Neurotransmitter activation of second messenger pathways for the control of growth cone behaviors

The generation and regeneration of neuronal form and connectivity both undoubtedly rely upon the integration of intrinsic and extrinsic information of many kinds. Our work has demonstrated that the concentration and spatial distribution of intracellular calcium is a key locus of integration of such information. Through a delicate balance of mechanisms that raise free calcium and mechanisms that lower free calcium, a steady state level is achieved that appears to have significant regulatory control over neuronal growth cone behavior. Cues, both internal and external, alter intracellular calcium levels, and consequently alter growth cone behavior. It is through the alteration of the various components of calcium homeostasis that we envision the complexities of neuronal architecture and connectivity may be fine-tuned throughout the life histories of neuronal ensembles.