Transactions on Medical Electronics v15 n3 July-September 1971, pp.
An Invasive Approach to High-Bandwidth
Dexter Wyckoffprincipal scientist, Mimecom Seldon
Research Center, Sebastopol , California
Department of Psychology. University of California at San Francisco
Wrightcomputer systems engineer, Project One, Berkeley,
ABSTRACT In previous
years one of the authors (Wyckoff) reported on the development of synthetic
neurotransmitter analogs that, administered intravenously, enhanced certain
mental functions, including memory formation and recall, and ability to maintain
attention for extended periods.
Further efforts in that direction yeilded diminishing returns. In an offshoot
of this work, the authors investigated the possibility of augmenting mental
function by physically linking brain structures to external computer hardware.
After locating a suitable neural connection site (the mammalian corpus callosum)
we developed hardware and software for the task. This paper describes our
first unambiguously successful results, obtained in a juvenile squirrel monkey,
which was able, in consequence,
to play chess and to read at the level of a schoolchild, activities far outside
of its normal competence.
Our approach generalizes straightforwardly
to human augmentation, and points to the additional possibility of gradually migrating
memories, skills and personality encoded in fragile and bounded neural
hardware to faster, more capacious and communicative, and less mortal, external
digital machinery--thus preserving and expanding the essential functional of a
mind, even as the nervous system
in which it arose was lost. A mind and personality, as an information-bearing
pattern, might thus be freed from the limitations and risks of a particular physical
body, to travel over information channels and through the ether, to reside
in alternative physical hosts.
human central nervous systems (CNS) and electronic computation and communication
devices have been linked via the bodily senses and musculature--an approach
requiring only simple technology
and incurring little medical risk. Unfortunately this straightforward
avenue has very low information bandwidth: effectively a few kilohertz of sensory
information (primarily vision) into the CNS, and a mere one tenth of that
figure out. Much higher transfer rates are observed within the CNS. In particular,
the corpus callosum connects the right and left cerebral hemispheres
with 500 million fibers in the human. Each fiber signals on average at
about ten hertz, for an aggregate
rate of several gigahertz: about one million times the bandwidth of the senses.
The corpus callosum connects to all major cerebral areas, offering a spectacular
opportunity for electronic interaction. The primary challenges are the
invasive nature and massive scale of any comprehensive link. In other publications
we have described the design of "neural combs" which can be inserted non-destructively
into nerve bundles to make contact with a large fraction of the
fibers: they are scaled up relatives
of cochlear implants used in nerve-deafness surgery. This paper describes
experiments in which neural combs were implanted into the callosa of primates,
and connected to a computers running adaptive algorithms that modeled the measured
neural traffic and correlated it with sensory, motor and cognitive states,
and later impressed external information on this flow.
The animals (squirrel
monkeys) used in the experiments have a CNS size about one two hundredth
that of a human, with a corpus
callosum of less than ten thousand fibers, greatly simplifying both the surgical
and computational aspects of the work. In each experiment a neural comb with
two thousand microfiber tines at ten micron separation, each carrying along
its length one hundred separate connection rings, was carefully worked between
the axons in the callosum of the experimental animal. After a week to heal surgical
trauma, a cable bundle from the comb to a PDP-10 ten teraops multiprocessor
was activated, and signals from
the tines were processed by a factor-analysis program. Once a rough relational
map had been obtained, a functional map was constructed by presenting the
animal with controlled sensory stimuli, and inducing it to perform previously trained
motor tasks, while correlating comb activity. The functional map was further
refined by processing the responses to synthesized sensations introduced
via the comb. After several days of stimulation and analysis, the PDP-10 had a
sufficiently good model of the
callosal traffic that we were able to elicit very complex and specific behavior,
including some that seem quite beyond the capacities of the unaugmented animals.
most notable results were obtained with animal number three (#3),
out of five subjects. In one demonstration, we interfaced #3 to the Greenblatt
chess program, supplied with the PDP-10 software. We began by fast-training
#3 to discriminate individual chess pieces we presented. Fast-training is similar
to conventional operant conditioning,
but greatly accelerated because the responses we seek and the intense
rewards we generate involve fast, unambiguous, callosal signals, rather than
clumsy physical acts. We then configured the PDP-10 to reward the animal (by
generating callosal stimuli similar to those occurring naturally when tasty fruit
is seen) when it scanned the chess board each time its turn to move arose.
During the scan, the callosal recognition and location signals for the various
chess pieces are translated,
by a program module we wrote, into a chessboard configuration, which is fed to
the chess program, which returns a suitable move. Our program then stimulates
#3's food grasping behavior, directed at the piece to be moved: in consequence,
the animal avidly grasps it. Next, the target square is singled out for attention,
causing the piece to be moved there. The attractiveness of the piece is
then reduced and the animal loses interest, and releases it. It took several
intense weeks of effort to "debug"
this program. Among the problems we encountered were #3's inattention to
other pieces on the board: in early tries it would often incidentally upset them
when reaching for the piece to be moved. We now activate an aversion response
we had noticed in the mapping process: as best we can determine, #3 now feels
about a chess move as it would feel about a luscious fruit that must be gingerly
teased out of a thorn bush. Another problem was the animal's wandering interest
as it waited for its opponent
to move. We solved this by a mild invocation of its response to certain predators.
It now quietly but alertly, somewhat apprehensively, awaits the move,
drawing no attention to itself.
Another demonstration gave #3 more autonomy.
We fast-trained the animal to recognize individual letters of the alphabet,
and to scan strings of such letters it encountered. The letter strings were
fed to a dictionary look up program, whose output was then translated into appropriate
recognition signals for
the objects, events and actions in the text. #3 soon learned to respond the
labels of containers, and to choose those whose contents were of interest (usually
culinary). When the program is running, #3 also shows an interest in books,
and registers appropriate reactions such as appetite, excitement, fear, lust
and so on appropriate to the stories it reads. Stories about food and outdoor
adventures seem to be preferred: curious for an animal that was raised in an
indoor breeding colony, and has
spent the last five years in small laboratory cages.
In future work we
plan to expand the behavioral latitude available to our animal subjects while
executing programmed tasks, by writing richer programs more responsive to the
animal's internal imperatives, and also by providing means for the animal to invoke
major programs on its own initiative. These extensions are, of course, interesting
in the context of future applications to human interface.