06-02-2013, 09:56 AM
Brain-Chip Interface
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INTRODUCTION
Individuals with severe disabilities face challenges performing normal every-day tasks. Today, researchers are developing a technology that could conceivably alleviate many difficulties associated with physical handicaps.
Brain-Computer Interface (BCI) technology allows a living, healthy brain to connect to an external computer system through a chip composed of electrodes. The electrode chip can be implanted into defined positions within the motor cortex in order to capture the brain’s natural electric signals that stimulate voluntary movement. Researchers today can record the electrical activity of neurons firing and use computers to convert the signals into actions by applying signal processing algorithms. Significant and intensely competitive research in this field over the past decade, which one scientist has called an "arms race," has led to the first human BCI implantation surgery directed by Brown University professor, John Donoghue.
On June 22, 2004, Professor Donoghue’s team implanted an electrode into Matthew Nagle’s brain which today has allowed him, after extensive training, to perform activities like opening his email and turning on and off a TV using his thoughts alone. The success of the device has caused excitement in the field and has led many to contemplate the possible applications of BCI’s in the future.
At the same time, however, not everyone is as optimistic as Donoghue about the current technology. Some researchers criticize Donoghue's group for rushing in to human trials when BCIs are still crudely designed. Others see big picture ethical problems that could arise from this new kind of "mind control."
Physiology
The brain is a tissue. It is a complicated, intricately woven tissue, like nothing else we know of in the universe, but it is composed of cells, as any tissue is. They are, to be sure, highly specialized cells, but they function according to the laws that govern any other cells. Their electrical and chemical signals can be detected, recorded and interpreted and their chemicals can be identified; the connections that constitute the brain's woven feltwork can be mapped. In short, the brain can be studied, just as the kidney can.
- David H. Hubel, 1981 Nobel Prize Winner
Introduction
In his statement on the brain, Hubel, a Nobel Prize recipient for his work on neurophysiology, puts forth his confidence in the potential success of researching the brain. Despite the complexity and intricacy of the connections and pathways in the brain, Hubel states that the brain is comprised of the cell, the basic foundation of any tissue. As a result, this organ, like any other, can be explored, studied, and understood. This belief and enthusiasm drive the constantly evolving knowledge and technology associated with the brain.
How does it work?
In general, there are three stages in the processing of information by the nervous system- sensory input, integration, and motor output. Sensory neurons transmit information from sensors that detect external stimuli (light, sound, heat, smell, taste, touch) and internal conditions (blood pressure, blood CO2 level, muscle tension). This information travels to the CNS where interneurons analyze and interpret (integration) the sensory input, incorporating the current circumstance with relevant situations from the past. The motor output then leaves the CNS via motor neurons which communicate with muscle or endocrine cells.
An Example
The knee-jerk reflex provides an example of this process. Here is what happens. First, tapping the tendon connected to the quadriceps (extensor) muscle initiates the reflex. Sensors then detect a sudden stretch in the quadriceps. Sensory neurons convey the information to the spinal cord in addition to communicating with the motor neurons that deliver information to the quadriceps. In return, the motor neurons convey signals to the quadriceps, causing the muscle to contract and jerk the lower leg forward. The sensory neurons from the quadriceps also communicate with interneurons in the spinal cord. In response, the interneurons inhibit motor neurons that supply the hamstring (flexor) muscle. This inhibition prevents the hamstring from contracting, which would resist the action of the quadriceps.
History:
History of brain-computer interfaces (BCI) is, indeed, a history of ideas
that is over a century old. BCI combines technologies from many different fields, including computer science, electrical engineering, neurosurgery and biomedical engineering, and has emerged from the same school of thought as Deep Brain Stimulation, which is the process of electrically “shocking” the brain to regulate it in individuals with movement disorders, epilepsy, and now, even depression.
1875: Richard Canton first discovers electrical signals on surface of animal brains.1
1929: Hans Berger publishes his first paper on experiments with EEG waves in a human. With this, he establishes the brain’s capacity for electric signaling.
1940s: Wilder Penfield maps the motor cortex for the first time using epilepsy patients as subjects.
1950s: Dr. Jose Delgado, a neurosurgeon at Yale University, invents the Stimoceiver, an electrode device that can be controlled wirelessly by FM radio. He tests it in the brain of a bull and is able to make the animal charge and change direction by the pushing of different buttons.
1960’s: Grey Walter, a neurophysiologist, guides electrodes through the human scalp and performs experiments to test stimulations that make the thumb of the subject move.