Selective Induction of LTP and LTD by Postsynaptic [Ca]i Elevation

Shao-Nian Yang, Yun-Gui Tang and Robert S. Zucker. Selective Induction of LTP and LTD by Postsynaptic [Ca]i Elevation. J. Neurophysiol. 81: 781–787, 1999. Long-term potentiation (LTP) and long-term depression (LTD), two prominent forms of synaptic plasticity at glutamatergic afferents to CA1 hippocampal pyramidal cells, are both triggered by the elevation of postsynaptic intracellular calcium concentration ([Ca]i). To understand how one signaling molecule can be responsible for triggering two opposing forms of synaptic modulation, different postsynaptic [Ca]i elevation patterns were generated by a new caged calcium compound nitrophenyl-ethylene glycol-bis(b-aminoethyl ether)-N,N,N9,N9-tetraacetic acid in CA1 pyramidal cells. We found that specific patterns of [Ca]i elevation selectively activate LTP or LTD. In particular, only LTP was triggered by a brief increase of [Ca]i with relatively high magnitude, which mimics the [Ca]i rise during electrical stimulation typically used to induce LTP. In contrast, a prolonged modest rise of [Ca]i reliably induced LTD. An important implication of the results is that both the amplitude and the duration of an intracellular chemical signal can carry significant biological information.