Properties of Excitatory Synaptic Events in Neurons of Primary Somatosensory Cortex of Neonatal Rats

摘要: We have characterized the development of synaptic responses from neurons rat parietal cortex. Whole-cell recording was used in slice preparations vitro. Neurons were stained with biocytin to allow their identification, and sample included pyramidal Cajal-Retzius cells. Dye-coupling 3-12 cells frequently observed day birth (P0) P3. On average, when recorded Cs(+)-filled electrodes, input resistances neonatal large (mean = 1.1 G omega) resting membrane potentials relatively depolarized -45 mV) compared mature neocortical neurons. The application an NMDA receptor antagonist usually hyperpolarized by 5-10 mV increased resistance increase 83%), suggesting that immature are tonically activated excitatory amino acids (EAA) our preparation. Excitatory postsynaptic (EPSPs) or currents (EPSCs) could be obtained animals as young P0 brief stimulation subplate. Synaptic at these early ages had long durations, often lasting over hundreds milliseconds, they reversed polarity around 0 mV, blocked tetrodotoxin EAA antagonists. Pharmacology current-voltage relationships demonstrated presence both receptor- non-NMDA receptor-dependent components most EPSPs. Unlike neurons, composed largely components. did not observe inhibitory inputs before P6. In some single shocks subplate region initiated spontaneous EPSPs lasted > 1 min. This study clearly demonstrates functional synapses neocortex rats on birth. Large receptor-mediated duration a major influence cortical circuits neonate.