A Bi-Directional Interface Between the Human Nervous System and the Internet
K. Warwick, P. Kyberd, M. Gasson, B. Hutt and I. Goodhew
Department of Cybernetics, University of Reading, UK.
Abstract
This paper describes an investigation into the use of implant technology in forming a bidirectional link between the human nervous system and a computer. The microelectrodeimplant and the required neurosurgery are described in detail. Various application
studies are described, including interaction with an articulated robot hand, a group ofautonomous mobile robots and extra sensory (ultrasonic) signal inputs to the humannervous system. Conclusions are drawn, as a result of the study, as to the long term
implant possibilities and future capabilities of those fitted with implants.
Introduction
Interaction between humans and computers is almost exclusively brought about by meansof signals external to the human body [1], despite the fact that this causes time delays,
errors and communication problems. The range of interaction tools is broad, including
keyboard, joystick, voice activation and visual stimuli. In each case different translationand timing problems occur. The main problem is that electro-chemical signals on thehuman nervous system need to be translated into some form of mechanical or lightenergy before being converted back into electrical energy in the computer. The same andother problems are also encountered when signals are transmitted in the reverse direction
from computer to human.
Substantial research is now ongoing in which biological signals are collected in a more
direct way [2]. Unfortunately, because signals are measured externally to the human
body, errors are induced because of the necessary energy transformations, overall neuralsignal averaging and the indirect nature of the measurements taken [3].
One line of present research involves the development of, what are described as,
wearable computers [4]. These devices range from kitting out everyday implements suchas shoes and jewellery with microcomputers, to directly monitoring indications of stressand alertness, and even to fitting a pair of glasses with a mini-television, allowing thewearer a remote televisual input. In reality all of these devices are far removed from thediscussion in this paper, in that they are positioned externally to the human body, they
operate on signals monitored on the outside of the body and returning signals need to beconverted by the normal/usual human senses.
In order to investigate the practicalities of a more direct interface with computers, various
animal studies have been carried out. Of relevance is the use of an extracted lamprey

1brain to control the movement of a small robot vehicle [5]. The lamprey is appears, has
an innate response to light, which helps it to navigate in water, in particular to stay theright way up. This innate feature has been used to control the robot such that it always
moves in the direction of a bright light source. Although it does function well, the trial ismore a case of proving a point, as; unfortunately, the isolated lamprey brain only has alimited life span of, at most a few hours or so.
Research employing rats is also relevant and has been ongoing for some time. John
Chapin chronically implanted electrodes into the motor cortex of rat’s brains [6] in orderto decode neuronal activity immediately prior to a lever pulling exercise that the rates
were trained for. Signals were processed, via the implant, before the rates actually pulled
the lever and a reward was instantly given. Several of the rates learnt that they no longer
had to actually pull the lever, but merely thinking about the action was sufficient toobtain the reward.
Of particular relevance to this article however, is the research of Philip Kennedy [7]whereby he enabled a brainstem stroke victim to control the movement of a cursor on acomputer screen. Functional MRI scans were taken to decide on the best positioning forthe electrode, since the patient had been asked to think about moving his hand. The
electrode, which was positioned where neuronal activity was most pronounced, consistedof a hollow glass cone containing two gold wires. Meanwhile positioned on the outsideof the patient’s head was an amplifier and radio transmitter. Subsequently, when thepatient thought about moving his hand, so associated signals were transmitted to thecomputer to cause the cursor to move around, thereby enabling a basic form ofcommunication.
Whilst it is certainly true that much work has also gone in to implant technology for suchas retina and cochlea implants, it is felt that, although there may be some concepts to belearned from, in general the links with this study are not strong. Essentially we wish toinvestigate here an adaptable bi-directional link involving the computer. Such“replacement” implants do not exhibit such characteristics.
With the background of other research as described here, the main aim of the research
discussed in this paper, was to form an operational adaptive bi-directional link between
the human nervous system and a computer. To this end the first named author (KW)
volunteered to receive an implant in his median nerve, the main group of nerve fibres
running from the brain to the hand area. Details of the implant itself, and the operation,
will now be given.
Microelectrode Implant
An array of one hundred individual needle electrodes was fired into the median nerve inthe left arm of KW, just below the wrist, on March 14, 2002, at the Radcliffe Infirmary,
Oxford, UK. The array measured 4mm x 4 mm with each of the, uniform length, pins
being 1.55mm. The median nerve fascicle was approx 4 mm in diameter, hence the pins,
when inserted, extended approx 40% of the way into the fascicle.

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One incision, extending for 4 cm proximally, was made just below the wrist, with asecond incision, extending for 2 cm, positioned centrally, 16 cm proximal to the wrist.
An open tube was passed between the incisions, following a tunnelling procedure. The
array, with associated wires, was then passed down the tube from the second incision to
the first. Subsequently the tube was removed, leaving the array adjacent to the median
nerve, with wires running subcutaneously up the arm, exiting at the second incision
where they linked to an external electrical connector pad. The array was pneumaticallyinserted into the radial side of the median nerve bundle.
Bi-directional Signalling
By finger movements, neural signals, associated with the muscle contraction, could be
generated and either passed directly to the computer, via an interface unit, or by means ofa digital radio link, positioned on a gauntlet arrangement work externally [8]. By
monitoring and processing these signals, in conjunction with a proportional-in-time
controller, the movement, in terms of the associated neural signals, could be used tocontrol a number of real-world devices.
A constant current stimulator was employed to stimulate the subpopulation of axons
affected by the electrodes. Charge balanced, bi-phasic rectangular pulses of 200 usec
duration were found to be best suited in allowing KW a stimulated sensation, hence
enabling feedback from external mechanisms. Currents of below 80 uA in magnitude
were seen to produce little effect, however at that current magnitude many of theelectrodes produced a recordable effect.
Stimulation of this nature was first attempted six weeks after implantation. With thestimulation applied randomly, initial trials produced a correct identification over therange 68-73% of the time. Over the period of experimentation this response gradually
improved. Final test, of the same nature, were carried out immediately prior to extractionof the implant, on June 18th 2002. At this time correct identification over the range 9398% was witnessed. This indicates that KW’s brain gradually learned to recognise theinjected current signals more clearly.
Articulated Hand
Prosthetic hands are conventionally controlled by means of visual feedback to theoperator, with an analogue input channel supplying a control signal to the hand generated
from the electromyograms (EMGs) from forearm muscles. It is usual for them to be
direct controlled in both opening and closing, hence ‘Voluntary Opening Voluntary
Closing’ (VOVC). Essentially, if the user can see the articulated hand’s actions and they
can generate the appropriate muscular commands, they can operate a hand effectively.
However without any internal intelligence or if the target object is obscured they may
continue to close until the motor stalls, thus the prostheses cannot be easily controlledwith finesse.

3Natural hands are controlled in a hierarchical manner. Low levels of the central nervous
system perform closed-loop control of individual fingers. Above this there is acoordinated action between the gripping force and the hand posture, minimising the grip
force by maximising the contact area between the hand and the object. On a higher level
still are the decision and planning areas of the brain, which deal with grasping strategy
and use of the held object. The low level control is learnt in infancy.
Because subtle control of a conventional prosthetic hand often necessitates visualfeedback it is hard to be controlled with the same low conscious effort and dexterity as anatural hand. In general they only have two motions (opening and closing), and one
posture (precision grip) and hence exhibit a limited prehensile range. In comparison thetype of articulated hand employed in this study has multiple degrees of freedom and canbe controlled in a hierarchical manner, the aim of which is to mimic the control
mechanisms apparent in a human hand. The prosthesis is currently undergoing clinicalassessment in Oxfordshire, UK [9].
Using the articulated hand described, referred to as the SNAVE hand, allowed formeasurements to be taken from force and slip sensors in the fingers. Further, the grip
shape could be altered, as could the force applied to an object.
In the studies carried out, the SNAVE hand opening and closing movements weredirectly controlled from the neural signals of KW’s own hand. So as KW opened andclosed his own hand, the SNAVE hand mimicked movements in response to the neuralsignals being fed to it.
Following this, the objective was set to grasp an object, using the SNAVE hand, by using
the lightest possible touch, without any visual feedback, whilst wearing a blindfold. As
KW applied more force to an object, which could be detected via the hand fingertips, so
this information was fed back through an increased amount of neural stimulation. Hence
if the hand was applying the lightest possible touch, almost no neural stimulation wasenacted.
After only 6 hours of learning to grip an object in this fashion, KW was able to achieve
considerable success. Over the next 12 days of testing KW’s ability to judge theappropriate force to apply improved more when both visual and force feedback wereavailable, than with either feedback alone [10].
On May 20th, 2002, KW was situated in a laboratory in the Department of Computer
Science, Columbia University, New York City. A link was established, by means of theInternet, between the implant and the SNAVE hand, still located at the University ofReading, UK. Processed signals from the neural implant were transmitted across theInternet to control the remote hand. Stimulation feedback was also provided, via theInternet, back to the implant. Allowing for the time delay present, due to the Internet,
KW was able to operate the hand in a respectable fashion.

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Autonomous Robots
In a separate study. Whilst the implant was in place, a small group of mobile,
autonomous robots were controlled, in terms of their general ‘mood’, by means of signals
from KW’s neural implant.
The robots permanently receive power from electrified strips in their flooring, via a set ofelectrical pick-up brushes. They are able to move around in their corralled environmentby means of two separately excited, differentially driven rear mounted wheels, balanced
at the front by a castor wheel.
Each robot contains ultrasonic range finders, which the robot uses to detect its distancefrom any solid object. The robots all also contain a circular array of infrared transmittersand receivers, which they use to find out the vicinity and identity of any other robots.
The robots can communicate with each other by radio, and also to/from a PC/Base station.
This station was also linked to the output from the implanted array.
The robots have a range of behaviours. At the bottom level is power seeking, thenobstacle avoidance. At the next level is flocking or, its opposite, evasion, which meansthat the robots move away from each other as rapidly as possible.
Neural signals were taken from the implant to control the higher-level behaviour of therobots. Hence, by generating neural signals, KW was able to cause the robots to either
flock together or evade each other. This example was taken to indicate how the sameneural signals could be used to control the behaviour or response of a domestic robot interms of its actions.
Extra Sensory Output
Ultrasonic sensors, identical to those employed by the autonomous robots, were fitted toa baseball cap work by KW. The output from the sensors was, in this case, fed down to
the neural implant, via the interface unit such that if objects were located in the vicinityof the sensors, so the rate of current injection onto the nervous system was increased. As
an object moved away from the sensors, so the rate of current injection decreased. The
stimulation procedure was therefore similar to that used for force feedback signallingfrom the articulated hand.
With only a few minutes practice, wearing a blindfold along with the ‘ultrasonic baseballcap’, KW was able to successfully differentiate the distance of different objects, to thedelimitation of the ultrasonic sensors themselves. In short while he was able to movearound the laboratory and detect objects in doing so, with his new ultrasonic sense. It is
felt that this sense could immediately be used, as a replacement, for blind people, but as
an extra sense for others.

5Other Applications
Other applications implemented using the array are presented in [11, 12]. In addition
To the straightforward medical applications, however, one important issue is the use of
implants on people who have no medical need, in order to enhance or augment theirperceptual abilities. For example, the interface to the user employed an active ultrasonicsensor. A 40 KHz signal was broadcast from transducers worn on the head the reflectedsignal was detected and that was used to trigger a stimulation signal at the array, thefrequency of the signal being proportional to the proximity of an object. This allows aform of ultrasonic vision to be applied. The same technique could be employed toestablish and alternative sensor of vision to ameliorate visual impairment rather than torestore sight. It has some advantages over other remote ultrasonic sensors based onconverting the ultrasound to audible sound [24] as the audible interfaces occupy a sensethat the person is able to use effectively without a device, potentially actually reducing
their capabilities. The implant would allow input channels unavailable or unoccupied tobe employed fully.
One of the key aspects of the project was however to see how the implant might be usefulfor those who have a disordered nerve function, for example [taken from 11]:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.

Re-education of the brain and spinal cord
Prevention of spinal deformity
Treatment of intractable neurogenic and other pain
Assisting bladder emptying
Improving bowel function
Treatment of spasticity
Improvement of respiratory function
Redirection of cardiovascular maleffectPrevention of pressure sores through sensory feedback
Improvement/restoration of sexual function
Improved mobility
Improvement in activities of daily living

In addition, via the bi-directional radio link, it was possible for the user to switch onlights and other general household appliances, directly from translated neural signals.
General control of a local/household environment for those with mobility impairment,such as the elderly and/or disabled can also be seen as possible application.
Conclusions
It is quite possible to make direct connection with the human nervous system, to control
technology directly from neural signals and to feedback signals onto the nervous system,
which relate directly to external, real world artefacts. Passing these signals across theInternet implies that the implanted individual’s nervous system extends, across theInternet, outside their regular body. Controlling an articulated hand directly from neuralsignals, 3,500 miles away, across the Internet was testimony to that.

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Although ultrasonic signals were successfully employed as an extra sense, this opens up
the possibility of a wide range of different senses for humans, including infrared and xrays. These will provide an exciting range of experiments in the years ahead.
One down side with the implant experiments carried out was mechanical fatigue in theimplant connecting wires. Whilst the array itself, lasted well, the connecting wires
gradually became open-circuit at their point of exit from the body. It is felt that when afull implant is employed this problem ill either be considerably reduced or evencompletely removed all together.
Successful though this project was felt to be by the authors, the follow up experiment will
necessarily involve a direct implant, or implants, into the brain. Direct thought control
and thought enhancement appear to be achievable, but these will require implants directly
into the bran, rather than merely the nervous system.

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