COMMENTARY The Development of Hippocampal Interneurons in Rodents

ABSTRACT: Interneurons are GABAergic neurons responsible for in-hibitory activity in the adult hippocampus, thereby controlling the activ-ity of principal excitatory cells through the activation of postsynaptic GABAA receptors. Subgroups of GABAergic neurons innervate specific parts of excitatory neurons. This specificity indicates that particular interneuron subgroups are able to recognize molecules segregated on the membrane of the pyramidal neuron. Once these specific connec-tions are established, a quantitative regulation of their strength must be performed to achieve the proper balance of excitation and inhibition. We will review when and where interneurons are generated. We will then detail their migration toward and within the hippocampus, and the maturation of their morphological and neurochemical characteristics. We will finally review potential mechanisms underlying the develop-ment of GABAergic interneurons. VC 2006 Wiley-Liss, Inc. KEY WORDS: hippocampus; development; interneuron; GABA; migration; synaptogenesis; GABAergic synapses; calcium-binding proteins; neuropeptide