This study shows that the precise spike timing of motoneurons controlling a feeding muscle of Aplysia has strong effect on its contraction. This is surprising because that muscle is a slow muscle that contracts over seconds, but adding or removing just one spike has a very strong and immediate effect on contraction, as shown in this figure (Fig. 1C):

The muscle is controlled by just two neurons, so it is a nice model system. The authors also show that natural spike patterns are irregular, but the neuromuscular transform is deterministic, which means that shifting spikes has a reproducible effect on the pattern of contraction, which is not just a temporal shift but also a strong change in amplitude, due to nonlinear effects. The result is that natural patterns produce twice more contraction than regular patterns of the same rate. In addition, these irregular patterns appear to be synchronized across the two sides of the animal, producing synchronized contractions. This is very convincing and supportive of spike-based theories of neural function (Brette 2015).