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Library Methods & Technology Methods & Technology Intro - Part II: Technology
Library Methods & Technology Methods & Technology Intro - Part II: Technology
| Methods & Technology Intro - Part II: Technology |
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| Neurohacking - Methods & Technology | |||||||||
| Written by NHA | |||||||||
| Sunday, 28 February 2010 03:49 | |||||||||
Methods & Technology - Part II: Technology
Introduction
There are several kinds of technology used in neurohacking: · Technology for diagnosis & investigation · Technology for damage repair & damage prevention · Technology for augmentation & exploration
There is some degree of overlap here however, since some tech can be used in any or all of these capacities depending on what you want to use it for. So we’ve discussed each type of tech under its most usual use in more detail than other uses. Dates of first introduction are given where known (the latest stuff is at the bottom of each section).
Diagnosis & Investigation
One aim of neurohacking is to be able to understand the brain mechanisms behind behavior, and to that end it is necessary to study the brain. Once upon a time the microscope was all we had at our disposal to study brain tissue and, unsurprisingly, not very much was revealed! Even the reality of synapses, the tiny gaps between brain cells, although theorised, had to wait until the advent of electron microscopes for verification in the 1950s. In the 1970s and 80s, scientists used radioactive material and dead brains to reveal that certain areas of the brain might be involved in different tasks, but now today’s technology [scanning] allows us to measure accurately which small areas of the brain are active during which behavioral tasks, and to do so in real time.
(1927) Angiography Or arteriography is a medical imaging technique in which an X-ray picture is taken to visualize the inner opening of blood filled structures, including arteries and veins. Angiograms require the insertion of a catheter into a peripheral artery, and because blood has the same radiodensity as the surrounding tissues, a radiocontrast agent (which absorbs X-rays) is added to the blood to make angiography visualization possible. The X-ray images may be taken as either still images, displayed on a fluoroscope or film, useful for mapping an area. Alternatively, they may be motion images, usually taken at 30 frames per second, which also show the speed of blood (actually the speed of radiocontrast within the blood) traveling within the blood vessel.
Chemicals and electricity Just as the normal sensory input to the brain can be bypassed with electrical or chemical stimulation, so the normal behavioral consequences of stimulation can be pre-empted, by using electrical and chemical activity. Chemicals and electricity can be used to stimulate the brain, and they can also be used to measure the activity of the brain. Blood, urine and cerebrospinal fluid can all be sampled and examined to see if they contain specific chemicals. The chemicals are of two types. Some chemicals are products secreted by the brain to influence other parts of the body, e.g., hormones and neurotransmitters. Other chemicals, known as breakdown products, or metabolites, give an indication of which chemicals have been used in the brain, just as wrappers in the bin give an indication of what someone has been eating. The breakdown products provide two pieces of information. They reveal which chemicals have been used and also, by their quantity, the extent to which they have been used.
To record chemical activity within the brain requires two very fine tubes or cannulae [singular cannula], one within the other, to be inserted through a hole in the skull. The inner cannula carries a salt solution into the brain and the outer cannula carries the salt solution out of the brain. At the tip of the two cannulae is some special tubing, called dialysis tubing, which allows chemicals in the fluid surrounding it to enter the cannulae. This happens because the salt solution entering the brain contains none of the chemicals of interest surrounding the cells of the brain. Those chemicals in the fluid surrounding the dialysis tubing are all moving and some just happen to move, to diffuse, across the dialysis tubing into the salt solution. The salt solution that leaves the brain also contains whatever chemicals have been picked up from within the brain. The process of collecting chemicals from within the brain using dialysis tubing is called microdialysis. Chemical analysis can then be applied to the outcoming fluid to determine which chemicals are present around the dialysis tubing.
Cranial ultrasound uses reflected sound waves to produce pictures of the brain and the inner fluid chambers (ventricles) through which cerebrospinal fluid (CSF) flows. Cranial ultrasound may be done to visualize brain masses during brain surgery. Ultrasound waves cannot pass through bones; therefore, an ultrasound to evaluate the brain cannot be done unless the skull has been surgically opened.
The brain can be stimulated by electricity, but the brain also generates electricity in quantities that vary with its activity. Electrical activity can be recorded using electrodes. A pair of electrodes, attached close together on the scalp with an electrically conducting gel, can be used to detect the cumulative effect of the tiny voltage changes [a few microvolts] generated by nearby neurons. The signal is amplified and fed into a computer. It is easier to visualise what the computer does by describing the older apparatus the computer has replaced. So, rather than the signal being amplified and fed to a computer, consider that the signal was amplified and fed to a device, a galvanometer, which converted the signal into the sideways movements of a pen. A strip of paper moved at a constant speed under the pen. As the current measured by the electrodes changed, so the pen moved back and forth across the paper, creating a long wiggly line, a brain wave. Usually there are several pairs of electrodes on the scalp, each feeding a different pen, or channel. There can be up to 40 channels on one multichannel recorder. The result, from the pen or from the computer, is the Electroencephalogram, or EEG. The electrical signals can be accurately timed. If a stimulus, e.g., a sound, is applied at a known time in relation to the EEG recording, then the effect of the stimulus on the EEG can be deduced. This process underlies the “event-related potential” [ERP]. In fact, the deduction requires a lot of computation, and repeated applications of the stimulus. Those electrical events that usually accompany the stimulus are enhanced, while those that only occasionally accompany the stimulus are reduced. Eventually, an averaged response emerges from the wealth of electrical signals, and a large, unmistakable, slow wave, the “event-related potential”, becomes clear. The wave is identified by its time in milliseconds after the stimulus, say, 200ms, and whether it is in the negative [N] i.e., downwards, or positive [P] i.e., upwards direction. The P200 is a fairly standard [i.e., regularly observed] ERP. ERPs have been used to investigate many types of cognitive processes, including memory, language and attention, face recognition in children, as well as degenerative disorders, such as Alzheimer’s disease.
The EEG has the same problems associated with the skull as those that disperse and attenuate an electrical impulse used to stimulate the brain; the skull also disperses and attenuates the weal electrical signals generated by the brain. The electrical interference of the skull can be minimised by using microelectrodes.
Microelectrodes can be used to record the electrical activity of relatively small groups of cells, or even of individual neurons, inside the brain. Micropipettes [sometimes called glass microelectrodes] have such fine tips that they can also be inserted into individual brain cells and used to record their activity.
These methods of recording electrical activity can be used in real time and while the subject is active and moving around. They can also detect changes occurring in a very short space of time, milliseconds, which is close to the timescale in which neurons operate.
There is an additional way to measure the electrical activity of the brain, but the device that is able to measure it requires the subject to keep very still. Any electrical current necessarily generates a magnetic field, and this is true of nerve cells even though the electric current and the magnetic field they generate is tiny. However, by placing an array of supercooled, highly sensitive detectors around the skull, it is not only possible to detect but also to identify the source of the magnetic fields generated by activity in the brain: this is the principle of the magnetoencephalogram, or MEG. The MEG allows the localised areas of electrical activity that arise in the brain in response to particular stimuli to be identified.
There are other devices that measure brain activity and that require the subject to be very still, but these devices do not measure electrical activity; they measure blood flow. The brain requires a continuous supply of blood to provide both energy, in the form of glucose, and oxygen. The brain can neither store these substances nor use alternatives. About 20% of the heart’s output of blood goes to the brain. The progress of the blood through the brain though is not a flood, but a carefully controlled irrigation. The network of blood vessels in the brain is under very sensitive, localised control, such that each area of the brain receives only the amount of blood that it requires: all areas of the brain do not receive equal amounts. Those areas that receive the most blood during a particular task [e.g., presentation of an auditory stimulus, thought or manual manipulation] and hence are in receipt of the most glucose and oxygen, are deemed to be the most active. The size of the area of activity and the intensity of the activity though should be taken only as a guide to the importance of that area for whatever task is being assessed. The relative importance of the crowd and the players at a sports match, compared to their size and energy consumption, is a useful analogy here.
(early 1970s) Computerized axial tomography (CAT or CT scanning) became available. Ever more detailed anatomic images of the brain became available for diagnostic and research purposes. Soon after the introduction of CAT in the early 1980s, the development of radioligands enabled single photon emission computed tomography (SPECT) and positron emission tomography (PET) scans of the brain. Two devices measure blood flow and distribution within the brain; positron emission tomography [PET] and magnetic resonance imaging [MRI].
(early 1980s) The PET scan –Radioactive material emits small, high-energy particles called positrons. Each emitted positron interacts with a nearby electron, resulting in the annihilation of them both and the production of gamma rays [a form of electromagnetic radiation like X-rays, but of higher energy]. The gamma rays disperse in equal and opposite directions from the point of positron-electron annihilation and can be detected by suitable sensors. A computer can reconstruct the source of the gamma rays using information about which sensors are activated and when. The process of reconstruction is called tomography –the T in PET. A patient or participant has a small amount of radioactive material injected into their bloodstream. The material is transported in the blood around the body and into the brain. The areas of the brain that command the greater volume of blood produce the most gamma rays and it is these areas that are computed and displayed by the PET scan.
(early 1980s) The MRI scan –Any charged particle that spins has magnetic resonance. Protons have a positive charge and they spin all the time. These properties mean that all atoms and molecules have magnetic resonance because they contain protons. The technique depends not only on the fact that different molecules have different magnetic resonance. Two molecular components of the blood are particularly interesting in this regard; they are variants on haemoglobin, the molecule that makes blood red. Haemoglobin with oxygen attached is called oxyhaemoglobin, while haemoglobin that has no oxygen attached to it is called deoxyhaemoglobin. The magnetic resonance of deoxyhaemoglobin is different from that of oxyhaemoglobin. When blood is diverted to particular areas of the brain, the ratio of oxy- to deoxyhaemoglobin will change, and the sensors can detect this change. Computers produce an image of where the change in ratio occurs. The MRI scan, tuned to detect the magnetic resonance of hydrogen, generates high-resolution, three-dimensional images of the brain. These images reveal the anatomy and structure of the brain in some detail. This is structural MRI. One advantage of MRI over PET is that it does not require the patient to be exposed to radioactive substances. The absence of any potentially dangerous exposure means that, unlike the situation with PET, images of the same person performing the same task can be repeatedly produced. However, MRI scanners are noisy and the patient is confined to a small space, having to use mirrors to see out of the scanner, and has to remain very still. The noise, constriction and motionlessness make for an uncomfortable experience. However, advances in technology have meant that a wider machine is now available.
(1985) Transcranial magnetic stimulation (TMS) is a recent addition in brain imaging. In TMS, a coil is held near a person's head to generate magnetic field impulses that stimulate underlying brain cells to make someone perform a specific action. Using this in combination with MRI, the researcher can generate maps of the brain performing very specific functions. Instead of asking a patient to tap his or her finger, the TMS coil can simply "tell" his or her brain to tap his or her finger. The images received from this technology are slightly different from the typical MRI results, and they can be used to map any subject's brain by monitoring up to 120 different stimulations. This technology has been used to map both motor processes and visual processes. In addition to fMRI, the activation of TMS can be measured using EEG) or near infrared spectroscopy (NIRS). Repetitive transcranial magnetic stimulation is known as rTMS and can produce longer lasting changes. Numerous small-scale pilot studies have shown it could be a treatment tool for various neurological conditions.
TMS and rTMS are used in different ways for different purposes. Single or paired pulse TMS. The pulse(s) causes neurons in the neocortex under the site of stimulation to depolarise and discharge an action potential. If used in the primary motor cortex it produces muscle activity referred to as a motor-evoked potential (MEP) which can be recorded on EMG. If used on the occipital cortex, “phosphenes” (flashes of light) might be detected by the subject. In most other areas of the cortex, the participant does not consciously experience any effect, but his or her behaviour may be slightly altered (e.g. slower reaction time on a cognitive task), or changes in brain activity may be detected using PET or fMRI. Effects resulting from single or paired pulses do not outlast the period of stimulation.
Repetitive TMS (rTMS) produces effects which last longer than the period of stimulation. rTMS can increase or decrease the excitability of corticospinal or corticocortical pathways depending on the intensity of stimulation, coil orientation and frequency of stimulation. The mechanism of these effects is not clear although it is widely believed to reflect changes in synaptic efficacy akin to long term potentiation (LTP) and long term activity-dependent reduction.
(1990) Blood-oxygen-level dependent (BOLD) is the MRI contrast of blood deoxyhemoglobin. Almost all current fMRI research uses BOLD as the method for determining where activity occurs in the brain as the result of various experiences
(1990) functional magnetic resonance imaging (fMRI) relies on the paramagnetic properties of oxygenated and deoxygenated hemoglobin to see images of changing blood flow in the brain associated with neural activity. This allows images to be generated that reflect which brain structures are activated (and how) during performance of different tasks. Functional imaging enables the processing of information by centers in the brain to be visualized directly. Such processing causes the involved area of the brain to increase metabolism and "light up" on the scan. (The computer effectively subtracts the images produced when the participant is not performing the task from the images produced when they are.) The difference in blood flow is usually represented as a color scale on images and indicates where the brain carries out the particular function. Most fMRI scanners allow subjects to be presented with different visual images, sounds and touch stimuli, and to make different actions such as pressing a button or moving a joystick. Consequently, fMRI can be used to reveal brain structures and processes associated with perception, thought and action. The resolution of fMRI is about 2-3 millimeters at present (2010), limited by the spatial spread of the hemodynamic response to neural activity. It has largely superseded PET for the study of brain activation patterns. PET, however, retains the significant advantage of being able to identify specific brain receptors associated with particular neurotransmitters through its ability to image radiolabelled receptor "ligands" (receptor ligands are any chemicals that stick to receptors). As well as research on healthy subjects, fMRI is increasingly used for the medical diagnosis of disease. Because fMRI is exquisitely sensitive to blood flow, it is extremely sensitive to early changes in the brain.
Diffuse optical imaging (DOI) or diffuse optical tomography (DOT) is an imaging modality which uses near infrared light to generate images of the body. The technique measures theoptical absorption of hemoglobn and relies on the absorption spectrum of haemoglobin varying with its oxygenation status.
Event-related optical signal (EROS) is a brain-scanning technique which uses infrared light through optical fibers to measure changes in optical properties of active areas of the cerebral cortex. Whereas techniques such as DOT and near infrared spectroscopy (NIRS) measure optical absorption of haemoglobin, and thus are based on blood flow, EROS takes advantage of the scattering properties of the neurons themselves, and thus provides a much more direct measure of cellular activity. EROS can pinpoint activity in the brain within millimeters (spatially) and within milliseconds (temporally). Its biggest downside is the inability to detect activity more than a few centimeters deep. EROS is a new, relatively inexpensive technique that is non-invasive to the test subject.
X-ray CT Scans that use X-rays are generally just referred to as CT [computerised tomography] scans and, although common, the resultant images are two-dimensional, and of comparatively low resolution. PET and fMRI scans can locate brain activity, whereas MRI and CT scans can only show structure. As we said above, each molecule has its own magnetic resonance, which means that magnetic resonance can also be used to locate particular molecules within the living brain. Localised magnetic resonance spectroscopy can be used for the detection of specific molecules such as neurotransmitters in a small volume within the brain.
T rays Sending tight bunches of electrons at nearly the speed of light through a magnetic field causes the electrons to radiate T-rays at a trillion cycles per second—the terahertz frequency that gives T-rays their name and that makes them especially useful for investigating biological molecules. Invisible T-rays bear comparison with radio waves, microwaves, infrared light and X-rays. But unlike those much-used forms of radiated energy, up until recently T-rays have been little exploited—in part because no one knew how to make them bright enough. T-rays are electromagnetic radiation of the safe, non-ionizing kind. They can pass through clothing, paper, cardboard, wood, masonry, plastic and ceramics. They can penetrate fog and clouds. Their wavelength—shorter than microwaves, longer than infrared—corresponds revealingly with biomolecular vibrations. Non-ionizing radiation does not damage tissues & DNA, unlike X rays. Some frequencies of terahertz radiation can penetrate several millimeters of tissue with low water content (e.g. fatty tissue) and reflect back. Terahertz radiation can also detect differences in water content and density of a tissue. Such methods could allow effective detection of some conditions with a safer and less invasive or painful imaging system. Some frequencies of terahertz radiation can also be used for 3D imaging of teeth and may be more accurate and safer than conventional X-ray imaging in dentistry. Spectroscopy in terahertz radiation could provide new information in chemistry/biochemistry.
Most recent developments in imaging have come via computer software and how the data is handled.
(mid 1990s) DTI/DSI (Diffusion tensor imaging/ Diffusion spectrum imaging) How’s it done?
(1) High-resolution T1 weighted and diffusion spectrum MRI (DSI) is acquired. DSI is represented with a zoom on the axial slice of the reconstructed diffusion map, showing an orientation distribution function at each position represented by a deformed sphere whose radius codes for diffusion intensity. Blue codes for the head-feet, red for left-right, and green for anterior-posterior orientations. (2) White and gray matter segmentation is performed from the T1-weighted image. (3a) 66 cortical regions with clear anatomical landmarks are created and then (3b) individually subdivided into small regions of interest (ROIs) resulting in 998 ROIs. (4) Whole brain tractography is performed providing an estimate of axonal trajectories across the entire white matter. (5) ROIs identified in step (3b) are combined with result of step (4) in order to compute the connection weight between each pair of ROIs. The result is a weighted network of structural connectivity across the entire brain.
(2006) optogenetics Thanks to molecular tinkering and new fiber-optic devices that deliver light deep into the brain via an implant, researchers can use optogenetics to study the effect of neural stimulation on different behaviors in live animals. To make neurons sensitive to light, scientists genetically engineer them to carry a protein adapted from green algae. When the modified neuron is exposed to light, via the fiber-optic implant, the protein triggers electrical activity within the cell that spreads to the next neuron in the circuit. The technology allows scientists to control neural activity much more precisely than previous methods, which generally involved delivering electrical current through an electrode. Optogenetics is allowing scientists to tackle major unanswered questions about the brain, including the role of specific brain regions in the formation of memory, the process of addiction, and the transition from sleep to wakefulness. Scientists are also using optogenetics to study depression, another disease that can be treated with electrical stimulation.
(2009) Myth-busting: Can brain scans read your mind? In the last few years, patterns in brain activity have been used to successfully predict what pictures people are looking at, their location in a virtual environment or a decision they are poised to make. The most recent results show that researchers can now recreate moving images that volunteers are viewing - and even make educated guesses at which event they are remembering. Some researchers, and some new businesses, are banking on fMRI to reveal hidden thoughts, such as lies, truths or deep desires. This is very foolish of them because scanning is NOT capable of mind reading (because the program can't decode any images or memories that it hasn't already been trained on). You can't stick somebody in a scanner and know what they're thinking. You can record what they're thinking and then tell if they are thinking about the same sort of thing when you record them again. One of the most dubious ways new imaging developments are being used by society is in the courtroom through claims of 'mind reading' and the detection of mental states. While courts accepting traditional GSR lie detector, or polygraph, tests was bad enough (they are just too unreliable to be certain) there are now a number of companies claiming to use neuroscience methods to detect lies. Some of these methods involve EEG, which has already been used in two forensic techniques which have appeared in courtrooms: brain fingerprinting and brain electrical oscillations signature (BEOS). Brain fingerprinting claims to test for 'guilty knowledge,' or memory of a kind that only a guilty person could have, which is completely unrealistic with current tech (2010). Other forms of hypothetical guilt detection, using functional magnetic resonance imaging (fMRI), are based on the assumption that lying and truth-telling are associated with distinctive activity in different areas of the brain. This is also extremely unreliable. The premature use of insufficiently accurate technology in justice issues is a dangerous development and it could lead to serious problems.
Damage Repair & Prevention
For drugs & supplements used in damage repair & prevention, see “drugs & chemicals” section of the library. For methods, see “Methods & Technology Introduction - Part I: Methods” (this section).
Surgery Brain surgery is a very emotive subject because quite naturally people feel uneasy about a surgeon interfering with such a vital organ! However, even though surgeons obviously have to be extremely skilled to do brain surgery, most of the brain withstands surgery very well. Brain tumors are the most emotive conditions affecting the brain that may need surgery but contrary to popular fear, the combination of tumor and brain is not necessarily a fatal one. Over a third of all brain tumors are benign and a further third are very slow-growing and do not spread much. The days of drills and hacksaws are also over. Gamma knife stereotactic radiosurgery is a well-established treatment method used to treat several conditions or diseases affecting the brain. More than 30,000 patients in the United States alone are treated with Gamma Knife radiosurgery each year. The Gamma Knife, however, isn’t a knife at all. It uses gamma rays produced by 201 cobalt-60 sources to precisely target and destroy abnormalities within the brain. The result is like a pinpoint of radiation so small and powerful it can reach the specific part of the brain that needs treatment without destroying healthy surrounding tissue. The doctor makes no incisions in you head and the treatment itself is painless. Cerebral aneurysm repair has come along somewhat too. A promising new alternative to open surgery is the use of inventional neuroradiology to treat aneurysms. The greatest advantages to this technique are that it is less invasive and requires less recovery time in most patients. This technique is also more effective than craniotomy for certain positions of aneurysms or for patients that have complicating conditions that would make them unable to tolerate the stress of the more traditional surgery. The decision of whether an aneurysm should be treated surgically with a clip or through inventional neuroradiological techniques is usually made as a team by the neurosurgeon and the endovascular radiologist. Inventional neuroradiology, also known as endovascular neuroradiology, utilizes fluoroscopic angiography, described above as a diagnostic imaging technique. Besides delivering the contrast material, the catheter can be used to place small coils, known as Gugliemlimi detachable coils, within the neck of the aneurysm using a delivery wire. Once the coil has been maneuvered into place, an electrical charge is sent through the delivery wire. This charge disintegrates the stainless steel of the coil, separating it from the delivery wire, which is removed from the body, leaving the coil. Anywhere from one to 30 coils may be necessary to block the neck of the aneurysm from the normal circulation and obliterate it, as occurs with the clip procedure. Although more research is needed to compare the two procedures, recent results indicate that intervention surgery for ruptured aneurysms may be safer than the traditionally more invasive procedure and may increase the chances of survival without disability after SAH.
Tech for electrical or chemical brain stimulation As well as presenting stimuli to the sense organs, it is also possible to stimulate the brain directly using electricity or chemicals [e.g. drugs such as alcohol]. In this way, direct stimulation can Be said to bypass the sensory systems. Chemicals, e.g., drugs, can be ingested [i.e., eaten or drunk], or injected, either into the bloodstream or directly into the brain. Drugs in the bloodstream are transported throughout the body and brain, so their place of action is not controlled. Even if the only part of the body which an detect and respond to injected chemicals is the brain, as is the case with mood-altering and stimulant drugs such as valium or amphetamine, the site/s of action within the brain remain uncontrolled. Many chemicals in the bloodstream cannot come into contact with neurons in the brain because of the Blood-brain barrier [formed from the tight junctions between endothelial cells].
An alternative and very precise method of delivering a chemical to the brain is with Microinjections. Very thin stainless steel needles can be pushed through an opening in the skull, into the brain and used to inject tiny quantities of chemicals into a ventricle, or a very small area of the brain. If required, the needles can be attached to minipumps to ensure continual infusion. It is even possible to inject chemicals to influence individual neurons, using very fine glass tubes, called micropipettes. This technique is called Microiontophoresis.
Electricity Can be used to stimulate the brain directly. The small electrical contacts that are used to deliver the electricity are called Electrodes, whether they are on the skull, on the surface of the brain or inside the brain. If the electrodes are on the surface of the skull, then any electrical impulse is both reduced in strength and dispersed by the skull before it can enter the brain. Such external electrodes therefore can deliver only a rather imprecise impulse. Also, the skull hinders the passage of electricity through it, a property known as impedance. To overcome the impedance of the skull, the electrical impulse needs to be relatively large. A large, imprecise electrical impulse is not a suitable stimulus for studying the finer workings of the brain. However, it is a suitable stimulus if the intention is to create excessive neuronal activity, a seizure. A violent electrical storm in the brain may seem an odd thing to want to induce; it is after all what happens in epilepsy, and epilepsy is very unpleasant. The reason for inducing a seizure, usually just in the non-speech-dominant hemisphere, used to be [and in some places still is] to treat depression. This treatment was called ECT [ElectroConvulsive Therapy].
Electrodes On the surface of the brain can deliver a small, localised impulse, but only to areas of the brain exposed by the removal of the overlying skull. This technique of Direct Electrical Cortical Stimulation [DECS] has been used to map the function of some parts of the surface of the brain and has proved particularly valuable where electrical stimulation produces specific movements of parts of the body, e.g., the fingers. More precision is possible, and smaller electrical currents can be used, when the electrodes are very thin tungsten wires. These Microelectrodes can be pushed deep into the brain through a suitable opening in the skull. The tungsten wire is insulated except for its extreme tip where a small electric current can stimulate a small, localised area of the brain or even individual cells.
One difficulty of using micropipettes and microelectrodes is in knowing where the tip is within the brain. This difficulty can be partly overcome by positioning the head in a stereotaxic frame. Markings on the frame enable the tip to be guided to a designated three-dimensional location in the brain. Alternatively, the tip can be watched and visually guided to its location using imaging machines, e.g., X-Ray scanners. A third option is to mark the position of the tip, for example by releasing a small amount of dye from the micropipette. This technique has the considerable limitation of requiring the direct examination of the brain at autopsy, where the dye can be seen and the position of the tip established.
Electricity can be induced in wires by using magnets. The same principle can be applied to the nervous system, where neurons, or more specifically, their axons, are the ‘wires’. By applying a suitable, focused pulse of magnetism it is possible to induce electrical activity in a small group of neurons in the brain. This procedure of Transcranial Magnetic Stimulation [TMS] is non-invasive and is completely reversible.
TENS units In Transcutaneous Electrical Neural Stimulation (TENS) small voltages are run across, for example, an aching joint, to stimulate healing and endorphin release. Makers of TENS and CES electro-stimulation hardware recommend against using their devices if you have a pacemaker or other built-in electronics, for the fairly obvious reason that the current might interfere with your existing circuitry. Also, TENS and CES hardware are supposed to be available in America only by prescription to persons under a doctor's supervision.
Cranial electrical stimulation (CES) Also called Cranial Electrostimulation or Cerebral Electrical Stimulation. This technology currently requires FDA approval and prescription in the US. There are some units that are available which are not FDA registered. These devices, often with electrodes attached to each ear lobe, or using a headband, will produce an almost instant mellow, relaxed state. CES is the direct feeding of low level electric impulses into the brain. Usually via a harness placed directly around the crown of the head. Some units may place a clip on your ear and feed current in that manner. Already used in many clinics to alleviate anxiety, treat depression and many other ailments, there is strong evidence to suggest that CES is effective. You typically use this device for thirty to sixty minutes for thirty to sixty days. CES seems to stimulate neurons to release neurochemicals such as endorphins, serotonin, norepinephrine and dopamine; all of which are associated with memory, learning and other cognitive abilities. CES may have an effect on the reticular activating system; the part of the brain that assesses input to moderate our state of alertness and general sense of consciousness and arousal. CES may stimulate parts of the brain that have taken a backseat to more dominant units of an individuals brain. This strengthening of the brain as a whole allows you to utilize the entire brain as a resource as opposed to some stronger, some weaker components. There is evidence that CES can increase brain functioning by stimulating parts of the brain not functioning at peak.
Implants
Brain implants Have been in use since 1997 to ease the symptoms of such diseases as epilepsy, Parkinson's Disease and recently depression. Current brain implants are made from a variety of materials such as tungsten, silicon, platinum-iridium, or stainless steel. Some implants are artificial devices used to replace or improve the function of an impaired nervous system, these are known as neural prostheses. The first neuroprosthetic in widespread use was the cochlear implant, with replacements for aspects of the visual system coming a close second. At the time of writing [2010] the first feasible brain-computer interface devices and memory replacement implants are just coming into being, bringing help for the paralysed and disabled, and those with brain injury or disease causing memory loss. However, as with the history of prosthetic limbs, it is likely to be some time before any technological replacement outperforms the biological original when in good working order.
Microelectrodes & DBS Are increasingly being used in the treatment of movement disorders, such as the rigidity and tremor caused by Parkinson’s disease. The treatment is called Deep Brain Stimulation [DBS] and has proved an effective alternative to drug therapy. DBS uses an implanted microelectrode to deliver continuous high-frequency electrical stimulation to either the thalamus, or the globus pallidus; one of the structures comprising the basal ganglia. Permanently implanted electrodes are also used to stimulate the spinal cord. Low-frequency electrical stimulation of the dorsal column is used to treat severe and intractable pain.
The positioning of the electrodes in DBS is done empirically; the patient is awake and the electrode tested, i.e., an appropriate amount of current is passed through it, until the location that the patient says best reduces the symptoms [tremor or rigidity in the case of Parkinson’s disease] is found. It’s a bit like getting someone to scratch an itch on your back, but you can’t give them directions on where to scratch [the patient does not know where the electrode is], only how successful the scratching is [how much the symptoms are reduced].
Microdermals (or “surface anchors”, or simply “anchors”) are a design of body jewelry that allows for a “single point” piercing. That is, a piercing that has only one visible end or bead. So for example, for decoration it allows one to place a single gemstone in a third eye position, and because of its design, no invasive procedure is required to implant it — it does not have the complexity of implantation of a transdermal implant (although it may have some of the complexity of removal). In addition, its versatile nature makes it an excellent tool for unusual formations of piercings as of course any number may be placed. Since their introduction as a prototype by Custom Steel at APP 2006, microdermals have been used by neurohackers as better connections for electrodes and CES clips, etc.
Brain-Machine Interface or brain/computer interface (BCI) Don't believe any of the hype that these have only recently been developed! 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 simulate movement, eventually enabling the patient to control a computer cursor in 1997. The first artificial hand using a BCI was achieved in 2005 as part of the first nine-month human trial of Cyberkinetics Neurotechnology’s BrainGate chip-implant. The 96-electrode implant allowed the user to control a robotic arm by thinking about moving his hand as well as a computer cursor, lights and TV. In 2006 professor Jonathan Wolpaw developed a Brain Computer Interface with electrodes located on the surface of the skull, instead of directly in the brain.
Development is rapid, both on the hardware side, where multielectrode recordings from more than 300 electrodes permanently implanted in the brain are currently state-of-the art, and on the software side, with computers learning to interpret the signals and commands. Early experiments on humans have shown that it is possible for profoundly paralyzed patients to control a computer cursor using just a single electrode implanted in the brain, and experiments have demonstrated that the kind of multielectrode recording devices used in monkeys would most likely also function in humans. Experiments in localized chemical release from implanted chips also suggest the possibility of using neural growth factors to promote patterned local growth and interfacing.
Non invasive BCI There have also been experiments using non invasive neuroimaging technologies as interfaces. Signals recorded in this way have been used to power muscle implants and restore partial movement in an experimental volunteer. Although they are easy to wear, non-invasive implants produce poor signal resolution because the skull dampens signals. Although the waves can still be detected it is more difficult to determine the area of the brain that created them or the actions of individual neurons. Some designs are used in gaming; these are not usually accurate enough for clinical use although they may be useful for basic biofeedback.
You can view some of the latest gaming BCIs on wikipedia: http://en.wikipedia.org/wiki/Comparison_of_Consumer_Brain-Computer_Interface_Devices
Since the original demonstration that electrical activity generated by ensembles of cortical neurons can be employed directly to control a robotic manipulator, research on brain–machine interfaces (BMIs) has experienced an impressive growth. Today BMIs designed for both experimental and clinical studies can translate raw neuronal signals into motor commands that reproduce arm reaching and hand grasping movements in artificial actuators.
(2008) Technology-assisted autonomy is inching closer to reality, with software that can determine what vowel and consonants a person is thinking of by recording activity from the surface of the brain. The system has about a 50-to-70% accuracy rate.
Wireless BCI By implanting an electrode into the brain of a person with locked-in syndrome, scientists have demonstrated how to wirelessly transmit neural signals to a speech synthesizer. The "thought-to-speech" system is “telemetric” - it requires no wires or connectors passing through the skin, eliminating the risk of infection. Instead, the electrode amplifies and converts neural signals into frequency modulated (FM) radio signals. These signals are wirelessly transmitted across the scalp to two coils, which are attached to the volunteer’s head using a water-soluble paste. The coils act as receiving antenna for the RF signals. The implanted electrode is powered by an induction power supply via a power coil, which is also attached to the head. The signals are then routed to an electrophysiological recording system that digitizes and sorts them. The sorted spikes, which contain the relevant data, are sent to a neural decoder that runs on a desktop computer. The neural decoder’s output becomes the input to a speech synthesizer, also running on the computer. Finally, the speech synthesizer generates synthetic speech (in the current study, only three vowel sounds were tested). The entire process takes about 50 milliseconds - the same amount of time for a non-paralyzed, neurologically intact person to speak their thoughts. The study marks the first successful demonstration of a permanently installed, wireless implant for real-time control of an external device.
Brain to brain (B2B) A research experiment used one person using BCI to transmit thoughts, translated as a series of binary digits, over the internet to another person whose computer receives the digits and transmits them to the second user's brain through flashing an LED lamp. While attached to an EEG amplifier, the first person generates and transmits a series of binary digits, imagining moving their left arm for zero and their right arm for one. The second person is also attached to an EEG amplifier and their PC picks up the stream of binary digits and flashes an LED lamp at two different frequencies, one for zero and the other one for one. The pattern of the flashing LEDS is too subtle to be picked by the second person, but it is picked up by electrodes measuring the visual cortex of the recipient. The encoded information is then extracted from the brain activity of the second user and the PC can decipher whether a zero or a one was transmitted. This shows true brain-to-brain activity.
Another B2B method is being explored using megnetic fields created by TMS. The method places two different people at a distance and puts a circular magnetic field around both, making sure they are connected to the same computer so they get the same stimulation, then if you flash a light in one person’s eye the person in the other room receiving just the magnetic field will show changes in their brain as if they saw the flash of light. (They will not be aware of this consciously).
Clearly, these developments hold promise for the restoration of limb mobility in paralyzed subjects. However, several problems remain in brain-machine interface currently [2010]. These include designing a fully implantable biocompatible wireless recording /transmitting device, further developing methods for providing the brain with sensory feedback from the actuators, and designing and building better prostheses that can be controlled directly by brain-derived signals. Future BMIs will be able to drive and control revolutionary prostheses that feel and act like the human arm.
By providing access to unconscious physiological information about which a person is generally unaware, biofeedback or neurofeedback allows users to gain control over physical or mental processes previously considered uncontrollable or automatic. This involves measuring a subject's bodily or brain processes such as blood pressure, heart rate, skin temperature, galvanic skin response (sweating), muscle tension, brainwave production etc., and conveying this information to them in real-time in order to raise their awareness and conscious control of the related states of mind and/or physiological activities.
Short history of Biofeedback tech. Biofeedback has been around for over 30 years, with a history that stretches back, when you include its roots in yoga and meditation, for millennia. The more recent history of biofeedback reflects the development of each of the different physiological modalities most often measured: John Basmajian pioneered EMG electromyography for muscle activity measurement in fifties and sixties, with articles in Science magazine. He showed how people could learn to voluntarily control the firing of single cells in the spinal cord. He used fine wire electrodes placed in muscles in his steps toward developing the EMG rehabilitation model of biofeedback. Elmer Green and Ed Taub both were involved in developing thermal or temperature biofeedback. Elmer was at the Menninger foundation, studying Shultz and Luthe’s Autogenic Training. They discovered that a migraine patient’s headache went away when she warmed her hands during autogenic training. They figured out how to use temperature biofeedback to teach hand warming to prevent and abort migraine headaches. Ed Taub, at the Institute for Behavioral Research researched the use of thermal feedback for raynauds, a disorder in which sufferers experience painful cold, blanching hands when exposed to cold, even air conditioning. Joe Kamiya pioneered the use of EEG electroencephalographic or brainwave biofeedback [neurofeedback]. His early colleague, Jim Hardt, published essential research in Science Magazine, proving that people could voluntarily control alpha brain waves with eyes closed. Other early pioneers in the EEG field include Max Cade, who worked with people such as yogis, gurus, executives and athletes. Cade is no longer living, but he trained Anna Wise, who wrote The High Performance Mind. Barry Sterman developed, with NIH and military funding, the use of EEG biofeedback with intractable epilepsy cases. Joel Lubar took Sterman’s model and developed EEG biofeedback for Attention Deficit Disorder Elmer Green and his wife Alyce, at the Menninger Foundation, developed alpha theta training. Green has described it as "instrumental Vipassana" which enables the individual to access the mind’s unconscious, (which he calls ‘planetary consciousness’ or ‘universal intelligence’.) He’s used this approach to ask questions of the unconscious mind (planetary or ‘universal intelligence’), and not surprisingly gets useful answers he could not have come up with intellectually or through conscious logic. What is really going on (no offense intended, cosmic dudes) is the longer periods of time spent using alpha/gamma switchover enable faster memory defragging and faster access to what is being defragged (it has the same effect as meditating or going to bed concentrating on a problem and waking up with new insights in the morning -intelligence has caught up with itself, or if you like, the software is given time to complete its run and the brain has caught up with the mind). Gene Penniston developed an alpha-theta protocol used to treat alcoholism and substance abuse. Tom Budzynski, Johann Stoyva and Charles Adler first reported the use of EMG biofeedback for relaxation training, and first developed audio biofeedback. Budzynski now often presents on the use of biofeedback to enhance mental functioning, particularly in the aging.
There are several biofeedback societies, AAPB, SSNR, and the Winter Brain Meeting specializing in biofeedback and the beginnings of a movement to establish a biofeedback ‘profession’. There is also the Biofeedback Certification Institute of America, with a general and an EEG Certification. Practising bio/neurofeedback does not require licensure [yet!]. But if we are working with or teaching others, it does require high levels of competence. The user of the instrumentation must be able to competently operate the equipment and understand the principles, techniques and approaches of biofeedback in an informed, effective way.
Types of bio/neurofeedback technology:
An electromyogram [EMG] Uses electrodes or other types of sensors to measure muscle tension. By the EMG alerting you to muscle tension, you can learn to recognize the feeling early on and try to control the tension right away. EMG is mainly used as a relaxation technique to help ease tension in those muscles involved in backaches, headaches, neck pain and grinding your teeth (bruxism). An EMG may be used to treat some illnesses in which the symptoms tend to worsen under stress, such as high blood pressure [hypertension], asthma and ulcers.
Peripheral Skin Temperature monitors Sensors attached to your fingers or feet measure your skin temperature. Because body temperature often drops when a person experiences stress, a low reading can prompt you to begin relaxation techniques. Temperature biofeedback can help treat certain circulatory disorders, such as Raynaud's disease, or reduce the frequency of migraines. The physiological process behind the temperature drop associated with the stress response is quite simply vasoconstriction (blood vessels narrowed by the smooth musculature in their walls)
Galvanic skin response monitors [GSR] Sensors measure the activity of your sweat glands and the amount of perspiration on your skin, alerting you to anxiety. This information can be useful in treating emotional disorders such as phobias, anxiety and stuttering. This is also the method most commonly used by lie detector machines. It is the most popular form of biofeedback, with over 500,000 hand-held GSR2 units having been purchased by consumers since the early 70's; it is also one of the biofeedback methods used by the video game series Journey to Wild Divine.
Electroencephalography (EEG) An EEG monitors the activity of brain waves linked to different mental states, such as wakefulness, relaxation, calmness, light sleep and deep sleep. This is the least common of the methods, mostly due to the higher cost of an EEG machine. However, enthusiasts have built their own versions of all of the above machines for lower cost than their commercial availability. Commercial games using neurofeedback are not yet accurate enough (2010) for clinical use (although if you can ascertain exactly what they are measuring they can be of some use in biofeedback).
‘Mind Machines’ "Mind machines" describes a whole range of technologies that work directly or indirectly on your mind, but when people say ‘mind machines’ they are usually referring to light & sound or electrical machines for bio/neurofeedback and training. Different techniques use different technology: 1. Direct, unadulterated feedback: Your own body signals or brainwaves are translated into an onscreen graph, or light/sound display and you learn through playing around how to alter them [in biofeedback, the blood pressure for example can be indicated by a rising tone and the person can reduce the pitch by relaxing and lowering the blood pressure, or the heartbeat is amplified and the person learns to slow it down by becoming more calm]. This method uses EEG, GSR, MCG and light & sound machines.
2. Frequency Response for input control: Whether using pulsing sounds or vibrations or strobing/flashing lights, the idea is to mimic the current state of the body or the current brainwave frequency and then to alter the frequency [which the brain then copies]. This also works in biofeedback if, for example a recording of the heartbeat is played and then slowed down; the body will keep pace [which is why dance music speeds up the heartbeat even if one is sitting still]. This method also uses EEG, GSR, MEG and light & sound machines, and also music and color therapy and other forms of input control [see “Methods” section].
Frequency response can also be used without the original state being represented at all [e.g. the practitioner is just presented with the frequency of the desired state of mind, but this is not as effective as initialising a shift from the current state into the desired one.
Input control with tech You can make your own input software very easily by recording music that begins in the tempo of an elevated heartbeat and slowly reducing the tempo. Listening to it will reduce your heartrate, blood pressure and shift your brainwave pattern to a slower rhythm. If the brain is given healthy input it will copy it. This means if we present the brain with an example of healthy brainwave patterns that it can detect, it will change its own patterns accordingly. This can be achieved with some biofeedback tech; notably light/sound machines with example presets such as the Proteus, and NMS devices (which work precisely by doing this). Many of these devices can induce particular brainwave patterns that correlate with different types of neurotransmitter release. This does not mean that one 'causes' the other; rather both are induced as a result of many types of input, and either can induce the other. Every individual is different, so it would be difficult to chart all correlations between brain activity, behavior and neurotransmission, however there are some basics that affect us all that can be used in NH. If you learn enough about correlations in the brain you will be able to use this tech to its extremes.
A quick introduction to brainwave frequencies:
· Sub-delta and Delta (<4 Hz) occur in deep sleep · Theta (4-8 Hz) occurs when a person is asleep and dreaming, sometimes with REM and/or hypnagogic imagery. · Alpha (8-12 Hz) is associated with meditation, unconscious awareness, focused alertness and relaxed mindfulness· ‘SMR’ (13-15 Hz) stands for Sensory Motor Rhythm and is associated with alert, focused relaxation, with very quiet muscles. A cat produces SMR when it silently, with perfect stillness, watches a mouse hole.
· ‘Mu waves', also known as the comb or wicket rhythm, are an alpha wave-like variant of in the frequency range of 8–13 Hz, and appear in bursts of at 9 – 11 Hz. Mu wave patterns arise from synchronous and coherent (in phase/constructive) electrical activity of large groups of neurons in the brain. This wave activity is diminished with movement or an intent to move, or when others are observed performing actions. EEG oscillations in the mu wave range over the sensorimotor cortex are thought to reflect mirror neuron activity. · Beta (15-30 Hz) Alert, cognitive awareness; in conscious thought mode. · Gamma (>30) Normal awareness, but sometimes also occurs during meditation [usually when performed by long-term practitioners]
NOTE * These are a rough guide only and because everyone is different you should accept plus or minus several Hz for these measurements in some individuals.
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