Intracerebral Transplants and Memory Dysfunction: Circuitry Repair or Functional Level Setting?

摘要

Intracerebral grafting techniques of fetal neural cells have been used essentially with two main types of lesion paradigms, namely damage to long projection systems, in which the source and the target are clearly separate, and damage to neurons that are involved in local circuits within a small (sub)region of the brain. With the’first lesion paradigm, grafts placed homotopically (in the source) are not appropriate because their fibers grow poorly through the host parenchyma and fail to reach their normal target. To be successful, the grafts must be placed ectopically in the target region of the damaged projection systems, where generally they work as level-setting systems. Conversely, with the second paradigm, the grafts are supposed to compensate for alocal loss of neurons and must be placedhomotopically to induce functional effects thatare based on the reconstruction of a point-to-pointcircuitry. By inserting a biological orartificial bridging-substrate between the sourceand the target of long projection systems, itmight be possible to combine the positiveeffects of both homotopic and ectopic graftingby achieving both target reinnervation andnormal control of the grafted neurons withinthe source area. These issues are illustratedand discussed in this review.