The synchronization matrices in Figure 2B illustrate how the degree of synchrony generally decreases with increasing distance between recordings sites, even within the same anatomical region, which is in accordance with earlier findings (Bullock et al., 1995a). To compare intra- and inter-regional synchrony, we therefore restricted the statistical analysis to the two most posterior entorhinal and the two most anterior hippocampal contacts, yielding from anterior to posterior three overlapping pairs of adjacent recording sites within the entorhinal cortex (EC–EC), on both sides of the entorhinal-hippocampal border (EC–Hi), and within the hippocampus (Hi–Hi), respectively (cf. Figure 2A). Synchrony values were thus calculated from contacts spaced at a constant distance.
