that variance comes from. A model of a thalamo-cortical network depicted in Fig 7B could explain another interesting observation in regard of theta input i.e. controlling for PFC suppressed nRE-HC theta correlation (Fig. 5E). Third, we have only found significant PFC-HC theta correlation in half of the experiment and in these rats HC-nRE theta correlation was smaller than in the general population (cf. Figs. 4E and 5A). In fact, a greater number of rats showed theta correlations in HC-nRE and nRE-PFC pairs than PFC-HC (Fig. 4D). This might suggest that HC theta may be directed either through the HC-PFC pathway or through the nRE link toward PFC. These alternatives appeared in individual rats under urethane but may represent alternative ways of functional coupling associated with different behaviors that could be explored in future experiments in freely moving rats.
