EEG ()

The electroencephalogram (EEG) makes a scalp recording of electrical activity, or brain waves, emitted by nerve cells from the cortex of the brain. The EEG has different "bands", defined by the frequency of the waves; delta (slow) waves are less than 4 Hz; the theta bands are 4-8 Hz, the alpha from 8 to 12 Hz, the beta from about 14-30 Hz and the gamma from 30-80 Hz. The alpha bands are best seen in the parieto-occipital area, and the beta bands are usually more prominent in the frontal and central regions. These bands, when simultaneously recorded, differ from each other and reflect different cognitive processes. The alpha rhythm is best seen when the subject is awake and relaxed, with eyes closed (Emerson, 1995), and beta waves during the REM stage of sleep (see later in the section on EEG studies and sleep). Brain electrical activity is also characterized by the amplitude or power of the oscillations. An increase is called synchronization whereas a decrease in amplitude is called desynchronization. Event related desynchronization/ synchronization (ERD/ERS) stands for a technique in which the power of a specific EEG frequency band is expressed as the relative change in power between two experimental conditions. It is a within-subject measure of relative changes in power between two experimental conditions and is expressed as a percentage (Krause et al., 2004).

Cook and colleagues (2006) comment that EEG and similar methods can be more easily applied to volunteers than brain imaging methods, since there is no ionizing radiation and no strong magnetic fields. However, interference can arise from applied ELF and RF fields. They state: "The EEG electrodes and leads can act as antennas that can a) inject current into the subject's scalp and b) induce potentials on the EEG leads which have significantly greater amplitude than the brain signals being measured. Hence reliable measurements during exposure are almost impossible".

Another method is the magnetoencephalogram (MEG), which offers better spatial resolution than the EEG, but disadvantages are that the brain magnetic filed activity is very weak and the MEG is extremely sensitive to external noise.

Some EEG studies have been done while the subjects are awake and resting (Table 1). Reiser (1995) reported a change in EEG tracings on exposure to 900 MHz radiation, but others have stated that similar changes can be seen when the level of awareness is altered. Roschke and Mann (1996) found no changes in healthy male volunteers exposed to 900 MHz, and Hietanen and colleagues (2000) found no effects on EEGs from exposure to different cell phones, using both 900 and 1800 MHz. Huber (2002) found changes in the alpha range during pulse-modulated exposure, but not with continuous wave exposure. Regel (2007) had similar findings, 30 minutes after pulse-modulated exposure, but not with continuous exposure. Croft (2002) found that EMF exposure decreased 1-4 Hz activity in right hemisphere sites, and was associated with increasing 8-12 Hz activity as a function of exposure duration in the midline posterior sites. Cook (2004) suggested that 30% of the variation in alpha activity seen in their study were due to the pulsed magnetic field exposure. Kramareko (2003) used a telemetric EEG, and found that within 20-40 seconds of exposure to a 900 MHz phone signal subjects showed slow-wave activity in the contralateral frontal and temporal areas. They lasted for one second and repeated every 15-20 seconds. When the signal was stopped the slow waves progressively disappeared in the next 10 minutes

Applications of BCI

Many of the examples of its applications are not achieved but expected to be achieved in the near future.
Most of the applications of BCI is clinically disable people as i mention them before like Locked in syndrome, tetraplegia , spelling problem.I will discuss some of the diseases which can be handled by BCI.

Locked in Syndrome :
Locked-in Syndrome (LIS) results from a lesion to the brain stem, most frequently an ischemic pontine lesion. It leads to particularly severe impairments resulting from the complete disruption of the motor pathways controlling eyes, face, trunk and limbs movements, as well as breathing, swallowing and phonation. Consciousness and cortical functions are preserved. Care and rehabilitation of the affected individuals, described as being "locked in", present great challenges. Access to communication is the main goal of treatment. Considering the current life expectancy of persons with locked-in syndrome, the top priority for the rehabilitation team is to help them reach the highest standards of quality of life possible.Lockedin syndrome


Tetraplegia :
Tetraplegia, also known as quadriplegia, is paralysis caused by illness or injury to a human that results in the partial or total loss of use of all their limbs and torso; paraplegia is similar but does not affect the arms. The loss is usually sensory and motor, which means that both sensation and control are lost. Tetraparesis or quadriparesis, on the other hand, means muscle weakness affecting all four limbs. It may be flaccid or spastic.

Tetraplegia is caused by damage to the brain or the spinal cord at a high level C1–C7—in particular, spinal cord injuries secondary to an injury to the cervical spine. The injury, which is known as a lesion, causes victims to lose partial or total function of all four limbs, meaning the arms and the legs. Tetraplegia is defined in many ways; C1–C4 usually affects arm movement more so than a C5–C7 injury; however, all tetraplegics have or have had some kind of finger dysfunction. So, it is not uncommon to have a tetraplegic with fully functional arms but no nervous control of their fingers and thumbs.

Typical causes of this damage are trauma (such as a traffic collision, diving into shallow water, a fall, a sports injury), disease (such as transverse myelitis, multiple sclerosis, or polio), or congenital disorders (such as muscular dystrophy).

It is possible to suffer a broken neck without becoming tetraplegic if the vertebrae are fractured or dislocated but the spinal cord is not damaged. Conversely, it is possible to injure the spinal cord without breaking the spine, for example when a ruptured disc or bone spur on the vertebra protrudes into the spinal column.

Alzheimer's Disease:

 Alzheimer's disease (AD) patients in the most advanced stages, who have lost the ability to communicate verbally, could benefit from a BCI that may allow them to convey basic thoughts (e.g., "yes" and "no") and emotions. There is currently no report of such research, mostly because the cognitive deficits in AD patients pose serious limitations to the use of traditional BCIs, which are normally based on instrumental learning and require users to self-regulate their brain activation. Recent studies suggest that not only self-regulated brain signals, but also involuntary signals, for instance related to emotional states, may provide useful information about the user, opening up the path for so-called "affective BCIs". These interfaces do not necessarily require users to actively perform a cognitive task, and may therefore be used with patients who are cognitively challenged. In the present hypothesis paper, we propose a paradigm shift from instrumental learning to classical conditioning, with the aim of discriminating "yes" and "no" thoughts after associating them to positive and negative emotional stimuli respectively. This would represent a first step in the development of a BCI that could be used by AD patients, lending a new direction not only for communication, but also for rehabilitation and diagnosis.

BCI versus neuroprosthetics

Neuroprosthetics is an area of neuroscience concerned with neural prostheses. That is, using artificial devices to replace the function of impaired nervous systems and brain related problems, or of sensory organs. The most widely used neuroprosthetic device is the cochlear implant which, as of December 2010, had been implanted in approximately 220,000 people worldwide. There are also several neuroprosthetic devices that aim to restore vision, including retinal implants.

The difference between BCIs and neuroprosthetics is mostly in how the terms are used: neuroprosthetics typically connect the nervous system to a device, whereas BCIs usually connect the brain (or nervous system) with a computer system. Practical neuroprosthetics can be linked to any part of the nervous system—for example, peripheral nerves—while the term "BCI" usually designates a narrower class of systems which interface with the central nervous system.

The terms are sometimes, however, used interchangeably. Neuroprosthetics and BCIs seek to achieve the same aims, such as restoring sight, hearing, movement, ability to communicate, and even cognitive function. Both use similar experimental methods and surgical techniques.

I am not going to discuss Nueroprosthetics in detail as my man focus is on BCI anyhow for further information on click on Neuroprosthetics c

BCI and its type

Brain Computer Interface:
A system which takes a bio-signal measured from the person  and predicts ( it in real time / on a single trial basis ) some abstract aspects of person  cognitive state.

Types:
There are several types of brain-computer interfaces that are reported. The basic purpose of these
devices or types is to intercept the electrical signals that pass between neurons in the brain and
translate them to a signal that is sensed by external devices.

Active BCI:  An active BCI is a BCi which derives its output from the brain activity which is directly consciously controlled by the user , independent of the environment around the user.

Reactive BCI: A reactive BCI is the BCI which derive its output from the brain activity rising in reaction of some  action  or some external simulation, which is further control for some application.e.g If you follow the flicker your brain will show some kind off activity or reaction which is interpreted by the computer and give the results.

• Passive BCI: A passive BCI is a BCI which derive its output from arbitrary brain activity without the purpose of voluntary control, for enriching a human computer interaction with implicit information.In other words the thing on which you don't have to focus or concentrate the things like relaxation,resting, driving etc. 

 Brain signals are interpreted by the different methods the key motility is (EEG ) Electroencephalogram because it has dry electrode and you don't have to wash gel.
Other methods are MRI, fMRI , Ecog etc which will we discuss later.Some other methods which are considered are :

Invasive BCI: Invasive Brain Computer Interface devices are those implanted directly into the brain and have the highest quality signals. These devices are used to provide functionality to paralyzed people. Invasive BCIs are also used to restore vision by connecting the brain with external cameras and to restore the

use of limbs by using brain controlled robotic arms and legs. As they rest in the grey matter, invasive 

devices produce the highest quality signals of BCI devices but are prone to scar-tissue build-up, 

causing the signal to become weaker or even lost as the body reacts to a foreign object in the brain. 

In vision science, direct brain implants have been used to treat non-congenital i.e. acquired blindness. 

One of the first scientists to come up with working brain interface to restore sight as private 

researcher, William Dobell. He implanted first prototype into Jerry, A man blinded in adulthood, in 

1978. He inserted single array BCI containing 68 electrodes into Jerry’s visual cortex and succeeded 

in producing the sensation of seeing light. In 2002, experiment was conducted on Jens Neumann 

where Dobell used more sophisticated implant enabling better mapping of phosphenes into coherent vision and after the experiment Neumann was interviewed on CBS’s show as shown in fig 2.BCIs focusing on motor Neuroprosthetics 

 aim to either restore movement in paralyzed individuals or 

provide devices to assist them, such as interfaces with computers or robot arms. Researchers at Emory 

University in Atlanta led by Philip Kennedy and Roy Bakay were first to install a brain implant in a 

human that produced signals of high enough quality to stimulate movement. 

Partially Invasive Brain Computer Interfaces:  Partially invasive BCI devices are implanted inside the skull but rest outside the brain rather than within the grey matter. Signal strength using this type of BCI is bit weaker when it compares to Invasive BCI. They produce better resolution signals than non-invasive BCIs. Partially invasive BCIs have less risk of scar tissue formation when compared to Invasive BCI. 

Electrocorticography (ECoG) uses the same technology as non-invasive electroencephalography, but 

the electrodes are embedded in a thin plastic pad that is placed above the cortex, beneath the dura 

mater. ECoG technologies were first trade-in humans in 2004 by Eric Leuthardt and Daniel Moran 

from Washington University in St Louis. In a later trial, the researchers enabled a teenage boy to play 

Space Invaders using his ECoG implant. This research indicates that it is difficult to produce 

kinematics BCI devices with more than one dimension of control using ECoG. 

Light Reactive Imaging BCI devices are still in the realm of theory. These would involve implanting 

laser inside the skull. The laser would be trained on a single neuron and the neuron’s reflectance 

measured by a separate sensor. When neuron fires, the laser light pattern and wavelengths it reflects 

would change slightly. This would allow researchers to monitor single neurons but require less 

contact with tissue and reduce the risk of scar-tissue build up.

 Non Invasive Brain Computer Interfaces: Non invasive brain computer interface has the least signal clarity when it comes to communicating with the brain (skull distorts signal) but it is considered to be very safest when compared to other types. This type of device has been found to be successful in giving a patient the ability to move muscle implants and restore partial movement. Non-Invasive technique is one in which medical scanning devices or sensors are mounted on caps or headbands read brain signals. This approach is 

less intrusive but also read signals less effectively because electrodes cannot be placed directly on the 

desired part of the brain. One of the most popular devices under this category is the EEG or electroencephalography capable of providing a fine temporal resolution. It is easy to use, cheap and 

portable.

Brain Computer interface History

History:

The history of brain–computer interfaces (BCIs) starts with Hans Berger's discovery of the electrical activity of the human brain and the development of electroencephalography (EEG). In 1924 Berger was the first to record human brain activity by means of EEG. Berger was able to identify oscillatory activity in the brain by analyzing EEG traces. One wave he identified was the alpha wave (8–13 Hz), also known as Berger's wave.

Berger's first recording device was very rudimentary. He inserted silver wires under the scalps of his patients. These were later replaced by silver foils attached to the patients' head by rubber bandages. Berger connected these sensors to a Lippmann capillary electrometer, with disappointing results. More sophisticated measuring devices, such as the Siemens double-coil recording galvanometer, which displayed electric voltages as small as one ten thousandth of a volt, led to success.

Berger analyzed the interrelation of alternations in his EEG wave diagrams with brain diseases. EEGs permitted completely new possibilities for the research of human brain activities.
Biography of Berger:

Berger was born in Neuses (now part of Coburg), Saxe-Coburg and Gotha, Germany.

After attending Casimirianum, where he gained his abitur in 1892, Berger enrolled as a mathematics student at the Friedrich Schiller University of Jena with a view to becoming an astronomer. After one semester, he abandoned his studies and enlisted for a year of service in the cavalry. During a training exercise, his horse suddenly reared and he landed in the path of a horse-drawn cannon. The driver of the artillery battery halted the horses in time, leaving the young Berger shaken but with no serious injuries.^[2] His sister, at home many kilometres away, had a feeling he was in danger and insisted their father telegram him. The incident made such an impression on Berger that, years later in 1940, he wrote: “It was a case of spontaneous telepathy in which at a time of mortal danger, and as I contemplated certain death, I transmitted my thoughts, while my sister, who was particularly close to me, acted as the receiver.”

On completion of his military service, and obsessed by the idea of how his mind could have carried a signal to his sister, Berger returned to Jena to study medicine with the goal of discovering the physiological basis of “psychic energy”. His central theme became “the search for the correlation between objective activity in the brain and subjective psychic phenomena”.

After obtaining his medical degree from Jena in 1897, Berger joined the staff of Otto Ludwig Binswanger (1852–1929) who held the Chair in psychiatry and neurology at the Jena clinic. Habilitated in 1901, he qualified as a senior university lecturer in 1906 and physician-in-chief in 1912, eventually succeeding Binswanger in 1919.^[6] He also collaborated with two famous scientists and physicians, Oskar Vogt (1870–1959) and Korbinian Brodmann (1868–1918), in their research on lateralization of brain function. Berger married his technical assistant, Baroness Ursula von Bülow, in 1911 and later served as an army psychiatrist on the Western front during World War I.^[7] He was elected Rector of Jena University in 1927.

In 1924, Berger succeeded in recording the first human electroencephalogram (EEG).^[8] Filled with doubt, it took him five years to publish his first paper in 1929 which demonstrated the technique for "recording the electrical activity of the human brain from the surface of the head".^[9] His findings were met with incredulity and derision by the German medical and scientific establishments.^[10] Having visited the EEG laboratory at Jena in 1935, American roboticist William Grey Walter noted that Berger "was not regarded by his associates as in the front rank of German psychiatrists, having rather the reputation of being a crank. He seemed to me to be a modest and dignified person, full of good humour, and as unperturbed by lack of recognition as he was later by the fame it eventually brought upon him. But he had one fatal weakness: he was completely ignorant of the technical and physical basis of his method. He knew nothing about mechanics or electricity." After British electrophysiologists Edgar Douglas Adrian and B. H. C. Matthews confirmed Berger's basic observations in 1934, the importance of his discoveries in electroencephalography (EEG) were finally recognized at an international forum in 1937.^[12] By 1938, electroencephalography had gained widespread recognition by eminent researchers in the field, leading to its practical use in diagnosis in the United States, England, and France.^[13]

In 1938, at the retirement age of 65, Berger was made Professor Emeritus in Psychology. According to biographers Niedermeyer and Lopes da Silva, the appointment occurred in an unceremonious manner as his relationship with the Nazi regime was particularly strained.^[14] Numerous sources report that, given their hostile relationship, the Nazis forced Berger into retirement that same year with a complete ban of any further work on EEG.^[15] These biographical accounts were contradicted in 2005 by Ernst Klee, the German journalist specializing in the exposure and documentation of Nazi medical crimes, who demonstrated that Berger was a member of the SS.^[16] In 2005, Dr Susanne Zimmermann, medical historian at the University of Jena, found evidence that Berger had not been forced into retirement but had "served on the selection committee for his successor"^[17] who was sacked as a Nazi after the war. Moreover, official records at the University of Jena dating from the 1930s proved that Berger had served on the Erbgesundheitsgericht(Court for Genetic Health) that imposed sterilizations while his diaries contained anti-Semitic comments.^[18] Dr Zimmermann's findings corroborated research published in Germany in 2003 documenting Berger's invitation by the SS racial hygienist Karl Astel to work for the EGOG (Court for Genetic Health) in 1941. Berger replied: "I am gladly willing to work again as an assessor at the Court for Genetic Health in Jena, for which I thank you."

After a long period of clinical depression, and suffering from a severe skin infection, Berger committed suicide by hanging on June 1, 1941 in the southern wing of the clinic.

Brain – computer Interfaces

 The ability of controlling computer using only the power of the mind is closer than one might think. Brain-computer interfaces, where computers can read and interpret signals directly from the brain, have already achieved clinical success in allowing quadriplegics, those suffering “locked-in syndrome” or people who have had a stroke to move their own wheelchairs or even drink coffee from a cup by controlling the action of a robotic arm with their brain waves. In addition, direct brain implants have helped restore partial vision to people who have lost their sight.
Recent research has focused on the possibility of using brain- computer interfaces to connect different brains together directly. Researchers at Duke University last year reported successfully connecting the brains of two mice over the Internet (into what was termed a “brain net”) where mice in different countries were able to cooperate to perform simple tasks to generate a reward. Also in 2013, scientists at Harvard University reported that they were able to establish a functional link between the brains of a rat and a human with a non-invasive, computer-to-brain interface. Other research projects have focused on manipulating or directly implanting memories from a computer into the brain. In mid-2013, MIT researchers reported having successfully implanted a false memory into the brain of a mouse. In humans, the ability to directly manipulate memories might have an application in the treatment of post-traumatic stress disorder, while in the longer term, information may be uploaded into human brains in the manner of a computer file. Of course, numerous ethical issues are also clearly raised by this rapidly advancing field

System for reading out information from the brain and translated into computer language to control or command motors is called system computer interface.

A brain–computer interface (BCI), sometimes called a mind-machine interface (MMI), or sometimes called a direct neural interface (DNI), synthetic telepathy interface (STI) or a brain–machine interface(BMI), is a direct communication pathway between the brain and an external device. BCIs are often directed at assisting, augmenting, or repairing human cognitive or sensory-motor functions.

Research on BCIs began in the 1970s at the University of California Los Angeles (UCLA) under a grant from the National Science Foundation, followed by a contract from DARPA.^[1][2] The papers published after this research also mark the first appearance of the expression brain–computer interface in scientific literature.

The field of BCI research and development has since focused primarily on neuroprosthetics applications that aim at restoring damaged hearing, sight and movement. Thanks to the remarkable cortical plasticity of the brain, signals from implanted prostheses can, after adaptation, be handled by the brain like natural sensor or effector channels.^[3] Following years of animal experimentation, the first neuroprosthetic devices implanted in humans appeared in the mid-1990s.
It is the vast field the Human computer interface have already become ubiquitous like key board mouse etc. However, the brain computer interface is going to give a new dimension to HCI and hope to the people who are not able to use HCI.
Brain computer interface is the future and this blog is going to give every information on this field and keep you updating with its updates.