Warlow et al., 2008). In practice, this process is not always evidence-based but many times guided by the practitioner's expertise. Thus, there is a necessity to investigate effective motor rehabilitation therapies to provide evidence for clinicians (Taub et al., 2002; Cramer et al., 2011; Langhorne et al., 2011).

Besides their clinical efficacy, rehabilitation techniques may be validated by evidence for neuroplasticity which is defined as the capacity of the central nervous system to reorganize its structure, function and connections in response to internal and external constraints and goals during learning, development or after injury (Kolb and Whishaw, 1998; Cramer et al., 2011). Neuroplasticity may be induced due to therapy as behavior can lead to a reorganization of representational maps (Nudo et al., 1996; Muellbacher et al., 2002) as well as intra- and interhemispheric changes and balance (Chollet et al., 1991; Murase et al., 2004; Grefkes et al., 2008).

One of the most studied rehabilitation techniques is the Constraint-Induced Therapy (CIT) (Taub et al., 1993), which comprises the forced use of the paretic extremity for many hours a day by restricting movement of the healthy extremity in combination with shaping techniques. Studies in subacute and chronic patients have shown improvements in motor function that are accompanied with cortical reorganization of motor regions evidenced by Transcranial Magnetic Stimulation (TMS) (Taub et al., 1993; Liepert et al., 1998). For example, Liepert et al. (2000) reported an expansion of the contralateral cortical area responsible for arm movements after the application of CIT. It has been suggested that the success of this therapy may rely on repetitive massed practice of movements performed with the affected extremity overcoming its learned non-use. Notice that learning processes feature prominently not only in neurorehabilitation (Krakauer, 2006) but also in the development of the motor deficits themselves. For example, patients with a motor deficit of the right hand will learn to perform movements predominantly with the (usually non-dominant) left hand. At the same time, this may lead to additional learned non-use of the right hand. It is important to develop new therapeutic strategies to overcome the learned non-use of the affected side, paying special attention on how to perform specific movements. A way to achieve this goal could be through techniques where there is a specific training for patients in activities that could represent the acquisition of new motor skills that could promote brain plasticity (Dayan and Cohen, 2011). During motor skill learning, massive practice of movements can reduce kinematic and dynamic execution errors (Krakauer et al., 1999; Doyon and Benali, 2005). On the other hand, motor skill training will be more effective if task variability is introduced in the training program. These variations could be related to sensorial cues involved in the training (multimodality) which leads to dynamic sensorimotor readjustments and, consequently, internal motor control models can be created and generalized to other situations (Conditt et al., 1997). In this regard, it has been demonstrated that neuroplasticity could be observed at cortical and subcortical levels due to motor skill learning (Karni et al., 1995; Nudo et al., 1996; Willingham, 1998; Draganski et al., 2004; Dayan and Cohen, 2011; Penhune and Steele, 2012).

One example of a skill involving movements of the hand is musical instrument playing. The presence of music during motor learning posits unique and complex demands for the central nervous system (Zatorre et al., 2007), as playing an instrument requires the integration of multimodal information (auditory, visual, and sensorimotor information) (Pantev and Herholz, 2011). During music performance there are feedback and feedforward interactions between the auditory and premotor areas of the cortex. As in other motor skills, motor, premotor, supplementary motor area (SMA), the cerebellum and the basal ganglia are involved in musical motor performance (Lotze et al., 2003; Meister et al., 2004). In addition, the sound of the instrument processed by the auditory cortex can be used to readjust movements leading to interactions between the auditory and motor systems (Zatorre et al., 2007). Compared to other sensorimotor activities, music learning involves the integrated activity of motor and auditory systems. Furthermore, because of the consequent and consistent auditory feedback (Zatorre, 2003), correction of errors in timing, strength and position of the movement is possible. Studies with functional Magnetic Resonance Imaging (fMRI) exploring professional musicians and non-musicians have demonstrated that musical training leads to structural and functional changes in motor regions of the brain, especially those involving auditory and sensorimotor cerebral networks (Gaser and Schlaug, 2003; Bengtsson et al., 2005; Bangert et al., 2006; Baumann et al., 2007; Hyde et al., 2009; Herholz and Zatorre, 2012; Steele et al., 2013). For instance, in healthy subjects, motor cortex was explored with TMS when participants were trained to play the piano showing an enlargement of the cortical representation of the hand after the training (Pascual-Leone et al., 1995). Therefore, learning to play the piano is an example of a music making activity that requires repetitive massed practice and entails variations in the training task (i.e., movement sequences), involving complex coordination. Moreover, playing the piano engages different regions of the brain and could be associated with structural and functional brain changes. Beyond the plasticity in motor regions associated to music making, studies investigating the effects of music listening as a rehabilitative intervention have revealed improvements in cognition and emotional factors (Särkämö et al., 2008; Särkämö and Soto, 2012). These findings add value to the interventions based on motor learning using music making because their possible impact in other cognitive and emotional domains aside from the expected motor improvements.

Recently, Schneider et al.(2007, 2010) have developed Music-supported therapy (MST) to restore motor function after stroke. In this therapy, patients are trained to play a MIDI piano and/or an electronic drum set that produces piano tones, involving fine and gross movements, respectively. MST has been tested in stroke patients showing improvements in the execution of movements revealed by an increase in the scores of behavioral motor tests after the application of MST (Schneider et al., 2007, 2010; Altenmüller et al., 2009). A recent study about a single chronic stroke patient showed that MST can lead to improvements in motor function after 2 years since stroke. Gains in motor function were accompanied by changes in motor cortex excitability (evaluated using motor mapping TMS) with an expansion of the cortical representation of the hand and by activation changes in fMRI (Rojo et al., 2011; Rodríguez-Fornells et al., 2012). In addition, Amengual et al. (2013) have reported evidence from a group of chronic patients that have been treated with MST. Patients improved their motor function as well as an increase of the excitability of the motor system was encountered. Moreover, gains in motor performance were correlated with changes in the cortical representation of a muscle of the paretic hand.

In the present study, MST was administered to stroke patients with hemiparesis of the upperlimb to restore their motor function. Thus, the aim of the present study is to investigate improvements in motor function in subacute stroke patients and whether this restoration is accompanied by neuroplastic changes in the sensorimotor cortex.

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