Neural transceiver

A neural transceiver was a device capable of granting access to an individual's brain. Implanted in the upper spinal column, this technology was utilized heavily by the Borg as the primary means of maintaining the neural link between an individual drone and the rest of the Collective. 

In 2371, in order to re-integrate Commander Chakotay's consciousness after his neural energy had been displaced by an alien weapon, The Doctor, EMH of the USS Voyager, utilized three neural transceivers, two cortical stimulators, and fifty gigaquads of computer memory, in a process which he described as "a remarkable procedure." 

In 2374, the group of former Borg drones known as "the Cooperative" attached a small neural transceiver to the base of Chakotay's skull, in order to allow him to receive a transfusion of neuro-electric energy with which to heal serious injuries he had sustained as a result of being fired upon with a particle weapon. Later that year, the Borg Collective attempted to perform the same procedure to Captain Janeway and Lieutenant Commander Tuvok, in order to maximize efficiency in developing a plan to combat Species 8472. Janeway and Tuvok refused to be linked, however, and instead chose to deal with a single representative of the Collective: Seven of Nine. After that task was complete, Seven attempted to take control of Voyager and return it to the Collective, but was stopped when Chakotay, utilizing a neural transceiver, established a neural link with Seven, distracting her long enough for the Voyager crew to initiate a power surge and disable Seven. After deciding to retain Seven as a crewmember aboard Voyager, Janeway ordered her neural transceiver neutralized, to preclude the possibility of her contacting the Collective. 

In 2375, a spaceborne lifeform known as a "telepathic pitcher plant" influenced the Voyager crew to attempt to deactivate Seven's implants, including her neural transceiver, by causing the crew to believe that a supposed wormhole they were approaching passed through a layer of subspace monitored by the Borg. Seven, realizing that the crew was being manipulated, managed to avoid deactivation and save the ship from being consumed by the lifeform. 

That same year, the Borg Queen accessed Seven's transceiver to deliver an ultimatum, whereby Seven would hand herself over to the Collective in exchange for sparing Voyager from assimilation. 

Later that year, the Voyager crew utilized Seven's transceiver to send an interference signal to the vessel belonging to the group known as "the Think Tank." This had the effect of disrupting the technology the group used to communicate telepathically, negating the advantage they held over Voyager. 

In 2376, Seven adapted a neural transceiver to interface with a portable regenerator, which would have allowed Icheb, a former drone liberated from the Collective by the Voyager crew, to regenerate while staying with his parents on the Brunali homeworld.