Biophysics of Biochemical Signaling in Dendritic Spines: Implications in Synaptic Plasticity

Abstract

Dendritic spines are mushroom-shaped postsynaptic compartments that host biochemical signal cascades important for synaptic plasticity and, ultimately, learning and memory. Signaling events in spines involve a signaling network composed of hundreds of signaling proteins interacting with each other extensively. Synaptic plasticity is typically induced by Ca²⁺ elevation in spines, which activates a variety of signaling pathways. This leads to changes in the actin cytoskeleton and membrane dynamics, which in turn causes structural and functional changes of the spine. Recent studies have demonstrated that the activities of these proteins have a variety of spatiotemporal patterns, which orchestrate signaling activity in different subcellular compartments at different timescales. The diffusion and the decay kinetics of signaling molecules play important roles in determining the degree of their spatial spreading, and thereby the degree of the spine specificity of the signaling pathway.

Figure 1

Illustration of signal spreading in response to stimulation of a single dendritic spine. Red: signaling restricted to the stimulated spine. Orange: signaling that spreads over a short stretch of dendritic segments (5–15 μm). Cyan: signaling that spreads over a longer distance. Dark blue: signaling that spreads into the nucleus. The area near the stimulated spines is magnified.