The SINTN seminar series proudly presents

R. Douglas Fields

Plasticity beyond the Synapse: Action Potentials and Myelination in Activity-Dependent Plasticity and Development

R. Douglas Fields
Chief, Nervous System Development and Plasticity Section
National Institutes of Health, NICHD

Website: Fields lab Web Site

Abstract:

Nervous system development and plasticity are regulated by functional activity arising during fetal development and by environmental experience in postnatal life. At a cellular level the mechanisms regulating synaptic transmission are the focus of research on learning and activity-dependent development, but we and others have begun broadening the scope of investigation to consider the out-put of neurons, action potentials, and glia located outside synaptic regions. The coincidence of action potential firing in the postsynaptic neuron with respect to activation of synaptic input is critical in regulating synaptic plasticity. Thus, the conduction velocity of impulse propagation in axons is an important factor in information processing and plasticity. Since the myelin sheath on axons formed by oligodendrocytes can increase conduction velocity 100 times, activity-dependent regulation of myelination could contribute to nervous system development and plasticity by modulating the speed and synchrony of impulse conduction through neural circuits to affect information processing and cognitive function/dysfunction. Our research shows that myelination can be regulated by impulse activity through several different mechanisms of axon-glial signaling, including the non-vesicular release of neurotransmitter from axons. Single photon imaging, in combination with other imaging methods, shows that neurotransmitter can be released from axons through volume regulated channels that are activated in response to action potential firing. Similarly, impulse activity can regulate development of astrocytes in developing hippocampus. Homeostatic synaptic plasticity in developing neural circuits is regulated in part through activity-dependent regulation of gene transcription and post-transcriptional control of microRNAs that suppress translation or promote degradation of synapse-associated mRNAs. Together these processes driven by action potential activity and operating beyond the synapse contribute to nervous system development, learning, and response to disease.

Download Calender Event