Most synapses form on small, specialized postsynaptic structures known as dendritic spines1. The influx of Ca2+ ions into such spines—through synaptic receptors and voltage-sensitive Ca2+ channels (VSCCs)—triggers diverse processes that underlie synaptic plasticity2. Using two-photon laser scanning microscopy3, we imaged action-potential-induced transient changes in Ca2+ concentration in spines and dendrites of CA1 pyramidal neurons in rat hippocampal slices4. Through analysis of the large trial-to-trial fluctuations in these transients, we have determined the number and properties of VSCCs in single spines. Here we report that each spine contains 1–20 VSCCs, and that this number increases with spine volume. We are able to detect the opening of a single VSCC on a spine. In spines located on the proximal dendritic tree, VSCCs normally open with high probability (∼0.5) following dendritic action potentials. Activation of GABAB receptors reduced this probability in apical spines to ∼0.3 but had no effect on VSCCs in dendrites or basal spines. Our studies show that the spatial distribution of VSCC subtypes and their modulatory potential is regulated with submicrometre precision.
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Harris, K. M. & Kater, S. B. Dendritic spines: cellular specializations imparting both stability and flexibility to synaptic function. Annu. Rev. Neurosci. 17, 341–371 (1994).
Zucker, R. S. Calcium- and activity-dependent synaptic plasticity. Curr. Opin. Neurobiol. 9, 305–313 ( 1999).
Denk, W., Strickler, J. H. & Webb, W. W. Two-photon laser scanning fluorescence microscopy. Science 248, 73–76 (1990).
Yuste, R. & Denk, W. Dendritic spines as basic functional units of neuronal integration. Nature 375, 682–684 (1995).
Jaffe, D. B. et al. The spread of Na+ spikes determines the pattern of dendritic Ca2+ entry into hippocampal neurons. Nature 357, 244–246 ( 1992).
Svoboda, K., Tank, D. W. & Denk, W. Direct measurement of coupling between dendritic spines and shafts. Science 272, 716– 719 (1996).
Hillyard, D. R. et al. A new Conus peptide ligand for mammalian presynaptic Ca2+ channels. Neuron 9, 69– 77 (1992).
Triggle, D. J. & Rampe, D. 1,4-Dihydropyridine activators and antagonists: structural and functional distinctions. Trends Pharmacol. Sci. 10, 507–511 ( 1989).
Kavalali, E. T., Zhuo, M., Bito, H. & Tsien, R. W. Dendritic Ca2+ channels characterized by recordings from isolated hippocampal dendritic segments. Neuron 18, 651– 663 (1997).
Barak, L. S. & Webb, W. W. Diffusion of low density lipoprotein-receptor complex on human fibroblasts. J. Cell Biol. 95, 846–852 (1982).
Katz, B. & Miledi, R. Membrane noise produced by acetylcholine. Nature 226, 962–963 (1970).
Koch, C. & Zador, A. The function of dendritic spines: devices subserving biochemical rather than electrical compartmentalization. J. Neurosci. 13, 413–422 (1993).
Christie, B. R., Eliot, L. S., Ito, K. I., Miyakawa, H. & Johnston, D. Different Ca2+ channels in soma and dendrites of hippocampal pyramidal neurons mediate spike-induced Ca2+ influx. J. Neurophysiol. 73, 2553– 2557 (1995).
Magee, J. C. & Johnston, D. Characterization of single voltage-gated Na+ and Ca2+ channels in apical dendrites of rat CA1 pyramidal neurons. J. Physiol. 487, 67–90 (1995).
Schiller, J., Schiller, Y. & Clapham, D. E. Amplification of calcium influx into dendritic spines during associative pre- and postsynaptic activation: the role of direct calcium influx through the NMDA receptor. Nature Neurosci. 1, 114–118 (1998).
Wu, L. G., Borst, J. G. & Sakmann, B. R-type Ca2+ currents evoke transmitter release at a rat central synapse. Proc. Natl Acad. Sci. USA 95, 4720–4725 (1998).
Bean, B. P. Neurotransmitter inhibition of neuronal calcium currents by changes in channel voltage dependence. Nature 340, 153– 156 (1989).
Kuo, C. C. & Bean, B. P. G-protein modulation of ion permeation through N-type calcium channels. Nature 365, 258–262 (1993).
Zamponi, G. W. & Snutch, T. P. Modulation of voltage-dependent calcium channels by G proteins. Curr. Opin. Neurobiol. 8, 351–356 ( 1998).
Boland, L. M. & Bean, B. P. Modulation of N-type calcium channels in bullfrog sympathetic neurons by luteinizing hormone-releasing hormone: kinetics and voltage dependence. J. Neurosci. 13, 516–533 (1993).
Page, K. M., Canti, C., Stephens, G. J., Berrow, N. S. & Dolphin, A. C. Identification of the amino terminus of neuronal Ca2+ channel α1 subunits α1B and α1E as an essential determinant of G-protein modulation. J Neurosci. 18, 4815–4824 ( 1998).
Isaacson, J. S., Solis, J. M. & Nicoll, R. A. Local and diffuse synaptic actions of GABA in the hippocampus. Neuron 10, 165– 175 (1993).
Petersen, C. C., Malenka, R. C., Nicoll, R. A. & Hopfield, J. J. All-or-none potentiation at CA3-CA1 synapses. Proc. Natl Acad. Sci. USA 95, 4732–4737 ( 1998).
Tottene, A., Moretti, A. & Pietrobon, D. Functional diversity of P-type and R-type calcium channels in rat cerebellar neurons. J. Neurosci. 16, 6353–6363 (1996).
Maravall, M., Mainen, Z. M., Sabatini, B. & Svoboda, K. Estimating intracellular calcium concentrations and buffering without wavelength ratioing. Biophys. J. 78, 2655– 2667 (2000).
Mainen, Z. F., Malinow, R. & Svoboda, K. Synaptic calcium transients in single spines indicate that NMDA receptors are not saturated. Nature 399, 151–155 (1999).
Markram, H., Helm, P. J. & Sakmann, B. Dendritic calcium transients evoked by single back-propagating action potentials in rat neocortical pyramidal neurons. J. Physiol. 485, 1–20 ( 1995).
Emptage, N., Bliss, T. V. P. & Fine, A. Single synaptic events evoke NMDA receptor-mediated release of calcium from internal stores in hippocampal dendritic spines. Neuron 22, 115–124 ( 1999).
Rice, S. O. in Noise and Stochastic Processes (ed. Wax, N.) 133– 294 (Dover, New York, 1954).
Jones, R., OIiver, C. J. & Pike, E. R. Experimental and theoretical comparison of photon-counting and current measurements of light intensity. Appl. Opt. 10, 1673–1680 (1970).
We thank B. J. Burbach and P. O'Brien for help with experiments, and Z. Mainen, R. Malinow, M. Maravall, W. Regehr, R. Weinberg and R. Yasuda for comments on the manuscript. This work was supported by the Pew, Klingenstein and Mathers Foundations, the Howard Hughes Medical Institute, NIH and a Helen Hay Whitney Fellowship.
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