Last updated: 2020-07-10
Requirements
The requirements necessary for replacement brainstem functionality involve the following high-level elements.
Input
Status: Research Phase
Organic Model: the most critical function the brainstem provides is that of interface between brain and body. With the most notable exception of signals from the optic nerves, nearly all communication between brain and body utilize the brainstem in some manner.
Engineered Models: interfacing with a high enough resolution to neural connection points is necessary before an engineered solution can have an equivalent amount of information feedback provided by the host body. Insufficient data received would likely result in subsatisfactory communication between the brain and the body, which would produce a whole host of problems, most likely fatal. As the brainstem in an organic model is effectively a central router between brain and body, there isn’t much that can be done to circumvent the need for equivalent high-resolution, low-latency connections between all relevant neural connection points. The more said neural connection points are engineered solutions themselves, however, the easier this may be to achieve.
Processing
Status: Research Phase
Organic Model: in addition to its primary function as communication intermediary between brain and body, portions of the brainstem provide a wide variety of basic but critical functions that can generally be thought of as part of the broader set of “brain functions”. These can include functions as complex as memory consolidation.
Engineered Models: provided an adequate quality, quantity, and latency of data is available to an engineered brainstem, software could be used to calculate appropriate changes to be made in the various organs under its purview. Data quality defines the best possible quality of the calculations that could be made. Data quantity determines the confidence in the data received, and helps with error correction and addressing mitigating factors. The latency of the data received determines the lowest possible response time the engineered solution can provide in the face of changing conditions, and helps mitigate under- or over-correction of the various responses issued by the brainstem.
Output
Status: Research Phase
Organic Model: like with input, the brainstem’s most common outputs consist of neural signalling. However, as with the hypothalamus, some output can be made via chemical (hormonal) signalling.
Engineered Models: just as the case with input into an engineered solution, output has similar considerations. The most elegant solution would be to use the inherent signalling mechanisms within the body, that being primarily the brain itself and the spinal cord, among other things such as the cranial nerves which provide connectivity with the face and head, and production of chemical signals as with the case in the hypothalamus. However, doing so for the most part requires successfully overcoming the same technical challenges as per input: adequate signal quality, quantity, and latency. As with input, this may be made easier the more these other connection points are themselves engineered solutions.
Available Devices
Pacemakers
Pacemakers have been in use for some time now, and offer independent regulation of heart rate, separate from the brain, using implanted and external devices. As with the hypothalamus, the brainstem does participate in regulation of heart rate, and so this can be a viable commercial replacement for this function of the brainstem. These devices are generally thought to be reliable, are widely commercially available, and relatively affordable.
All other functions
In order to make viable functional replacement of the brainstem possible, significant advances must be made in the ability to individually interconnect with a large number of neurons, within a small space, and at high density. Given the location of the braintsem, this would best be done in-situ, however it may be possible to host the engineered solution externally to the body, if the size of or power requirements for the solution itself prohibit in-situ installation. The density of connections necessary between all the neural connection points to the engineered solution, however, does not appear to be realistically avoidable.
