Figure 2.

Effect of isotonic sucrose blockade of thoracic cord segments on cervical and lumbar locomotor rhythmicity. A, Left, Schematic of experimental procedure. Middle, Raw extracellular and integrated activity from cervical (bilateral C8) and lumbar (bilateral L2) ventral roots during 5-HT/NMA/DA-induced fictive locomotion. Right, Respective autocorrelograms of rectified data recorded from right C8 and right L2 ventral roots and cross-correlation between homolateral C8 and L2 activity showing an in-phase relationship (indicated by a positive cross-correlation coefficient at lag 0) in control conditions. Correlograms were computed from 120 to 190 s of activity and are superimposed with 95% (±2 SEM) confidence intervals (dashed lines). B, Loss of rostrocaudal coordination after sucrose block of thoracic segments (schematic to the left). Same presentation as in A. Note that, despite decoupling (indicated by near flat cross-correlogram), both cervical and lumbar generators continued to operate at regular (see autocorrelograms) and similar (see Fig. 3A) frequencies. C, Recovery of control in-phase anteroposterior coordination after removal of sucrose blockade. C, Cervical ventral root; L, lumbar ventral root.