INTRODUCTION:
How indispensable it is for us to use our hands and feet, in fact our whole body to perform various functions. The minimalists of tasks involve hand and body motions. The possibility of not accomplishing something just because we are impaired of that movement is a tragic blow to one’s mind.
In yesteryears it was a very difficult and nearly impossible task to reform a person suffering with any neural disorder. Many health problems like stroke and cervical spine injuries to neurodegenerative diseases such as multiple sclerosis and amyotrophic lateral sclerosis, affected the nervous system and left the patient severely impaired of his or her bodily functions, therefore depriving him of any movement. However, the important point to note is that the injury did not affect the brain cells which mean that the person could think of moving or performing tasks using his body, but couldn’t perform them. Thus, creating a psychological effect on the person that he is unable to do the functions others can perform quite easily. This thought further discouraged the individual and left him in a vulnerable state.
BACKGROUND OF PROSTHETICS :
The variety of nervous disorders like paralysis and Parkinson disease etc. are quite common these days; technology is moving with the speed of light, coming up with different solutions so as to provide aid in the form of implants for the mind and body. Prosthetics are basically artificial devices that are used to improve or help the defect present in the nervous system. In the past, prosthetics like artificial limbs & other organs have been used but they were large in sizes & not very efficient. The patient required a lot of conservation so as to control the device. As a result, the severely suffering patients could not be treated due to in competency of the prosthetics.
Neural science is a revolution as it can cater to the severely paralyzed or amputated individuals & that too, through a much improved approach. A complete understanding of the brain’s neural cords and its interpretation is a core to this science primarily allied to the vast and ever progressing fields of neuroscience and bio-medical engineering.
Many types of sensory prosthetics used to impart input and motor prosthetics for outputs have been developed up till now, neural or cognitive prosthetics are underway. They are basically brain controlled devices that restore interaction and movement between the brain and the body to aid the defected parts of body, hence restoring function. This act is obtained by using electrical stimulation. A lot of work is being done to manufacture device called hippocampal prosthesis that might be able to copy the part of brain responsible for forming memories.
SENSORY PROSTHETICS : These include prosthetics like
Visual prosthetics that involve implanting electrodes in the visual cortex, enabling the individual to see.
Auditory prosthetics like the bionic ear which can help a hearing impaired person to hear sounds.
Prosthetics for pain relief like the spinal cords stimulator.
MOTOR PROSTHETICS: That are related to the neuro prosthetics as they help in the movement. These include
Artificial pacemaker for heart stimulation.
Bladder control implants
Various other prosthetics have also been developed for controling or enhancing movement through stimulating the nervous system.
Since the restoration of movement is a very important and much needed factor, and no proper treatment is available, much emphasis is being laid on this particular field nowadays.
NEURAL PROSTHETICS:
Deciphering the brain and transferring the messages to the nervous system in order to create movement in any area of the body is an extremely complex process. The disruption or breaking of the message links in the nervous system causes paralysis or failure of movement in any particular region of the body. Neural engineering, is a revolutionary science that focuses on the interpretation of brain waves to the body in order to create motion in the defected area. This feat is accomplished by electric stimulation using electrodes- long slender fibers that conduct transmissions from the brain to the spinal cord.
“Two broad approaches are used in this field: neurons are stimulated or inhibited by applied current, or their activity is recorded to intercept motor intention. Stimulation can be used for its therapeutic efficacy, as in deep brain stimulation to ameliorate the symptoms of Parkinson’s disease or to communicate input to the nervous system.” (Neuron, 52)
Every neural prosthetic or the BCI which stands for brain controlled interface has the same derivation, i.e. to comprehend the desired body movement or function and carry it out successfully. Different tests are being carried out so as to check the authenticity of each research so that it fully complies.
WORKING & SIGNIFICANCE OF NEURAL PROSTHETICS:
The core of this research is to design such a prosthetic that might allow the patients with most impaired nervous systems, full body control by simply using their minds to control their movements. The implants are either placed on top of the cerebral cortex beneath the skull or surgically implant electrodes on the brain.
“The alternate version is an electroencephalogram (EEG), which are basically scalp electrodes. The main difference between the two is the strength and clarity of the signal.” (Aum, 5)
It is perceived that using the central nervous system can help in providing numerous channels of transmission & hence gain more power to control the impaired body part. Experiments conducted on monkeys; by placing electrodes on the parietal reach region to transfer electric signals to an outward source, depicted that the part of the brain that manages arm movement (PRR) can direct a prosthetic cursors on computer or even a robotic limb by simply using thought patterns. The purpose of the prosthetic defines its functioning & working. It works using signals interpreted directly from the nervous system. The signals are copied & filtered for any unwanted noise or distraction, since it might create hindrances in the proper functioning of the device. The signals are then analyzed & the message from the brain converted into simple form.
The focal point is that, accessing information from the directly related region is a far better option, as it maybe more operative & can function without distracting the motor cortex. If proven correct in humans as well, a discovery like this can help paralyzed people by using planned or direct movements to create subtle activities like reaching out to something or controlling small objects just by mind control. (Benson, 11) the process of implanting the electrodes & its working is shown in the illustration below:
(TRENDS in Cognitive Sciences Vol.8 No.11 November 2004)
CONFRONTING CHALLENGES:
Conversely, the confrontation faced by the neuro-scientists is great. Understanding the complex human brain and its working is not an easy task. Therefore, even after all the advance research and tests being conducted; the neural science is nowhere near the desired endeavor. A thorough insight is required to come up with neural prosthetics that are efficient and are long-lasting to provide maximum aid in movement restoration as well as in speech retardation. Once planted permanently in the brain, it is difficult to remove or adjust the electrodes, in view of the fact, that the brain tissue shifts accordingly along with the electrodes over time entailing invariable modification of the electrodes.
If movable electrodes are used, they might waft to the brain matrix due to constant body movements is present & therefore move away from the active cells making it lose its function. (Cognitive neural prosthetics) The testing is being done on monkeys, whose brain working is very much similar with the humans, especially the thinking factor. The perfect results & the efficiency, however, can only be tested & confirmed after it is used in the human body.
It is vital that the information being conducted from the electronic device should match the brain, so that the information can be used to re establish control.
The scientists & engineers are working diligently on the advancement of neural prosthetics so as to restore movement in paralysis patients. Such a day will arrive after over coming all the deficiencies of technology & create state of the art prosthetic, enabling severely impaired patients to perform simple actions easily. Object control using thought processes can be a major accomplishment of neural science & consequently provide a better life to the severely paralyzed people.
References
Brain-Controlled Interfaces: Movement Restoration with Neural Prosthetics, Neuron 52, 205–220, October 5, 2006 ª2006 Elsevier Inc. DOI 10.1016/j.neuron.2006.09.019
Stanford Scientific Magazine, 2006- Advances in Neural Prosthetics: Translating neural signals into movement by David Aum, 13 November 2007.
<http:// www.stanford.edu/group/stanscimag/volume5-1/articles5-1/neu…>
Stanford Report: Stanford engineer studies neural prosthetics, Etienne Benson. 11/13/07 <http://www.eurekalert.org/pub_releases/2001-11/su-ses112801.php>
TRENDS in Cognitive Sciences: R.A. Andersen, J.W. Burdick, S. Musallam, B. Pesaran and J.G. Cham .Vol.8 No.11 November 2004
Cognitive neural prosthetics: sciencedirect.com 2004 Elsevier Ltd.
All rights reserved. doi:10.1016/j.tics.2004.09.009
University of California – San Francisco (2007, February 27). Harnessing The Brain’s Plasticity Key To Treating Neurological Damage. ScienceDaily. Retrieved November 21, 2007, from http://www.sciencedaily.com/releases/2007/02/070220013458.htm
