RT Journal Article SR Electronic T1 Early Development of Neuronal Activity in the Primate HippocampusIn Utero JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 9770 OP 9781 DO 10.1523/JNEUROSCI.21-24-09770.2001 VO 21 IS 24 A1 Roustem Khazipov A1 Monique Esclapez A1 Olivier Caillard A1 Christophe Bernard A1 Ilgam Khalilov A1 Roman Tyzio A1 June Hirsch A1 Volodymyr Dzhala A1 Brigitte Berger A1 Yehezkel Ben-Ari YR 2001 UL http://www.jneurosci.org/content/21/24/9770.abstract AB Morphological studies suggest that the primate hippocampus develops extensively before birth, but little is known about its functional development. Patch-clamp recordings of hippocampal neurons and reconstruction of biocytin-filled pyramidal cells were performed in slices of macaque cynomolgus fetuses delivered by cesarean section. We found that during the second half of gestation, axons and dendrites of pyramidal cells grow intensively by hundreds of micrometers per day to attain a high level of maturity near term. Synaptic currents appear around midgestation and are correlated with the level of morphological differentiation of pyramidal cells: the first synapses are GABAergic, and their emergence correlates with the growth of apical dendrite into stratum radiatum. A later occurrence of glutamatergic synaptic currents correlates with a further differentiation of the axodendritic tree and the appearance of spines. Relying on the number of dendritic spines, we estimated that hundreds of new glutamatergic synapses are established every day on a pyramidal neuron during the last third of gestation. Most of the synaptic activity is synchronized in spontaneous slow (≈0.1 Hz) network oscillations reminiscent of the giant depolarizing potentials in neonatal rodents. Epileptiform discharges can be evoked by the GABA(A) receptor antagonist bicuculline by the last third of gestation, and postsynaptic GABA(B) receptors contribute to the termination of epileptiform discharges. Comparing the results obtained in primates and rodents, we conclude that the template of early hippocampal network development is conserved across the mammalian evolution but that it is shifted toward fetal life in primate.