In the study of fornix stimulation in AD patients, volume changes of fornix and mammillary bodies were highly correlated with hippocampal volume change after fornix stimulation, which strongly suggests the critical role of Papez circuit
in memory function regulation.
The aim of the present study was to investigate the impact of DBS at three separate targets in the Papez circuit, including the anterior nucleus of thalamus (ANT), the entorhinal cortex (EC), and the fornix (FX), on cognitive behaviors in an Alzheimer's disease (AD) rat model.
As a major pathway of the limbic system, the Papez circuit plays a vital role in memory formation and storage.
Moreover, because the DBS and sham DBS groups showed no differences in the latency during the training session of MWM, it could be assumed that DBS of the Papez circuit may have a limited effect on the acquisition of spatial learning.
Stimulation of parts of the Papez circuit has been known to prompt effects on fear and anxiety levels due to its interconnectedness with the amygdala.
Previous animal and clinical case studies have shown that DBS of the Papez circuit may enhance spatial memory by various mechanisms.
Although the present study did not reveal the molecular mechanism of DBS, our results indicate that the Papez circuit should be considered as a structural underpinning of DBS for AD.