Last posts on motor imagery

Sleep contribution to motor memory consolidation: a motor imagery study

2010-01-07T18:52:49+01:00

Sleep contribution to motor memory consolidation: a motor imagery study.

Sleep. 2009 Dec 1;32(12):1559-65

Authors: Debarnot U, Creveaux T, Collet C, Doyon J, Guillot A

STUDY OBJECTIVES: Sleep is known to enhance performance following physical practice (PP) of a new sequence of movements. Apart from a pilot study, it is still unknown whether a similar sleep-dependent consolidation effect can be observed following motor imagery (MI) and whether this mnemonic process is related to MI speed. DESIGN: Counterbalanced within-subject design. SETTING: The laboratory. PARTICIPANTS: Thirty-two participants. INTERVENTIONS: PP, real-time MI, fast MI, and NoSleep (control) groups. MEASUREMENTS AND RESULTS: Subjects practiced an explicitly known sequence of finger movements, and were assigned to PP, real-time MI, or fast MI, in which they intentionally imagined the sequence at a faster pace. A NoSleep group subjected to real-time MI, but without any intervening sleep, was also tested. Performance was evaluated before practice, as well as prior to, and after a night of sleep or a similar time interval during the daytime. Compared with the NoSleep group, the results revealed offline gains in performance after sleep in the PP, real-time MI, and fast MI groups. There was no correlation between a measure of underestimation of the time to imagine the motor sequence and the actual speed gains after sleep, neither between the ease/difficulty to form mental images and performance gains. CONCLUSIONS: These results provide evidence that sleep contributes to the consolidation of motor sequence learning acquired through MI and further suggests that offline delayed gains are not related to the MI content per se. They extend our previous findings and strongly confirm that performance enhancement following MI is sleep dependent.

Inducing a virtual hand ownership illusion through a brain-computer interface

2009-10-20T17:43:00+02:00

Inducing a virtual hand ownership illusion through a brain-computer interface.

Neuroreport. 2009 Apr 22;20(6):589-594

Authors: Perez-Marcos D, Slater M, Sanchez-Vives MV

The apparently stable brain representation of our bodies is easily challenged. We have recently shown that the illusion of ownership of a three-dimensional virtual hand can be evoked through synchronous tactile stimulation of a person's hidden real hand and that of the virtual hand. This reproduces the well-known rubber-hand illusion, but in virtual reality. Here we show that some aspects of the illusion can also occur through motor imagery used to control movements of a virtual hand. When movements of the virtual hand followed motor imagery, the illusion of ownership of the virtual hand was evoked and muscle activity measured through electromyogram correlated with movements of the virtual arm. Using virtual bodies has a great potential in the fields of physical and neural rehabilitation, making the understanding of ownership of a virtual body highly relevant.

Driving dreams: cortical activations during imagined passive and active whole body movemen

2009-09-21T17:00:52+02:00

Driving dreams: cortical activations during imagined passive and active whole body movement.

Ann N Y Acad Sci. 2009 May;1164:372-5

Authors: Flanagin VL, Wutte M, Glasauer S, Jahn K

It is unclear how subjects perceive and process self-motion cues in virtual reality environments. Movement could be perceived as passive, akin to riding in a car, or active, such as walking down the street. These two very different types of self-motion were studied here using motor imagery in fMRI. In addition, the relative importance of visual and proprioceptive training cues was examined. Stronger activations were found during proprioceptive motor imagery compared with visual motor imagery, suggesting that proprioceptive signals are important for successful imagined movement. No significant activations were found during active movement with proprioceptive training. Passive locomotion, however, was correlated with activity in an occipital-parietal and parahippocampal cortical network, which are the same regions found during navigation with virtual reality stimuli.

Neurofeedback-based motor imagery training for brain-computer interface

2009-09-21T16:53:19+02:00

Neurofeedback-based motor imagery training for brain-computer interface (BCI).

J Neurosci Methods. 2009 Apr 30;179(1):150-6

Authors: Hwang HJ, Kwon K, Im CH

In the present study, we propose a neurofeedback-based motor imagery training system for EEG-based brain-computer interface (BCI). The proposed system can help individuals get the feel of motor imagery by presenting them with real-time brain activation maps on their cortex. Ten healthy participants took part in our experiment, half of whom were trained by the suggested training system and the others did not use any training. All participants in the trained group succeeded in performing motor imagery after a series of trials to activate their motor cortex without any physical movements of their limbs. To confirm the effect of the suggested system, we recorded EEG signals for the trained group around sensorimotor cortex while they were imagining either left or right hand movements according to our experimental design, before and after the motor imagery training. For the control group, we also recorded EEG signals twice without any training sessions. The participants' intentions were then classified using a time-frequency analysis technique, and the results of the trained group showed significant differences in the sensorimotor rhythms between the signals recorded before and after training. Classification accuracy was also enhanced considerably in all participants after motor imagery training, compared to the accuracy before training. On the other hand, the analysis results for the control EEG data set did not show consistent increment in both the number of meaningful time-frequency combinations and the classification accuracy, demonstrating that the suggested system can be used as a tool for training motor imagery tasks in BCI applications. Further, we expect that the motor imagery training system will be useful not only for BCI applications, but for functional brain mapping studies that utilize motor imagery tasks as well.

Neurofeedback-based motor imagery training for brain-computer interface

2009-06-24T18:48:12+02:00

Neurofeedback-based motor imagery training for brain-computer interface (BCI).

J Neurosci Methods. 2009 Apr 30;179(1):150-6

Authors: Hwang HJ, Kwon K, Im CH

Effect of Motor Imagery in the Rehabilitation of Burn Patients

2009-06-24T18:45:10+02:00

Effect of Motor Imagery in the Rehabilitation of Burn Patients.

J Burn Care Res. 2009 Jun 5;

Authors: Guillot A, Lebon F, Vernay M, Girbon JP, Doyon J, Collet C

Although there is ample evidence that motor imagery (MI) improves motor performance after CNS injury, it is still unknown whether MI may enhance motor recovery after peripheral injury and most especially in the rehabilitation of burn patients. This study aimed to investigate the effects of a 2-week MI training program combined with conventional rehabilitation on the recovery of motor functions in handed burn patients. Fourteen patients admitted to the Medical Burn Center were requested to take part in the study and were randomly assigned to the imagery or the control group. Behavioral data related to the ability to perform each successive step of three manual motor sequences were collected at five intervals during the medical procedure. The results provided evidence that MI may facilitate motor recovery, and the belief in the effectiveness of MI was strong in all patients. MI may substantially contribute to improve the efficacy of conventional rehabilitation programs. Hence, this technique should be considered as a reliable alternative method to help burn patients to recover motor functions.

Neurofeedback-based motor imagery training for brain-computer interface

2009-06-09T19:59:25+02:00

Neurofeedback-based motor imagery training for brain-computer interface (BCI).

J Neurosci Methods. 2009 Apr 30;179(1):150-156

Authors: Hwang HJ, Kwon K, Im CH

In the present study, we propose a neurofeedback-based motor imagery training system for EEG-based brain-computer interface (BCI). The proposed system can help individuals get the feel of motor imagery by presenting them with real-time brain activation maps on their cortex. Ten healthy participants took part in our experiment, half of whom were trained by the suggested training system and the others did not use any training. All participants in the trained group succeeded in performing motor imagery after a series of trials to activate their motor cortex without any physical movements of their limbs. To confirm the effect of the suggested system, we recorded EEG signals for the trained group around sensorimotor cortex while they were imagining either left or right hand movements according to our experimental design, before and after the motor imagery training. For the control group, we also recorded EEG signals twice without any training sessions. The participants' intentions were then classified using a time-frequency analysis technique, and the results of the trained group showed significant differences in the sensorimotor rhythms between the signals recorded before and after training. Classification accuracy was also enhanced considerably in all participants after motor imagery training, compared to the accuracy before training. On the other hand, the analysis results for the control EEG data set did not show consistent increment in both the number of meaningful time-frequency combinations and the classification accuracy, demonstrating that the suggested system can be used as a tool for training motor imagery tasks in BCI applications. Further, we expect that the motor imagery training system will be useful not only for BCI applications, but for functional brain mapping studies that utilize motor imagery tasks as well.

Facilitation of motor imagery through movement-related cueing

2009-05-03T21:15:41+02:00

Facilitation of motor imagery through movement-related cueing.

Brain Res. 2009 Apr 27;

Authors: Heremans E, Helsen WF, De Poel HJ, Alaerts K, Meyns P, Feys P

In the past few years, the use of motor imagery as an adjunct to other forms of training has been studied extensively. However, very little attention has been paid to how imagery could be used to greatest effect. It is well known that the provision of external cues has a beneficial effect on motor skill acquisition and performance during physical practice. Since physical execution and mental imagery share several common mechanisms, we hypothesized that motor imagery might be affected by external cues in a similar way. To examine this, we compared the motor imagery performance of three groups of 15 healthy participants who either physically performed or imagined performing a goal-directed cyclical wrist movement in the presence or the absence of visual and/or auditory external cues. As outcome measures, the participants' imagery vividness scores and eye movements were measured during all conditions. We found that visual movement-related cues improved the spatial accuracy of the participants' eye movements during imagery, while auditory cues specifically enhanced their temporal accuracy. Furthermore, both types of cues significantly improved the participants' imagery vividness. These findings indicate that subjects may imagine a movement in a better way when provided with external movement-related stimuli, which may possibly be useful with regard to the efficiency of mental practice in (clinical) training protocols.

Development of hierarchical structures for actions and motor imagery

2009-04-16T02:26:54+02:00

Development of hierarchical structures for actions and motor imagery: a constructivist view from synthetic neuro-robotics study.

Psychol Res. 2009 Apr 8;

Authors: Nishimoto R, Tani J

The current paper shows a neuro-robotics experiment on developmental learning of goal-directed actions. The robot was trained to predict visuo-proprioceptive flow of achieving a set of goal-directed behaviors through iterative tutor training processes. The learning was conducted by employing a dynamic neural network model which is characterized by their multiple time-scale dynamics. The experimental results showed that functional hierarchical structures emerge through stages of developments where behavior primitives are generated in earlier stages and their sequences of achieving goals appear in later stages. It was also observed that motor imagery is generated in earlier stages compared to actual behaviors. Our claim that manipulatable inner representation should emerge through the sensory-motor interactions is corresponded to Piaget's constructivist view.

Sleep-related improvements in motor learning following mental practice

2008-10-08T19:08:00+02:00

Sleep-related improvements in motor learning following mental practice.

Brain Cogn. 2008 Oct 4;

Authors: Debarnot U, Creveaux T, Collet C, Gemignani A, Massarelli R, Doyon J, Guillot A

A wide range of experimental studies have provided evidence that a night of sleep may enhance motor performance following physical practice (PP), but little is known, however, about its effect after motor imagery (MI). Using an explicitly learned pointing task paradigm, thirty participants were assigned to one of three groups that differed in the training method (PP, MI, and control groups). The physical performance was measured before training (pre-test), as well as before (post-test 1) and after a night of sleep (post-test 2). The time taken to complete the pointing tasks, the number of errors and the kinematic trajectories were the dependent variables. As expected, both the PP and the MI groups improved their performance during the post-test 1. The MI group was further found to enhance motor performance after sleep, hence suggesting that sleep-related effects are effective following mental practice. Such findings highlight the reliability of MI in learning process, which is thought consolidated when associated with sleep.

Centrally controlled heart rate changes during mental practice in immersive virtual environment

2008-01-13T21:43:31+01:00

Centrally controlled heart rate changes during mental practice in immersive virtual environment: A case study with a tetraplegic.

Int J Psychophysiol. 2007 Nov 29;

Authors: Pfurtscheller G, Leeb R, Friedman D, Slater M

A tetraplegic patient was able to induce midcentral localized beta oscillations in the electroencephalogram (EEG) after extensive mental practice of foot motor imagery. This beta oscillation was used to simulate a wheel chair movement in a virtual environment (VE). The analysis of electrocardiogram (ECG) data revealed that the induced beta oscillations were accompanied by a characteristic heart rate (HR) change in form of a preparatory HR acceleration followed by a short-lasting deceleration in the order of 10-20 bpm (beats-per-minute). This provides evidence that mental practice of motor performance is accompanied not only by activation of cortical structures but also by central commands into the cardiovascular system with its nuclei in the brain stem.

Movement imagery increases pain in people with neuropathic pain following complete thoracic spinal cord injury

2007-10-24T16:50:00+02:00

Movement imagery increases pain in people with neuropathic pain following complete thoracic spinal cord injury.

Pain. 2007 Oct 15;

Authors: Gustin SM, Wrigley PJ, Gandevia SC, Middleton JW, Henderson LA, Siddall PJ

Spinal cord injury (SCI) results in deafferentation and the onset of neuropathic pain in a substantial proportion of people. Based on evidence suggesting motor cortex activation results in attenuation of neuropathic pain, we sought to determine whether neuropathic SCI pain could be modified by imagined movements of the foot. Fifteen subjects with a complete thoracic SCI (7 with below-level neuropathic pain and 8 without pain) were instructed in the use of movement imagery. Movement imagery was practiced three times daily for 7days. On the eighth day, subjects performed the movement imagery in the laboratory and recorded pain ratings during the period of imagined movement. Six out of 7 subjects with neuropathic pain reported an increase in pain during imagined movements from 2.9+/-0.7 during baseline to 5.0+/-1.0 during movement imagery (p<0.01). In SCI subjects without neuropathic pain, movement imagery evoked an increase in non-painful sensation intensity from a baseline of 1.9+/-0.7 to 4.8+/-1.3 during the movement imagery (p<0.01). Two subjects without a history of pain or non-painful phantom sensations had onset of dysesthesia while performing imagined movements. This study reports exacerbation of pain in response to imagined movements and it contrasts with reports of reduction pain in people with peripheral neuropathic pain. The potential mechanisms underlying this sensory enhancement with movement imagery are discussed.

Internal and external imagery perspective measurement and use in imagining open and closed sports skills

2007-08-02T19:05:17+02:00

Internal and external imagery perspective measurement and use in imagining open and closed sports skills: an exploratory study.

Percept Mot Skills. 2007 Apr;104(2):387-404

Authors: Spittle M, Morris T

This study explored the measurement and use of internal and external imagery perspectives during imagery of open and closed sports skills. Participants (N=41; male=23; female=18), ages 14 to 28 (M = 19.4 yr.; SD = 3.1), who were recruited from undergraduate classes in human movement and physical education, and local sporting teams, completed the Imagery Use Questionnaire and then imagined performing eight common sports skills, four open skills and four closed skills, in a random order. Participants provided concurrent verbalisation during their imagery. Immediately after imagining each skill, participants completed a rating scale and retrospective verbalisation of imagery perspective use. Analysis indicated that the questionnaire gave a general imagery perspective preference but was not a strong predictor of imagery used on specific occasions. The three measures of imagery perspective were equivalent in imagining performing particular skills. Participants experienced more internal imagery than external imagery while imagining the eight sports skills, but there was no significant difference between perspective use on the open and closed skills.

Adolescent development of motor imagery

2007-01-02T22:58:27+01:00

Adolescent development of motor imagery in a visually guided pointing task.

Conscious Cogn. 2006 Dec 28;

Authors: Choudhury S, Charman T, Bird V, Blakemore SJ

The development of action representation during adolescence was investigated using a visually guided pointing motor task (VGPT) to test motor imagery. Forty adolescents (24 males; mean age 13.1 years) and 33 adults (15 males; mean age 27.5 years) were instructed to both execute and imagine hand movements from a starting point to a target of varying size. Reaction time (RT) was measured for both Execution (E) and Imagery (I) conditions. There is typically a close association between time taken to execute and image actions in adults because action execution and action simulation rely on overlapping neural circuitry. Further, representations of actions are governed by the same speed-accuracy trade-off as real actions, as expressed by Fitts' Law. In the current study, performance on the VGPT in both adolescents and adults conformed to Fitts' Law in E and I conditions. However, the strength of association between E and I significantly increased with age, reflecting a refinement in action representation between adolescence and adulthood.

Temporal classification of multichannel near-infrared spectroscopy signals of motor imagery for developing a brain-compu

2007-01-02T22:57:23+01:00

Temporal classification of multichannel near-infrared spectroscopy signals of motor imagery for developing a brain-computer interface.

Neuroimage. 2006 Dec 28;

Authors: Sitaram R, Zhang H, Guan C, Thulasidas M, Hoshi Y, Ishikawa A, Shimizu K, Birbaumer N

There has been an increase in research interest for brain-computer interface (BCI) technology as an alternate mode of communication and environmental control for the disabled, such as patients suffering from amyotrophic lateral sclerosis (ALS), brainstem stroke and spinal cord injury. Disabled patients with appropriate physical care and cognitive ability to communicate with their social environment continue to live with a reasonable quality of life over extended periods of time. Near-infrared spectroscopy is a non-invasive technique which utilizes light in the near-infrared range (700 to 1000 nm) to determine cerebral oxygenation, blood flow and metabolic status of localized regions of the brain. In this paper, we describe a study conducted to test the feasibility of using multichannel NIRS in the development of a BCI. We used a continuous wave 20-channel NIRS system over the motor cortex of 5 healthy volunteers to measure oxygenated and deoxygenated hemoglobin changes during left-hand and right-hand motor imagery. We present results of signal analysis indicating that there exist distinct patterns of hemodynamic responses which could be utilized in a pattern classifier towards developing a BCI. We applied two different pattern recognition algorithms separately, Support Vector Machines (SVM) and Hidden Markov Model (HMM), to classify the data offline. SVM classified left-hand imagery from right-hand imagery with an average accuracy of 73% for all volunteers, while HMM performed better with an average accuracy of 89%. Our results indicate potential application of NIRS in the development of BCIs. We also discuss here future extension of our system to develop a word speller application based on a cursor control paradigm incorporating online pattern classification of single-trial NIRS data.

Kinesthetic but not visual imagery assists in normalizing the CNV in Parkinson's disease

2006-12-18T17:48:59+01:00

Kinesthetic but not visual imagery assists in normalizing the CNV in Parkinson's disease.

Clin Neurophysiol. 2006 Oct;117(10):2308-14

Authors: Lim VK, Polych MA, Holländer A, Byblow WD, Kirk IJ, Hamm JP

OBJECTIVE: This study investigated whether kinesthetic and/or visual imagery could alter the contingent negative variation (CNV) for patients with Parkinson's disease (PD). METHODS: The CNV was recorded in six patients with PD and seven controls before and after a 10min block of imagery. There were two types of imagery employed: kinesthetic and visual, which were evaluated on separate days. RESULTS: The global field power (GFP) of the late CNV did not change after the visual imagery for either group, nor was there a significant difference between the groups. In contrast, kinesthetic imagery resulted in significant group differences pre-, versus post-imagery GFPs, which was not present prior to performing the kinesthetic imagery task. In patients with PD, the CNV amplitudes post-, relative to pre-kinesthetic imagery, increased over the dorsolateral prefrontal regions and decreased in the ipsilateral parietal regions. There were no such changes in controls. CONCLUSIONS: A 10-min session of kinesthetic imagery enhanced the GFP amplitude of the late CNV for patients but not for controls. SIGNIFICANCE: While the study needs to be replicated with a greater number of participants, the results suggest that kinesthetic imagery may be a promising tool for investigations into motor changes, and may potentially be employed therapeutically, in patients with Parkinson's disease.

Modulation of corticospinal excitability during both actual and imagined movements

2006-12-18T17:46:38+01:00

Movement-specific enhancement of corticospinal excitability at subthreshold levels during motor imagery.

Exp Brain Res. 2006 Dec 8;

Authors: Li S

This study examined modulation of corticospinal excitability during both actual and imagined movements. Seven young healthy subjects performed actual (3-50% maximal voluntary contractions) and imagined index finger force production, and rest. Individual responses to focal transcranial magnetic stimulation (TMS) in four fingers (index, middle, ring, and little) were recorded for all three tested conditions. The force increments at the threshold of activation were predicted from regression analysis, representing the TMS-induced response at the threshold activation of the corticospinal pathways. The measured increment in the index finger during motor imagery was larger than that at rest, but smaller than the predicted increment at the threshold of activation. On the other hand, the measured increment in the uninstructed (middle, ring, and little), slave fingers during motor imagery was larger than that at rest, but not different from the predicted increment at the threshold of activation. These contrasting results suggest that the degree of imagery-induced enhancement in corticospinal excitability was significantly less than what could be predicted for threshold levels from regression analysis, but only for the index finger, and not the adjacent slave fingers. It is concluded that corticospinal excitability for the explicitly instructed index finger is specifically enhanced at subthreshold levels during motor imagery.

Graded motor imagery for pathologic pain

2006-11-05T21:27:58+01:00

Graded motor imagery for pathologic pain. A randomized controlled trial.

Neurology. 2006 Nov 2;

Authors: Moseley GL

Phantom limb and complex regional pain syndrome type 1 (CRPS1) are characterized by changes in cortical processing and organization, perceptual disturbances, and poor response to conventional treatments. Graded motor imagery is effective for a small subset of patients with CRPS1. OBJECTIVE: To investigate whether graded motor imagery would reduce pain and disability for a more general CRPS1 population and for people with phantom limb pain. METHODS: Fifty-one patients with phantom limb pain or CRPS1 were randomly allocated to motor imagery, consisting of 2 weeks each of limb laterality recognition, imagined movements, and mirror movements, or to physical therapy and ongoing medical care. RESULTS: There was a main statistical effect of treatment group, but not diagnostic group, on pain and function. The mean (95% CI) decrease in pain between pre- and post-treatment (100 mm visual analogue scale) was 23.4 mm (16.2 to 30.4 mm) for the motor imagery group and 10.5 mm (1.9 to 19.2 mm) for the control group. Improvement in function was similar and gains were maintained at 6-month follow-up. CONCLUSION: Motor imagery reduced pain and disability in these patients with complex regional pain syndrome type I or phantom limb pain, but the mechanism, or mechanisms, of the effect are not clear.

EEG-based brain-computer interface

2006-10-11T21:49:03+02:00

Electro-encephalogram based brain-computer interface: improved performance by mental practice and concentration skills.

Med Biol Eng Comput. 2006 Oct 7;

Authors: Mahmoudi B, Erfanian A

Mental imagination is the essential part of the most EEG-based communication systems. Thus, the quality of mental rehearsal, the degree of imagined effort, and mind controllability should have a major effect on the performance of electro-encephalogram (EEG) based brain-computer interface (BCI). It is now well established that mental practice using motor imagery improves motor skills. The effects of mental practice on motor skill learning are the result of practice on central motor programming. According to this view, it seems logical that mental practice should modify the neuronal activity in the primary sensorimotor areas and consequently change the performance of EEG-based BCI. For developing a practical BCI system, recognizing the resting state with eyes opened and the imagined voluntary movement is important. For this purpose, the mind should be able to focus on a single goal for a period of time, without deviation to another context. In this work, we are going to examine the role of mental practice and concentration skills on the EEG control during imaginative hand movements. The results show that the mental practice and concentration can generally improve the classification accuracy of the EEG patterns. It is found that mental training has a significant effect on the classification accuracy over the primary motor cortex and frontal area.

Mapping implied body actions in the human motor system

2006-07-31T16:45:56+02:00

Mapping implied body actions in the human motor system.

J Neurosci. 2006 Jul 26;26(30):7942-9

Authors: Urgesi C, Moro V, Candidi M, Aglioti SM

The human visual system is highly tuned to perceive actual motion as well as to extrapolate dynamic information from static pictures of objects or creatures captured in the middle of motion. Processing of implied motion activates higher-order visual areas that are also involved in processing biological motion. Imagery and observation of actual movements performed by others engenders selective activation of motor and premotor areas that are part of a mirror-neuron system matching action observation and execution. By using single-pulse transcranial magnetic stimulation, we found that the mere observation of static snapshots of hands suggesting a pincer grip action induced an increase in corticospinal excitability as compared with observation of resting, relaxed hands, or hands suggesting a completed action. This facilitatory effect was specific for the muscle that would be activated during actual execution of the observed action. We found no changes in responsiveness of the tested muscles during observation of nonbiological entities with (e.g., waterfalls) or without (e.g., icefalls) implied motion. Thus, extrapolation of motion information concerning human actions induced a selective activation of the motor system. This indicates that overlapping motor regions are engaged in the visual analysis of physical and implied body actions. The absence of motor evoked potential modulation during observation of end posture stimuli may indicate that the observation-execution matching system is preferentially activated by implied, ongoing but not yet completed actions.

Science News: Fitness is good for the brain

2006-02-28T18:05:00+01:00

From the latest article in Science News Online:

New research suggests that physical exercise encourages healthy brains to function at their optimum levels. Fitness prompts nerve cells to multiply, strengthens their connections, and protects them from harm. Benefits seem to extend to brains and nerves that are diseased or damaged. These findings could suggest new treatments for people with Alzheimer's disease, Parkinson's disease, and spinal cord injuries.
[...]
Preliminary studies indicated that when lab animals exercise, their nerve cells release chemicals called neurotrophic factors. These proteins buffer nerve cells against illness or injury, prompt them to grow and multiply, and strengthen each neuron's connection with other nerve cells.
[...]
Furthermore, memory tests given to 1,740 people over 65 during a 6-year project have linked moderate exercise to reduced risk of dementia. These results were published in the Jan. 17 Annals of Internal Medicine by a Seattle research team.

Modulation of beta oscillations in the subthalamic area during motor imagery in Parkinson's disease

2005-12-22T22:50:00+01:00

Brain. 2005 Dec 19;

Authors: Kühn AA, Doyle L, Pogosyan A, Yarrow K, Kupsch A, Schneider GH, Hariz MI, Trottenberg T, Brown P

Activation of the basal ganglia has been shown during the preparation and execution of movement. However, the extent to which the activation during movement is related to efferent processes or feedback-related motor control remains unclear. We used motor imagery (MI), which eliminates peripheral feedback, to further investigate the role of the subthalamic area in the feedforward organization of movement. We recorded local field potential (LPF) activity from the region of the subthalamic nucleus (STN) in eight patients with Parkinson's disease off dopaminergic medication during performance of a warned reaction time task. Patients were instructed to either extend the wrist [motor execution (ME)], to imagine performing the same task without any overt movement (MI), or, in a subgroup, to perform a non-motor visual imagery (VI) task. MI led to event-related desynchronization (ERD) of oscillatory beta activity in the region of the STN in all patients that was similar in frequency, time course and degree to the ERD occurring during ME. The degree of ERD during MI correlated with the ERD in trials of ME and, like ME, was accompanied by a decrease in cortico-STN coherence, so that STN LFP activity during MI was similar to that in ME. The ERD in ME and MI were both significantly larger than the ERD in VI. In contrast, event-related synchronization (ERS) was significantly smaller in trials of MI, and even smaller in trials of VI, than during ME. The data suggest that the activity in the region of the human STN indexed by the ERD during movement is related to the feedforward organization of movement and is relatively independent of peripheral feedback. In contrast, sensorimotor feedback is an important factor in the ERS occurring in the STN area after completion of movement, consistent with a role for this region in trial-to-trial motor learning or the re-establishment of postural set following movements.

Mental imagery combined with physical practice of approach shots for golf beginners

2005-12-17T12:40:00+01:00

Percept Mot Skills. 2005 Aug;101(1):203-11

Authors: Brouziyne M, Molinaro C

Recent research on motor skills of golf have pointed to the usefulness of mental imagery. In golf, such training is rarely used as a teaching technique for beginners on the grounds that only top professionals stand to gain from mental imagery. This study tested whether mental imagery combined with physical practice can improve golf performance for the approach shot. 23 volunteer beginners, 8 women and 15 men, M age 23.4 yr. (SD = 3.7), enrolled in the University Physical and Sporting Activities Department, were divided into three groups, using a combination of physical practice of the approach shot plus mental imagery, physical practice only, and a third group engaging in various sporting activities instead of either mental or physical practice of the chip shot. Analysis showed that the beginners' approach shot performance improved most in the group combining physical practice and mental imagery when compared with the group just physically practising the approach shot. It seems mental training can be used effectively to improve performance even with beginners.

Improvement and generalization of arm motor performance through motor imagery practice

2005-12-15T01:30:00+01:00

Neuroscience. 2005 Dec 7;

Authors: Gentili R, Papaxanthis C, Pozzo T

This study compares the improvement and generalization of arm motor performance after physical or mental training in a motor task requiring a speed-accuracy tradeoff. During the pre- and post-training sessions, 40 subjects pointed with their right arm as accurately and as fast as possible toward targets placed in the frontal plane. Arm movements were performed in two different workspaces called right and left paths. During the training sessions, which included only the right path, subjects were divided into four training groups (n=10): (i) the physical group, subjects overtly performed the task; (ii) the mental group, subjects imagined themselves performing the task; (iii) the active control group, subjects performed eye movements through the targets, (iv) the passive control group, subjects did not receive any specific training. We recorded movement duration, peak acceleration and electromyographic signals from arm muscles. Our findings showed that after both physical and mental training on the right path (training path), hand movement duration and peak acceleration respectively decreased and increased for this path. However, motor performance improvement was greater after physical compared with mental practice. Interestingly, we also observed a partial learning generalization, namely an enhancement of motor performance for the left path (non-training path). The amount of this generalization was roughly similar for the physical and mental groups. Furthermore, while arm muscle activity progressively increased during the training period for the physical group, the activity of the same muscles for the mental group was unchanged and comparable with that of the rest condition. Control groups did not exhibit any improvement. These findings put forward the idea that mental training facilitates motor learning and allows its partial transfer to nearby workspaces. They further suggest that motor prediction, a common process during both actual and imagined movements, is a fundamental operation for both sensorimotor control and learning.

Influence of imagined posture and imagery modality on corticospinal excitability

2005-11-30T23:25:00+01:00

Behav Brain Res. 2005 Nov 25

Authors: Fourkas AD, Ionta S, Aglioti SM

Single pulse transcranial magnetic stimulation (TMS) was used to test the assumption that kinesthetic imagery of action is more 'motor' than visual imagery of action. We assessed corticospinal excitability during motor imagery of a thumb-palm opposition movement by recording potentials evoked by TMS from two hand muscles that would (opponens pollicis, OP, target) or would not (abductor digiti minimi, ADM, control) be activated during actual performance of the very same movement. Participants were asked to imagine the thumb-palm opposition movement while maintaining first person imagery that was either purely visual or predominately kinesthetic. The motor imagery task was performed in two conditions in which the imagined and the actual hand could be either congruent or incongruent. Facilitation of potentials recorded from OP was higher during imagery carried out in mentally congruent than incongruent postures. This effect was largely due to lack of excitability recorded during incongruent kinesthetic imagery, which was indistinguishable from baseline imagery of the static hand. All other conditions differed from static imagery regardless of position. No significant effects were found in a control muscle (ADM) thus indicating that the effect was not related to spatial coding. Subjective reports obtained after the experiment indicate that the results cannot be ascribed to qualitative differences in the imagery experienced. For relatively simple motor tasks requiring no 'expertise' we found no detectable difference in the motor cortex due to imagery modality.

EMG Activity in Selected Target Muscles During Imagery Rising on Tiptoes in Healthy Adults and Poststroke Hemiparetic Pa

2005-11-26T11:55:00+01:00

J Mot Behav. 2005 Nov;37(5):475-83

Authors: Dickstein R, Gazit-Grunwald M, Plax M, Dunsky A, Marcovitz E

The authors sought to gain further knowledge about activation of target muscles during imagery engagement in a motor task. Six hemiparetic patients and 9 healthy participants performed 3 real rises on tiptoes and then, after pausing, 3 imagery rises on tiptoes. Metronome beats guided the rate of rises and descents. Electromyographic (EMG) activity from the medial gastrocnemius and the rectus femoris muscles were monitored bilaterally throughout the performance of both tasks. In 3 healthy participants and 3 individuals with hemiparesis, EMG activity was related to the imagery task in at least 1 of the target muscles. Conversely, in the other participants, motor imagery practice was not accompanied by task-related EMG activity in the monitored muscles. In all cases, the increment in activation level during motor imagery practice was very low in comparison with that of real performance. The findings were not unequivocal; therefore, EMG activity may sometimes, but not always, be recorded during motor imagery practice both in healthy individuals and in poststroke hemiparetic participants. Further research is needed to align motor imagery practice with the objectives of motor rehabilitation.

Mirror therapy for alleviating chronic pain

2005-11-03T00:45:00+01:00

via Medgadget

McCabe and co-workers from the University of Bath and the Royal National Hospital for Rheumatic Diseases (RNHRD)have published in the journal Clinical Medicine the results of a study, which has investigated the use of mirror as a therapeutic mean to alleviate pain. The treatment consists in asking patients patients suffering from complex regional pain syndrome to carry out routine exercises in front of a mirror.

Results showed that more than half experienced pain relief during and after the exercise and further investigations indicated that even greater improvements can be achieved if the tasks are practiced beforehand.

McCabe explain these findings with the ‘cortical’ model of pain. According to this theory, the brain’s image of the body can become faulty, resulting in a mismatch between the brain’s movement control systems and its sensory systems, causing a person to experience pain when they move a particular hand, foot or limb.

Mirror therapy has proven effective also in the treatment of post-stroke hemiplegia as well as in the rehabilitation of "phantom limb" and visual hemineglect.

More to explore

Sathian K, Greenspan AI, Wolf SL. Doing it with mirrors: a case study of a novel approach to neurorehabilitation.
Neurorehabil Neural Repair. 2000;14(1):73-6.

Ramachandran VS, Altschuler EL, Stone L, Al-Aboudi M, Schwartz E, Siva N.

Can mirrors alleviate visual hemineglect? Med Hypotheses. 1999 Apr;52(4):303-5.

Altschuler EL, Wisdom SB, Stone L, Foster C, Galasko D, Llewellyn DM, Ramachandran VS.

Rehabilitation of hemiparesis after stroke with a mirror. Lancet. 1999 Jun 12;353(9169):2035-6.

Theta brainwave triggered training boosts old brains

2005-10-26T16:35:00+02:00

It has long been known that hippocampus is involved in the learning process. A study published on the Proceedings of the National Academy of Science (USA) has shown that theta brainwave triggered training can enhance learning rate in old rabbits, contrasting the deficit determined by the aging process. This study could have important implications in the development of nonpharmacological treatments for age-related memory deficits.

Nonpharmacological amelioration of age-related learning deficits: The impact of hippocampal -triggered training

Yukiko Asaka, Kristin N. Mauldin, Amy L. Griffin , Matthew A. Seager, Elizabeth Shurell and Stephen D. Berry

Abstract. Age-related learning deficits are often attributed to deterioration of hippocampal function. Conversely, a well studied index of hippocampal activity, the rhythm, is known to enhance hippocampal plasticity and accelerate learning rate in young subjects, suggesting that manipulations of activity might be used as a means to counteract impairments related to the aging process. Here, young and older rabbits were given eyeblink conditioning trials either when exhibiting hippocampal (+) or regardless of hippocampal activity (yoked control). Although, as expected, older-yoked control animals showed a learning deficit, the older + group learned as fast as young controls, demonstrating that aging deficits, at least in eyeblink classical conditioning, can be overcome by giving trials during episodes of hippocampal activity. The use of several learning criteria showed that the benefits of hippocampal -triggered training in both age groups during the early phase of acquisition, the enhancement persisted in older animals, peaking during later performance. These findings have implications for theories of age-related memory deficits and may contribute to the development of beneficial treatments. depend on different cognitive or motor processes. Whereas there was a benefit of

Mental rotation in a patient with an implanted electrode grid in the motor cortex

2005-10-22T19:15:00+02:00

Neuroreport. 2005 Nov 7;16(16):1795-1800

Authors: Tomasino B, Budai R, Mondani M, Skrap M, Rumiati RI

We investigated the effects of cortical stimulation on mental rotation tasks in a patient with an electrode array placed over his left primary motor cortex. The array was implanted to relieve chronic pain resulting from right brachial plexus damage. Tasks involving motor imagery were slowed down by cortical stimulation, whereas those involving visual imagery were not. When the patient performed the motor-imagery task, the interference effect on response times disappeared if the stimulator was switched off. We also probed two of the sites (anterior-lateral and posterior-medial position), and found that stimulation of the more anterior-lateral one consistently disrupted motor imagery.

Imagery-induced Cortical Excitability Changes in Stroke

2005-09-08T12:45:00+02:00

Results of this focal transcranial magnetic stimulation study recently published on Cerebral Cortex by a team of Italian neuroscientists suggest that motor imagery could induce a pronounced motor output enhancement in the hemisphere affected by stroke. These findings strongly support the use of motor imagery as a therapeutic mean in post-stroke motor rehabilitation.

Cicinelli P, Marconi B, Zaccagnini M, Pasqualetti P, Filippi MM, Rossini PM.

Cerebral Cortex, 2005 May 4 (Epub ahead of print)

Focal transcranial magnetic stimulation (TMS) was employed in a population of hemiparetic stroke patients in a post-acute stage to map out the abductor digiti minimi (ADM) muscle cortical representation of the affected (AH) and unaffected (UH) hemisphere at rest, during motor imagery and during voluntary contraction. Imagery induced an enhancement of the ADM map area and volume in both hemispheres in a way which partly corrected the abnormal asymmetry between AH and UH motor output seen in rest condition. The voluntary contraction was the task provoking maximal facilitation in the UH, whereas a similar degree of facilitation was obtained during voluntary contraction and motor imagery in the AH. We argued that motor imagery could induce a pronounced motor output enhancement in the hemisphere affected by stroke. Further, we demonstrated that imagery-induced excitability changes were specific for the muscle 'prime mover' for the imagined movement, while no differences were observed with respect to the stroke lesion locations. Present findings demonstrated that motor imagery significantly enhanced the cortical excitability of the hemisphere affected by stroke in a post-acute stage. Further studies are needed to correlate these cortical excitability changes with short-term plasticity therefore prompting motor imagery as a 'cortical reservoir' in post-stroke motor rehabilitation.

Brain-imaging study on action observation and acquired motor skills

2005-02-10T13:20:00+01:00

Earlier studies with monkeys revealed that brain cells called “mirror neurons” respond both when we do something, like pick up an object, and when we simply watch someone else do it. It was known that these neurons fire when we perform an action, but it was unexpected that the same cells also fired when we only saw that action being performed. This new study by Calvo-Merino and coll., recently published on the journal “Cerebral Cortex”, goes a step further by showing that such a system operates differently depending on what a person is physically expert at doing.

According to the authors of the experiment, this is the first proof that our personal motor repertoire - the things that we have learned to do - changes the way that our brain responds when we see the movement. In particular, these findings suggest that once the brain has learned a skill, it may simulate the skill without even moving, through simple observation: an injured dancer might be able to maintain his skill despite being temporarily unable to move, simply by watching others dance.

These results provide further support to the I-Learning Project clinical rationale, and justify the use of I-Learning technology to better rehabilitate people whose motor skills were damaged by stroke.

Reference: B. Calvo-Merino, D.E. Glaser, J. Grezes, R.E. Passingham and P. Haggard, Action Observation and Acquired Motor Skills: An fMRI Study with Expert Dancers, Cerebral Cortex, Dec. 2004