Figure 1
From: Analysis of input-output relationships of CPG elements and their contributions to rhythmic output
Circuit diagrams and rhythmic motor output from the leech heartbeat central pattern generator (A) and the crayfish swimmeret system (B). A, left: Heart (HE) motor neurons in segments 8 and 12 both receive synaptic input from premotor hear (HN) interneurons located in segments 3,4,6 and 7, which sculpt stereotyped motor output as shown in the simultaneous extracellular recordings of HE motor neurons in segments 8 and 12, which illustrate the peristaltic motor phase progression (right panel). B, left: circuit diagram for the independent oscillator in segment 4 (A4) driving PS4 motor activity observed in the extracellular recordings (right panel; Return stroke [RS(4)] activity not shown). Coordinating interneurons ASC and DSC in A4 encode information that is delivered to an interneuron (C1) in segments 3 (ASC) and 5 (DSC), resulting in the stereotyped rear-to-front activity pattern observed across segments 5,4 and 3 (right panel).