Neural interlink frequency

The neural interlink frequencies were the interactive signals that formed the basis of the Borg collective consciousness. The signals were sent across a subspace domain in the lower subspace bands, in a similar fashion as the matter stream of a transporter. The frequencies interconnected the minds of all the drones in the Borg Collective. (TNG: "The Best of Both Worlds, Part II") They were generated by the vinculi aboard Borg vessels, and were received through each drone's interlink node.

In 2375, Seven of Nine detected a neural interlink frequency emitted by a vinculum infected with Species 6339's synthetic pathogen. The malfunctioning vinculum tapped into her cortical implant and caused dormant neural patterns of assimilated individuals to emerge, nearly killing her. (VOY: "Infinite Regress")

In 2376, when the Delta Flyer was captured by a Borg cube, the USS Voyager crew activated Harry Kim's combadge using a Borg interlink frequency to hide their carrier wave. (VOY: "Collective")

Later that year, the Borg Queen dismantled hundreds of drones with the mutation that allowed them access to Unimatrix Zero, so as to determine their interlink frequency. The Borg intended to release a nanovirus into Unimatrix Zero, destroying all the individuals within. To stop them, Captain Kathryn Janeway ordered The Doctor to disrupt the interlink frequency and permanently shut down Unimatrix Zero. (VOY: "Unimatrix Zero", "Unimatrix Zero, Part II")