We have located the source of the Borg neural interlink frequency in the debris field.
seven_of_nine has confirmed that this unit is a Borg vinculum, the processing device at the core of every Borg vessel. It interconnects the minds of all the drones as well as purges individual thoughts and disseminates information relevant to the Collective. We believe this vinculum has for some reason identified Seven as an 'errant drone' and has established a link with her; as the vinculum is malfunctioning for some reason, the effect instead is to disrupt Seven's cortical implant by sending her erratic commands. Hence her suffering from the Borg equivalent of multiple personality disorder, as
emh put it.
That's the good news. The bad news is we are unable to disable the vinculum remotely, as that would take several days, increasing the risk that the Collective will send more vessels to this area. Seven cannot sever the link on her own; our only alternative is to beam the device aboard and disable it manually. (Outright destruction of the device is not an option either; it is in our best interest to discover how and why it began to malfunction. Additionally, there is no telling what effect its destruction will have on Seven while it is linked with her).
It's not an alternative I like, but I appear to have no choice. Based on bizarre log entries, as well as other incidents that have occurred on Voyager (like the 'Midnight Snacker' or
naomiwildman's 'playdate' with Seven), Seven started showing effects of the vinculum long before we came into close physical proximity with the debris field, and will certainly continue to be affected for some time, even as we put as much distance between it and ourselves as possible. The Doctor believes he has stabilized her condition, for now, with an inhibitor, but he admits he does not know how long it is going to last. Seven continues to be at risk for even more neural patterns manifesting, aside from the ones we have already discovered. So we're bringing the vinculum on board, but I've made it very clear to Tuvok that at the first sign of trouble we're going to beam that thing back in space. Who knows what it can do to the rest of our crew, or the ship's systems? As I told Seven, we haven't had the best of luck with the Borg.