February 15, 1967 Period Cover'ed: June 15, 1966 Lo January 31, 1967 I. Summary dinas obtained during this first phase Certain key e..cperimental fin 0 acions cited in oZ the research have been combined with earlier observ the project propcsal to produce a model of best fit for the electroder-@-,Ial system. It encompasses both a dual peripheral effector -rechanis,-.i and a central control system. It assians little or no fuaction to vascular mechanisms. It lias been used to develoo a new 7@ethcd 'or analysis o-i@' the skin conductance response which has been hi-l2-hly s@--czesslul in accon,plishino sortina of qualitatively different behavidral states without utilizing reosponse amplitude as such. The new method should lend itself readily to automation. II. Snec fic Experimenta! Flndines A. Periphe-:al @lectianism 1. microelectrode Observations: 2.@c,in potentials were sirultaneously recor6ed from sweat pores and from areas on the palmar surface between sweat pores I.epi-derrial sites), tocether tiith-a macroscopic recordi@ng from a nearby 0.3cm2 site (a25 subjects). Pure positive waves pure negative waves and biphasic waves were usu2ally obtained from either ri-croscopic site with equal frequency, althou-n in a few subjects, the epidermal sit-s showed predo,-tinantly positive responses uhile the pores produced ne-ative or bi- phasic waves. For the population as a wlole, no pattern was detectable which allowed prediction of the particular 2@iave- form at eitlier type of microscopic site. One observation of interest was the frequent occl-sions in wh3ch the microelectrodes on tne sweat pore and epidermis showed only positive waves while the macroscodic site shoi;ed pure ne-ative waves (Fig. 1). This is attribiited to the Fact 0 that the -,iacroscopic site was covered with el-actrode par-te and Approve,i fcr @lelzs$3 PaLe .......... 2- mv EP I DERM I s G,ZC)SS 2 SEC us riicroelectrode recordings frord a smeat pore frori I. Si-,,nultaneo 2 " 11 on rom a nearby macroscopic site a the area betwee-n sweat pores, and f the volar surface of the fin"ller. in this exa-,iple the aross site shows a 0 a negative response,, 4despite the positive activity in the mic3ro- scopi.c sites. '@ie,.-ative is upwards. with an electrode while the microclectrode si@,es were exposed to air and were considerably drier. 1-.Iicn dry macroscopic electrodes made of woven silver cloth (to all:)w the site to remain dry) were used, the same effect was obtained, nl-riely prominent positive waves at the 2dry site, while negative waves or negative with weak positive components occurred at the wet site (Fig. 2). This effect is 'consistent with the predictions of a hydration effect reczntly disc7overed at this labora:ory and investigated further under the present contract. It poi-its 2out that the presence of two areas in the skin with different potentials must result in internal circuit currents. The potential observed at the surface is then deter-mined by the value of the ttio *enerators and their internal resistances. If the internal resistance (which includes the sweat duct and the horn2y layer, as well as any r-embranes involved) is reduced, the surface potential will move in the direction of that generator wnose internal resistance is affected. Thus, when sweat overflows into the dry corneum, it reduces the resistance of the horny layer and brings ttie surface potential closer to the potential of the epi2der-,nis which is less ne-ative than the sweat pore. This mechanism makes it i!Tperat@.ve to work with a completely hydrated preparation if this spur@@ous effect is not to be confused with true positive potentials, such as @-,,ay be recorded with the site irur,.ersed tn 2dilute saline. S-'@nce the spiral duct appears to be rela:ively freely per- meable to ions as it passes through the horny layer, the corneum acts as a volume conductor when r,,.oist and interferes with the separation of sweat gland and membrane effects by means of 'S@it'Lace -,iicroelectrode record2in-s. To eliminate this effect and also the hydration effect described above, the skin is now being prepared by slicing at-ay most of the cor-ieun, so that the microelectrode may rest alriiost on the granular layer, or may be inserted directly into the exposed sweat duct at Lhis Level. About 122 exploratory experiments have been run to de,.,elop this technique and a series with -a fixed experi-.nental desi-n has beeti initiated. Sur-Drisinaly, the potential at the surfa@--e pore is 10 to 20 -,nv more neoative than the potential within the lumen of the duct at the aranulax or 2 iialpi-hian layer. This may be in,laicative of a diffusicn potential across the spiral duct wall. Also surprisin- is t@-e observation of positive as well as neeacive and bipha-sic waves from %iithin the exposed lumen a-6 the deeper level. Experiments entailing simultaneous0 microelectrode recordings froin the duct and fro-,a the -ranular layer are in progress. These should hopefully furn'ish definici-@ie infor,-,,iation on the ori-ia of the different for,TE of potential response. 2 m ----------------- 2 mv DRY -C 10 SEC 8 .10 mv Fig. 2. Comparison of recordit,gs from a conventional (iiet) site and a si-nilai dry site covered with porous sil-ver cloth. Note greater positivity in the dry site. 3 2. Aninial E--