Physiology of graft-host interactions in the rat hippocampus

The transplanted tissue can promote local processes of regeneration, prevent retrograde degeneration, or simply serve as a slow-release biological capsule, which discharges the appropriate neurotransmitter in a random fashion into the intercellular space. This chapter describes the physiology of graft-host interactions in the rat hippocampus. The chapter also addresses two main questions that guide the research on the physiology of graft-host interactions, (1) can the graft substitute for the damaged host tissue, be incorporated into host circuits and function as expected of a normal host tissue; and (2) can the graft serve as a simple model system for asking questions relevant to normal brain operation. Independent of the possible restoration of functions, the graft can be used as a simple model for complex networks in the brain. The chapter indicates that given the existing limitation of resolution of electrophysiological techniques in the in vitro slice preparation, the heterogeneity of grafted tissue and synapse formation with selective populations of host neurons, the graft should be useful for examining basic questions relevant to central neurotransmission.