Some sophisticated approaches to applying ESB are being developed in animals, with the vision of providing people with physical disabilities control over artificial limbs, or even control of virtual environments.

Motor control and feedback

Stimulation of the motor cortex can incite movement in the body part which it represents according to the functional mapping of the body over this area. Stimulating these areas can invoke quite complex and coordinated movements of the limbs.
[Graziano et al,2005]

Theodor Fritsch and Eduard Hitzig demonstrated that motor cortex contains a representation of the body's musculature, a topographical map. This map shows consistencies between individuals and between species. The map exists for motor activation, as well as sensation from body regions. Naturally these provide targets for electrical stimulation.

Devices have been used in rats, mice and primates that integrate recordings from neurons in the motor and premotor cortex to control an external 'limb' such as a lever or robotic arm. This is done with a reward of food or water to give a motive for using the system.
[Chapin et al,1999]

Primates can learn to reach and grasp for objects by controlling a robot arm through a brain–machine interface composed of an implant and external processing electronics. The processor uses mathematical models to extract several motor parameters, such as hand position, velocity, and gripping force from the electrical activity of fronto-parietal neurons.
As single neurons contribute to encoding several motor parameters, accurate interpretation required recording from large neuronal ensembles.

By using visual feedback the monkeys succeeded in using the robot to reach-and-grasp even when their arms did not move. Learning to operate the brain-machine interface caused functional adaptation in the cortex, suggesting that dynamic properties of the interface were integrated with the existing cortical motor representations.
The next t step will be to provide feedback via a neural link, so that the animal can use tactile sensation to guide it, as well as visual feedback.
[Carmena et al,2003]

Mind control

Rats have been surgically implanted with electrode arrays that allow control over their behaviour. These advances follow original work by Hess that demonstrated how an animal, including a human, could show intense like or dislike for stimulation to certain parts of the brain. These emotional responses could be classically conditioned, anchored to stimuli which would then be either pursued or avoided. The depth of association depended solely on the duration of training.
[Skinner, 1938]

More recently the use of implanted devices has been used to 'guide' behaviour in rats, mice and snails. By giving animals an electronic pulse in the medial forebrain bundle one can 'approve' its current behaviour and spur it on. Conversely one can stimulate the anterior/ventrolateral hypothalamus or peri-aqueductal grey to 'disapprove' and avert the behaviour, although this hasn't been integrated into the implant yet.

Control is extended beyond mere affirmation and vetoing of behaviour by implanting electrodes into the whisker zone on both sides of the somatosensory cortex. By stimulating these whisker-monitoring neurons, a rat can be persuaded that there is an obstacle to one side or the other. In this way, combined with 'approval' stimulations, one can get the animal to turn. This allows an operator to guide the robo-rat around complex obstacle courses.
[Talwar et al, 2002]

These behaviour-control techniques can and have been applied to other animals including mice and snails. The gap to humans is only theoretical and ethical. This kind of research does raise concern, especially when one extrapolates the possibilities to humans. Naturally such treatment will significantly alter the animal, though those subjected to these augmentations seem, on the surface, to have normal well-being. On the other hand these kind of devices are exciting in their potential, and represent the frontier in interfaces between whole organisms and human machines. What will come after robo-rats?

Mind opening

Scientists such as Allan Snyder are probing effects of transcranial magnetic stimulation on mental functioning in a diverse range of complex tasks, like drawing stereotypical images and identifying prime numbers. It is accepted that TMS can disable speech, in a similar way to the Wada test, although research into other functions is minimal.

Intuition from studying autistics lead Snyder to consider that these individuals' disabilities could be the key to savant-like characteristics that they often display. By tuning down certain brain regions with TMS pulses Snyder claims that creativity can be enhanced. Many scientists are dubious, although this area is so thinly understood that dismissing Snyder's observations would be presumptuous.
[Snyder et al,2004]

If transcranial magnetic stimulation becomes more accurate, penetrating and portable, it is possible that one day we might wear a helmet at night to improve our health and vitality, re-balancing activity in the hypothalamus and limbic system to harmonise body and mind.

Self-stimulation

 

Self-stimulation is where an animal will voluntarily apply stimulation to a part of it's brain, repeatedly. Self stimulation of has been used to understand addictive processes and the roles of specific neural pathways. Brain centers associated with sex and feeding, and some other regions, can support self-stimulation and are termed 'reward centers'.

Facilitation of self-stimulation is an effect that abusable drugs have in common, despite their individual pharmacological characteristics. Thus facilitation of self-stimulation may be relevant for the dependence-creating properties of drugs, and may represent one of the basic mechanisms of drug dependence.

The animal is first habituated to self-stimulation. Drugs are then administered to the animal, and it's frequency of self-stimulation is noted. Ideally, when one sees an increase in frequency, the drug is promoting 'seeking' and 'craving' reflexes; while a decrease in frequency shows the animal is sated or indifferent.
In reality things are much more complex, for instance a drug might make a creature sleepy or clumsy, reducing it's self-stimulation by necessity, rather than through an action on the central 'seeking' pathways.
[Van Ree et al,1999]

Similar experiments have been done in humans, where electrodes are implanted into brain or spinal areas, and the patient is given voluntary control over their own stimulation. Central reward pathways usually provoke repeated button-pressing, as in rats and mice, however humans do seem to possess a higher degree of control over how they pleasure themselves.
Another famed example of self-stimulation in humans is the 'orgasmatron' where a spinal center is stimulated, producing intense orgasms. This is being pioneered for anorgasmic couples, although there are concerns over abuse potential.
[Sample,2001]