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Galvanic Skin Responses
Description of the GSR measurements process:
Circuit of the DC current: steps of the current transfer from active electrode to passive electrode
Steps of the current transfer from anode to cathode and then, from cathode to anode for each pathway.
Step 1 and 2 : Entrance of the Current from the active electrode
Because voltage lower than 10 V cannot penetrate the stratum corneum1, the only way for the current to enter the body is through the eccrine sweat ducts. This route represents the physiological pathway of the interstitial fluid, ie, the source of the eccrine sweat. 2
Step 3 : Pathway into the human body between the 2 electrodes:
1.According to the Fricke’s circuit, At DC current, the plasma membrane acts as an insulator and the current is not able to penetrate the cell, and most of the current flows around the cell and therefore in the interstitial fluid. 3, 4
2.In the interstitial fluid, the free ions are able to conduct electric current in the presence of an external electrical field. We can consider biological tissue electrically and macroscopically an ionic conductor. The total ionic conductance of a solution depends on the concentration, activity, charge and mobility of all free ions in the solution.3,4
3.The free ionic concentration and mobility are proportional to the ratio intensity/voltage; more the ionic concentration and mobility increase, more intensity and less voltage are observed. 3,4
4.Electrical dispersion: The cell membrane has the ability to store capacitive energy (dielectric or insulator properties). The cell membrane is the cellular structure with the major contribution to the dielectric behavior of living tissue. Living tissue is considered as a dispersive medium. 5-7
Cole (1940) introduced the first mathematical expression able to describe the ‘depressed semicircles’ found experimentally. It is known as the Cole equation. 5-7
The α value can also be regarded as a parameter denoting the derivation from Fricke–Morse model. That is, the Cole equation with α = 1 is equal to the Fricke–Morse model.In the case of living tissues, the spectral width of the electrical Bioimpedance dispersions (closely related with αparameter in the Cole equation) evolves during the ischemic periods. The simulations indicate that the dispersion width could be determined by the morphology of the extra-cellular spaces.8
Step 4, 5 and 6 : Process of the exit of the Current to the passive electrode
Electrical stimulation of the post sympathetic cholinergic fiber causes sweat rate response.9
The mechanical shear stress causes a phosphorylation cascade that removes phosphate groups from proteins and kinases activating endothelial nitric oxide (NO) synthase to synthesize NO. Nitric oxide is produced facilitating the release of cyclic guanosine monophosphate and a change in potassium permeability. The relaxation of the smooth muscle and vasodilatation of the vessels allows an exchange between vessels and sweat gland facilitates the production of sweat.10, 11
The release of acetylcholine (Ach) is also regulated by the hypothalamus and, the sweat response, acts as a response to an increase in blood and/or skin temperature.11
As regard to the EIS method , the mechanical response is not dependent on a temperature increase and it appears that the electrical stimulation acted as a mechanical shear stress activator, 10,11 describe above.
Step 7 : Electrochemical reactions on the bulk of the passive electrode (electrolysis)
-From Grimmes, S. & Martinsen, Ø. G. (2000).
Electrolytics. Bioimpedance & Bioelectricity.12
Analysis of the DC current in cathode and anode in electrolytic solution Na+ Cl- using metal electrodes: The electrochemical window is defined by both reduction and oxidation of water according to the following reactions: 12
At the Cathode
First of all, Na+ ions are not discharged at the cathode. Sodium has a very electro-negativity which means that it takes a large energy and a large negative voltage on the cathode to impose electrons on Na+ ions. At lower voltage there is reduction of dissolved oxygen and decomposition of water molecules. Both processes are linked with non-charged species which are transported to the electron transfer sites by diffusion not by migration.
At voltage supply adjusted (> 1V), the oxygen reduction current is sufficient. Na+ need not be considered, but Na+ ions are necessary for the conductance of the solution.
The water electrochemical reaction (reduction) at the cathode is:
2H2O + (2e -) = (H2) + (2 OH-)
At the Anode
Is the current at the anode due to the discharge of C1- ions? Yes. Chloride is highly electronegative, but less energy is necessary for taking electrons from the chloride ions than from water molecules. The water electrochemical reaction (oxidation) at the anode is:
2H2O = (O2) + (4H +) + (4e-)
In interstitial fluid the Na+ represents 96% of the positive free ions and Cl- and HCO3- ions represents also 96 % of the negative free ions.12
The interstitial fluid can be considered as electrolytic solution of Na+ and Cl-and because, HCO3-and Na+ ions may not discharged and they do not contribute very much to the DC current transfer. (3), the electrochemical model in vitro describe above could be applied only for dissolved oxygen diffusion at the cathode and Cl- ions at the anode.12
Analysis of the DC current in cathode and anode in electrolytic solution Na+ Cl- using Ag/Ag Cl: The Cotlove coulometric chloride titrator method.13
The technique measures the total chloride concentration. With this method, the passage of a constant direct current between Ag/AgCl electrodes produces silver ions. The free silver ions react with the chloride forming silver chloride as follow:
Ag => Ag+ Ag+ + (Cl-) => AgCl
After all the chloride combines with Ag+, free silver ions accumulate and precipitate , causing an increase in current across the electrodes and indicating the end point to the reaction..
Chizmadzhev YA, Andrey V. Indenbom, PI. Kuzmin, SV. Galichenko, JCW, Russell OP. Electrical Properties of Skin at Moderate Voltages: Contribution of Appendageal Macropores. Biophysical Journal.1998.74 (2) : 843–856
Hashimoto K. Demonstration of the Intercellular Spaces of the Human Eccrine Sweat Gland by Lanthanum. J. Ultrastructure research.1971.36: 249--262
S. Gabriel, R. Lau W, Gabriel C. The dielectric properties of biological tissues: III. Parametric models for the dielectric spectrum of tissues, Physics in Medicine and Biology. 1996. 2271-2293
Foster K R, Schwan, H. P. Dielectric Properties of Tissues and Biological Materials: A Critical Review. CRC Critical Reviews in Biomedical Engineering.1989 17(1): 25-104.
Cole, K. S. Electric phase angle of cell membranes. Journal of General Physiology.1932. 15: 641-649.
Cole, KS., Li CL,Bak AF. Electrical analogues for tissues. Exp Neurol. 1969. 24(3): 459-473.
Cole K S, Cole R H. Dispersion and absorption in dielectrics. I. Alternating-current characteristics. Journal of Chemical Physics. 1941. (9): 341-351.
Ivorra A, Genesca M, Sola A, Palacios L, Villa R, Hotter G, Aguilo J. Bioimpedance dispersion width as a parameter to monitor living tissues. Physiol. Meas. 26.2005. 1(9).
Donadio V, Lenzi P, Montagna P, Falzone F, Baruzzi A, Liguori R. Habituation of sympathetic sudomotor and vasomotor skin responses: neural and non-neural components in healthy subjects. Clin Neurophysiol. 2005;116:2542-2549.
Soucy KG, Ryoo S, Benjo A, et al. Impaired shear stress-induced nitric oxide production through decreased NOS phosphorylation contributes to age-related vascular stiffness. J Appl Physiol. 2006;101:1751-1759.
Petrofsky J, Hinds CM, Batt J, Prowse M, Suh HJ.The interrelationships between electrical stimulation, the environment surrounding the vascular endothelial cells of the skin, and the role of nitric oxide in mediating the blood flow response to electrical stimulation. Med Sci Monit. 2007.13:CR1-CR7.
Grimmes S. ,Martinsen Ø G. Electrolytics. In Bioimpedance & Bioelectricity Basics: Academic Press.2000
Cotlove E, Nishi HH. Automatic titration with direct read out of chloride concentration. Clin Chem. 1961; 7:285–91.
Uwezekano wa kuhamisha umeme kutoka kwa anode hadi cathode: Uwezekano wa kuhamisha umeme kutoka kwa anode hadi cathode: Uwezekano wa kuhamisha umeme kutoka kwa anode hadi cathode. Mzunguko wa 1 na 2: Kuingia kwa umeme kutoka kwa electrode ya kazi, kwa sababu voltage ya chini ya 10V haiwezi kupenya stratum corneum, njia pekee ya kuingia kwa umeme ni kupitia mifereji ya jasho ya eccrine. Njia hii inawakilisha njia ya kisaikolojia ya kioevu cha kati, yaani, chanzo cha jasho la eccrine. "Mfano wa ""mzunguko wa Frick"" ni kwamba wakati wa mzunguko wa DC, utando wa plasma unafanya kazi kama insulator na sasa hauwezi kupenya ndani ya seli, na sehemu kubwa ya mkondo inapita karibu na seli na kwa hivyo katika kioevu cha kati." Katika interstitial fluid, ioni huru zinaweza kuongoza umeme wakati wa uwepo wa uwanja wa umeme wa nje. Tunaweza kufikiria tishu ya kibiolojia umeme na macroscopically conductor ionic. Uwezo wa ionic wa jumla unategemea mkusanyiko, shughuli, malipo na mwendo wa ioni zote huru katika suluhisho.3,4 Mkusanyiko wa ionic huru na mwendo ni sawa na uwiano wa nguvu na voltage. 3.4.4 - Kuenea kwa umeme: membrane ya seli ina uwezo wa kuhifadhi nishati ya capacitive (dielectric au insulator mali). Mzunguko wa seli ni muundo wa seli na mchango mkubwa kwa tabia dielectric ya tishu hai. Tissue hai ni kuchukuliwa kama vyombo vya kueneza. Cole (1957-40) alianzisha usemi wa kwanza wa hisabati uwezo wa kuelezea <unk> depressed semicircles <unk> kupatikana kimajaribio. Inajulikana kama usawa wa Cole. 5- α thamani pia inaweza kuchukuliwa kama parameter kuonyesha derivation kutoka Fricke <unk> Morse mfano. Hii ni kwa sababu, kwa mfano, katika mfano wa Fricke-Morse, mlinganisho wa Cole na mlinganisho wa Cole ni sawa na mlinganisho wa Fricke-Morse. Utaratibu wa kupanua kwa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko wa mtiririko. Nitric oksidi hutengenezwa kuwezesha kutolewa kwa cyclic guanosine monophosphate na mabadiliko katika potasiamu permeability. "Kupumzika kwa misuli laini na vasodilation ya mishipa ya damu inaruhusu kubadilishana kati ya mishipa na kibofu cha jasho, na kuwezesha uzalishaji wa jasho. ""Utoaji wa acetylcholine (A) pia umedhibitiwa na hypothalamus na majibu ya jasho hufanya kazi kama majibu ya kuongezeka kwa joto la damu na ngozi. ""Kwa njia ya EIS, majibu ya mitambo haitegemei kuongezeka kwa joto na inaonekana kwamba kuchochea umeme hufanya kazi kama kichocheo cha shinikizo." "Mfano wa ""mfano wa electrode"" ni Grimms, S. & Martinsen, O.G. Stepp." Vifaa vya kuondoa umeme. Bioimpedance na Bioelectricity: Uchambuzi wa DC sasa katika cathode na anode katika suluhisho la umeme NaCl na kutumia electrodes za chuma: dirisha la electrochemical linafafanuliwa na kupunguza na oxidation ya maji kulingana na athari zifuatazo: Sodium ina electro-negativity kubwa, ambayo inamaanisha kwamba inachukua nishati kubwa na voltage kubwa hasi kwenye cathode ili kuingiza elektroni kwenye ioni za Na +. Katika voltage ya chini kuna kupunguzwa kwa oksijeni iliyomwagika na uharibifu wa molekuli za maji. Utaratibu wote ni kushikamana na aina zisizo na malipo ambayo ni kusafirishwa kwa maeneo ya uhamisho wa elektroni na kuenea si kwa uhamiaji. Katika voltage usambazaji kurekebishwa (> 1V), oksijeni kupunguza sasa ni ya kutosha. Na + haihitaji kuzingatiwa, lakini ioni za Na + zinahitajika kwa conductivity ya ufumbuzi. Mageuzi ya umeme ya maji kwenye cathode ni: H2O + (2H2) + (2OH) + (H2) + (2OH) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) + (H2) Ndio, nina hakika. Chloride ni electronegative sana, lakini nishati kidogo ni muhimu kwa ajili ya kuchukua elektroni kutoka ions chloride kuliko kutoka molekuli za maji. Katika anode ya anode, na-ion ya H2O2 (H2O2) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 (H2O3) + H2O3 ( Kwa mfano, in vitro electrochemical model inaweza kutumika tu kwa ajili ya dissolved oksijeni diffusion katika cathode na Cl ions katika anode.12 Uchambuzi wa DC sasa katika cathode na anode katika suluhisho electrolytic NaCl na AgCl, kutumia CotLove coulometric chloride titration mbinu.13 Utaratibu hupima jumla ya chloride mkusanyiko. Kwa njia hii, kupita kwa mtiririko wa moja kwa moja wa mara kwa mara kati ya electrodes Ag / AgCl inazalisha ions fedha. Chloride ya fedha hufanyiza Ag+Ag+Ag++Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag+Ag Kuzmin, SV. Galchenko, JCW, Russell OP. Mali za umeme za ngozi katika voltage wastani: Mchango wa Macropores Appendageal. Biophysical Journal, 1998: 843856 Hashimoto K. Maonyesho ya Intercellular Spaces ya binadamu Eccrine Sweat Gland na Lanthanum. Utafiti wa Ultrastructure: S. Gabriel, R. Lau, W. Gabriel, C. Mifano ya parameter kwa ajili ya dielectric spectrum ya tishu, Fizikia katika Tiba na Biolojia. Mwaka 1996 na 1996. "Foster, K. R. Schwan, H. P. ""Ubora wa Dielectric ya Tissues na Biological Vifaa: A Review Critical.""" CRC: Maelezo muhimu katika Uhandisi wa Biomedical (1989) 17 (1) 25-104. Cole, K. S. Electric awamu pembe ya utando wa seli. Jarida la General Physiology, 1932 15:64-64 na Zaburi ya 6:9. Cole, KS, Li CL, Bak AF. Analogs umeme kwa ajili ya tishu. Neurol ya Exp. Mwaka 1969 24 (3) 459-473. Cole K S, Cole R H. Dispersion na kunyonya katika dielectrics. I. Alternating-mzunguko sifa. Jarida la Kimwili cha Kemikali. Mwaka 1941 (Mdo.34:1-31) Ni nini kilichotokea? Ivorra, A. Genesca, M. Sola, A. Palacios, L. Villa, R. H. G. Aguilón, J. Upana wa kutawanyika kwa bioimpedance kama parameter ya kufuatilia tishu za kuishi. Physiol. Meas. 26 ya mwaka 2005. 1 (k) Donadio V, Lenzi P, Montagna P, Falzone F, Baruzzi A, Liguori R. Habituation ya sympathetic sudomotor na vasomotor majibu ya ngozi: neural na non-neural vipengele katika masomo afya. Klin Neurophysiol. 2005;116:2542-2549. Soucy KG, Ryoo S, Benjo A, et al. Uharibifu wa shinikizo la shear-induced nitric oxide through decreased NOS phosphorylation contributes to age-related vascular stiffness. Jpl Physiol. 2006;101:1751-1759. Petrovsky, J. Hinds, J. Prowse, M. Suh, H. J. The interrelationships kati ya umeme stimulation, mazingira ya kuzunguka mishipa endothelial seli ya ngozi, na jukumu la nitrous oxide katika kuingilia kati ya damu mtiririko majibu ya umeme stimulation. Med Sci Monit. 2007: CR1 na CR7. Grimmes S.,Martinsen Ø G. Electrolytics. Bioimpedance na Bioelectricity Basics: Academic Press, 2000 (Cotlove, N.H.) Titration moja kwa moja na moja kwa moja kusoma nje ya mkusanyiko chloride. Kliniki ya Kem. 1961; 7:285<unk>91.