A. Porta et al., CLASSIFICATION OF COUPLING PATTERNS AMONG SPONTANEOUS RHYTHMS AND VENTILATION IN THE SYMPATHETIC DISCHARGE OF DECEREBRATE CATS, Biological cybernetics, 75(2), 1996, pp. 163-172
The spontaneous low- and high-frequency rhythms in the sympathetic dis
charge of decerebrate artificially ventilated cats are affected by ext
ernal ventilation, Two graphical methods (i.e. the space-time separati
on plot and the frequency tracking locus) are used to classify the non
-linear interactions. The observed behaviours in the sympathetic disch
arge consist of phase-locked periodic dynamics (at various frequency r
atios with ventilation), quasiperiodic and aperiodic patterns. They de
pend on the experimental condition. In control condition the sympathet
ic discharge appears more frequently locked to each ventilatory cycle
(1:1 dynamics). However, some cases of quasiperiodic dynamics are foun
d. A sympathetic activation stimulus, such as inferior vena cava occlu
sion, is able to synchronise slow rhythms in the sympathetic discharge
to a subharmonic of ventilation. During a sympathetic inhibition stim
ulus, such as aortic constriction, 1:1 dynamics is detected but the am
plitude of the sympathetic responses can be modulated by unlocked slow
rhythms. Moreover, some cases of aperiodic dynamics are observed. Vag
otomy reduces the 1:1 coupling between sympathetic outflow and ventila
tion. Vagotomy plus spinalisation disrupts periodic dynamics in the sy
mpathetic discharge so that irregular and complex patterns are found.