A model of dendritic spine Ca2+ concentration exploring possible bases for a sliding synaptic modification threshold.
AUTOR(ES)
Gold, J I
RESUMO
We used a biophysical model of an isolated dendritic spine to assess quantitatively the impact of changes in spine geometry, Ca2+ buffer concentration, and channel kinetics on Ca2+ dynamics following high-frequency activation of N-methyl-D-aspartate receptors. We found that varying the buffer concentration in the postsynaptic density from 50 to 500 microM can result in an 8-fold difference in the peak Ca2+ concentration following three pulses at 100 Hz. Similarly, varying the spine neck diameter from 0.1 to 0.55 micron can result in a 15-fold difference in the peak Ca2+ concentration. The amplification of peak Ca2+ concentration also depended on temporal summation of N-methyl-D-aspartate-mediated excitatory postsynaptic currents. Variation of the current duration on the order of 100 msec can significantly affect summation at a given stimulation frequency, resulting in a 10-fold difference in the peak Ca2+ concentration at 100 Hz. It is suggested that activity-dependent modifications of these parameters may be important for the regulation of synaptic plasticity in the brain.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=43698Documentos Relacionados
- Inhibition by Ca2+ of inositol trisphosphate-mediated Ca2+ liberation: a possible mechanism for oscillatory release of Ca2+.
- Critical intracellular Ca2+ concentration for all-or-none Ca2+ spiking in single smooth muscle cells.
- Latency correlates with period in a model for signal-induced Ca2+ oscillations based on Ca2(+)-induced Ca2+ release.
- Properties of intracellular Ca2+ waves generated by a model based on Ca(2+)-induced Ca2+ release.
- Structural model of a synthetic Ca2+ channel with bound Ca2+ ions and dihydropyridine ligand.