IMPLANTABLE BIOELECTRONIC INTERFACES FOR LOST NERVE FUNCTIONS

Neuronal cells are unique within the organism. In addition to forming long-distance connections with other nerve cells and non-neuronal targ ets, they lose the ability to regenerate their neurites and to divide during maturation. Consequently, external violations like trauma or di sease frequently lead to their disappearance and replacement by non-ne uronal, and thus not properly functioning cells. The advent of microte chnology and construction of artificial implants prompted to create pa rticular devices for specialised regions of the nervous system, in ord er to compensate for the loss of function. The scope of the present wo rk is to review the current devices in connection with their applicabi lity and functional perspectives. (1) Successful implants like the coc hlea implant and peripherally implantable stimulators are discussed. ( 2) Less developed and not yet applicable devices like retinal or corti cal implants are introduced, with particular emphasis given to the rea sons for their failure to replace very complex functions like vision. (3) Material research is presented both from the technological aspect and from their biocompatibility as prerequisite of any implantation. ( 4) Finally: basic studies are presented, which deal with methods of sh aping the implants, procedures of testing biocompatibility and modific ations of improving the interfaces between a technical device and the biological environment. Thr review ends by pointing to future perspect ives in neuroimplantation and restoration of interrupted neuronal path ways. (C) 1998 Elsevier Science Ltd. All rights reserved.