Printer Friendly

Is neuroplasticity promoted by task complexity?

INTRODUCTION

Neuroplasticity is the brain's potential to adapt its structural and functional organisation as a result of experience (Nudo 2006). These adaptations span a continuum from short term improvements in the synaptic efficiency of neurons to long term changes in structural organisation of the nervous system (Shumway-Cook and Woollacott 2001). For many years it was thought that the central nervous system had little or no capacity for adaptation. However, scientific advances in the past twenty years suggest otherwise. Evidence of neuroplasticity is provided by research that demonstrates changes in neural connections and cortical representation in response to increases or decreases in sensory and motor input (Cohen et al 1991, Karni et al 1995, Liepert et al 1995, Pascual-Leone and Torres 1993). It is now recognized that much of the improvement seen during motor learning reflects neuroplasticity in both healthy people and those with pathology (Ploughman 2002).

Motor learning is the process of acquiring or refining a motor skill, resulting in improved performance and a reduction in the attention required to perform the task (Cannonieri et al 2007). Fitts and Posner (1967) describe the process of motor learning in terms of three reasonably distinct stages (as cited in O'Sullivan 2007a). These phases of motor learning are: the primary cognitive stage when an elevated level of cognitive processing is required; the associative stage of learning when continual practice is used until the motor plan becomes more co-ordinated, controlled and refined; and the autonomous stage of learning when minimal cognitive input is required to perform the task (O'Sullivan 2007a). The process of motor learning is thought to be associated with neuroplastic adaptation of cortico-motor pathways, as demonstrated by studies showing different patterns of cortical activation during motor learning (Doyon and Benali 2005). It has been suggested that the complexity of a motor task may influence the amount of neuroplasticity that results from practice of that task (Carey et al 2005). A complex motor task is one that requires a high degree of attention, memory and motor difficulty (Carey et al 2005). It is hypothesized that neuroplasticity may be more pronounced when the task is more engaging and requires a greater amount of learning to accomplish it (Nielsen and Cohen 2008). Therefore the purpose of this narrative review is to evaluate whether practice of a complex motor task results in greater neuroplastic changes than practice of a simple motor task. These findings would have significance for physiotherapists, people aiming to achieve a high level of proficiency in a motor skill and those aiming to regain a motor skill after illness or injury.

One challenge for physiotherapists in reviewing the evidence for neuroplasticity is interpreting the scientific methods used in current research. Studies investigating neuroplastic changes utilise a variety of sophisticated measurement tools such as transcranial magnetic stimulation (TMS), magnetoencephalography (MEG), electroencephalography (EEG), magnetic resonance imaging (MRI) and functional magnetic resonance imaging (fMRI). TMS can be used to map cortical representations of the brain by stimulating the motor cortex with an electromagnetic coil placed over the skull and measuring the resultant electromyographic (EMG) activity in the target muscle (Taylor et al 2008). Decreased activation thresholds, increased amplitude of response, shorter latency from stimulation to muscle activity and reduced repolarization time indicate increased efficiency of neural connections (Ploughman 2002). MEG can also be used to map motor representations in the cortex by measuring the cortical magnetic fields produced by electrical currents in the brain, as a result of stimulation of a muscle (Wuhle et al 2006). A shift in the centre of cortical responsivity, a change in the angle between two cortical representation areas and changes in the level of neural activity all imply neuroplasticity. EEG measures cortical electrical activity recorded by electrodes placed on the scalp (Niemann et al 1991). A change in the area of activation or a decrease in surface electronegativity suggests functional reorganization of the cortex and a lesser requirement of cortical activation as a motor skill becomes more automatic. EEG also assesses the amount of cortical coupling, which is a measure of the synchronization of activity between different cortical regions. A decrease in cortical coupling indicates that a task requires less cortical control and is therefore more autonomous. MRI uses a powerful magnetic field to produce three dimensional images of brain structures by measuring the interaction of the magnetic field with nuclear particles (O'Sullivan 2007b). MRI images can therefore be utilised to compare differences in grey matter volume. These structural changes indicate changes in cortical representation, potentially demonstrating neuroplastic changes. Lastly, fMRI measures changes in regional blood flow, which are thought to accompany changes in neural activity during performance of a motor task (Logothetis et al 2001). Neuroplasticity may be demonstrated when there are changes in the area of cortical activation and the amount of activation decreases as a motor task becomes more automatic.

METHODS

Experimental research investigating aspects of neuroplasticity following training of complex motor tasks in healthy subjects was identified using the following electronic search engines: Ovid, Evidence Based Medicine Reviews, Allied and Complementary Medicine, CINAHL, MEDLINE, PsychINFO, and EBSCOhost. The key search terms used were: neural plasticity, neuroplasticity, synaptogenesis, cortical representation, cortical organisation, cortical mapping, cortical change, long term potentiation, neural representation, neural organisation, neural change, neural pathway, brain mapping; and task, activity, exercise, practice, train, practise, motor learning, task training, random practice, blocked practice; and complex, difficult, challenge, effort, demand, complicated, contextual interference. To ensure all forms of the searched words were included, truncation and wild card characters were used. Limiters were set so only English and human studies published prior to May 2008 were included. The reference lists of included studies were also screened and author searchers undertaken to identify other relevant studies.

Two independent reviewers (AM & LJ) screened the titles of the sourced articles to ascertain their relevance to the review. The abstracts of the selected articles were then read. Studies were included if they evaluated aspects of neuroplasticity in relation to the practice of complex motor tasks in healthy humans. If the study evaluated neuroplasticity in response to practice of a complex motor task, only studies that incorporated a control group who practised a simple motor task for an equal duration were included. If the study evaluated changes in the organization of the cortico-motor system in experts of a complex motor task, only studies that incorporated a novice control group were included. The two bodies of research were evaluated in this review as the studies comparing simple and complex motor task practice generally did not assess long term changes in neuroplasticity. By comparing the cortical differences between experts and novices of a complex motor task we were able to assess whether the neuroplastic changes may be long lasting. If it was not clear whether a study should be included, the full text was retrieved and discussed by the reviewers. If the reviewers could not reach a consensus a third reviewer (NS) was consulted. The full text versions of the articles that met the inclusion criteria were then independently assessed by two reviewers (AM & LJ) using the McMaster University Critical Review Form (Law et al 1998) to analyse the quality of the evidence. This process included evaluating the studies' characteristics including study design, participants, intervention, outcomes and measures as well as key results, clinical importance and limitations. Any differences identified in the review forms were discussed until agreement was reached.

RESULTS

Of the 5219 studies identified in the initial search, 16 studies met the criteria for inclusion in this review. These papers were divided into two groups: seven comparing subjects who practised either a simple or a complex motor task, and nine that compared the cortical differences between novices and experts of a complex motor task. A summary of the study characteristics for each of these bodies of research is provided in Table 1 and Table 2 respectively. The methodological quality of the studies is described in Table 3.

Of the seven studies comparing practice of simple and complex motor tasks, two compared the differences in neural activity during practice and found greater increases in those practising the complex motor task (Niemann et al 1991, 1992). The other five studies compared neuroplastic adaptations after practice and found greater neuroplasticity in those in the complex motor task groups (Busk and Galbraith 1975, Draganski et al 2004, Hlustik et al 2004, Pascual-Leone et al 1995, Wuhle et al 2006).

All nine studies evaluating cortical differences between novice and expert groups found a positive correlation between neuroplasticity and the amount of experience at a complex motor task [Cannonieri et al 2007, Gaser and Schlaug 2003, Hund-Georgiadis and Von Cramon 1999, Janeke et al 2000, Krings et al 2000, Meister et al 2005, Pierce et al 2000, Schwenkreis et al 2007, Tyc et al 2005).

DISCUSSION

Simple versus Complex

Half of the studies investigating response to simple versus complex motor tasks assessed short terra neuroplastic changes after a single practice session (Busk and Galbraith 1975, Niemann et al 1991, 1992, Wuhle et al 2006), while the other three studies involved more long term practice (Draganski et al 2004, Hlustik et al 2004, Pascual-Leone et al 1995). Overall, the literature demonstrated that practice of a more complex motor task results in greater neuroplasticity than practice of a simple motor task.

A greater increase in neural activity during learning of a complex motor task compared to a simple motor task was demonstrated using EEG in several studies. Both studies by Niemann et al (1991, 1992) showed a greater degree of neural activity during initial practice of the complex matchstick manipulation task compared to the simple button pressing task. These findings suggest an increase in task complexity requires an increase in neural activity, though it is unclear whether increasing neural activity actually results in greater long term neuroplastic changes. Niemann et al (1991) also found that after practice of the complex motor task there was a greater reduction in neural activity in the supplementary motor area (SMA). This reduction is likely due to a decrease in the SMA's required involvement in voluntary initiation and timing control as the task becomes more automatic. These findings suggest that the central nervous system is more active during practice of a complex motor task and that this activity reduces as the task becomes more automatic.

A higher level of cortical coupling was seen during learning of a complex motor task compared to a simple motor task (Busk and Galbraith 1975). This indicates that tasks of higher complexity require the activation of additional cortical regions and greater synchronization between these different regions. This extensive activation may lead to more widespread neuroplastic changes and greater efficiency of the connections between brain regions. The group practising the more complex motor task also demonstrated that after practice there was a greater reduction in cortical coupling as a result of practice (Busk and Galbraith 1975). This reduction in coupling is likely due to the task becoming more autonomous and requiring a lesser degree of cortical activation.

Pascaul-Leone et al (1995) found greater increases in cortico-motor excitability after practice of a complex motor task, compared to practice of a simple motor task. This is likely due to greater synaptic efficiency.

Several studies found a greater increase in cortical representation after practice in the complex motor task group compared to the simple motor task group using either fMRI (Hlustik et al 2004), TMS (Pascual-Leone et al 1995), MRI (Draganski et al 2004) or MEG (Wuhle et al 2006). For example, after three weeks practice of the complex sequence task, Hlustik et al (2004) found greater increases in both sensory and motor representations of the fingers using fMRI. A comparable result was found in the motor cortex in Pascaul-Leone et al's (1995) study using TMS. Draganski et al (2004) also found increases in grey matter volume using MRI after 3 months of juggling practice. However, these changes were no longer significant at follow-up three months later. This was the only study that included a follow-up to determine whether changes were sustained beyond the period of practice.

These findings suggest that the brain is capable of adapting its structural and functional organisation in response to motor learning. These neuroplastic changes include increases in neural activity, cortical synchronization, excitability and cortical representation, and appear to occur to a greater extent immediately following practice of a more complex motor task. However, one study suggests that these changes may not be sustained three months after practice termination.

Novices versus Experts

Nine studies were identified that looked at cortico-motor differences between novices and experts of a complex motor task (Cannonieri et al 2007, Gaser and Schlaug 2003, Hund-Georgiadis and Von Cramon 1999, Jancke et al 2000, Krings et al 2000, Meister et al 2005, Pierce et al 2000, Schwenkreis et al 2007, Tyc et al 2005). In all the studies the expert group involved participants that were professionals in their various activities. Overall, the results indicate that neuroplastic changes exist as a result of longer term practice of a complex motor task and that these changes appear to be long lasting.

Several studies used fMRI to measure differences in neural activity between novices and experts when performing a complex motor task. These studies demonstrated less neural activation in the primary motor cortex, pre-motor area (PMA) and SMA in the expert pianists compared to novices during various finger tapping tasks (Hund-Georgiadis and Von Cramon 1999, Jancke et al 2000, Krings et al 2000, Meister et al 2005). This may be due to the expert group requiring less cognitive processing and attention as a result of familiarity with the task. A reduction in activation in the primary motor cortex and SMA was demonstrated in the novice group after practice as they too become proficient at the task (Hund-Georgiadis and Von Cramon 1999).

Studies by Cannonieri et al (2007) and Gaser and Schlaug (2003) measured the differences in grey matter volume between novices and experts using MRI. Results showed a significant positive correlation between increased grey matter volume and years of experience. This reinforces the theory that long term practice of a complex motor task can induce cortical structural reorganization, the extent of which correlates to years of experience and frequency of practice. TMS was used to measure changes in cortical representation of particular important muscles for the various activities in the studies performed by Pearce et al (2000), Schwenkreis et al (2007), and Tyc et al (2005). The results of these three studies showed an enlargement and displacement of the cortical area for the relevant muscles in the expert group compared to the novices. Within the expert group, there was a greater cortical representation of relevant muscles in the hemisphere controlling the limb performing the complex motor task. This again demonstrates the brain's potential for functional reorganization as a result of long term experience.

Overall, these results suggest long term neuroplastic changes as a result of extensive practice of a complex motor task. This is demonstrated through comparative increases in grey matter volume and cortical representation, and a reduction in SMA and PMA activation in experts of a complex motor task. However, it is also possible that the differences observed between novices and experts may be the result of differences in innate ability that has a biological basis (Gaser and Schlaug 2003).

Strengths and Limitations of the Research

The methodological rigour of the trials discussed was generally poor (see Table 3). However, the purpose of the studies and the interventions were usually well described, allowing the studies to be readily repeated. Many of the studies had small sample sizes and none estimated the required sample sizes based on power calculations. Small sample sizes may threaten external validity, and increase the possibility of a type II error. Only five of the studies (Cannonieri et al 2007, Gaser and Schlaug 2003, Krings et al 2000, Pascual-Leone et al 1995, Pearce et al 2000) used a sample that was representative of the general population rather than limiting the sample to young adults. This may limit the potential to apply these findings clinically to people of other age groups. None of the studies described the validity or reliability of the measurement tools used. Therefore, it is difficult to ascertain whether the results are truly significant or if they are accurately assessing the outcomes they claim to be measuring. Only four studies took confounders such as daily occupation and hobbies of the participants into account (Hund-Georgiadis and Von Cramon 1999, Pascual-Leone et al 1995, Schwenkreis et al 2007, Tyc et al 2005). Just three studies made efforts to blind either the assessors (Pascual-Leone et al 1995) or the participants (Niemann et al 1991, 1992). Failing to blind may have an effect on the internal validity of the research. The use of randomisation was not appropriate for the novice versus expert studies. However, in the simple versus complex studies only Busk and Galbraith (1975) and Pascaul-Leone et al (1995) described random group allocation. This may have resulted in a reduction in internal validity in the other five studies (Draganski et al 2004, Hlustik et al 2004, Niemann et al 1991, 1992, Wuhle et al 2006) as there is a potential for bias with group allocation. Draganski et al's (2004) study was the only one to include a follow-up to assess the longevity of neuroplastic changes. Also, none of the studies used motor tasks that are functional or reflective of the type of motor task that would be used in a physiotherapy setting for either training or rehabilitation. Therefore, we can not apply the findings directly to a clinical setting. Overall, due to the poor methodological quality of the studies, caution must be applied when interpreting the results.

Limitations of the Review Process

Several limitations may have occurred during the process of reviewing the literature. As the review process was undertaken by novice investigators, our ability to interpret the complex neuroscientific terminology and understand the results may have been compromised. The review also only included articles in the English language. It was difficult to identify an appropriate critiquing tool for the types of studies reviewed. The McMaster University Critical Review Form (Law et al 1998) used has not been evaluated for its reliability or validity. However, the researchers found it to be a valuable tool in assessing the quality of the research and understanding the significance of the study findings.

Suggestions for Future Research

Future research should incorporate prospective studies of more rigorous methodology, including larger sample sizes, randomisation to groups, blinding of assessors and control of confounding variables. Studies should be conducted in both the general population and with people with pathology to aid in the application of findings to the clinical setting. Use of motor tasks that are functional and reflective of the type of motor tasks used in a physiotherapy setting would also assist in making the findings more clinically relevant. Future studies should consider the optimal duration, intensity and frequency of practice of a complex motor task to induce neuroplastic changes. Follow-up should be undertaken after the termination of practice to assess whether the neuroplastic changes are transient or longer lasting.

Clinical Relevance

The brain's ability to adapt as a result of practice is likely to contribute to the recovery of function for those with pathology. However, it is also of significance for all people aiming to achieve a high level of proficiency in a complex motor task, such as athletes and musicians. Our findings suggest that these adaptations occur to a greater extent after practising tasks of higher complexity. Therefore, it would be appropriate to prescribe more difficult tasks that require greater cognitive processing in both the rehabilitation and training setting. By practising complex motor tasks therapeutic interventions are more likely to take full advantage of the brain's potential for neuroplasticity. The duration, frequency and intensity of practice required to produce long lasting neural adaptation is currently unclear.

CONCLUSION

Greater motor task complexity has been shown to be associated with increased neuroplasticity. These changes include greater neural activity, cortical coupling and activation of the pre-motor area and supplementary motor area during practice of a complex motor task. Neuroplastic adaptations seen after practice of a complex motor task include increased cortical excitability, reduced coupling, reduced pre-motor area and supplementary motor area activity and increased cortical representation. It is currently unclear whether these neuroplastic changes are transient or long lasting, although evidence from studies comparing novices and experts of complex motor tasks suggest that sustained practice results in significant neuroplastic adaptation. The brain's potential to adapt in response to practice, especially of a complex motor task, has clinical relevance to physiotherapists designing training programmes for people with and without pathology. Research in healthy subjects suggests that physiotherapists should select complex motor tasks to promote neuroplasticity during training. Further research is required in this field, particularly to identify the optimal training parameters for promoting neuroplasticity and to establish the longevity of adaptations after practice termination.

Key Points

* Practice of a complex motor task results in greater short term neuroplastic changes than practice of a simple motor task. It is unclear whether these changes are sustained when practice is terminated.

* It is suggested that long term neuroplastic changes occur in response to extensive practice of complex motor tasks, as evidenced by comparison of novices and experts.

* These findings suggest that physiotherapists should select motor tasks that are complex when training patients to maximize the potential for neuroplasticity and motor learning.

ACKNOWLEDGEMENTS

The authors would like to express appreciation to Eve Saucier, Roisin Welsh and Nicola Saywell for their valuable feedback during the preparation of this manuscript.

REFERENCES

Busk J and Galbraith G (1975): EEG correlates of visual-motor practice in man. Electroencephalography and Clinical Neurophysiology 38(4): 415-422.

Cannonieri G, Bonilha L, Fernandes P, Cendes F and Li L (2007): Practice and perfect: length of training and structural brain changes in experienced typists. Neuroreport 18(10): 1063-1066.

Carey J, Bhatt E and Nagpal A (2005): Neuroplasticity promoted by task complexity. Exercise and Sport Sciences Reviews 33(1): 24-31.

Cohen L, Bandinelli S, Findley T and Hallett M (1991): Motor reorganisation after upperlimb amputation in man. Brain 114: 615-627.

Doyon J and Benali H (2005): Reorganisation and plasticity in the adult brain during learning of motor skills. Current Opinion in Neurobiology 15(2): 161-167.

Draganski B, Gaser C, Busch V, Schuierer G, Bogdahn U and May A (2004): Changes in grey matter induced by training. Nature 427(6972): 311-312.

Gaser C and Schlaug G (2003): Brain structures differ between musicians and non-musicians. The Journal of Neuroscience 23(27): 9240-9245.

Hlustik P, Solodkin A, Noll D and Small S (2004): Cortical plasticity during three-week motor skill learning Journal of Clinical Neurophysiology 21(3): 180-191.

Hund-Georgiadis M and Von Cramon Y (1999): Motor-learning-related changes in piano players and non-musicians revealed by functional magnetic-resonance signals. Experimental Brain Research 125(4): 417-425.

Jancke L, Shah N and Peters M (2000): Cortical activations in primary and secondary motor areas for complex bimanual movements in professional pianists. Cognitive Brain Research 10: 177-183.

Karni A, Meyer G, Jezzard P, Adams M, Turner R and Ungereider L (1995): Functional MRI evidence for adult motor cortex plasticity during motor skill learning. Nature 377: 155-158.

Krings T, Topper R, Foltys H, Erberich S, Sparing R, Willmes K et al (2000): Cortical activation patterns during complex motor tasks in piano players and control subjects. A functional magnetic resonance imaging study. Neuroscience Letters 278: 189-193.

Law M, Stewart D, Pollock N, Letts L, Bosch J and Westmorland M (1998): Critical review form- Quantitative studies. http://www.srs-mcmaster.ca/Portals/20/pdf/ebp/quanreview_form1.doc [Accessed April 17, 2008].

Liepert J, Tegenthoff M and Malin J (1995): Changes of cortical motor area size during immobilization. Electroencephalography and Clinical Neurophysiology 97: 382-386.

Logothetis N, Pauls J, Augath M, Trinath T and Oeltermann A (2001): Neurophysiological investigation of the basis of the fMRI signal. Nature 412(6843): 150-157.

Meister I, Krings T, Foltys H, Boroojerdi B, Muller M, Topper R et al (2005): Effects of long-term practice and task complexity in musicians and nonmusicians performing simple and complex motor tasks: implications for cortical motor organization. Human Brain Mapping 25: 345-352.

Nielsen J and Cohen L (2008):The olympic brain. Does corticospinal plasticity play a role in acquisition of skills required for high-performance sports? Journal of Physiology 586(1): 65-70.

Niemann J, Winker T, Gerling J, Landwehrmeyer B and Jung R (1991): Changes of slow cortical negative DC-potentials during the acquisition of a complex finger motor task. Experimental Brain Research 85(2): 417-422.

Niemann J, Winker T and Jung R (1992): Changes in cortical negative DC shifts due to different motor task conditions. Electroencephalography and Clinical Neurophysiology 83(5): 297-305.

Nudo R (2006): Plasticity. NeuroRx The Journal of the American Society for Experimental NeuroTherapeutics 3(4): 420-427.

O'Sullivan SB (Ed.) (2007a): Strategies to improve motor function (5th ed.). Philadelphia: FA Davis Company.

O'Sullivan, S. B. (Ed.) (2007b):Stroke. Philadelphia: FA Davis Company.

Pascual-Leone A, Dang N, Cohen L, Brasil-Neto J, Cammarota A and Hallett M (1995): Modulation of muscle responses evoked by transcranial magnetic stimulation during the acquisition of new fine motor skills. Journal of Neurophysiology 74(3): 1037-1045.

Pascual-Leone A and Torres F (1993): Plasticity of the sensorimotor cortex representation of the reading finger of Braille readers. Brain 116: 39-52.

Pearce A, Thickbroom G, Byrnes M and Mastaglia F (2000): Functional reorganisation of the corticomotor projection to the hand in skilled racquet players. Experimental Brain Research 130(2): 238-243.

Ploughman M (2002): A review of brain neuroplasticity and implications for the physiotherapeutic management of stroke. Physiotherapy Canada 54(3): 164-176.

Schwenkreis P, El Tom S, Ragert P, Pleger B, Tegenthoff M and Dinse H (2007): Assessment of sensorimotor cortical representation asymmetries and motor skills in violin players. European Journal of Neuroscience 26(11): 3291-3302.

Shumway-Cook A and Woollacott M (2001): Motor control: theory and practical applications. Baltimore: Williams and Wilkins.

Taylor P, Walsh V and Eimer M (2008): Combining TMS and EEG to study cognitive function and cortico-cortico interactions. Behavioural Brain Research 191(2): 141-147.

Tyc F, Boyadjian A and Devanne H (2005): Motor cortex plasticity induced by extensive training revealed by transcranial magnetic stimulation in human. European Journal of Neuroscience 21(1): 259-266.

Wuhle A, Fahlbusch J and Braun C (2006): Effects of motor activity on the organisation of primary somatosensory cortex. Neuroreport 17(1): 39-43.

ADDRESS FOR CORRESPONDENCE

Nada Signal, Health k Rehabilitation Institute, School of Rehabilitation and Occupation Studies, Faculty of Health and Environmental Sciences, AUT University, Private Bag 92006, Auckland 1020, New Zealand. Email: nada.signal@aut.ac.nz Telephone: 09 9219999 extn. 7062; Fax: (09) 921 9629.

Alanna L Muir, BHSc (Physiotherapy)

Lana M Jones, BHSc (Physiotherapy)

At the time of writing these authors were final year undergraduate physiotherapy students at the School of

Rehabilitation and Occupation Studies, AUT University

Nada EJ Signal, MHSc (Rehabilitation), BHSc (Physiotherapy)

Senior Research Officer, Health & Rehabilitation Institute, AUT University
Table 1. Summary of Simple versus Complex Study Characteristics

Study           Sample Size      Intervention

Busk k          N=15             Turn table with target,
Galbraith       3 groups (n=5)   Tasks:Eye tracking (E),
(1975)          Age=18-22        Hand tracking (H), Eye-hand
                                 tracking (EH),
                                 20 trails of 20secs,
                                 10 secs rest,

Draganski et                     Experimental group- 3 months
al N=24         Age=20-24        practice of a classic 3 ball
(2004)                           cascade juggling routine,
                                 Control- no practice,

Hlustik et al   N=10             Complex task - numerical keypad
(2004)          2 groups (n=5)   sequencing task, using the three
                Age=23-34        middle fingers.
                                 Simple task- squeezing a sponge,
                                 Practiced 15 minutes, every week
                                 day, for 3 weeks,

Niemann et al   N=21             Complex task- moving a
(1991)          n=14 complex     matchstick back and forth
                task only        between ingers of the left hand
                n=7 simple and   twice,
                complex tasks    Simple task- pressing 4 buttons
                Age=19-32        sequentially, Repeated 3 times,
                                 Both repeated the tasks 60-80
                                 times over 60 minutes,

Niemann et al   N=17             Complex task-moving a
(1992)          Age=18-32        matchstick back and forth
                                 between ingers twice.
                                 Simple task- pressing 4 buttons
                                 sequentially, Repeated three
                                 times,
                                 Each task was repeated 20 times,

Pascaul-Leone                    Complex- one handed 5 finger
N=18            Age=38-51        piano sequence in time with a
et al (1995)                     metronome
                                 Simple-played the piano at will
                                 Rest-no practice
                                 Practice- 2 hours for 5 days

Wuhle et al     N=11             Rest- no movement
(2006)          Age=20-32        Hold- hold a transducer in a
                                 pincer grip at a constant
                                 force of 2,5 Newtons,
                                 Tracking- Requested grip force
                                 varied (0.5-5.5 N) k visual
                                 feedback given,
                                 2 x 8 mins of each task

Study           Measurements

Busk k          Cortical coupling-EEG
Galbraith       2 pre tests k 2 post tests
(1975)          No follow up

Draganski et    Grey matter volume
al N=24         differences- MRI
(2004)          Pre test, post test k 3 month
                follow up

Hlustik et al   Cortical changes- fMRI
(2004)          During the complex and simple
                tasks.
                During flexion and extension
                of thumb, little finger and
                wrist after practice,

Niemann et al   Changes in neuronal activity-
(1991)          EEG DC potentials
                Measured 1st and last 15 runs

Niemann et al   Changes in neuronal activity-
(1992)          EEG DC potentials
                Pre task, during and post task

Pascaul-Leone   Cortical representation-TMS
N=18            kEMG
et al (1995)    Pre-test and post-test after
                each day of practice

Wuhle et al     Somatosensory representation--
(2006)          whole head MEG
                Grip Force-force transducer
                Pre and post-test

Study           Main Findings

Busk k          Coupling was highest during the
Galbraith       EH tracking task (most difficult)
(1975)          and lowest during the E tracking
                task (easiest), (p=0.01).
                The Eh group had a significant
                reduction in the amount of
                coupling after practice (p=0.05).

Draganski et    Jugglers demonstrated a
al N=24         signiicant bilateral expansion in
(2004)          grey matter in the mid-temporal
                area and in the left posterior
                intraparietal sulcus after practice
                (p<0.05). This was not maintained
                at 3 month follow up.
                The non-jugglers showed no
                changes.

Hlustik et al   The  sensory  and motor
(2004)          increased in representations
                volume after practice for both
                groups (p = 0.03; p = 0.0054),
                especially between the first and
                second session. The increase
                in motor representation was
                greater for the sequencing
                group but not signiicantly.
                The  increase in sensory
                representation was signiicantly
                greater for the sequencing
                group (p<0.0001).

Niemann et al   The complex task had a non-
(1991)          significantly larger amount of
                cortical negativity during the
                first 15 trials than the simple task.
                There was a signiicant reduction
                in surface electonegativity after
                practice for the complex task but
                not the simple task. This reduction
                was greater for the SMA than the
                PMA (p<0.05),

Niemann et al   There was a significantly greater
(1992)          surface electronegativity during
                the complex task compared to
                the simple task in the contralateral
                sensori-motor cortex.

Pascaul-Leone   Complex task group: Reduced
N=18            activation threshold of the long
et al (1995)    finger flexors and extensors after
                practice.
                Increased cortical output map
                for both muscles after practice,
                Simple task group: Slight
                decrease in activation threshold
                and increase in cortical
                representation after practice.
                However, these changes were
                significantly smaller than the
                complex group (p<0.001).
                Rest group-No cortical or
                activation threshold changes,

Wuhle et al     After practice the rest condition
(2006)          had the smallest polar angle
                between the thumb and
                ring finger, while the tracking
                condition (most dificult) had the
                largest (p<0.05).

Note: EEG= Electroencephalography; MRI= Magnetic resonance imaging;
MEG= Magnetoencephalography; fMRI= Functional magnetic resonance
imaging; DC= Direct current; SMA= Supplementary motor area; PMA=
Pre motor area; v= versus; TMS= Transcranial magnetic stimulation,
secs=seconds, mins= minutes, cm= centimetres.

Table 2. Summary of Novice versus Expert Study Characteristics

Study           Sample Size/                 Task
                Characteristics

Cannonieri      17 experts (professional     N/A
et al. (2007)   typists), compared to
                an in-house developed
                template constructed
                using 96 controls,
                Age=27-58

Gaser k         N=80                         N/A
Schlaug         n=20 experts
(2003)          (professional musicians)
                n=20 amateurs
                (recreational musicians)
                n=40 non-musician
                controls
                Age=18-40

Hund-           N=33                         Finger opposition task,
Georgiadisk     n=10 expert pianists         with the dominant hand
Von Cramon      n=23 non-musician            for 35mins and the
(1999)          controls                     non-dominant hand for
                Age=23-31                    7mins.

Jancke, Shah    N=4                          6 experimental
k Peters        n=2 expert pianists          conditions involving
(2000)          n=2 non-musician             hand tapping.
                controls
                Age=22-26

Krings et       N=8                          Complex inger
al. (2000)      n=4 expert pianists          opposition task using
                n=4 non-musician             dominant hand.
                controls                     Task 32 seconds, rest 32
                Age=22-51                    seconds, 6 times.

Meister et      N=24                         Simple task-key pressing
al. (2005)      n=12 expert musicians        sequence.
                Mean age= 26.6               Complex task- omitting
                n=12 non-musician            varying fingers of the
                controls                     sequential movement
                Mean age=25.4                and starting each
                                             sequence with a
                                             different key.

Pearce et       N=20                         N/A
al. (2000)      n=5 elite badminton
                players
                n=5 social players
                n=10 non racquet sport
                playing controls
                Age=22-50

Schwenkreis     N=50                         N/A
et al. (2007)   n=15 expert violin players
                n=35 non-musician
                controls
                Age=19-31

Tyc,            N=10                         N/A
Boyadjian,      n=5 expert volleyball
& Devanne       players
(2005)          n=5 non arm activity
                sport controls
                Age=20-28

Study           Measurements

Cannonieri      Differences in grey
et al. (2007)   matter volume- MRI

Gaser k         Differences in grey
Schlaug         matter- MRI
(2003)

Hund-           Cortical activation
Georgiadisk     differences- fMRI
Von Cramon
(1999)

Jancke, Shah    Cortical activation
k Peters        differences- fMRI
(2000)

Krings et       Cortical activation
al. (2000)      differences- fMRI

Meister et      Cortical activation
al. (2005)      differences- fMRI

Pearce et       MEP amplitude,
al. (2000)      threshold, latency
                and silent-period
                duration (re-
                polarisation time)-
                Electromyography
                and TMS.

Schwenkreis     Somatosensory
et al. (2007)   representation area-
                Somatosensory
                evoked potential
                using EEG
                Motor representation
                area of the FDI- TMS

Tyc,            Cortical
Boyadjian,      representation of
& Devanne       MD and ECR-TMS
(2005)

Study           Main Findings

Cannonieri      Grey matter volume was positively correlated with
et al. (2007)   experience in six regions: left medial inferior
                cerebellar hemisphere (p=0.038), right medial inferior
                cerebellar hemisphere (p=0.027), right medial orbital
                region (p=0.028), right paracentral lobule (p=0.024)
                and the right temporal pole (p=0.042).

Gaser k         Significant positive correlation between musician
Schlaug         status and grey matter volume in the primary motor
(2003)          area, primary somatosensory area, PMA, the temporal
                gyrus bilaterally, left cerebellum, left precentral
                gyrus, left Heschl's gyrus, right superior parietal
                cortex, and left inferior frontal gyrus. No
                significant correlations between white matter volume
                and musician status.

Hund-           During the task, activation of the primary motor
Georgiadisk     cortices decreased in the non-musician group (p<0.04;
Von Cramon      p<0.001). Piano players had slightly increased
(1999)          activation.
                During the task activation of the SMA was much
                greater in the non-musician group (p<0.05)
                During the task non-musicians had greater
                contralateral (p<0.025) and ipsilateral (p<0.014)
                pre-motor activation compared to piano players.
                No group differences in somatosensory cortical
                activation during the task.
                During the task the piano players exhibited greater
                activation of the contralateral primary motor cortex
                when using the non-dominant hand compared with the
                dominant hand (p<0.05).
                Both groups had a significant reduction in activation
                of the SMA after practice (p<0.05).

Jancke, Shah    During the task the control subjects showed greater
k Peters        activation in the motor cortex, SMA, and pre-SMA for
(2000)          nearly all movement conditions.

Krings et       During the task piano players had a lesser amount of
al. (2000)      activation than controls in the primary somatosensory
                area, SMA and PMA (p=0.029), no significant
                differences in SPA.

Meister et      During the complex task, non-musicians had a greater
al. (2005)      activation in the left PMA and bilateral pre-SMA,
                compared to during the simple task. In musicians
                there were no differences.
                During both the simple and complex tasks, there was a
                greater activation of the PMA and the SMA of the left
                hemisphere in non-musicians compared to musicians.

Pearce et       No significant differences between sides for location,
al. (2000)      amplitude, latency or silent period duration in the
                control or the social players.
                Greater decrease in corticomotor threshold and higher
                MEP amplitude on the playing side compared to the non
                playing side for 2/5 elite athletes.
                Maps of the athletes playing sides were displaced 5,
                7 and 10 mm medially in 3 participants, and 6 and
                12mm laterally in the other 2 participants in
                comparison to the other side.

Schwenkreis     Significant right-left difference in polar angles in
et al. (2007)   violin players (p=0.002)
                Significantly greater motor output map of the left
                FDI muscle than the right in violin players and not
                controls (p=0.034)
                The left FDI motor map was significantly more
                laterally localized than the right in violin players,
                but not in the controls (p=0.009).
                The extent of asymmetry in the primary somatosensory
                cortex was correlated with the extent of asymmetry in
                the primary motor cortex.

Tyc,            MD representation area in volleyball players was
Boyadjian,      significantly greater on the dominant side than non
& Devanne       dominant side (p<0.01); no difference in runners.
(2005)          Representation area for MD on dominant side was
                greater in volleyball group than control group
                (p<0.01); no differences for non-dominant side.
                No differences between sides for either group for
                ECR representation.

Note: PMA= Premotor area, SMA= supplementary motor area, SPA= superior
parietal area, MD= medial deltoid, ECR= extensor carpi radialis, MEP =
Motor evoked potential, TMS = Transcranial magnetic stimulation, FDI =
First dorsal interosseus, yrs= years, hrs= hours, MRI= Magnetic
Resonance Imaging, fMRI= Functional Magnetic Resonance Imaging, EEG =
Electroencephalography, secs= seconds, mins=minutes

Table 3. Methodological Quality Assessment of Included Studies Using
Key Criteria from the McMaster University Critical Review Form

Study                       Purpose   Sample size   Appropriate
                            stated     justified    randomisation
                            clearly

Simple vs Complex
Busk k Galbraith (1975)     [check]   x             [check]
Draganski et al (2004)      [check]   x             X
Hlustik et al (2004)        [check]   X             X
Niemann et al (1991)        [check]   X             X
Niemann et al (1992)        [check]   X             X
Pacual-Leone et al (1995)   [check]   X             [check]
Wuhle et al (2006)          [check]   X             X
Novice vs Experts
Cannonieri et al (2007)     [check]   X             N/A
Gaser k Schlaug (2003)      [check]   X             N/A
Hund-Georgiadis k           [check]   X             N/A
Von Cramon (1999)
Jancke et al (2000)         [check]   X             N/A
Krings et al (2000)         [check]   X             N/A
Meister et al (2005)        [check]   X             N/A
Pearce et al (2000)         [check]   X             N/A
Schwenkreis et al (2007)    [check]   X             N/A
Tyc et al (2005)            [check]   X             N/A

Study                       Blinding of    Blinding of
                            participants   assessors

Simple vs Complex
Busk k Galbraith (1975)     X              X
Draganski et al (2004)      X              X
Hlustik et al (2004)        X              X
Niemann et al (1991)        [check]        X
Niemann et al (1992)        [check]        X
Pacual-Leone et al (1995)   X              [check]
Wuhle et al (2006)          X              X
Novice vs Experts
Cannonieri et al (2007)     N/A            X
Gaser k Schlaug (2003)      N/A            X
Hund-Georgiadis k           N/A            X
Von Cramon (1999)
Jancke et al (2000)         N/A            X
Krings et al (2000)         N/A            X
Meister et al (2005)        N/A            X
Pearce et al (2000)         N/A            X
Schwenkreis et al (2007)    N/A            X
Tyc et al (2005)            N/A            X

Study                       Description      Statistical
                            of reliability   significance of
                            &/ validity of   results reported
                            measures
Simple vs Complex
Busk k Galbraith (1975)     X                [check]
Draganski et al (2004)      X                [check]
Hlustik et al (2004)        X                [check]
Niemann et al (1991)        X                [check]
Niemann et al (1992)        X                X
Pacual-Leone et al (1995)   X                X
Wuhle et al (2006)          X                [check]
Novice vs Experts
Cannonieri et al (2007)     X                [check]
Gaser k Schlaug (2003)      X                [check]
Hund-Georgiadis k           X                [check]
Von Cramon (1999)
Jancke et al (2000)         X                X
Krings et al (2000)         X                [check]
Meister et al (2005)        X                [check]
Pearce et al (2000)         X                [check]
Schwenkreis et al (2007)    X                [check]
Tyc et al (2005)            X                [check]
COPYRIGHT 2009 New Zealand Society of Physiotherapists
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2009 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:ML Roberts Prize Winner
Author:Muir, Alanna L.; Jones, Lana M.; Signal, Nada E.J.
Publication:New Zealand Journal of Physiotherapy
Article Type:Report
Geographic Code:8NEWZ
Date:Nov 1, 2009
Words:6614
Previous Article:The physiotherapy management of infants with congenital muscular torticollis: a survey of current practice in New Zealand.
Next Article:Cortical plasticity following motor skill learning during mental practice in stroke.
Topics:

Terms of use | Privacy policy | Copyright © 2019 Farlex, Inc. | Feedback | For webmasters