The findings described above, which show that CFC can be entrained to behavioral events and dynamically and independently modulated in multiple task-relevant areas, support the claim that phase-amplitude CFC has a functional role but does not provide a clear and unambiguous link to performance. Such a link is provided by a recent study showing a strong correlation of CFC strength to performance in a learning task [39]. In this learning task the strength of hippocampal CFC increased over time as the rodent improved performance, with CFC strength and task performance both reaching a plateau (Figure 4). Early in the training phase, however, both CFC strength and task performance are low, suggesting that CFC is not simply an epiphenomenon occurring independent of behavior. In fact, phase-amplitude CFC strength appears to be the most predictive neurophysiological marker of learning yet found, and promises to be a valuable tool for future experimentalists.
