Ubiquitous technological implant for connecting a sophont's brain to their exoself, the Net, equipment, and other beings.
The first commercial DNI system was invented in antiquity by medical start-up Biotronics Incorporated and the VR-entertainment megacorporation Inscape. This was the "Gibson neural jack" (named after the famous writer of cyberpunk). Incredibly exclusive the Neural jack could only be afforded by the rich and had to be implanted by specialist neurosurgeons. It was also very simple, offering little more than an Augmented Reality/Virtual Reality and sub-vocalisation interface. Despite these limitations the neural jack stimulated interest in the field, particularly as neurosoftware advanced and allowed DNI users to massively increase their productivity. Once self-inserting models were developed during the Nanotech Age their widespread adoption was all but assured, with only temporary halts during the Technocalypse and Amalgamation crises. Over the millennia, DNIs have advanced and been refined to near perfection (from a modosophont perspective at least), offering a plethora of capabilities and functions to their users.
DNI installation is one of the most common augmentive procedures in the Terragen Sphere (alongside medisystem infusion). There are many ways a sophont can have a DNI inserted depending on their requirements; some clades (particularly Biopolity superiors) have gone so far as to engineer biotech versions into their genome to benefit from the technology from birth. For all other bionts the three most common installation methods are:
In situ assembly: Technocyte spores are introduced into the body in the form of a nasal spray, small injection or consumable food or beverage. Following their programming, the technocytes migrate to the central nervous system (CNS) via the vascular system before carefully crossing the blood-brain barrier and distributing themselves to key locations, where they begin to replicate. As they do so they differentiate and organise themselves into complex fibrillar components. Different growths develop into different DNI components, eventually linking up into one connected system. This method is the simplest and most comfortable, but also the slowest, taking weeks or months to complete. Nefarious uses of this method include covert DNI installation on third-parties for bodyjacking, neural rewrites, and bindings.
Whole self-insertion: The key phyisical components of a DNI are embedded in a surgiconic delivery system. This unit is then applied to the head or neck of the user where it inserts millimeter-width tendrils through an available entry point in the skull (for baseline humans this includes the foramen magnum, ear canal, and optic nerve). The tendrils numb the nerves along their point of entry to remove discomfort as they penetrate into the CNS before implanting DNI components. This process can take a few hours after which the tendrils retract, plugging their entry passages with regenerative tissue scaffolds. After a few days to a week the components have sufficiently integrated with each other and the surrounding neural tissue to activate. It is very common for this method to be bundled along with the surgicons used in a medisystem implantation.
Docbox surgery: The fastest possible means of installing a DNI requires a docbox. After sedating the user, the autodoc performs several major craniotomies, removing sections of the skull for bulk access to the brain. Thousands of assembly and support fibers infiltrate the brain to rapidly build a complete DNI. To avoid fatal heat damage, the majority of support fibers pump coolant to maintain optimum temperature. After a few hours the surgery is complete and the sophont is woken up ready to use their DNI (operational tutorials are often installed as knowledge grafts during the procedure). Mild side effects and fine surgical scars fade in a few days as the user acclimatises and medicyte clusters perform final tissue remodelling.