Restorative Neurology and Neuroscience - Volume 29, issue 6

Authors: Coslett, H. Branch | Hamilton, Roy

Article Type: Research Article

DOI: 10.3233/RNN-2011-0626

Citation: Restorative Neurology and Neuroscience, vol. 29, no. 6, pp. 361-363, 2011

Authors: Antal, Andrea | Paulus, Walter | Nitsche, Michael A.

Article Type: Research Article

Abstract: The visual system has the most complex circuitry of all the sensory systems and it also possesses the ability to undergo induced and spontaneous neuroplastic changes. Most of what we know about the functional organization of the visual system is derived from animal experiments or by correlating circumscribed anatomical lesions in patients and their visual perceptual deficits or dysfunctions. However, in the past years, significant achievements have been made in characterizing visual information processing in the human using non-invasive neurophysiological techniques, such as electrical stimulation of the brain. Transcranial direct (tDCS) and alternating current stimulation (tACS) applied through the skull …was shown to directly modulate the excitability of the motor and visual cortices in human subjects. This review article focuses on these stimulation methods and summarizes the latest results with regard to the application of these method over the visual areas in healthy subjects and clinical populations. Show more

Keywords: Vision, tDCS, tACS, human

DOI: 10.3233/RNN-2011-0609

Citation: Restorative Neurology and Neuroscience, vol. 29, no. 6, pp. 365-374, 2011

Authors: Chrysikou, Evangelia G. | Hamilton, Roy H.

Article Type: Research Article

Abstract: Aphasia is a common consequence of unilateral stroke, typically involving perisylvian regions of the left hemisphere. The course of recovery from aphasia after stroke is variable, and relies on the emergence of neuroplastic changes in language networks. Recent evidence suggests that rehabilitation interventions may facilitate these changes. Functional reorganization of language networks following left-hemisphere stroke and aphasia has been proposed to involve multiple mechanisms, including intrahemispheric recruitment of perilesional left-hemisphere regions and transcallosal interhemispheric interactions between lesioned left-hemisphere language areas and homologous regions in the right hemisphere. Moreover, it is debated whether interhemispheric interactions are beneficial or deleterious to recovering …language networks. Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) are two safe and noninvasive procedures that can be applied clinically to modulate cortical excitability during poststroke language recovery. Intervention with these noninvasive brain stimulation techniques also allows for inferences to be made regarding mechanisms of recovery, including the role of intrahemispheric and interhemispheric interactions. Here we review recent evidence that suggests that TMS and tDCS are promising tools for facilitating language recovery in aphasic patients, and examine evidence that indicates that both right and left hemisphere mechanisms of plasticity are instrumental in aphasia recovery. Show more

Keywords: Aphasia, stroke, neuroplasticity, transcranial magnetic stimulation, transcranial direct current stimulation, neurorehabilitation, interhemispheric interactions

DOI: 10.3233/RNN-2011-0610

Citation: Restorative Neurology and Neuroscience, vol. 29, no. 6, pp. 375-394, 2011

Authors: Hoyer, Erik H. | Celnik, Pablo A.

Article Type: Research Article

Abstract: Stroke is the leading cause of long-term disability. Understanding how people recover from stroke and other brain lesions remain one of the biggest conundrums in neuroscience. As a result, concerted efforts in recent years have focused on investigating the neurophysiological changes that occur in the brain after stroke, and in developing novel strategies to enhance motor recovery. In particular, transcranial magnetic stimulation (TMS) is a non-invasive tool that has been used to investigate the brain plasticity changes resulting from stroke and as a therapeutic modality to safely improve motor function. In this review, we discuss the contributions of TMS to …understand how different motor areas, such as the ipsilesional hemisphere, secondary motor areas, and contralesional hemisphere are involved in motor recovery. We also consider recent studies using repetitive TMS (rTMS) in stroke patients to enhance upper extremity function. Although further studies are needed, these investigations provide an important starting point to understand the stimulation parameters and patient characteristics that may influence the optimal response to non-invasive brain stimulation. Future directions of rTMS are discussed in the context of post-stroke motor recovery. Show more

Keywords: Transcranial magnetic stimulation, stroke, plasticity

DOI: 10.3233/RNN-2011-0611

Citation: Restorative Neurology and Neuroscience, vol. 29, no. 6, pp. 395-409, 2011

Authors: Nair, Dinesh G. | Renga, Vijay | Lindenberg, Robert | Zhu, Lin | Schlaug, Gottfried

Article Type: Research Article

Abstract: Purpose: It is thought that following a stroke the contralesional motor region exerts an undue inhibitory influence on the lesional motor region which might limit recovery. Pilot studies have shown that suppressing the contralesional motor region with cathodal transcranial Direct Current Stimulation (tDCS) can induce a short lasting functional benefit; greater and longer lasting effects might be achieved with combining tDCS with simultaneous occupational therapy (OT) and applying this intervention for multiple sessions. Methods: We carried out a randomized, double blind, sham controlled study of chronic stroke patients receiving either 5 consecutive days of cathodal tDCS (for 30 minutes) applied …to the contralesional motor region and simultaneous OT, or sham tDCS+OT. Results: we showed that cathodal tDCS+OT resulted in significantly more improvement in Range-Of-Motion in multiple joints of the paretic upper extremity and in the Upper-Extremity Fugl-Meyer scores than sham tDCS+OT, and that the effects lasted at least one week post-stimulation. Improvement in motor outcome scores was correlated with decrease in fMRI activation in the contralesional motor region exposed to cathodal stimulation. Conclusions: This suggests that cathodal tDCS combined with OT leads to significant motor improvement after stroke due to a decrease in the inhibitory effect that the contralesional hemisphere exerts onto the lesional hemisphere. Show more

Keywords: Rehabilitation, stroke recovery, non-invasive brain-stimulation, fMRI, tDCS

DOI: 10.3233/RNN-2011-0612

Citation: Restorative Neurology and Neuroscience, vol. 29, no. 6, pp. 411-420, 2011

Authors: Oliveri, Massimiliano

Article Type: Research Article

Abstract: The application of brain stimulation techniques for modulation of cortical excitability changes underlying spatial neglect following right-brain-damage has been the first application of brain stimulation in the rehabilitation setting. Several factors concur in making neglect a prototype of cognitive disorders that can be modulated by brain stimulation: 1) neglect is highly lateralized deficit, 2) neglect is a network disorder in which lesion of a network node impacts affects excitability of intrahemispehric and interhemispheric connections, and 3) lesions of the right hemisphere, the most frequent cause of neglect, are associated with a transcallosally mediated increase of facilitation of the left hemisphere …more frequently than are lesions of the left hemisphere associated with right hemisphere facilitation. We review the main applications of TMS for modulation of neglect disorder and we discuss the different potentialities of inhibition of the unaffected and facilitation of the affected hemisphere. Moreover, we suggest potential interactions of TMS with other behavioral techniques in the rehabilitation setting. Show more

Keywords: Transcranial magnetic stimulation, stroke, neglect, interhemispheric interactions

DOI: 10.3233/RNN-2011-0613

Citation: Restorative Neurology and Neuroscience, vol. 29, no. 6, pp. 421-425, 2011

Authors: Song, Sunbin | Sandrini, Marco | Cohen, Leonardo G.

Article Type: Research Article

Abstract: Purposeful manipulation of cortical plasticity and excitability within somatosensory regions may have therapeutic potential. Non-invasive brain stimulation (NBS) techniques such as transcranial magnetic stimulation (TMS) or transcranial direct current stimulation (tDCS) have shown promise towards this end with certain NBS protocols augmenting somatosensory processing and others down-regulating it. Here, we review NBS protocols which, when applied to primary somatosensory cortex, facilitate cortical excitability and tactile acuity (i.e., high-frequency repetitive TMS (rTMS), intermittent theta burst stimulation (TBS), paired associative stimulation (PAS) N20-5 to 0, anodal tDCS), and protocols that inhibit the same (i.e., low-frequency rTMS, continuous TBS, PAS N20-20, cathodal tDCS). …Other studies have targeted multisensory regions of the brain to modulate somatosensory processing. These studies in full present a wide array of strategies in which NBS can be utilized to influence somatosensory processing in a behaviorally and clinically relevant capacity. Show more

Keywords: Noninvasive brain stimulation, transcranial magnetic stimulation, transcranial direct current stimulation, somatosensory processing

DOI: 10.3233/RNN-2011-0614

Citation: Restorative Neurology and Neuroscience, vol. 29, no. 6, pp. 427-437, 2011

Authors: Zaghi, Soroush | Thiele, Bruna | Pimentel, Daniel | Pimentel, Thais | Fregni, Felipe

Article Type: Research Article

Abstract: Purpose: There remains an unmet clinical need for the development of new therapeutic approaches for the treatment of pain. Recent findings have confirmed significant changes in the pain-related neural networks among patients with chronic pain, opening novel possibilities for investigation. Two non-invasive techniques (transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS)) have emerged as interesting, effective, and promising modalities for pain relief. Methods: Here we review the clinical efficacy of these techniques for the treatment of pain through an updated systematic meta-analysis on the effects of primary motor cortex stimulation on pain and we discuss potential mechanisms of …action based on insights from brain stimulation studies. Our meta-analysis includes 18 studies, which together show that non-invasive brain stimulation is associated with an effect size of −0.86 (95% C.I., −1.54, −0.19) on a standardized pain scale ranging from 0 (no pain) to 10 (worst pain possible). Results and Conclusions: Besides its use as a therapeutic tool, non-invasive brain stimulation can also be used to measure cortical reactivity and plasticity in chronic pain. Such measurements could potentially be used as biomarkers for the dysfunctional chronic pain-related neural network and might be helpful in measuring the efficacy of interventions designed for chronic pain. Show more

Keywords: Non-invasive brain stimulation, transcranial direct current stimulation, transcranial magnetic stimulation, motor cortex stimulation, pain, meta-analysis

DOI: 10.3233/RNN-2011-0615

Citation: Restorative Neurology and Neuroscience, vol. 29, no. 6, pp. 439-451, 2011

Authors: Olma, Manuel C. | Kraft, Antje | Roehmel, Jasper | Irlbacher, Kerstin | Brandt, Stephan A.

Article Type: Research Article

Abstract: Purpose: TDCS can increase excitability in the visual cortex. It is a matter of current debate if tDCS can improve visual performance. Promising parameters to measure detection sensitivity may be those of the signal detection theory ( = SDT), as it allows differentiating between response bias and detection sensitivity changes. The measure of detection sensitivity can be used to predict actual performance under a wide variety of different response criteria. Methods: Here we test if the SDT can quantify tDCS-induced effects in a visual contrast discrimination task in healthy subjects. Results: Anodal stimulation of the visual cortex improved performance, as …calculated by detection sensitivity for stimuli presented in the center of the visual field. More peripheral locations in the visual field were unaffected by anodal stimulation. Cathodal stimulation and sham stimulation of the visual cortex had no consistent effect on detection sensitivity. The response bias was not affected by any type of stimulation. Conclusions: Neuroplastic changes in the visual cortex induced by anodal tDCS can be measured by SDT, suggesting SDT could prospectively be a useful approach for monitoring restorative tDCS-effects on visual function in patients with central visual deficits. Show more

Keywords: Transcranial direct current stimulation (tDCS), neuromodulation, visual psychophysical performance, signal detection theory, visual cortex

DOI: 10.3233/RNN-2011-0607

Citation: Restorative Neurology and Neuroscience, vol. 29, no. 6, pp. 453-461, 2011

Authors: Nitsche, Michael A. | Paulus, Walter

Article Type: Research Article

Abstract: Non-invasive brain stimulation with weak direct currents (transcranial direct current stimulation (tDCS)) has emerged as one of the major tools to induce neuroplastic cortical excitability alterations in humans since its (re-) introduction to the arsenal of plasticity-inducing brain stimulation tools. In this review, we gather newly emerged knowledge about the effect of tDCS on brain function in both, basic and applied research. This overview will deliver an update of the last two years of research, because especially during this time numerous important studies were published covering the above-mentioned fields.

Keywords: Neuroplasticity, human, brain stimulation, transcranial direct current stimulation, TMS

DOI: 10.3233/RNN-2011-0618

Citation: Restorative Neurology and Neuroscience, vol. 29, no. 6, pp. 463-492, 2011