The Journal of Neuroscience, April 15, 1999, 19(8):3183-3197
Sympathetic Neuronal Oscillators are Capable of Dynamic
Synchronization
Hong-Shiu
Chang,
Kevin
Staras,
Julia E.
Smith, and
Michael P.
Gilbey
Autonomic Neuroscience Institute, Department of Physiology, Royal
Free and University College Medical School, University College London,
London NW3 2PF, United Kingdom
In this paper we show that the discharges of sympathetic neurons
innervating an identified peripheral target are driven by multiple
oscillators that undergo dynamic synchronization when an entraining
force, central respiratory drive (CRD), is increased. Activity was
recorded from postganglionic sympathetic neurons (PGNs) innervating the
caudal ventral artery of the rat tail: (1) at the population level from
the ventral collector nerve (VCN); and (2) from pairs of single PGNs
recorded simultaneously using a focal recording technique. Autospectral
analysis of VCN activity revealed a more prominent rhythmical component
in the presence of CRD than in its absence, suggesting that (1)
multiple oscillators drive the discharges of PGNs and (2) these
oscillators can be entrained and therefore synchronized by CRD. This
interpretation was supported by analysis of the firing behavior of PGN
pairs. Autocorrelation and cross-correlation analysis showed that pairs were not synchronized in the absence of CRD but showed significant synchronization when CRD was enhanced. Time-evolving spectral analysis
and raster plots demonstrated that the temporal stability of PGN-to-PGN
and CRD-to-PGN interactions at a given level of CRD were also dynamic
in nature, with stable constant phase relationships predominating as
CRD was increased. This is the first reported example of dynamic
synchronization in populations of single postganglionic sympathetic
neurons, and we suggest that, as in sensory processing and motor
control, temporal pattern coding may also be an important feature of
neuronal discharges in sympathetic pathways.
Key words:
postganglionic sympathetic neuron; central respiratory
drive; neural oscillator; synchronization; entrainment; blood vessel; in vivo; Sprague Dawley rat
Copyright © 1999 Society for Neuroscience 0270-6474/99/1983183-15$05.00/0