Brain imaging is a fairly recent discipline within medicine and neuroscience. Brain imaging falls into two broad categories -- structural imaging and functional imaging. The former deals with the overall structure of the brain and the precise diagnosis of intracranial disease and injury. The latter is used for neurological and cognitive science research and building brain-computer interfaces. It enables, for example, the processing of sensory information coming to the brain and of commands going from the brain to the organism to be "lit up" or visualized directly instead of by simple clinical inference. Medicine is a branch of health science concerned with maintaining health and restoring it by treating disease. ... Neuroscience is a field of study which deals with the structure, function, development, genetics, biochemistry, physiology, pharmacology and pathology of the nervous system. ... A direct mind-computer interface or direct neural interface is literally that - a direct cybernetic link between a mind and a computer. ... Senses are the physiological methods of perception. ... In biology and ecology, an organism (in Greek organon = instrument) is a living being. ...

Brain imaging was honored in a US Postal Service Stamp

Types of brain imaging

CAT

Computed axial tomography (CT or CAT) scanning uses a series of x-rays of the head taken from many different directions. Typically used for quickly viewing brain injuries, CT scanning has a computer program that uses a set of algebraic equations to estimate how much x-ray is absorbed in a small area within a cross section of the brain (Jeeves 21). In the final analysis, the harder a material is, the whiter it will appear on the scan. CT scans are primarily used for evaluating swelling from tissue damage in the brain and in assessment of ventricle size. Modern CT scanning exposes the subject to about as much radiation as a single x-ray and can provide reasonably good images in a matter of minutes. CT apparatus in a hospital Computed axial tomography (CAT), computer-assisted tomography, computed tomography, CT, or body section roentgenography is the process of using digital processing to generate a three-dimensional image of the internals of an object from a large series of two-dimensional X-ray images taken around... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... Algebra is a branch of mathematics which may be roughly characterized as a generalization and extension of arithmetic, in which symbols are employed to denote operations, and letters to represent number and quantity; it also refers to a particular kind of abstract algebra structure, the algebra over a field. ...

MRI

Magnetic Resonance Imaging (MRI) uses magnetic fields and radio waves to produce high quality two- or three-dimensional images of brain structures without injecting radioactive tracers. During an MRI, a large cylindrical magnet creates a magnetic field around the head of the patient through which radio waves are sent. When the magnetic field is imposed, each point in space has a unique radio frequency at which the signal is received and transmitted (Preuss). Sensors read the frequencies and a computer uses the information to construct an image. The detection mechanisms are so precise that changes in structures over time can be detected. Using MRI, scientists can create images of both surface and subsurface structures with a high degree of anatomical detail. MRI scans can produce cross sectional images in any direction from top to bottom, side to side, or front to back. The problem with original MRI technology was that while it provides a detailed assessment of the physical appearance of the brain, it fails to provide information about how well the brain is working at the time of imaging. The distinction is now made between MRI imaging and functional imaging since the brain's function rather than the brain's structure is of interest. Magnetic Resonance Image Magnetic resonance imaging (MRI) - also called magnetic resonance tomography (MRT) - is a method of creating images of the inside of opaque organs in living organisms as well as detecting the amount of bound water in geological structures. ... Magnetic lines of force of a bar magnet shown by iron filings on paper A magnet is an object that has a magnetic field. ... Current flowing through a wire produces a magnetic field (M) around the wire. ... Radio frequency, or RF, refers to that portion of the electromagnetic spectrum in which electromagnetic waves can be generated by alternating current fed to an antenna. ... Anatomical drawing of the human muscles from the Encyclopédie. ...

PET

Positron Emission Tomography (PET) measures emissions from radioactively labeled chemicals that have been injected into the bloodstream and uses the data to produce two or three-dimensional images of the distribution of the chemicals throughout the brain (Nilsson 57). The positron emitting radioisotopes used are produced by a cyclotron and chemicals are labelled with these radioactive aroms. The labeled compound, called a radiotracer, is injected into the bloodstream and eventually makes its way to the brain. Sensors in the PET scanner detect the radioactivity as the compound accumulates in different regions of the brain. A computer uses the data gathered by the sensors to create multicolored two or three-dimensional images that show where the compound acts in the brain. Positron emission tomography (PET) is a nuclear medicine medical imaging technique which produces a three dimensional image or map of functional processes in the body. ... A positron is the antiparticle of the electron. ... A radionuclide is an atom with an unstable nucleus. ... 60-inch cyclotron, circa 1939, showing beam of accelerated ions (perhaps protons or deuterons) escaping the accelerator and ionizing the surrounding air causing a blue glow. ...

The greatest benefit of PET scanning is that different compounds can show blood flow and oxygen and glucose metabolism in the tissues of the working brain. These measurements reflect the amount of brain activity in the various regions of the brain and allow us to learn more about how the brain works. PET scans were superior in terms of resolution and speed of completion (as little as 30 seconds) when they first came online. The improved resolution permitted better judgments to be made as to the area of the brain activated by a particular task. The biggest drawback of PET scanning is that because the radioactivity decays rapidly, it is limited to monitoring short tasks (Nilsson 60). Before fMRI technology came online, PET scanning was the preferred method of brain imaging, and it still continues to make large contributions to neuroscience. A space-filling model of glucose Glucose, a simple monosaccharide sugar, is one of the most important carbohydrates and is used as a source of energy in animals and plants. ... Santorio Santorio (1561-1636) in his steelyard balance, from Ars de statica medecina, first published 1614 Metabolism (from μεταβολισμος(metavallo), the Greek word for change), in the most general sense, is the ingestion and breakdown of complex compounds, coupled with the liberation of energy, and the consequent generation of waste... Neuroscience is a field of study which deals with the structure, function, development, genetics, biochemistry, physiology, pharmacology and pathology of the nervous system. ...

SPECT

SPECT is similar to PET. Single photon emission computed tomography (SPECT) uses gamma ray emitting radioisotopes and a gamma camera to record data that a computer uses to construct two- or three-dimensional images of active brain regions (Ball). SPECT tracers are considered to be more limited than PET scanners in the kinds of brain activity they have the ability to monitor. SPECT tracers are longer lasting than those of PET, which allows for different, longer lasting brain functions to be examined, but this also requires more time for the SPECT scan to be completed. The resolution of a SPECT is poor (about 1 cm) compared to that of PET. SPECT (Single Photon Emission Computed Tomography) is a nuclear medicine tomographic imaging technique using gamma rays. ... This article is about electromagnetic radiation. ... A radionuclide is an atom with an unstable nucleus. ... A gamma camera is a medical imaging device used in nuclear medicine. ...

MEG

Magnetoencephalography (MEG) is similar to EEG, but magnetic fields are measured instead of electric fields. Magnetoencephalography (MEG) is the measurement of the magnetic fields produced by electrical activity in the brain, usually conducted externally, using extremely sensitive devices such as SQUIDs. ...

fMRI

Functional MRI (fMRI) relies on the magnetic properties of blood to enable scientists to see images of blood flow in the brain as it occurs. This mapping of blood flow allows for dynamic brain mapping to take place (Shorey). During the test, the subject is normally asked to perform a repetitive motion like tapping a finger or tapping a foot. FMRI has taken the place of PET scanning as the king of brain imaging because fMRI can produce images of the brain every second, and scientists can determine with great precision when brain regions become active and for how long. Also, fMRI has such high resolution that it can distinguish structures less than a millimeter apart. This allows scientists to know exactly which areas of the brain are being activated. PET, however, retains the significant advantage of being able to identify which brain receptors are being activated by neurotransmitters, drugs, and potential treatment compounds. Functional Magnetic Resonance Imaging (or fMRI) describes the use of MRI to measure hemodynamic signals related to neural activity in the brain or spinal cord of humans or other animals. ... Red blood cells (erythrocytes) are present in the blood and help carry oxygen to the rest of the cells in the body Blood is a circulating tissue composed of fluid plasma and cells (red blood cells, white blood cells, platelets). ... Neurotransmitters are chemicals that are used to relay, amplify and modulate electrical signals between a presynaptic and a postsynaptic neuron. ...

Drawbacks of fMRI are few but substantial at this point. First, it takes quite a bit of time to perform the procedure and the patient needs to be completely still for often more than twenty minutes at a time. Second, and more importantly, interpretations of fMRI results are still vague. It is difficult to determine if the subject was thinking about something that caused certain parts of the brain to activate, if the scanner picked up real data or noise, and so on (Shorey). For these and other reasons, fMRI technology has begun to be combined with EEG technology.

History

See main article History of brain imaging The history of brain imaging, began in the early 1900s with a technique called pneumoencephalography. ...

In 1918 the American neurosurgeon Walter Dandy introduced the technique of ventriculography whereby X-ray images of the ventricular system within the brain were obtained by injection of filtered air directly into one or both lateral ventricles of the brain. Dandy also observed that air introduced into the subarachnoid space via lumbar spinal puncture could enter the cerebral ventricles and also demonstrate the cerebrospinal fluid compartments around the base of the brain and over its surface. This technique was called pneumoencephalography. In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... The ventricular system is a fluid conducting system within the brain. ... Pneumoencephalography is a painful and now obsolete medical procedure in which cerebrospinal fluid is drained from around the brain and replaced with air to allow the structure of the brain to show up more clearly on an X-ray picture. ...

In 1927 Egas Moniz, professor of neurology in Lisbon, introduced cerebral angiography, whereby both normal and abnormal blood vessels in and around the brain could be visualized with great accuracy. António Caetano de Abreu Freire Egas Moniz (November 29, 1874 - December 13, 1955) was a Portuguese physician and neurologist. ... Lisbon (in Portuguese, Lisboa) is the capital and largest city of Portugal. ... 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, veins and the heart chambers. ...

In the early 1970s, Allan McLeod Cormack and Godfrey Newbold Hounsfield brought about the use computerized axial tomography (CAT or CT scanning), and ever more detailed anatomic images of the brain became available for diagnostic and research purposes. Cormack and Hounsfield won the 1979 Nobel Prize for Physiology or Medicine for their work. Soon after the introduction of CAT, the development of radioligands allowed single photon emission computed tomography (SPECT) and positron emission tomography (PET). Allan McLeod Cormack (February 1924 - May 7, 1998) was a South Africa-born American physicist who shared a part of the 1979 Nobel Prize in Physiology or Medicine for his work on the computerized axial tomography (CAT) scan. ... Sir Godfrey Newbold Hounsfield (28 August 1919 - 12 August 2004) was an English electrical engineer who shared the 1979 Nobel Prize for Physiology or Medicine with Allan McLeod Cormack for his part in developing the diagnostic technique of computerized axial tomography (CAT). ... CAT apparatus in a hospital Computed axial tomography (CAT), computer-assisted tomography, computed tomography, CT, or body section roentgenography is the process of using digital processing to generate a three-dimensional image of the internals of an object from a large series of two-dimensional X-ray images taken around... List of Nobel Prize laureates in Physiology or Medicine from 1901 to the present day. ... A radioligand is a radioactive biochemical substance that is used to study the receptor systems of the brain. ... SPECT (Single Photon Emission Computed Tomography) is a nuclear medicine tomographic imaging technique using gamma rays. ... Positron emission tomography (PET) is a nuclear medicine medical imaging technique which produces a three dimensional image or map of functional processes in the body. ...

More or less concurrently, magnetic resonance imaging (MRI or MR scanning) was developed by researchers including Peter Mansfield and Paul Lauterbur, who were awarded the Nobel Prize for Physiology or Medicine in 2003. During the 1980s a veritable explosion of technical refinements and diagnostic MR applications took place. Scientists soon learned that the large blood flow changes measured by PET were also imaged by MRI. Functional magnetic resonance imaging (fMRI) was born. Since the 1990s, fMRI has come to dominate the brain mapping field due to its low invasiveness, lack of radiation exposure, and relatively wide availability. Magnetic Resonance Image Magnetic resonance imaging (MRI) - also called magnetic resonance tomography (MRT) - is a method of creating images of the inside of opaque organs in living organisms as well as detecting the amount of bound water in geological structures. ... Sir Peter Mansfield FRS, (born October 9, 1933), is a British physicist who was awarded the 2003 Nobel Prize in Physiology or Medicine for his discoveries concerning magnetic resonance imaging (MRI). ... Paul Christian Lauterbur, (born May 6, 1929) is an American chemist who shared the Nobel Prize in Physiology or Medicine in 2003 with Peter Mansfield for his work which made the development of magnetic resonance imaging (MRI) possible. ... List of Nobel Prize laureates in Physiology or Medicine from 1901 to the present day. ... Functional Magnetic Resonance Imaging (or fMRI) describes the use of MRI to measure hemodynamic signals related to neural activity in the brain or spinal cord of humans or other animals. ...

In early 2000s the field of brain imaging reached the stage where limited practical applications of functional brain imaging became feasible. The main application area is crude forms of brain-computer interface. A direct mind-computer interface or direct neural interface is literally that - a direct cybernetic link between a mind and a computer. ...

See also

• functional neuroimaging
• Human Cognome Project
• medical imaging
• statistical parametric mapping

Functional neuroimaging is the use of brain imaging technology to measure an aspect of brain function, often with a view to understanding the relationship between activity in certain brain areas and specific mental functions. ... The Human Cognome Project seeks to reverse-engineer the human brain, parallelling in many ways the Human Genome Project and its success in deciphering the human genome. ... Medical imaging is the process by which physicians evaluate an area of the subjects body that is not normally visible. ... Statistical parametric mapping or SPM is a statistical technique for examining differences in brain activity recorded during functional neuroimaging experiments using brain imaging technologies such as fMRI or PET. It may also refer to a specific piece of software created by the Wellcome Department of Imaging Neuroscience (part of University...

Works cited

• Ball, Philip. "Brain Imaging Explained." Online at http://www.nature.com/nsu/010712/010712-13.html
• Beaumont, J. Graham. Introduction to Neuropsychology. New York: The Guilford Press, 1983. 314 pages.
• Changeux, Jean-Pierre. Neuronal Man: The Biology of Mind. New York: Oxford University Press, 1985. 348 pages.
  • Jeeves, Malcom. Mind Fields: Reflections on the Science of Mind and Brain. Grand Rapids, MI: Baker Books, 1994. 141 pages.
• Johnson, Keith A. "Neuroimaging Primer." [1] (http://www.med.harvard.edu/AANLIB/hms1.html)
• Leventon, Michael. "Transcranial Magnetic Stimulation." In assosiation with MIT AI Lab. [2] (http://www.ai.mit.edu/projects/medical-vision/surgery/tms.html)
• Lister, Richard G. and Herbert J. Weingartner. Perspectives on Cognitive Neuroscience. New York: Oxford University Press, 1991. 508 pages.
• Mattson, James and Merrill Simon. The Pioneers of NMR and Magnetic Resonance in Medicine. United States: Dean Books Company, 1996. 838 pages.
• Nilsson, Lars-Goran and Hans J. Markowitsch. Cognitive Neuroscience of Memory. Seattle: Hogrefe & Huber Publishers, 1999. 307 pages.
• Norman, Donald A. Perspectives on Cognitive Science. New Jersey: Ablex Publishing Corporation, 1981. 303 pages.
• Pande, G.C. "Neurosciences and Philosophy." [3] (http://www.iias-library.org/Dissemination%20of%20knowledge%20series/Neuroscience%20and%20Philosphy.htm)
• Rapp, Brenda. The Handbook of Cognitive Neuropsychology. Ann Arbor, MI: Psychology Press, 2001. 652 pages.
• Shorey, Jamie. "Foundations of fMRI." [4] (http://www.ee.duke.edu/~jshorey/MRIHomepage/MRImain.html)