Chapter 1 The development of functional connections between transplanted embryonic and mature cortical neurons

Abstract

Publisher Summary This chapter discusses the development of specific functional circuits between mature host and embryonic donor sensory cortex. The chapter addresses four main issues to establish functional graft innervations: (1) does the maturational state of the embryonic cells at the time of grafting affect the subsequent formation of graft-host interconnections, (2) can the axons of mature thalamic sensory relay neurons in the ventral posterior, the lateral geniculate or the medial geniculate nuclei of adult host animals be induced to grow into grafts by manipulation of the host brain prior to transplantation, (3) do the initially synapse-free donor neurons develop synapses equivalent in type and density to those of adult cortex after normal development, and (4) can newly generated synapses between host thalamic neurons and graft cell dendrites adjust their strength in response to the use of host sensory systems. To produce functional grafts, it is necessary to understand the molecular and cellular mechanisms that regulate the ability of cortical neurons to change their responses to excitatory inputs, especially to sensory inputs. The chapter presents certain assumptions about mature neurons that attempt to reorganize their connections, such as neurons in the mature central nervous system (CNS) retain the potential for axonal elongation, or that elongation progresses until synapse formation occurs.