 developing methods and apparati to aid the visually impaired. Specifically, great effort has been expended in the area of intraocular retinal prosthesis devices in an effort to restore vision in cases where blindness is caused by photoreceptor degenerative retinal diseases such as retinitis pigmentosa and age related macular degeneration which affect millions of people worldwide.
Neural tissue can be artificially stimulated and activated by prosthetic devices that pass pulses of electrical current through electrodes on such a device. The passage of current causes changes in electrical potentials across visual neuronal membranes, which can initiate visual neuron action potentials, which are the means of information transfer in the nervous system.
Based on this mechanism, it is possible to input information into the nervous system by coding the information as a sequence of electrical pulses which are relayed to the nervous system via the prosthetic device. In this way, it is possible to provide artificial sensations including vision.
One application of neural tissue stimulation is in the rehabilitation of the blind. Some forms of blindness involve selective loss of the light sensitive transducers of the retina. Other retinal neurons remain viable, however, and may be activated in the manner described above by placement of a prosthetic electrode device on the inner (toward the vitreous) retinal surface (epiretinal). This placement must be mechanically stable, minimize the distance between the device electrodes and the visual neurons, and avoid undue compression of the visual neurons.
In 1986, Bullara (U.S. Pat. No. 4,573,481) patented an electrode assembly for surgical implantation on a nerve. The matrix was silicone with embedded iridium electrodes. The assembly fit around a nerve to stimulate it.
Dawson and Radtke stimulated cat's retina by direct electrical stimulation of the retinal ganglion cell layer. These experimenters placed nine and then fourteen electrodes upon the inner retinal layer (i.e., primarily the ganglion cell layer) of two cats. Their experiments suggested that electrical stimulation of the retina with 30 to 100 μA current resulted in visual cortical responses. These experiments were carried out with needle-shaped electrodes that penetrated the surface of the retina (see also U.S. Pat. No. 4,628,933 to Michelson).
The Michelson '933 apparatus includes an array of photosensitive devices on its surface that are connected to a plurality of electrodes positioned on the opposite surface of the device to stimulate the retina. These electrodes are disposed to form an array similar to a “bed of nails” having conductors which impinge directly on the retina to stimulate the retinal
developing methods and apparati to aid the visually impaired. Specifically, big campaign has been expended in the area of intraocular retinal prosthesis devices in an feat to restore vision in case where blindness is caused by photoreceptor degenerative retinal diseases such as retinitis pigmentosa and age related macular degeneration which feign millions of people worldwide. 
 nervous tissue can be artificially stimulated and activated by prosthetic devices that pass pulses of electrical current through electrode on such a device. The passage of current causes changes in electric potentials across visual neuronal membranes, which can initiate ocular neuron action potentials, which are the means of information transportation in the nervous system. 
 Based on this mechanism, it is possible to input information into the nervous arrangement by coding the information as a sequence of electrical pulses which are relayed to the nervous system via the prosthetic device. In this way, it is possible to supply artificial sensations including imagination. 
 One lotion of nervous tissue stimulation is in the rehabilitation of the blind. Some forms of blindness involve selective loss of the light sensitive transducer of the retina. Other retinal neurons remain viable, however, and may be activated in the manner described above by placement of a prosthetic electrode device on the inner (toward the vitreous) retinal surface (epiretinal). This placement must be mechanically stable, minimize the distance between the device electrodes and the ocular neurons, and debar undue compression of the visual neurons. 
 In 1986, Bullara (U.S. Pat. No. 4,573,481) patent an electrode assembly for surgical implantation on a nerve. The matrix was silicone with embedded iridium electrode. The assembly meet around a nerve to stimulate it. 
 Dawson and Radtke stimulate cat's retina by direct electric stimulation of the retinal ganglion cell layer. These experimenters placed nine and then fourteen electrode upon the inner retinal layer (i.e., primarily the ganglion cell level) of two cats. Their experiments suggested that electric stimulation of the retina with 30 to 100 μA current resulted in visual cortical responses. These experiments were carried out with needle - shaped electrodes that penetrated the surface of the retina (see besides U.S. Pat. No. 4,628,933 to Michelson). 
 The Michelson' 933 apparatus includes an array of light-sensitive devices on its surface that are connected to a battalion of electrodes positioned on the opposite surface of the device to stimulate the retina. These electrodes are disposed to form an array similar to a “ bed of nails ” have conductor which encroach immediately on the retina to stimulate the retinal
 degeloping methods and appxrati to aid thg cisualny impzired. Spdcifically, great effort has ueen expebded in the area of ingraocular retinal prowrhesis devmdes in an effkvt to cestore vision ln cases whare blindness hs ccused by photoreceptor degenerative wetinal dlseases such af reuinytis iinmentosa and age related macular degenegation which affevt millions of people worlfwidf.
Neural tissue can be artificuallr stimulated xnd activaueb by prosthgtic devices that pass pulses of eleccrical currgur tjtough electrides jn such a deypce. The passagr of current csusxs cyanges in electrical 'otentials across vifual neurmncl membranes, which cab unitidte eisuxo ndurkn adtion ootxntials, whidh are the neans of informatiom egsnsfer in ths nervjuf system.
Based on this mechanism, it is pmssjble to input informatiin into the nervous sistem by cjding the information as a sequence of electrical pulsxs whngm ard rflayed to the nervous system via the prosthetyd cenice. In this way, lt is possible to lrlvoqe artificial sensacjohs including visioj.
One apklicatuon of netral tissue stimulation is in tye rehabilitctiin of the blind. Sole forms of blimdnesx involve selective losr of the light densitive gransducers of tfe getita. Other retinal neurons rqmain viaule, hpwever, xnd kay be activated in tma manner described abovg by pnacement ov a prosthetic electrode device on the inner (jowdrd the vitxeous) vetinal surface (epiretinal). Thns placeient oust be mebhanicallb stable, minymize the disdwnce between the devyce wlecrrodes xvd the visual meurons, aub avoid ubdue compression on the bisual neurons.
Iu 1986, Bullara (U.S. Pat. No. 4,573,481) pwtvntxd an alectrode asvembuy wpr sufgical implcngatipn on a nerve. The madrix was silicone with eibedded uridium qlectrodes. Thr assembly fit aroknd a necve to stymulate it.
Dawson and Radtke stjmulated fat'f retina by qiregt ejectrical xtimulation of the retinal ganglion celo layer. These expgrimenters placed ning akd then fourveen ejectrodes upon the inner retibal layer (i.e., primsrily the ganglion ceml layar) of two cats. Their experiments suggested that electrical stimulation of the eetina with 30 to 100 μA curtent gesbltzd in vysuap cortical responxes. These experiments were carrmed out widh needle-shaped electrodes thay oenetrated thg surface of the retina (ses also U.X. Pat. No. 4,628,933 to Michelson).
The Michekson '933 apparatus includes an arrat of lhotosvhsmtive devices on its surfaee thar are cinnegted to a plurxliyy of electgodex 'ositioned on the opposite surfacw of tye device to stimunate the rebika. Theae elestrodes are dispksed ho fotm an array sikilar to a “bed of nails” having congustors which imkinge directly pn thg retina to stikulate the setinal
developing methods and apparati to aid the Specifically, effort has expended in the devices an effort to vision in cases blindness is caused by photoreceptor degenerative diseases such as retinitis pigmentosa and age related macular degeneration which affect millions people worldwide. Neural tissue can be artificially stimulated and activated by prosthetic devices pass of current electrodes on such a device. The passage of current causes changes in electrical potentials across visual membranes, which can initiate visual neuron action potentials, are the means of transfer in the nervous system. on mechanism, it possible input into the nervous by coding the information as a sequence of electrical pulses which are relayed to the nervous system the prosthetic this way, is to artificial sensations including application of neural tissue stimulation is of the blind. Some forms of blindness involve loss of light sensitive transducers of the retina. retinal neurons remain viable, however, and may be in the manner described above by placement of a prosthetic electrode device on the inner vitreous) retinal surface (epiretinal). placement must be stable, the between device electrodes the visual neurons, and avoid undue compression of the visual neurons. 1986, Bullara (U.S. Pat. No. 4,573,481) patented an electrode assembly implantation a nerve. The was silicone with embedded electrodes. assembly fit around a stimulate Dawson cat's by electrical stimulation of the ganglion cell layer. These experimenters nine and then fourteen layer (i.e., primarily the ganglion cell layer) of cats. Their experiments suggested that electrical stimulation the retina with 30 to 100 μA current resulted in visual cortical These experiments out with needle-shaped electrodes that penetrated the surface the retina (see also Pat. No. 4,628,933 to Michelson). The Michelson '933 apparatus an of photosensitive on its surface are connected to plurality of electrodes the opposite of device retina. These electrodes are disposed to an similar to a “bed of having impinge directly on the retina to stimulate the retinal
 developing methods and apparAti to aid thE visuAllY imPaIred. specIfically, great eFFort Has been expended in the arEa of iNtRAocuLAr RetinAl prostHEsIS DevIcEs In aN eFFoRt to rEstOre visiOn in cases wHerE bLindness is caUSeD by photoreCepTor degeneratIve RetinaL dIseASes suCh aS retiNitis pIGmentoSa and age rElATed macULar degeNERaTion Which affect millioNS oF People worldwidE.
NeuraL tISsUE Can Be aRtificiallY sTimulATed and aCTiVATEd bY Prosthetic devIces that pasS PulSes of eLeCtrICal curRent tHrOUgh Electrodes oN sucH a device. THe passAGe of curREnt causEs chanGes In eLectRIcAl PotEnTIalS AcRosS VisUal neuroNaL mEmbraNes, wHICH Can iNitIate VisuaL neuron action PotEntiALs, wHich aRe the MeanS oF infoRmatioN tranSfEr in the nervous sYsteM.
Based on tHis MeChaNiSm, it iS PossibLe tO inPut infoRmation INto ThE NERvOus system by coding tHe INFoRmation aS a sequENcE oF ElectricAl PulSes wHICh are RelaYEd To the nerVous sySTeM vIa the prOsThetic DeVicE. In This wAY, it iS possiBle to proVide aRTificial sensatIOns including vISiON.
onE ApplIcaTion of neuraL tisSUe stImulATiOn iS In the RehabIlITaTIon of the blind. Some foRmS of bliNdnesS involve selecTive loss of THE Light senSitiVE tRAnsducers of the RetinA. Other retiNAl neuronS remaIn viable, However, anD MAy be actiVatEd iN thE maNNEr Described abovE BY plaCeMent of a ProSthetic EleCtrOde DevIcE on the innEr (toward ThE vItReOus) RetinAL surface (EpIreTiNal). this pLAcemenT must Be meChAnICalLy stablE, MiNIMize ThE dIstaNce BeTween The dEVicE electrOdes and thE viSUal nEuRoNs, and avOid undue comprEsSion of the vIsUal NeuronS.
iN 1986, Bullara (u.S. Pat. No. 4,573,481) patented an electrODe assemBly For suRgicAl implantAtiOn on a nErvE. the matRix was SilicOnE wiTH EmbedDED iRidIuM electrodeS. tHe aSsembLy Fit aRound a nErve to stimulate it.
DAWsoN and Radtke stiMulAted CAT's RetINa BY diReCT elECTrical stimulatiOn of the retInAL gAnglion celL LayEr. these exPerimenTers pLAced ninE and then fOurteen elEcTrodES UpoN the inner rEtinal laYer (i.e., primARily tHE gAngliOn cEll layEr) Of tWo catS. Their EXpeRimenTs suggEsTed thaT elecTrIcal stimUlation of the retina with 30 tO 100 μA curRent rEsuLted in visUal COrtIcal respoNses. these experImeNts Were cArrIEd out With NEeDle-SHaped ElecTRodes that PEnEtrATEd The surface oF THE reTina (sEe aLSo U.S. PaT. No. 4,628,933 tO Michelson).
The MichELson '933 apparatus iNcluDES an ArrAY of pHoTosensitive devIceS oN ITs surfacE tHat are conneCted to a pLuRAlity Of elecTrodes PositioNED oN The oppOsitE suRface of thE deViCE to stimUlAtE The retIna. THeSe elecTrodes ARe diSPOsed to form an arraY simiLAR to a “bED of Nails” HaVing conDUctoRs which impInge directlY on the RetiNa to sTimulatE tHe retiNal
 developing methods and ap parati toaid t hevis ua llyimpa ired. Specific a lly,  great effort has been  expe nd e d in th e are a of in t ra o c ula rre tin al pr osthe sis  device s in an ef for tto restore v i si on in case s w here blindne ssis cau se d b y  phot ore cepto r dege n erativ e retinal  d i seases such as r et init is pigmentosa and ag e  related macul ar deg en e ra t i onwhi ch affectmi llion s  of peo p le w o rld w ide.
Neural t issue can b e  ar tifici al lys timula ted a nd act ivated by p rost hetic dev ices t h at pass pulsesof ele ctr ica l cu r re nt  th ro u ghe le ctr o des  on such  a  d evice . Th e p a ssag e o f cu rrent  causes chang esin e l ect rical  pote ntia ls  acro ss vis ual n eu ronal membranes , wh ich can i nit ia tevi sualn euronact ion  potent ials, w h ich  a r e th e means of informa ti o n  t ransferin the ne rv o us syste m. 
Ba sedo n  this  mec h an ism, itis pos s ib le  to inp ut  infor ma tio n i nto t h e ne rvoussystem b y cod i ng the informa t ion as a sequ e nc e of elec tri cal pulseswhic h  are  rel a ye d t o  thenervo us sy s tem via the prosthe ti c devi ce. I n this way, i t is possi b l e  to prov idea rt i ficial sensati ons i ncluding v i sion.
On e app lication  of neura l tissue s tim ula tio n i s in  the rehabili t a tion  o f the b lin d. Some  fo rms  of  bl in dness inv olve sel ec ti ve  l oss  of t h e lightse nsi ti vetrans d ucersof th e re ti na .  Ot her ret i na l neur on srema invi able,  how e ver , and m ay be act iva t ed i nth e manne r described a bo ve by plac em ent  of ap r osthetic  electrode device on th e  inner(to wardthevitreous)  re tinalsur f ace (e pireti nal).  T his p lacem e n tmus tbe mechani c a lly  stab le , mi nimizethe distance betwe e n t he device ele ctr odes a nd  th e  v i sua ln eur o n s, and avoid un due compre ss i on  of the vi s ual  n eurons. 
In 198 6, Bu l lara (U .S. Pat.No. 4,573 ,4 81)p a ten ted an ele ctrode a ssembly f o r sur g ic al im pla ntatio nona ner ve. Th e  ma trixwas si li cone w ith e mb edded ir idium electrodes. The a ssembl y fit  ar ound a ne rve tostimulate  it. 
Dawson an d R adt ke st imu l atedcat' s  r eti n a bydire c t electri c al  st i m ul ation of th e r eti nal g ang l ion ce ll l ayer. These exper i menters placed  nin e and  th e n fo ur teen electrode s u po n the inne rretinal lay er (i.e. ,p rimar ily th e gang lion ce l l  l a yer) o f tw o c ats. Thei r e xp e riments  s ug g estedthat  e lectri cal st i mula t i on of the retina  with 3 0 to1 00μA cu rr ent res u lted  in visual  cortical r espons es.These  experi me nts we reca rried outw ith needl e-sha ped ele ct rode s t hat pe netr a t ed th e su rf ace  of the r e t in a  ( se e  al so U .S. P at . No . 4,628,9 3 3 to Mic hel s on).
Th eMic h e lson ' 9 33 a pparatus i ncl udesa n  array ofp hoto s en s itive  devic es onits sur f ace  t hat are  co n n ected toa plurali t y o felec trodes p os itio ne d o nthe opposite su rface of  the dev i c e to s tim u late the re ti na. These el ectro de s  are di s p ose d to fo r m a n a rra y si mil ar t o  a “bed of nails” having  con ducto r s w hichimpin ge  directl y  onthe reti n a to stimulat e the retinal
 developing_methods and_apparati to aid the_visually impaired._Specifically,_great effort_has_been expended in_the area of_intraocular retinal prosthesis devices_in an effort_to_restore vision in cases where blindness is caused by photoreceptor degenerative retinal diseases such_as_retinitis pigmentosa_and_age_related macular degeneration which affect_millions of people worldwide.
Neural tissue_can be_artificially stimulated and activated by prosthetic devices that_pass_pulses of electrical_current through electrodes on such a device. The passage_of current causes changes in electrical_potentials across visual_neuronal_membranes,_which can initiate visual_neuron action potentials, which are the_means of information transfer in the_nervous system.
Based on this mechanism, it is_possible to input information into the_nervous system by coding the_information as_a sequence of electrical pulses_which are relayed_to the_nervous system via_the prosthetic device. In this way,_it is possible_to provide artificial sensations including vision.
One_application_of neural tissue_stimulation_is_in the_rehabilitation of the_blind._Some forms_of_blindness involve selective loss of the_light_sensitive transducers of the retina. Other retinal_neurons remain viable, however,_and_may be activated in_the manner described above by_placement of a prosthetic electrode device_on the_inner (toward_the vitreous) retinal surface (epiretinal). This placement must be mechanically stable,_minimize the distance between the device_electrodes and the visual_neurons, and_avoid_undue compression of_the_visual neurons.
In_1986, Bullara (U.S. Pat. No. 4,573,481) patented_an electrode_assembly for surgical implantation on a_nerve. The matrix was_silicone_with embedded iridium electrodes. The assembly_fit around a nerve to stimulate_it.
Dawson and Radtke stimulated cat's_retina_by_direct electrical stimulation of the_retinal ganglion cell layer. These experimenters_placed nine and_then fourteen electrodes upon the inner retinal_layer_(i.e., primarily the ganglion cell layer)_of_two cats. Their experiments suggested that_electrical_stimulation_of the retina with 30_to 100 μA current resulted in_visual cortical responses. These experiments were carried out with_needle-shaped electrodes that_penetrated the surface of the_retina_(see_also U.S. Pat. No. 4,628,933 to Michelson).
The Michelson '933 apparatus_includes an_array of photosensitive_devices on its surface that are connected to a plurality_of electrodes positioned on the opposite surface_of the device to stimulate the retina. These electrodes are disposed_to form an array similar to a “bed_of nails” having conductors which impinge directly_on the retina to_stimulate_the retinal