Abstracts & Publications
A list of resources and associated links.

For tDCS Publications & Abstracts, click here.
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For Ultra Low Field MRI Publications & Abstracts, click here.


tDCS Links

tDCS Publications

TDCS guided using fMRI significantly accelerates learning to identify concealed objects
Neuroimage. 2012 Jan 2;59(1):117-28. Epub 2010 Nov 19.
TDCS guided using fMRI significantly accelerates learning to identify concealed objects. Clark VP, Coffman BA, Mayer AR, Weisend MP, Lane TD, Calhoun VD, Raybourn EM, Garcia CM, Wassermann EM.
Mind Research Network, Albuquerque, NM 87106, USA.

The accurate identification of obscured and concealed objects in complex environments was an important skill required for survival during human evolution, and is required today for many forms of expertise. Here we used transcranial direct current stimulation (tDCS) guided using neuroimaging to increase learning rate in a novel, minimally guided discovery-learning paradigm. Ninety-six subjects identified threat-related objects concealed in naturalistic virtual surroundings used in real-world training. A variety of brain networks were found using functional magnetic resonance imaging (fMRI) data collected at different stages of learning, with two of these networks focused in right inferior frontal and right parietal cortex. Anodal 2.0 mA tDCS performed for 30 min over these regions in a series of single-blind, randomized studies resulted in significant improvements in learning and performance compared with 0.1 mA tDCS. This difference in performance increased to a factor of two after a one-hour delay. A dose-response effect of current strength on learning was also found. Taken together, these brain imaging and stimulation studies suggest that right frontal and parietal cortex are involved in learning to identify concealed objects in naturalistic surroundings. Furthermore, they suggest that the application of anodal tDCS over these regions can greatly increase learning, resulting in one of the largest effects on learning yet reported. The methods developed here may be useful to decrease the time required to attain expertise in a variety of settings.
Transcranial direct current stimulation (tDCS)
Neurosci Lett. 2011 Aug 1;500(1):67-71. Epub 2011 Jun 12.
Transcranial direct current stimulation (tDCS) produces localized and specific alterations in neurochemistry: a ¹H magnetic resonance spectroscopy study.
Clark VP, Coffman BA, Trumbo MC, Gasparovic C.
Source: Department of Psychology, University of New Mexico, Albuquerque, NM 87131, USA.
Transcranial direct current stimulation (tDCS) has been found to produce significant changes in behavior, including a large increase of learning and performance for a difficult visual perceptual task (Clark et al., NeuroImage 2010). The mechanisms by which tDCS produces these behavioral effects are currently uncertain. One hypothesis is that anodal tDCS leads to increased metabolic activity in the brain, which enhances cognitive and memory processes. Here we examined the neuronal mechanisms by which tDCS influences learning by measuring changes in brain metabolite concentrations using proton magnetic resonance spectroscopy (¹H MRS). As perception and learning can also influence neurochemistry, here we applied tDCS during rest. MRS data was obtained before and after 2.0 mA of anodal tDCS was applied for 30 min over electrode site P4, with the cathode placed on the contralateral arm. MRS data were acquired from the right parietal lobe beneath the anodal tDCS electrode, and from the homologous regions of the left hemisphere once before and once after tDCS. Significantly higher combined glutamate and glutamine levels were found in right parietal cortex, beneath the stimulating electrode, with non-significant increases in homologous regions of the opposite hemisphere. In addition, a significant interaction between hemispheres was found for tDCS effects on tNAA. These results suggest that changes in glutamatergic activity and tNAA may be related to the mechanisms by which tDCS influences learning and behavior.
PMID: 21683766 [PubMed - indexed for MEDLINE]
Impact of tDCS on performance and learning of target detection
Neuropsychologia. 2012 Jun;50(7):1594-602. Epub 2012 Mar 19.
Impact of tDCS on performance and learning of target detection: interaction with stimulus characteristics and experimental design.
Coffman BA, Trumbo MC, Flores RA, Garcia CM, van der Merwe AJ, Wassermann EM, Weisend MP, Clark VP.
Source: The Mind Research Network and Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM 87131-2006, USA.
We have previously found that transcranial direct current stimulation (tDCS) over right inferior frontal cortex (RIFC) enhances performance during learning of a difficult visual target detection task (Clark et al., 2012). In order to examine the cognitive mechanisms of tDCS that lead to enhanced performance, here we analyzed its differential effects on responses to stimuli that varied by repetition and target presence, differences related to expectancy by comparing performance in single- and double-blind task designs, and individual differences in skin stimulation and mood. Participants were trained for 1h to detect target objects hidden in a complex virtual environment, while anodal tDCS was applied over RIFC at 0.1 mA or 2.0 mA for the first 30 min. Participants were tested immediately before and after training and again 1h later. Higher tDCS current was associated with increased performance for all test stimuli, but was greatest for repeated test stimuli with the presence of hidden-targets. This finding was replicated in a second set of subjects using a double-blind task design. Accuracy for target detection discrimination sensitivity (d'; Z(hits)-Z(false alarms)) was greater for 2.0 mA current (1.77) compared with 0.1 mA (0.95), with no differences in response bias (?). Taken together, these findings indicate that the enhancement of performance with tDCS is sensitive to stimulus repetition and target presence, but not to changes in expectancy, mood, or type of blinded task design. The implications of these findings for understanding the cognitive mechanisms of tDCS are discussed.
Transcranial direct current stimulation augments perceptual sensitivity
PLoS One. 2012;7(4):e34993. Epub 2012 Apr 12.
Transcranial direct current stimulation augments perceptual sensitivity and 24-hour retention in a complex threat detection task.
Falcone B, Coffman BA, Clark VP, Parasuraman R.
Center of Excellence in Neuroergonomics, Technology, and Cognition (CENTEC), George Mason University, Fairfax, Virginia, United States of America.
We have previously shown that transcranial direct current stimulation (tDCS) improved performance of a complex visual perceptual learning task (Clark et al. 2012). However, it is not known whether tDCS can enhance perceptual sensitivity independently of non-specific, arousal-linked changes in response bias, nor whether any such sensitivity benefit can be retained over time. We examined the influence of stimulation of the right inferior frontal cortex using tDCS on perceptual learning and retention in 37 healthy participants, using signal detection theory to distinguish effects on perceptual sensitivity (d') from response bias (ß). Anodal stimulation with 2 mA increased d', compared to a 0.1 mA sham stimulation control, with no effect on ß. On completion of training, participants in the active stimulation group had more than double the perceptual sensitivity of the control group. Furthermore, the performance enhancement was maintained for 24 hours. The results show that tDCS augments both skill acquisition and retention in a complex detection task and that the benefits are rooted in an improvement in sensitivity (d'), rather than changes in response bias (ß). Stimulation-driven acceleration of learning and its retention over 24 hours may result from increased activation of prefrontal cortical regions that provide top-down attentional control signals to object recognition areas.
PMID: 22511978 [PubMed - in process] PMCID: PMC3325218

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Oral Orthotics

Oral Orthotic Publications

Suppression of movement disorders by jaw realignment.
Pain Med. 2012 May;13(5):731-2. doi: 10.1111/j.1526-4637.2012.01364.x. Epub 2012 Apr 11.
Suppression of movement disorders by jaw realignment.
Sims AB, Clark VP, Cooper MS.
PMID: 22494698
It is well established that movement disorders can develop from peripheral nerve injury in the craniocervical region. Here, we discuss how mechanical realignment of the jaws and temporomandibular joints (TMJs) can be used to rapidly suppress a number of movement disorders, some of which may have been precipitated by peripheral nerve injury near the TMJ.
Related information and videos of treated patients.
Neuroinflammation, Neuroautoimmunity, and the Co-Morbidities of Complex Regional Pain Syndrome.
J Neuroimmune Pharmacol. 2012 Aug 25. [Epub ahead of print]
Neuroinflammation, Neuroautoimmunity, and the Co-Morbidities of Complex Regional Pain Syndrome.
Cooper MS, Clark VP.
Complex Regional Pain Syndrome (CRPS) is associated with non-dermatomal patterns of pain, unusual movement disorders, and somatovisceral dysfunctions. These symptoms are viewed by some neurologists and psychiatrists as being psychogenic in origin. Recent evidence, however, suggests that an autoimmune attack on self-antigens found in the peripheral and central nervous system may underlie a number of CRPS symptoms. From both animal and human studies, evidence is accumulating that neuroinflammation can spread, either anterograde or retrograde, via axonal projections in the CNS, thereby establishing neuroinflammatory tracks and secondary neuroinflammatory foci within the neuraxis. These findings suggest that neuroinflammatory lesions, as well as their associated functional consequences, should be evaluated during the differential diagnosis of non-dermatomal pain presentations, atypical movement disorders, as well as other "medically unexplained symptoms", which are often attributed to psychogenic illness.

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Ultra Low Field MRIs
Physics Flash - Michelle Espy
SQUIDs vs. Induction Coils
Matlashov AN, Schultz LJ, Espy MA, Kraus RH, Savukov IM, Volegov PL, Wurden CJ.
IEEE Trans Appl Supercond. 2011;21(3):465-468.
PMID: 21747638[PubMed]
Free PMC Article
Non-cryogenic anatomical imaging
Savukov I, Karaulanov T, Castro A, Volegov P, Matlashov A, Urbatis A, Gomez J, Espy M.
J Magn Reson. 2011 Aug;211(2):101-8. Epub 2011 Jun 1.
PMID: 21700482 [PubMed - indexed for MEDLINE]
Free PMC Article
Related Citations
Magnetic Resonance Relaxometry at Low and Ultra low Fields

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