In vivo activation of channelrhodopsin-2 used to determine the role of spontaneous neural activity in axonal guidance

Chapter 1.General introduction I. Axonal guidance and signaling of motoneurons A. Spinal motoneuron specification and axonal projections B. Active guidance and outgrowth along permissive pathways a. Axonal pathfinding b.PSA on NCAM c. Ephrins and their receptors II.Electrical activity and its role during development A. Bursting activity in the vertebrate spinal cord B. Developmental switch in GABA and glycine signaling C. Calcium Signaling III.Slight alterations in the frequency of bursting activity result in pathfinding errors 5 IV.Channelrhodopsin-2 V. Overview of results Chapter 2. In vivo activation of channelrhodopsin-2 reveals that normal patterns of spontaneous activity are required for motoneuron guidance and maintenance of guidance molecules Summary maintained the expression levels of EphA4, EphB1 and polysialic acid on NCAM, three molecules previously shown to be necessary for this pathfinding decision.These observations demonstrate that precise frequency and pattern of spontaneous activity are necessary for proper development of spinal motor circuits, and that any drugs that alter this activity could result in developmental defects.