Figure 6.

In the absence of cephalic inputs, a chain of DA-biased ganglia reveals uncoordinated and unstable DE-3 bursting, but a single ganglion isolated from this chain transitions to stable and robust fictive crawling. A, Schematic of a chain of 5 ganglia (M8–M12) (left) and motor activity recorded from DP nerves 8, 10, and 12 (right). Recordings revealed the lack of robust rhythmic DE-3 bursting and showed an inappropriate metachronal wave of intersegmental DE-3 activity. B, Left, Schematic showing the physical isolation of one ganglion (M8) from the chain. Right, DP nerve activity from the same preparation as in A 4.7 min after transecting the M8–M9 connectives. DE-3 bursting in the isolated ganglion became more robust and burst structure solidified; unstable bursting activity in DP(10) continued. C, DP recordings 8 min after transection showing the emergence of robust fictive crawling [DP(8)] with stable shorter crawl periods (top trace). DE-3 bursting in the other two ganglia was absent (middle and bottom traces).