Figure 8.

Crawl-like drive from an individual crawl oscillator extends to multiple posterior ganglia; signals can be carried via fibers of passage spanning two ganglia away from their source. A, C, D, Left, Schematic drawings indicating site of DA placement (shaded well; 100 μm DA) and specific ganglia recorded. Shaded recording traces correspond only to those ganglia treated with DA. A, Fictive crawling in the DA-treated ganglion (top trace) and crawl-like activity driven in untreated ganglia up to two segments away (middle and bottom traces). B, Percentage of preparations exhibiting DE-3 bursting in response to DA on a given single ganglion (G/DA); drive extended up to 3 segments away (G/+3). Numbers inside bars denote sample sizes. C, Ganglia showing tonic DE-3 activity across 3 segments [DP(9, 10, 11)] before treatment. D, DP recordings from the same preparation as in C after DA-activated fictive crawling was induced (top trace) but chemical synaptic transmission was blocked in the adjacent posterior ganglion (middle trace). Box (left) surrounding ganglion M10 (↑Mg²⁺/↓Ca²⁺) indicates procedure that resulted in no unit activity in DP(10) (middle trace). As shown in the DP(11) recording (bottom trace), DE-3 bursting was present, although weak, thus indicating that some crawl-like drive extended past this silenced ganglion.