SYNCHRONOUS INHERENT OSCILLATIONS OF POTENTIALS WITHIN THE RAT LUMBARSPINAL-CORD

Dorsal root potentials (DRPs) and dorsal cord potentials (DCPs) were r ecorded from the lumbar spinal cord in anaesthetised rats. With the sp inal cord intact, low-voltage low-frequency spontaneous DRPs were reco rded in synchrony on all lumbar dorsal roots. When the cord was cut at T12, spontaneous large-voltage approximately 10 Hz DRPs appeared imme diately in synchrony on all dorsal roots. Section of the dorsolateral funiculus (DLF) was necessary to release these 10 Hz waves. They persi sted unchanged for at least 2 h and were not affected by section of al l lumbar, sacral and coccygeal dorsal roots. Selective transverse lesi ons were made to locate the fibres responsible for the synchrony of th e oscillations of DRPs recorded on L1 and L6 dorsal roots; Synchrony w as maintained with lesions of the entire cord medial to the Lissauer t ract but disappeared when the lesion was extended to include the Lissa uer tract. We conclude that the isolated cord contains a synchronous o scillatory mechanism inhibited by impulses descending in the DLF and s ynchronised by way of intrinsic axons in the Lissauer tract. Copyright (C) 1996 Elsevier Science Ireland Ltd.