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project:brain_hacking:tdcs [2013/01/17 13:12]
ata
project:brain_hacking:tdcs [2013/04/29 22:05] (current)
ata F3 locator (program)
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 +======  Transcranial direct current stimulation - tDCS  ======
 +{{template>../infobox|
 +name=Biofeedback,\\ Brain hacking|
 +image=brain.jpg|
 +founder=[[user:ATA]]|
 +interested=[[user:harvie]],\\ [[user:ruza]],\\ [[user:pborky]],\\  [[user:niekt0]]|
 +status=active
 +}}
 +
 {{http://www.diytdcs.com/media/petrEarlyTdcs.jpg}} {{http://www.diytdcs.com/media/petrEarlyTdcs.jpg}}
  
-====== Transcranial direct current stimulation - tDCS ====== + Transcranial direct current stimulation is a type of nonivasive cortical modulations technique witch use low DC current in order 25-80uA/cm2(more in HD-tdcs) via skalp electrodes to change resitng potentials of neurones.This chanages depend of polarity of stimulation = orintation od el. field to the neurones,the anodal (+) stimulation increases the neuronal excitability and  Cathodal (-) neuronal excitability.When positive stimulation causes a depolarization of the resting membrane potential, which increases neuronal excitability and allows for more spontaneous cell firing. When negative stimulation is delivered, the current causes a hyperpolarization of the resting membrane potential. This decreases neuron excitability due to the decreased spontaneous cell firing.TDCS also have neuroplastic effect Anodal tDCS could induce long-term potentiation (LTP) through increased pre-synaptic activity coupled with postsynaptic depolarisation; conversely, cathodal tDCS could induce long-term depression (LTD) through reduced presynaptic discharge and postsynaptic hyperpolarisation. 
- Transcranial direct current stimulation is a type of nonivasive cortical modulations technique witch use low DC current in order 25-80uA/cm2(more in HD-tdcs) via skalp electrodes to change resing potentials of neurones.This chanages depend of polarity of stimulation = orintation od el. field to the neurones,the anodal (+) stimulation increases the neuronal excitability and  Cathodal (-) neuronal excitability.When positive stimulation causes a depolarization of the resting membrane potential, which increases neuronal excitability and allows for more spontaneous cell firing. When negative stimulation is delivered, the current causes a hyperpolarization of the resting membrane potential. This decreases neuron excitability due to the decreased spontaneous cell firing.TDCS also have neuroplastic effect Anodal tDCS could induce long-term potentiation (LTP) through increased pre-synaptic activity coupled with postsynaptic depolarisation; conversely, cathodal tDCS could induce long-term depression (LTD) through reduced presynaptic discharge and postsynaptic hyperpolarisation. +
  
 ===== Safety considerations for tDCS ===== ===== Safety considerations for tDCS =====
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 ===== Current density on electrodes ===== ===== Current density on electrodes =====
  
-====What this means, how to count  ====+====What this means, how to count it  ====
 This means current from the device devided by surface volume of electrodes.Moustly write in this manner uA/cm2 or mA/cm2 in some sudy you may find A/m2. This means current from the device devided by surface volume of electrodes.Moustly write in this manner uA/cm2 or mA/cm2 in some sudy you may find A/m2.
   *uA means 0,001 mA    *uA means 0,001 mA 
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 **Anode +** **Anode +**
  
-Brain function under the electrode site is enhanced by roughly 20 to 40% when the current density exceeds 40 µa/cm2 (260 µa/inch2).+Brain function under the electrode site is enhanced by roughly 20 to 40% when the electrode current density exceeds 40 µa/cm2 (260 µa/inch2).
  
 **Cathode -** **Cathode -**
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 larger reference electrode minimalize the unwanted effect,current density below 27uA/cm2 is in some studies considered functional unefective. larger reference electrode minimalize the unwanted effect,current density below 27uA/cm2 is in some studies considered functional unefective.
   * this also not entirely true, it is oversimplified read further section for more info   * this also not entirely true, it is oversimplified read further section for more info
 +  * my recomandation is use for the return electrode current below 20uA if it possible
  
   *Nitsche and Paulus found that a minimum current density of 17 µa/cm2 was needed to excite motor neurons. Studies involving other regions of the brain have suggested that 20 to 25 µa/cm2 are needed to excite neurons under the electrode. One depression study using anodal stimulation at F3 noted alleviated depression using 1 mA into a 35 cm2 electrode (28 µa/cm2). Iyer, et al., observed that when stimulating the left prefrontal cortex there was no effect on verbal fluency with a 1 mA current, but significant improvements at 2 mA (current density of 20 µa/cm2 vs 41 µa/cm2). Two depression studies by Boggio, et al., 2007; Boggio, et al., 2007) also used 2 ma.   *Nitsche and Paulus found that a minimum current density of 17 µa/cm2 was needed to excite motor neurons. Studies involving other regions of the brain have suggested that 20 to 25 µa/cm2 are needed to excite neurons under the electrode. One depression study using anodal stimulation at F3 noted alleviated depression using 1 mA into a 35 cm2 electrode (28 µa/cm2). Iyer, et al., observed that when stimulating the left prefrontal cortex there was no effect on verbal fluency with a 1 mA current, but significant improvements at 2 mA (current density of 20 µa/cm2 vs 41 µa/cm2). Two depression studies by Boggio, et al., 2007; Boggio, et al., 2007) also used 2 ma.
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 {{http://upload.wikimedia.org/wikipedia/commons/3/35/Gray726.png}} {{http://upload.wikimedia.org/wikipedia/commons/3/35/Gray726.png}}
   *main sulci map   *main sulci map
 +
 +{{http://classconnection.s3.amazonaws.com/997/flashcards/1355997/jpg/central_sulcus1336398738694.jpg}}
 +  *central sulcus , motor cortex
 +
 +{{http://www.nature.com/nrn/journal/v11/n6/images/nrn2833-f1.jpg}}
 +  *M1 area 4 position in the sulcus (usefull for radial/tangental field optimalization)  
  
 ==Interidividual variabality== ==Interidividual variabality==
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   * new site with resources about tDCS http://www.alltdcs.com   * new site with resources about tDCS http://www.alltdcs.com
  
-  *tests http://www.cambridgebrainsciences.com/+  * tests http://www.cambridgebrainsciences.com/ 
 + 
 +---- 
 +6.3 2013 
 +  * Voltage ripple poroblem  in  the ActivaDose II device  
 +    http://speakwisdom.wordpress.com/2012/12/29/tdcs-does-ripple-voltage-matter/ 
 + 
 +  * Trought the wormhole about tDCS 
 +{{youtube>I13IOKfeLzw?medium}} 
 +  *Dave Siever from Mind Alive Inc.gives an overview of tDCS, how it’s theorized to work, and includes a set of tDCS montages for various purposes.  
 + http://www.diytdcs.com/2012/11/dave-siever-mind-alive-revisited 
 + 
 +---- 
 +7.3 2013 
 +  *Open Source Hardware TDCS (based on LM334Z) 
 +{{https://nocko.se/assets/tdcs-article/v2-board-front.png}} 
 +{{https://nocko.se/assets/tdcs-article/v2-board-back.png}} 
 +https://nocko.se/2012/07/30/brain-zapping-is-fun/ 
 +https://github.com/nocko/tdcs/ 
 + 
 +  * Soterix Medical - 4x1 multichannel stimulation Device (good look to the soterix HD electrode)  
 +   {{youtube>6y9aG30Rpzg?medium}} 
 + 
 +---- 
 +8.3 2013 
 + 
 +{{http://wiki.hacdc.org/images/1/11/Opentdcs-v4.png}} 
 +The v4 is designed to drive higher impedance electrodes in addition to the usual sponge+saline electrodes by using the LT1026 charge pump controller to produce +18V to -18V split source from a 9V battery. It uses the LM334Z IC for fine current limiting control and a JFET as a gross 5mA limiter in case of LM334Z failure. ESD protection comes from two varistors. from:[[http://wiki.hacdc.org/index.php/TDCS]] 
 + 
 +---- 
 +12.3 2013 
 + 
 +**Ramping capacitor - possible problem ** 
 +  *Yesterday i was bulding some tDCS with LM334 and try for first time use ramping capacitor. When i test device with load (5KOhms) all was ok ramping when i turn device on and ramping down when off. But when i change load (5kOhms potentiometer) during stimulation (testing) it create current peak up to 5 mA. I test it with few different capacitor and behavior is allwayes the same (only diffrent value of peak nad the time to return to normal ). Device without capacitor work witkout poroblem. In result of this i use instead of capacitor serail load ( linear potentiometr 100kOhms ) allows me to do manual ramping (0,07mA to setup current). 
 + 
 +My question is can anybody test this capacitor problem maybe i do semething wrong , bad multimetter etc.. . If is this problem real is very bad idea use capacitor for ramping in use the resistance change is not to quick but stil can cause pretty high current peaks. 
 + 
 +**New posibilities for electrodes material**  
 +NOT TESTED only ideas :  
 +  * Polyimid resistive foil (50um , 100 Ohm/cm2 ) http://www.gme.cz/vodive-pryze/polyimidova-odporova-folie-26x20cm-100ohm-p661-130/ 
 + 
 +---- 
 +7.4 2013 
 + 
 + 
 +Prof. Marom Bikson “Using Computational Models in tDCS Dose” 
 +http://www.diytdcs.com/2013/04/prof-marom-bikson-using-computational-models-in-tdcs-dose/ 
 +  * about problems with extracephalic electrodes  
 +  * HD-tDCS electrodes - not use saline soaked sponge -) risk of burn  
 +    *i plan test skin tolerability and sensation limits for sponge based HD-tDCS electrodes   
 +  * direction of current (in , out , tangental , radial) 
 +  * Comparing cortical plasticity induced by conventional and high-definition 4x1 ring tDCS 
 +    *time course difference , longer effect 
 +  *focality of HD-tDCS 
 +  *Inter-subject variation in susceptibility >2x in TES 
 +  *Dose normalization: Determine role of individual variation and predict requisite adjustments in subject 
 +specific dose. 
 + 
 + 
 + 
 +Comparing cortical plasticity induced by conventional and high- 
 +definition 4x1 ring tDCS: a neurophysiological study  
 +Brain Stimulation 2012  
 +Kuo HI, Datta M, Bikson M, Minhas P, Paulus W, Kuo MF, Nitsche MA  
 + 
 +---- 
 +8.4 
 +Test of HD-tDCS electrodes  
 + 
 +   * problem with contact to polyimide foil  
 +   * current desity with no pain/tingeling  
 +    *270 uA/cm2  for saline soaked sponge  
 +    *320 uA/cm2  for TEN20 EEG gel  
 +    *(3,14cm2 electrodes on skin , cleaned by alcohol pad and abrasion by nuprep )  
 +   * voltage problem after skin preparation 8,3 V at 1mA (9V power suply ) to close to the device limit  
 +    --------) rebuild device to 18V version  
 + 
 +---- 
 + 
 +9.4 
 +  *rebuild to 18V version  
 +  *too strong abrasion by nuprep -) increased pain in stimulation (damaged skin by abarasion) 
 +  * current desity test up to 620uA/cm2 
 +    * its posible stimulate with 620uA/cm2 without any fealing but result are not stable and is needed electrode improvements  
 +    * better result for EEG gel than for saline soaked sponge  
 +    * saline soaked sponge : not even saline distribution ? , to dry ? ---) more tests  
 + 
 +to do: 
 +    *rebuild electrodes from 3,14cm2 to 4 cm2 ( to reduce current density , new info : soterix use 4cm2 ,easier counting of current density )   
 +    *lower height of elastic ring around electrode for EEG gel electrodes ( too much consumption of EEG gel )  
 +    *sponge electrodes : Filling tube for guaranteed the same moisture for whole stimulation 
 +      *sringe  
 +      *gravity autofilling (3cm filling tube) 
 +       *head movement caused spillage ? , end of the tube ?  
 +      *improve elastic ring (reduce spillage of saline)     
 +    * electrode cap for M1/SO 35cm2  
 +      *fixation to holder 
 +      *faster shape adjusting  
 +    * electrode cap for 4X1 M1 HD-tDCS   
 +      *EEG gel electrodes adhesion : usage witout cap ? 
 +    * EEG electrode cap for 4X1 M1 HD-tDCS  
 +      *hair problem in EEG cap --) find something to move away hair 
 +      *holder allows one by one electrodes adding (easier to move away hair than in version where all electrodes fimly fixed to 4x1 holder) 
 +    * TESTS painless/sesationless current desities for all types of electrodes , alcohol Y/N ,abrasion Y/N , alcohol + abrasion  
 +      * arm or leg , forehead, hair area    
 + 
 +    *few interesting designs of caps 
 + {{http://biomedicaloptics.spiedigitallibrary.org/data/Journals/BIOMEDO/926250/JBO_18_2_027005_f001.png}} 
 + 
 +[[http://biomedicaloptics.spiedigitallibrary.org/article.aspx?articleid=1567852]] 
 +  
 +{{ http://www.wired.com/images_blogs/gadgetlab/2011/03/3-22-11-mynd-eeg-headset.jpg }} 
 + 
 +{{http://gearmedia.ign.com/gear/image/article/772/772295/gdc-2007-emotiv-systems-unveils-shocking-neural-interface-device-20070312035005901-000.jpg}} 
 + 
 +   * dry electrodes 
 +     * HD tdcs dry electrodes are crazy idea but worth some tests like current desity without iritation and hi-frequenci pulsed TDCS (4khz) 
 +       *comercial EEG dry electrodes  
 +{{http://www.gtec.at/var/plain_site/storage/images/media/images/products/g.sahara/gsaharalongpin/26508-1-eng-GB/gSAHARAlongpin.jpg}} 
 + 
 +{{http://beweb.ucsd.edu/courses/senior-design/projects/2010/project_17/electrode.jpg}} 
 + 
 + 
 +------- 
 +11.4 
 +  
 +    *<del>rebuild electrodes from 3,14cm2 to 4 cm2 ( to reduce current density , new info : soterix use 4cm2 ,easier counting of current density ) </del> **rebuild to 4,9cm2** 
 +     
 +    *<del>lower height of elastic ring around electrode for EEG gel electrodes ( too much consumption of EEG gel )</del> **OK (ring from tape)**  
 +    *<del>sponge electrodes : Filling tube for guaranteed the same moisture for whole stimulation</del> **OK** 
 +           *<del>sringe</del>  
 +           *<del>gravity autofilling (3cm filling tube)</del> **Change of design** 
 +           *<del>head movement caused spillage ? , end of the tube ?</del> **OK (capilar effect)** 
 +           *<del>improve elastic ring (reduce spillage of saline)</del> **OK**     
 +    *<del>electrode cap for M1/SO 35cm2</del> **OK** 
 +    *<del>fixation to holder</del> **OK** 
 +    *<del>faster shape adjusting</del> **OK**  
 +    
 +    <del>*electrode cap for 4X1 M1 HD-tDCS </del>  
 +    *<del>EEG gel electrodes adhesion : usage witout cap ?</del> **OK** 
 +      *holder allows one by one electrodes adding (easier to move away hair than in version where all electrodes fimly fixed to 4x1 holder) 
 +    *<del>EEG electrode cap for 4X1 M1 HD-tDCS hair problem in EEG cap --) find something to move away hair</del> **Hole in cap is too small to put in electrode from top** 
 +    * TESTS painless/sesationless current desities for all types of electrodes , alcohol Y/N ,abrasion Y/N , alcohol + abrasion  
 +      * arm or leg , forehead, hair area    
 + 
 +**TO DO** 
 +    *elstic rings 
 +    <del>*filling tube 
 +    *elctrode holder 
 +    *HD-TDCS cap</del> 
 +    *TESTS 
 + 
 +----------------- 
 + 
 +29.4 
 +**Usefull tool for locating DLPFC**  
 + 
 +An efficient and accurate new method for locating the F3 position for prefrontal TMS applications 
 + 
 +http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2882797/ 
 + 
 +http://clinicalresearcher.org/F3/ 
  
 **My Email** **My Email**
 ORLIN1@seznam.cz  ORLIN1@seznam.cz 
 
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