TY - JOUR
T1 - Calcium-mediated spine stem restructuring
AU - Verzi, D. W.
AU - Baer, Steven
N1 - Funding Information:
*Author to whom all correspondence should be addressed. DWV was supported by NSF DBI-9602226: Research Training Grant--Nonlinear Dynamics in Biology, awarded to the University of California, Davis; and Faculty Grant-in-Aid 242122 from San Diego State University. SMB was supported by NSF DMS-9320597. The authors gratefully acknowledge M.B. Rheuben of Michigan State University for helpful discussions, and Armando Solorzano of El Centro, CA for graphics.
PY - 2005/7
Y1 - 2005/7
N2 - A spine is a protrusion from the dendritic (or somatic) surface of a neuron. In recent experiments, caffeine-induced calcium released from internal stores was shown to cause elongation of dendritic spine stems in slice cultures. Still another experiment indicates that glutamate-induced increases in calcium may cause spine stem shortening. Harris draws a schematic model to explain these seemingly conflicting results, indicating that a small amount of activity may increase free calcium within the spines and cause spine stem elongation, but an excessive amount of activity may increase intraspine calcium beyond a critical level and cause spine stem shortening (see [1, Figure 2]). This paper develops a mathematical model for a fixed population of spines along the dendrite, each with a dynamic structure and calcium level. The system is integrated over time and space to observe an interdependent relationship between calcium, morphology and chemical/electrical activity. Results of simulation qualitatively capture phenomena observed in recent experiments and exhibit periodic oscillations in potential when the spines have excitable membrane properties by allowing spine structure to transition through threshold geometries for generation of action potentials in a bidirectional manner. As in recent experiments, a variety of chemical and structural profiles emerge, depending on membrane properties, patterns of synaptic input, and initial conditions considered.
AB - A spine is a protrusion from the dendritic (or somatic) surface of a neuron. In recent experiments, caffeine-induced calcium released from internal stores was shown to cause elongation of dendritic spine stems in slice cultures. Still another experiment indicates that glutamate-induced increases in calcium may cause spine stem shortening. Harris draws a schematic model to explain these seemingly conflicting results, indicating that a small amount of activity may increase free calcium within the spines and cause spine stem elongation, but an excessive amount of activity may increase intraspine calcium beyond a critical level and cause spine stem shortening (see [1, Figure 2]). This paper develops a mathematical model for a fixed population of spines along the dendrite, each with a dynamic structure and calcium level. The system is integrated over time and space to observe an interdependent relationship between calcium, morphology and chemical/electrical activity. Results of simulation qualitatively capture phenomena observed in recent experiments and exhibit periodic oscillations in potential when the spines have excitable membrane properties by allowing spine structure to transition through threshold geometries for generation of action potentials in a bidirectional manner. As in recent experiments, a variety of chemical and structural profiles emerge, depending on membrane properties, patterns of synaptic input, and initial conditions considered.
KW - Dendritic spines
KW - Intraspine calcium
KW - Synapse restructuring
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U2 - 10.1016/j.mcm.2004.02.040
DO - 10.1016/j.mcm.2004.02.040
M3 - Article
AN - SCOPUS:26844552562
SN - 0895-7177
VL - 42
SP - 151
EP - 165
JO - Mathematical and Computer Modelling
JF - Mathematical and Computer Modelling
IS - 1-2
ER -