Neuroimaging
From Biohack
Contents |
MRI (Magnetic Resonance Imaging)
http://www.biologynews.net/archives/2008/06/03/gene_that_magnetically_labels_cells_shows_potential_as_imaging_tool.html -- so subcellular resolution in neuroscience would be interesting for a number of reasons.
Winnipeg homegrown portable MRI
http://www.cbc.ca/news/story/2000/04/28/mb_mri042800.html
Manitobans
An MRI Machine On Every Desktop
http://io9.com/321928/an-mri-machine-on-every-desktop
You'll be taking pictures of your brain while checking email with new, consumer-grade magnetic resonance imaging (MRI) machines developed by an Israeli company called Aspect Technologies. Yesterday the company announced a six million dollar cash infusion from a secret US investor. Usually getting an MRI is very expensive, and can only be done in a hospital, but now Aspect Technologies might make these machines into fancy bio-feedback devices that you could use to see which part of your brain is active when you are stressed — and which parts light up when you have an orgasm.
Just as people who do bio-feedback can train themselves to calm down, you could train yourself to have extra-intense orgasms by learning what it is you're doing when your brain shows the most intense orgasms occurring. Think I'm kidding? Rutgers University professor Barry Komisaruk has suggested that this would be an ideal use for home MRI machines. Not to mention that they can help you locate damage in carpal tunnel syndrome, and figure out exactly where there's blockage in your hands to make the circulation so bad in your fingers. Someday, MRI machines will be as common in the home as thermometers are today. Image by MAURICIO LIMA via Getty.
fMRI (functional Magnetic Resonance Imaging)
1.5 teslas ... hm.
EROS (Event Related Optical Signal)
http://en.wikipedia.org/wiki/Event_Related_Optical_Signal
http://answers.google.com/answers/threadview?id=433034
http://www.nmr.mgh.harvard.edu/PMI/research/probe-central.htm - mechanical design of the optical probes
Gratton, G. and M. Fabiani, Shedding light on brain function: the event-related optical signal. Trends in Cognitive Sciences, 2001. 5(8): p. 357-363.
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 diffuse optical imaging (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 provide a much more direct measure of cellular activity. EROS can pinpoint activity in the brain within millimeters (spatially) and within milliseconds (temporally). Currently, its biggest limitation is the inability to detect activity more than a few centimeters deep, which thus limits this fast optical imaging to the cerebral cortex. EROS is a new, relatively inexpensive technique that is non-invasive to the test subject. It was developed at the University of Illinois at Urbana-Champaign where it is now used in the Cognitive Neuroimaging Laboratory of Dr. Gabriele Gratton and Dr. Monica Fabiani.
A central focus of the research conducted in our Lab is the integration of different neuroimaging methods including fast optical (EROS), optical spectroscopy (NIRS), functional MRI (fMRI) and evoked potentials (ERPs). By combining different methods we get a more complete picture of the physiological events that occur in the brain during information processing. Optical methods, which record both neuronal signals (EROS) and slower signals related to hemodynamic activity (NIRS), play a pivotal role in this endeavor. We have developed techniques for the alignment of measurements obtained with different techniques as well for the software integration of the different signals.
http://cnl.beckman.uiuc.edu/research_topics.html
Our laboratory uses near-infrared light to study two distinct signals the brain produces in response to stimuli and cognitive activity; the Event Related Optical Signal (EROS), and Near InfraRed Spectroscopy (NIRS). The measurement of the optical parameters can be conducted non-invasively by using near-infrared (NIR) light which penetrates several cm inside the head. With appropriate methodologies it is possible to focus the measurements to relatively small areas (less than 1 cc) and to distinguish signals from different depths. This yields very good spatial resolution. Other advantages of these techniques are safety (because only a very small amount of non-ionizing radiation is used), relatively low cost, and versatility.
EROS is based on the measurement of the changes in optical parameters (scattering and absorption) of active neurons. Some of these changes occur very rapidly, simultaneously with the electrical activity of the neurons. For this reason EROS has very good temporal resolution. For this reason, EROS can be used to analyze the relative timing of activity in different areas, to study the order of recruitment of different cortical areas, and to examine the connections between areas. These are all questions that are difficult to study with other brain imaging methods. Due to its high temporal resolution, EROS allows the use of the full range of paradigms normally used in cognitive psychology.
NIRS is a widely used technique which measures changes in the absorption of two (or more) wavelengths of light, and allows detection and quantification of changes in the concentration of oxy and deoxy-hemoglobin resulting from brain activity. These relatively slow changes (taking several seconds) are also the basis for fMRI measurements, but NIRS is able to separately estimate changes in blood volume and hemoglobin concentration, which fMRI is not able to do. Because NIRS and EROS measurements can be made simultaneously and they measure virtually identical tissue regions, they provide unique opportunities for studying the relation between neuronal activity and the hemodynamic response.
We routinely record EROS, NIRS and ERPs simultaneously. EROS and NIRS are also compatible with functional magnetic resonance imaging (fMRI) and we are developing methods for making these measurements simultaneously.
Current limitations of EROS include its shallow penetration (~3-4 cm), which makes it particularly useful for studying cortical (rather than sub-cortical) activity, and its signal-to-noise ratio, which typically requires averaging data across a number of subjects. The development of EROS is one of the major lines of research in our Lab, and has been funded by the National Institute of Mental Health. Additional relevant research in this area is conducted at the Laboratory for Fluorescence Dynamics (LFD, University of California, Irvine), directed by Dr. Enrico Gratton.
http://cnl.beckman.uiuc.edu/mri_fmri.html
We use MRI images of brain anatomy in several ways. First, we coregister our EROS, NIRS and ERP data to each subjects MRI brain image in order to accurately determine which brain structures are being measured. We also make quantitative measurements of the size of various brain structures to see how their variation across subjects correlates with both behavior and with optical and electrical responses. In addition we are exploring the use of Diffusion Tensor Imaging (DTI) to trace fiber tracts in the brain, which can be compared to the functional connectivity maps derived from EROS measurements. Finally, we are investigating the utility of using MRI images to model the optical properties of each subject's head and brain in order to improve the spatial localization and resolution of optical measurements.
Functional Magnetic Resonance Imaging is an established technique which provides images with very good spatial resolution (0.5 cm or less) and has a temporal resolution of the order of .5 to 5 seconds, depending on the situation. Thus, whereas its temporal resolution is inferior to that of ERPs and EROS, the spatial information it provides is excellent. For this reason, MRI and fMRI provide data that effectively compliments that from optical measurements.
