Brain Scanning
Published on Dec 01, 2015
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HAIKU DECK FINDS STUNNING IMAGES TO MATCH
The fMRI aims to use radio waves to measure its activity.It relies on the fact that blood at different parts of the body has a different magnetic resonance. The more active areas of the brain recieve more oxygenated blood and the fMRI picks up this increased blood flow to pinpoint greater activity.
Photo by onkel_wart (thomas lieser)
How does it work?
The MRI machine aims radio waves at the protons in the area. As the magnetic field hits the protons, they line up. The machine then starts releasing short bursts of radio waves that knock the protons out of their alignment. After this has ended the protons fall back in line and sends out signals that the MRI picks up. The protons in the area of oxygenated blood produce the strongest signals. A computer now uses these signals to create a 3D image of the brain.
MAGNETROPHENCEPHALOGRAPHY
MAGNETROOHENCEPHALOGRAPHY
More commonly known as MEG
MEG measures the magnetic fields generated by the neuronal activity of the brain. The spatial distributions of the magnetic fields are analyzed to laocalize the sources of activity within the brain. This is superimposed on anatomical images such as MRI to provide information about both the structure and function of the brain.
How does it work?
Magnetics fields are found whenever there is a current flow, whether in a wire or a neutronal element. The magnetic field passes unaffected through the brain tissue and the skull, so it can be recorded outside the head. The magnetic field is extremely small, but it can be detected by sophisticated sensors based on superconductivity.
MEG is a direct measure of brain function unlike fMRI, PET or SPECT. Events with time scales on the order of milliseconds can be resolved. It also has excellent spatial precision. MEG does not need injection of isotopes or exposure to Xrays or magnetic fields which makes it suitable for usage on children.
A PET scan uses radiation to produce a 3D, color image of the functional processes within the human brain. It can be used to diagnose a health condition as well as for finding out how an existing condition is devoloping. They are often used to see how effective an ongoing treatment is.
How does it work?
- RADIOTRACER: Before carrying out the scan, a radioactive medicine is produced in a machine called the cyclotron. The radioactive medicine is then tagged to a natural chemical such as glucose, water or ammonia. This is then injected into the patient.
- When inside the body, the tracer will to areas where the brain uses the natural chemical. A PET scan detects the energy emitted by positively-charged particles (positrons) created when the radiotracer is broken down. This energy appears as a 3D image.
CAT scanning is the process of using computers to generate a 3D image from a 2D X-ray image. It is very useful to get a very detailed image of the brain. CAT scans are usually the most preferred method of diagnosing brain tumors as its size and exact location can be measured, as well as how much it has affected the nearby tissue.
How does it work?
A CT scanner emits a series of narrow beams through the human brain as it moves through the arc. Inside the CT scanner there is an X-ray detector which can see hundreds of different levels of density. It can see tissues inside a solid organ. This data is transmitted to a computer, which builds up a 3D cross-sectional picture of the part of the body and displays it on the screen. The accuracy of a CT scan can be improved by using a spiral CT where the X-ray beam takes a spiral path during the scanning. This helps gather continuous data with no gaps between images.
ELECRTROENCEPHALOGRAPHY
Photo by scribbletaylor
EEG is the recording of electrical activity along the scalp. It measures the voltage fluctuations resulting from ionic current flows within the neurons of the brain. It is used in the diagnosis of coma and encephalopathies and also serves as an adjunct test of brain death.
How does it work?
The brains electrical charge is maintained by billions of neurons which is an electrically excitable cell that processes and transmitts signals through electrical and chemical signals. When a wave of ions reach the electrode on the scalp, they can push or pull electrons on the metal on the electrodes, The difference in push or pull voltages between any 2 electrodes can be measured and recording these voltages over time gives us the EEG.
iBrain
The iBrain was devised as the first EEG handset to monitor brain waves through a single channel only. It consists of a simple fabric headband that holds a tiny device containing a small electrode to the skull. Through the use of an algorithm formulated by Low, it reads brainwave activity and transmits it wirelessly back to a computor. With the help of this data, a person can for example, control virtual hands on a computer screen.
Brain Mapping
Brain mapping attempts to relate the brain's structure to its function. In mapping brain functions, scientists use imaging to watch the brain working on various tasks. Researchers must collect images of the brain, turn these images into data and then use the data to analyze what happens in the brain as it develops.
The iBrain was devised as the first EEG headset to monitor brainwaves through a single-channel only (though it is no longer the only single-channel EEG on the market). It consists of a simple fabric headband that holds a tiny device containing a small electrode to the skull, and it weighs less than a pack of cigarettes.
Through the use of an algorithm formulated by Low, the iBrain reads brainwave activity and transmits it wirelessly back to a computer. As Dr. Low points out, the iBrain can collect data regardless of where a person is or what they are doing. For this reason it is a welcome alternative to the masses of electrodes and wires that hospitals and sleep labs generally use when assessing a patients brain activity.
Hawking was fitted with the head-band device and asked to “imagine that he was scrunching his right hand into a ball.” While he can’t actually move his hand, the motor cortex in his brain can still issue the command and generate electrical waves in his brain. The algorithm then translates these thoughts into signals, which show up on the monitor as spikes on a grid. These signals are stored into the computer as a thought of scrunching right hand.
With the help of this stored data, Hawking can control the virtual hands on the screen. By simply imagining brain signal are generated, that are read by the iBrain resulting in the action on the virtual right hand.
With the help of iBrain paralyzed patients can control an electric wheelchair and make music using only the power of their minds.
Photo by Ben Grey
