Markerless recurrence analysis of gastric electrophysiology during vagus nerve stimulation.

Objective: Gastric bioelectrical slow waves exhibit complex, temporally dynamic patterns affected by various regulatory inputs and stimulation protocols. This paper uses recurrence analysis to determine the re-occurrence of activity patterns in gastric slow waves measured using high-resolution electrode mapping arrays.

Methods: Experimental data were obtained from the ventral gastric serosa of five rats, and three different electrical vagus nerve stimulation protocols were administered repeatedly to induce changes in slow wave activity. Data were sinusoidally recomposed, and phase-portraits were embedded to generate recurrence plots. Recurrence rate (RR) and average diagonal line length (L) were calculated.

Results: During stimulation the periodicity and stability of slow wave activity decreased (RR: p = 0.0010; L: p = 0. 0085). The patterns of slow wave activity were stable and periodic both before and after stimulation in all subjects but exhibited different spatiotemporal propagation patterns. Using a mixed linear model, it was determined that the periodicity (RR: 0.095 ± 0.063 vs 0.062 ± 0.039) and stability (L: 6.13 ± 3.52 vs 4.18 ± 1.59) of activity during periods with the same nerve stimulation protocol was greater than when different protocols were applied.

Conclusion: Recurrence analysis is a useful tool for determining the consistency of slow wave activity over time. Repeated applications of the same nerve stimulation protocols resulted in consistent spatiotemporal perturbations that were more similar than when different stimulation protocols were applied.

Significance: Recurrence analysis can be used to distinguish long-term changes in slow wave activity. Future applications could establish how nerve stimulation augments natural variation in slow wave activity.