Stepwise Stochastic Dictionary Adaptation Improves Microstructure Reconstruction with Orientation Distribution Function Fingerprinting.

Fitting of the multicompartment biophysical model of white matter is an ill-posed optimization problem. One approach to make it computationally tractable is through Orientation Distribution Function (ODF) Fingerprinting. However, the accuracy of this method relies solely on ODF dictionary generation mechanisms which either sample the microstructure parameters on a multidimensional grid or draw them randomly with a uniform distribution. In this paper, we propose a stepwise stochastic adaptation mechanism to generate ODF dictionaries tailored specifically to the diffusion-weighted images in hand. The results we obtained on a diffusion phantom and in vivo human brain images show that our reconstructed diffusivities are less noisy and the separation of a free water fraction is more pronounced than for the prior (uniform) distribution of ODF dictionaries.

Assessment of quantitative magnetic resonance imaging metrics in the brain through the use of a novel phantom.

OBJECTIVE: Multisite and longitudinal neuroimaging studies are important in uncovering trajectories of recovery and neurodegeneration following traumatic brain injury (TBI) and concussion through the use of diffusion tensor imaging (DTI) and other imaging modalities. This study assessed differences in anisotropic diffusion measurement across four scanners using a human and a novel phantom developed in conjunction with the Chronic Effects of Neurotrauma Consortium. METHOD: Human scans provided measurement within biological tissue, and the novel physical phantom provided measures of anisotropic intra-tubular diffusion to serve as a model for intra-axonal water diffusion. Intra- and inter-scanner measurement variances were compared, and the impact on effect size was calculated. RESULTS: Intra-scanner test-retest reliability estimates for fractional anisotropy (FA) demonstrated relative stability over testing intervals. The human tissue and phantom showed similar FA ranges, high linearity and large within-device effect sizes. However, inter-scanner measures of FA indicated substantial differences, some of which exceeded typical DTI effect sizes in mild TBI. CONCLUSION: The diffusion phantom may be used to better elucidate inter-scanner variability in DTI-based measurement and provides an opportunity to better calibrate results obtained from scanners used in multisite and longitudinal studies. Novel solutions are being evaluated to understand and potentially overcome these differences.

The Gastrointestinal Pain Pointer: A Valid and Innovative Method to Assess Gastrointestinal Symptoms.

Abdominal pain is a chronic condition experienced by approximately 20% of individuals in the United States. The purpose of the study was to assess the validity of the Gastrointestinal Pain Pointer as a measure of abdominal pain intensity. A prospective longitudinal time-series study design was utilized. The sample included 93 outpatients (58.1% female). Participants met Rome III criteria for irritable bowel syndrome (n = 32) or were healthy controls (n = 61). The Gastrointestinal Pain Pointer, a new electronic pain assessment tool, was used to assess self-reported abdominal pain intensity among participants before and after ingestion of an intestinal permeability test solution across 11 time points over a 5-hour time period. The results were compared with the Short-Form McGill Pain Questionnaire. The Gastrointestinal Pain Pointer was found to be valid in the assessment of abdominal pain intensity. The tool is a novel and valid measure of abdominal pain intensity that enhances the ability for clinicians to better quantify, in real time, patient-related pain outcomes for both clinical care and research.

Reducing audio stimulus presentation latencies across studies, laboratories, and hardware and operating system configurations.

Using differing computer platforms and audio output devices to deliver audio stimuli often introduces (1) substantial variability across labs and (2) variable time between the intended and actual sound delivery (the sound onset latency). Fast, accurate audio onset latencies are particularly important when audio stimuli need to be delivered precisely as part of studies that depend on accurate timing (e.g., electroencephalographic, event-related potential, or multimodal studies), or in multisite studies in which standardization and strict control over the computer platforms used is not feasible. This research describes the variability introduced by using differing configurations and introduces a novel approach to minimizing audio sound latency and variability. A stimulus presentation and latency assessment approach is presented using E-Prime and Chronos (a new multifunction, USB-based data presentation and collection device). The present approach reliably delivers audio stimuli with low latencies that vary by ≤1 ms, independent of hardware and Windows operating system (OS)/driver combinations. The Chronos audio subsystem adopts a buffering, aborting, querying, and remixing approach to the delivery of audio, to achieve a consistent 1-ms sound onset latency for single-sound delivery, and precise delivery of multiple sounds that achieves standard deviations of 1/10th of a millisecond without the use of advanced scripting. Chronos's sound onset latencies are small, reliable, and consistent across systems. Testing of standard audio delivery devices and configurations highlights the need for careful attention to consistency between labs, experiments, and multiple study sites in their hardware choices, OS selections, and adoption of audio delivery systems designed to sidestep the audio latency variability issue.

Computer assessment of mild cognitive impairment.

Many older individuals experience cognitive decline with aging. The causes of cognitive dysfunction range from the devastating effects of Alzheimer's disease (AD) to treatable causes of dysfunction and the normal mild forgetfulness described by many older individuals. Even mild cognitive dysfunction can impact medication adherence, impair decision making, and affect the ability to drive or work. However, primary care physicians do not routinely screen for cognitive difficulties and many older patients do not report cognitive problems. Identifying cognitive impairment at an office visit would permit earlier referral for diagnostic work-up and treatment. The Computer Assessment of Mild Cognitive Impairment (CAMCI) is a self-administered, user-friendly computer test that scores automatically and can be completed independently in a quiet space, such as a doctor's examination room. The goal of this study was to compare the sensitivity and specificity of the CAMCI and the Mini Mental State Examination (MMSE) to identify mild cognitive impairment (MCI) in 524 nondemented individuals > 60 years old who completed a comprehensive neuropsychological and clinical assessment together with the CAMCI and MMSE. We hypothesized that the CAMCI would exhibit good sensitivity and specificity and would be superior compared with the MMSE in these measures. The results indicated that the MMSE was relatively insensitive to MCI. In contrast, the CAMCI was highly sensitive (86%) and specific (94%) for the identification of MCI in a population of community-dwelling nondemented elderly individuals.

PsychMate: providing psychology majors the tools to do real experiments and learn empirical methods.

PsychMate is a set of software tools for undergraduate psychology students to run, develop, and analyze computerized experiments. It includes 30 psychological experiments in the areas of perception, cognition, social psychology, human factors, and cognitive neuroscience. Students run experiments themselves and see basic results immediately. The automatic spreadsheet analysis forms allow them to aggregate data and create analyses, presentations, and Web pages with a single click. Students can use the Psychology Experiment Authoring Kit experiment editor to create their own experiments in minutes and run experiments with other students using Web-based experiment-management tools. The BrainTutor and BrainViewer applications teach brain anatomy and permit students to analyze fMRI brain imaging data from subjects who have performed the same memory experiments in which they participated. PsychMate has been used in 83 classes in which 1,533 students submitted 5,464 completed experiments with few (less than 1%) requests for help and a very positive rating of the research experience.

Psychology Experiment Authoring Kit (PEAK): formal usability testing of an easy-to-use method for creating computerized experiments.

In academic courses in which one task for the students is to understand empirical methodology and the nature of scientific inquiry, the ability of students to create and implement their own experiments allows them to take intellectual ownership of, and greatly facilitates, the learning process. The Psychology Experiment Authoring Kit (PEAK) is a novel spreadsheet-based interface allowing students and researchers with rudimentary spreadsheet skills to create cognitive and cognitive neuroscience experiments in minutes. Students fill in a spreadsheet listing of independent variables and stimuli, insert columns that represent experimental objects such as slides (presenting text, pictures, and sounds) and feedback displays to create complete experiments, all within a single spreadsheet. The application then executes experiments with centisecond precision. Formal usability testing was done in two stages: (1) detailed coding of 10 individual subjects in one-on-one experimenter/subject videotaped sessions and (2) classroom testing of 64 undergraduates. In both individual and classroom testing, the students learned to effectively use PEAK within 2 h, and were able to create a lexical decision experiment in under 10 min. Findings from the individual testing in Stage 1 resulted in significant changes to documentation and training materials and identification of bugs to be corrected. Stage 2 testing identified additional bugs to be corrected and new features to be considered to facilitate student understanding of the experiment model. Such testing will improve the approach with each semester. The students were typically able to create their own projects in 2 h.