Neurocognition & Performance Technologies
Volume 002 -- Issue 007 -- July, 2008
| Age-Dependent Changes in Gene Expression | June, 2008 |
Genetic mutations are linked with several human diseases, but many other human diseases do not have a strong genetic component. One burgeoning field of study known as epigenetics examines the contributory role of altered gene expression on disease susceptibility. The hypothesis is that over- or under-expression of a normal gene can generate a pathological state. Rate of gene expression is influenced by changes in the topography of DNA superstructure brought about by the addition or removal of methyl and acetyl groups. One recent paper by a group of researchers at Johns Hopkins University, Hjartavernd in Iceland, the Karolinska Institute of Sweden, the National Institute on Aging, the University of Utah, and Temple University Medical School, investigated whether epigenetic modification of the genome changes over time within an individual. Results of this study showed that the degree of DNA methylation within an individual changes over time and can either increase or decrease. The pattern of change over time was consistent within families, suggesting a commonality of genetics or environment. The authors suggest that changes in epigenetics over time may play a role in age-related disease onset, although additional research will be necessary.
References
- Bjornsson, H., M. Sigurdsson, et al. (2008). "Intra-individual Change Over Time in DNA Methylation with Familial Clustering." JAMA 299(24): 2877-2883.
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| Real Time Imaging of Intracranial Blood Flow | June, 2008 |
A real-time portable imaging device capable of detecting localized brain hemorrhage would be of great value on the battlefield, or for early assessment of stroke. A group of researchers led by Stephen Smith at Duke University has prototyped the first real-time contrast-enhanced transcranial ultrasound device. The researchers simultaneously piloted an online analysis method to correct for phase aberration of the signal due to skull thickness inconsistencies. The ultrasound device records a 65 degree pyramid-of-view taken through the suboccipital or temporal windows of the skull. When a contrast agent was applied intravascularly, major blood vessels were clearly recognizable in 51-71% of the subjects, including visible blood flow changes during breathing and across heartbeats. The authors were confident that within 5-10 years this technology will provide a reliable portable method for the detection of intracranial bleeding, for use in ambulances and on the battlefield.
References
- Ivancevich, N. M., G. F. Pinton, et al. (2008). "Real-Time 3-D Contrast-Enhanced Transcranial Ultrasound and Aberration Correction." Ultrasound Med Biol.
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| Caffeine + Carbs Post-Exercise Restores Muscle Glycogen | May, 2008 |
A team of researchers led by John A. Hawley of the RMIT University in Australia has determined that high levels of caffeine combined with carbohydrate consumption post-exercise increases muscle glycogen levels at the fastest recorded physiological rate recorded (58 mmol/kg dry weight/hour). This resynthesis rate is 66% higher than control (carbohydrates alone). Seven trained endurance cyclists were exercised to exhaustion on a stationary ergometer at 70% VO2 peak. Immediately following the trial, 4 mg/kg body mass caffeine was administered, and the same amount was given after 2 hours. Carbohydrates in the form of sports bars, gels, and energy drinks, were administered to each participant immediately after exercise, and at 1, 2, and 3 hours post-exercise, for a total of 4 g/kg body mass. Glycogen accumulation in biopsied muscle tissue was equivalent between control and experimental groups after 1 hour, but showed a dramatic increase in the caffeine + carbohydrate group at the 4 hour mark. This study represents the first evidence that caffeine can increase glycogen production in skilled athletes after rigorous exercise, and stands in contrast to the negative effects of caffeine on glycogen resynthesis in inactive persons.
References
- Pedersen, D. J., S. J. Lessard, et al. (2008). "High Rates of Muscle Glycogen Resynthesis after Exhaustive Exercise When Carbohydrate Is Co-Ingested with Caffeine." J Appl Physiol.
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| Multispectral MRI Contrast Agents | June, 2008 |
Magnetic Resonance Imaging (MRI) frequently is frequently combined with the use of intravenous contrast agents to provide a monochromatic image of higher resolution. Traditional contrast agents are composed of paramagnetic metal composites that generate micro magnetic fields, but these fields are variable in size and strength. A team of researchers led by Alan Koretsky at the National Institute of Neurological Disorders and Stroke has recently developed a novel approach to contrast agents. The microfabricated agents are comprised of two gold-coated nickel discs held a certain distance apart by non-paramagnetic spacers. A radio-frequency pulse characteristic of each tracer type can then stimulate a uniform magnetic field between the discs; adjusting the distance between the tracer discs alters the frequency at which the internal water particles are excited. Because water molecules are free to diffuse in and out of the central cavity of the contrast agent, using repeated radio-frequency pulses affects a large volume of water molecules that happen to pass through the inter-disc gap during each pulse; this characteristic results in "diffusion-driven signal enhancement," thereby permitting a low concentration of tracer to be used. Multiple tracer types of different geometries can be administered simultaneously to produce a "colored" image wherein the reading from each tracer is assigned a different color profile. Before it can provide clinical utility, the novel tracer must be miniaturized and tested for biocompatibility. The authors foresee that the best application of this technology will be to create different tracers with unique tissue targeting properties to produce a multispectral MRI highlighting different tissue types.
References
- Zabow, G., S. Dodd, et al. (2008). "Micro-engineered local field control for high-sensitivity multispectral MRI." Nature 453(7198): 1058-63.
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| Intravenous PEG Improves TBI Outcome | June, 2008 |
Several studies have described the salutary effects of polyethylene glycol (PEG) treatments in repairing or preventing neuronal damage due to traumatic brain injury (TBI) in animal models. These treatments were administered directly on the wound or intravenously. Recently, a group of researchers headed by Richard Borgens from Purdue University showed that intravenous PEG following TBI in male rats results in marked retention of locomotor abilities following a brain impact acceleration injury known to impair movement. Indeed, when PEG was administered within 0-4 hours post-TBI, injured animals exhibited near-normal locomotor behaviors, measured via the parameters of speed, exploration time, and distance traveled. The researchers are currently testing PEG in naturally injured canines and intend to seek approval for human trials.
References
- Koob, A. O., J. M. Colby, et al. (2008). "Behavioral recovery from traumatic brain injury after membrane reconstruction using polyethylene glycol." J Biol Eng 2(1): 9.
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| Smart Clothing Records EMG | July, 2008 |
With the objective of developing a clothing system capable of continuous electromyography (EMG) and electrocardiography (ECG) measurements, the ConText Project funded by the European Union includes members from Phillips Research, Technische Universitat Berlin, Katholieke Universiteit Leuven, Textile Research Institute Thuringia-Vogtlandia, Netherlands Organisation for Applied Scientific Research, and Clothing Plus Oy. The result is a vest incorporating capacitive EMG sensors formed of embroidered conductive threads (silver coated polyamide ELITEX® fibers, TITV), including a conductive ribbon in the neckline that serves as a ground to reduce noise. The sensors function even when the vest is worn over an intervening shirt. ConText currently has two prototyped items incorporating EMG. The first is a vest wherein the EMG sensors are situated over the trapezius muscle. Because tension of back and neck muscles (including the trapezius) during heavy cognitive (mental) workloads is a sign of high stress, remote monitoring of Operator stress levels may be possible. This vest can also monitor the early warning signs of repetitive strain injury. The second offering is a prototype EMG vest that can interface with video game systems, with potential application for postural/procedural training. Due to the high motion artifact associated with capacitive sensors, this dry portable EMG system is not currently feasible for high mobility/military applications, although a ConText spokesman believes that it may become possible with future developments. ConText is also working on a system designed to aid field hockey coaches assess the skills of their players. This vest employs inertial sensor technology to record directional motion and posture of the player, and a ground plate to sense speed accuracy of hitting the ball.
References
- Taelman, J., T. Adriaensen, et al. (2007). "Textile integrated contactless EMG sensing for stress analysis." Conf Proc IEEE Eng Med Biol Soc 2007: 3966-9.
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| Interconnectivity Map of the Human Cortex | July, 2008 |
In diffusion spectrum imaging (DSI), the movement of water molecules in the brain is detected by recording the effects of a pulsed magnetic field gradient on water-based protons. Water molecules moving along the corridor provided by a nerve fiber exhibit different relaxation time to the magnetic field than water moving randomly via Brownian motion within a nexus of neuronal cell bodies. This unique characteristic makes it possible to visualize nerve fiber pathways in the cranium. Researchers from the University of Lausanne and the Ecole Polytechnique Federale de Lausanne in Switzerland, Indiana University, and Harvard Medical School have just published a study mapping for the first time the normative nerve fiber interconnectivity of the human cortex. The primary investigator, Olaf Sporns of Indiana University, and his team of collaborators used DSI to determine nodes and relative density of cortical nerve fiber connectivities. Subsequent network analysis revealed a suite of brain areas that had the highest degree of connectivity, forming what the authors termed the "structural core," including primarily the posterior medial and parietal cortex as well as small discrete temporal and frontal contributory regions. The core regions also exhibited the highest resting metabolic activity, measured by functional magnetic resonance imaging (fMRI). The resulting atlas of brain fiber tractography will be an essential tool for comparing nerve networks in psychiatric and pathological conditions with a normal baseline, and for informing theoretical models of functional brain activity networks.
References
- Hagmann, P., L. Cammoun, et al. (2008). "Mapping the Structural Core of Human Cerebral Cortex." PLoS Biol 6(7): e159.
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