Based on already published large evidence, non-invasive brain stimulation (NIBS) techniques like tdCS represent very important approach for the improvement of abnormal brain functions in various conditions (psychiatric and neurological). NIBS can induce temporary changes of neural oscillations and performance on various functional tasks. One of the key-points in understanding a mechanism of NIBS is the knowledge about the brains response to current stimulation and underlying brain network dynamics changes. Until recently, concurrent observation of the effect of NIBS on multiple brain networks interactions and most importantly, how current stimulation modifies these networks remained unknown because of difficulties in simultaneous recording and current stimulation. Recently, in Neuroelectrics wireless hybrid EEG/tCS 8-channel neurostimulator system has been developed that allows simultaneous EEG recording and current stimulation. Now, a relatively new imaging technique called magnetoencephalography (MEG) has emerged as a procedure that can bring new inside into brain dynamics. In this context, our group conducted a successfully proof of concept test to ensure the feasibility of concurrent MEG recording and current stimulation using Starstim and a set of non-ferrous electrodes (Figure 1). But first of all, what actually is MEG? Magnetoencephalography (MEG) is a noninvasive recording method of the magnetic flux from the head surface. Magnetic flux is associated with intracranial electrical currents produced by neural activity (the neural currents are caused by a flow of ions through postsynaptic dendritic membranes). From Maxwell equations, magnetic fields are found whenever there is a current flow, whether in a wire or a neuronal element. Hence, MEG detects these magnetic fields generated by spontaneous or evoked brain activity.
Posts Tagged tCS
[BLOG POST] A window into the brain networks: magnetoencephalography (MEG) and simultaneous Transcranial Current Stimulation (tCS). | Blog Neuroelectrics
18 December, 2014
by Aureli Soria-Frisch
While heading to Petronas Technology University where I will give a course on transcranial current stimulation (tCS) basics I summarized the basics of the technology and particularly on Starstim, the device we envisioned and started to develop within the HIVE project. tCS devices allow the controlled injection of low-amplitude electrical currents into the cerebral cortex through the electrodes, which are non-invasively placed on the scalp.
In this sense they play the opposite role to EEG, i.e. not for monitoring brain activity but for modifying it. There has been some advancement in the tCS field, but the technology and its effects on the brain are still not fully understood. Well, the effects are showing up more and more as studies and clinical trials increase. As a matter of fact, publications on tCS have multiplied by a factor of 4 in the last 4 years, and the clinical trials involving it, even by a factor of 10. But what is still not really understood is what causes this effect from both an electrophysiological as well as therapeutic point of view. I would like to comment on the electrophysiological effects giving some quick hints on what makes the applied electrical current affect the brain activity at the neuronal level. The state of the art is far from this understanding on its effects at neuronal population level and at a global brain level, i.e. connectivity, which have been much less studied.
Different types of tCS
…WHAT IS NEUROGAMING?
Well to start with NeuroGaming refers to combining a videogame with physiological (ECG, GSR, etc.) and neurophysiological (EEG, NIRS, etc.) monitoring. In this context the signals obtained affect the game specifically by moving objects or creating movement, or generally by adjusting the game difficulty and other general parameters. Additionally, recently, brain stimulation such as transcranial current stimulation (tCS) has been added to the NeuroGaming definition as it increases brain plasticity during game play…
Is transcranial current stimulation (tCS, including direct current, tDCS, alternating current, tACS, or random noise stimulation tRNS) effective for the treatment of depression?
Under what conditions? With what montages? We focus here on a review of the recent literature on this topic. We have relied on Google Scholar and also PubMed to carry out the search, including the terms of tDCS, tACS, tRNS as well as Depression (from March 2012 and till Sep 2013).
As you can read below, there quite a few encouraging results in this area, and study group sizes (the famous N) are moderately large. We try to indicate group size and the use of a sham-controlled, double-blind experimental technique. Most studies are careful about these crucial aspects. In addition, it is worth mentioning that there continues to be a lack of bad news from the safety point of view. This seems to be a common pattern of tDCS research (or tCS, in fact). I will discuss this further in a future post on an update on tCS Safety.
The typical target for treatment is anodal on the left DLPFC (F3 in the 10-20 EEG system) with the cathode over the contralateral orbit or, sometimes, over the right DLPFC. As in prior posts, in what follows we concentrate on relevant, study-oriented papers with patients, and leave reviews to the end. In order to make the reading lighter, we have edited the abstracts a bit (please click on the title link if you are interested in the paper)… Full Text PDF