Effects Of Non-invasive Brain Stimulation Research Articles

Repetitive Transcranial Magnetic Stimulation Improves Handwriting in Parkinson’s Disease

Background. Parkinson disease (PD) is characterized by hypometric movements resulting from loss of dopaminergic neurons in the substantia nigra. PD leads to decreased activation of the supplementary motor area (SMA); the net result of these changes is a poverty of movement. The present study determined the impact of 5 Hz repetitive transcranial magnetic stimulation (rTMS) over the SMA on a fine motor movement, handwriting (writing cursive “l”s), and on cortical excitability, in individuals with PD. Methods. In a cross-over design, ten individuals with PD were randomized to receive either 5 Hz or control stimulation over the SMA. Immediately following brain stimulation right handed writing was assessed. Results. 5 Hz stimulation increased vertical size of handwriting and diminished axial pressure. In addition, 5 Hz rTMS significantly decreased the threshold for excitability in the primary motor cortex. Conclusions. These data suggest that in the short term 5 Hz rTMS benefits functional fine motor task performance, perhaps by altering cortical excitability across a network of brain regions. Further, these data may provide the foundation for a larger investigation of the effects of noninvasive brain stimulation over the SMA in individuals with PD.

Why non-invasive brain stimulation should not be used in military and security services

In a recent review article by Levasseur-Moreau et al. (2013), the authors discussed the effects of non-invasive brain stimulation (NIBS) on cognitive functions and proposed a potential application of NIBS in security or military personnel. We believe that this research endeavor is questionable since it might disclose several scientific as well as ethical concerns. In the following, we highlight our reservations about the potential use of NIBS in army and/or security services. Over the past decades, non-invasive brain stimulation (NIBS) techniques such as transcranial magnetic (TMS) or transcranial direct current stimulation (tDCS) have been extensively used to investigate brain function and brain plasticity in the living human brain. Early studies provided evidence that NIBS is capable of evoking short-lasting modulatory effects on brain functions. Based on this finding, subsequent proof-of-principle studies quickly progressed to also affect motor and cognitive functions. Originally, NIBS techniques were primarily used in basic research to unravel physiological brain processes and/or to establish brain-behavior relationships. The underlying motivation for many researchers is to extend the boundaries of knowledge and to translate findings of basic research into clinical science, that is, to develop new adjuvant therapeutic tools. In fact, NIBS might be a promising tool for the treatment of neurological and psychiatric diseases (Floel, 2013). For example, Hummel and colleagues showed a beneficial effect of a short period of tDCS in chronic stroke patients on paretic hand function (Hummel et al., 2005). Based on this finding, the authors and other subsequent studies (Lindenberg et al., 2010) suggested that such interventional strategies in combination with customary rehabilitative treatments may play an adjuvant role in neurorehabilitation. Nevertheless, clinical trials on larger patient samples are still needed to confirm the promising results that have been achieved so far by smaller clinical studies. Apart from a translation to the clinical settings, it has been suggested to use these techniques for “neuroenhancement” in cognitive abilities or sports, fueling a vivid discussion concerning ethical issues of the use of NIBS in healthy human subjects (Hamilton et al., 2011; Brukamp and Gross, 2012; Cohen Kadosh et al., 2012; Banissy and Muggleton, 2013). However, to our mind, the use of these techniques in military or security personnel goes even a step further and accentuates concerns as compared to the use in “civilians.” First, the use of NIBS in military or security services is problematic with respect to the autonomy of individuals receiving NIBS: In the military context, the risk of coercion is much more pronounced and autonomous decisions cannot always be warranted (Tennison and Moreno, 2012). Second, safety issues might be aggravated in this context and might not only apply to the person receiving NIBS but also to third persons. Both safety and autonomy represent principles that may help to identify ethical problems and guide related decisions (Beauchamp and Childress, 1994; Walker, 2009; Brukamp and Gross, 2012).

Non-invasive brain stimulation and language processing in the healthy brain

Background: Non-invasive brain stimulation (NIBS) has been used as a probe to modulate cognitive functions in humans for the last 20 years. The two most commonly reported techniques are transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), which have both been used with different stimulation parameters to increase or decrease excitability in target cortical regions. Aims: In the present review, we highlight recent developments in TMS and tDCS in language research in healthy individuals. Main Contribution: We will first describe how tDCS and TMS have been employed to improve either performance of language tasks, or learning in the language domain (facilitatory brain stimulation). Then, we will show how these techniques were used as interference techniques (inhibitory brain stimulation) for understanding brain–behaviour interactions and to explore possible cause–effect links between altered activity in specific brain areas and particular behaviours. We will only review studies in healthy individuals, and first pilot trials in patient population with more general cognitive impairments (idiopathic Parkinson's Disease, Alzheimer's Disease). For tDCS studies in aphasia, see Holland and Crinion (2012); for TMS studies in aphasia, see Medina et al. (2012). Conclusions: In the healthy brain, NIBS can be used to delineate the functional significance of a particular brain region for the respective language task under study. Here, new possibilities of combining TMS or tDCS with functional imaging techniques offer unique opportunities to not only address the functional significance of a brain area underlying the coil or electrode, but in addition allow testing NIBS effects on an entire network. In this setting, TMS, both in its single-pulse and its repetitive form, allows the modulation of a specific function within milliseconds (single-pulse) or the order of seconds (particularly high-frequency rTMS trains), while tDCS has the disadvantage of requiring longer stimulation times. On the other hand, the relatively easy use of tDCS in the magnetic resonance scanner environment will render simultaneous recording of brain function and activation much more accessible, thus offering novel avenues in the study of network effects of NIBS. For proof-of principle studies to improve language learning in the healthy brain, tDCS may be the most fruitful approach due to its easy applicability and excellent safety profile. Subsequent use of this technique in parallel to training protocols to improve re-acquisition of language functions aphasic patients offers exciting possibilities in the realm of neurorehabilitation.

P.8.a.015 The power of expectation bias

Behavioral language treatment approaches represent the standard of care for persons with aphasia (PWA), but the benefits of these treatments are variable. Moreover, due to the logistic and financial limitations on the amount of behavioral therapy available to patients, it is often infeasible for PWA to receive behavioral interventions with the level of frequency, intensity, or duration that would provide significant and lasting benefit, underscoring the need for novel, effective treatment approaches. Noninvasive brain stimulation (NIBS) techniques, such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), have emerged as promising neurally-based tools to enhance language abilities for PWA following stroke.This chapter first provides an overview of the methods and physiologic basis motivating the use of NIBS to enhance aphasia recovery followed by a selective review of the growing evidence of its potential as a novel therapeutic tool. Subsequent sections discuss some of the principles that may prove most useful in guiding and optimizing the effects of NIBS on aphasia recovery, focusing on how the functional state of the brain at the time of stimulation interacts with the behavioral aftereffects of neuromodulation. We conclude with a discussion of current challenges and future directions for NIBS in aphasia treatment.

What Can Neuroimaging Tell Us About Aphasia?

What Can Neuroimaging Tell Us About Aphasia?

Improvement of Motor Function with Noninvasive Cortical Stimulation in a Patient with Chronic Stroke

This manuscript reports the effects of transcranial DC stimulation (tDCS), a technique that enhances cortical plasticity in healthy humans, on motor function in a patient with chronic subcortical ischemic stroke. tDCS but not sham applied in a double-blind protocol to motor regions of the affected hemisphere led to improvements in pinch force, Jebsen-Taylor Hand Function Test, and simple reaction times in the paretic hand that outlasted the stimulation period for at least 40 min. These changes were accompanied by increased corticomotor excitability identified by enhanced recruitment curves and reduced intracortical inhibition to transcranial magnetic stimulation. These results document a beneficial effect of noninvasive brain stimulation on motor function in a human patient with stroke and raise the hypothesis of its potential application in neurorehabilitation.