Sensory node

From Memory Alpha, the free Star Trek reference

A sensory node is a cybernetic device implanted within each Borg drone, that mediates a drone's sensory perceptions. The sensory node is connected to both the ocular node and the cortical node, located within the Borg cortical array. (VOY: "Equinox, Part II")

In 2374, the Doctor adjusted Seven of Nine's sensory nodes to a phase variance of 0.15, allowing her to perceive the cloaked Srivani that had infiltrated USS Voyager. (VOY: "Scientific Method")

Later that year, the Doctor speculated that subnucleonic radiation from a Mutara-class nebula could be altering neurotransmitter levels in Seven of Nine's sensory nodes, causing hallucinations. (VOY: "One")

In 2376, the Doctor was reprogrammed by the renegrade crew of the USS Equinox to perform an invasive surgical procedure and remove Seven of Nine's cortical array. (VOY: "Equinox, Part II") As he did so, he sang:

The ocular node's connected to the...sensory node,

The sensory node's connected to the...cortical node,

The cortical node's connected to the...reticular node...