College of Health and Human Services

Spatially explicit data pose a series of opportunities and challenges for all the actors involved in providing data for long-term preservation and secondary analysis-the data producer, the data archive, and the data user. We report on opportunities and challenges for each of the three players, and then turn to a summary of current thinking about how best to prepare, archive, disseminate, and make use of social science data that have spatially explicit identification. The core issue that runs through the paper is the risk of the disclosure of the identity of respondents. If we know where they live, where they work, or where they own property, it is possible to find out who they are. Those involved in collecting, archiving, and using data need to be aware of the risks of disclosure and become familiar with best practices to avoid disclosures that will be harmful to respondents.

As parents, we take our kids along on our journeys, without them exactly knowing what they are getting into. I began my Ph.D. when my son, John, was 7 and he is now 12. Much of his life thus far has involved sacrifice so that I could finish this degree. He was always cheerful, helpful, entertaining, and understanding. The greatest cost was his, I am forever indebted, and I pledge to make it count. My study participants were a constant source of inspiration and I am very grateful for their willingness to participate, for their faith in me, and for the intervention participants, their resolve to attend sessions during Michigan's polar vortex. I am also grateful for program's cohort model and the support of my fellow students, who are now friends and colleagues. I would additionally like to thank my committee members for their valuable suggestions and edits, and Amy Curtis, who helped during early planning. Thanks also to Nickola Nelson, for her encouragement and guidance. The Michigan Parkinson Foundation (MPF) supported this work through the 2015 Raymond Bauer Research Award. Winning this award was a great inspiration, and I could not have completed the project in the way that I was able without the financial support provided by the award. Thanks especially to Karen Freshwater, MPF professional advisory board member, who encouraged me to apply for the award and provided valuable assistance throughout the project. The Blue Cross Blue Shield of Michigan Foundation also provided a grant that offset equipment cost.

When data are made available to others to analyze for their purposes, steps must be taken to ensure confidentiality, that is to prevent the identities of the persons or institutions that were studied are not disclosed and cannot be deduced. Disclosure risk analysis is conducted in order to create a public--use file (PUF) from confidential, or restricted--use, data. Based on this analysis of disclosure risks, statistical disclosure limitation (SDL) methodologies are applied to the data to create the PUF. The public--use file (PUF) is the only version of the microdata to which most researchers ever have access and the version from which much of the utility of the data is extracted. Therefore, decisions made to create the PUF, in terms of variable changes (e.g., deletions, recodes) and the selection of statistical disclosure limitation (SDL) methods (e.g., data swapping, imputation collapsing categories) are very important and must match the key intended purposes of the data collection and the disclosure risk. Typically, decisions regarding disclosure risk are made after data collection is completed. This article will describe a new model for conducting disclosure risk analysis for the creation of PUFs that moves decisions regarding disclosure risk to the beginning of the survey research process. Early thinking and decision--making regarding disclosure risk can lead to a more analytically useful PUF and the most optimal set of data products that can be developed (tables, maps, online analysis, and so on, in addition to the PUF). Efficiencies created between the various stages of the research process by the model will shorten the time between data collection and data release, thus increasing the value of the shared data to secondary analysts and to science.

Posture and postural reactions to mechanical perturbations require the
harmonic modulation of the activity of multiple muscles. This precision can become suboptimal in the presence of neuromuscular disorders and result in higher fall risk and associated levels of comorbidity. This study was designed to investigate neurophysiological principles related to the generation and distribution of inputs to skeletal muscles previously recognized as a synergistic group. Specifically, we investigated the current hypothesis that correlated neural inputs, as measured by intermuscular coherence, are the mechanism used by the central nervous system to coordinate the formation of postural muscle synergies. This hypothesis was investigated by analyzing the strength and distribution of correlated neural inputs to postural muscles during the execution of a quiet stance
task. Nine participants, 4 females and 5 males, mean age 29.2 years old (±6.1 SD), performed the task of standing while holding a 5-kg barbell in front of their bodies at chest level. Subjects were asked to maintain a standing position for 10 s while the activity of three postural muscles was
recorded by surface electrodes: soleus (SOL), biceps femoris (BF), and lumbar erector spinae (ERE). EMG–EMG coherence was estimated for three muscle pairs (SOL/BF, SOL/ERE, and BF/ERE). Our choice of studying these muscles was made based on the fact that they have been reported as components of a functional (synergistic) muscle group that emerges during the execution of bipedal stance. In addition, an isometric contraction can be easily induced in this muscle group by simply adding a weight to the body’s anterior aspect. The experimental condition elicited a significant increase in muscle activation levels for all three muscles (p < 0.01 for all muscles). EMG–EMG coherence analysis revealed significant coherence within two distinct frequency bands, 0–5 and 5–20 Hz. Significant coherence within the later frequency band was also found to be significantly uniformly distributed across the three muscle pairs. These findings are interpreted as corroborative with the idea of a hierarchic system of control where the controller may use the generation of common neural inputs to reduce the number of variables it manipulates.

We used the framework of the uncontrolled manifold hypothesis to study the coordination of body segments and eye movements in standing persons during the task of shifting the gaze to a target positioned behind the body. The task was performed at a comfortable speed and fast. Multi-segment and head–eye synergies were quantified as co-varied changes in elemental variables (body segment rotations and eye rotation) that stabilized (reduced the across trials variability) of head rotation in space and gaze trajectory. Head position in space was stabilized by co-varied rotations of body segments prior to the action, during its later stages,
and after its completion. The synergy index showed a drop that started prior to the action initiation (anticipatory synergy adjustment) and continued during the phase of quick head rotation. Gaze direction was stabilized only at movement completion and immediately after the saccade at movement initiation under the ‘‘fast” instruction. The study documents for the first time anticipatory synergy adjustments during whole-body actions. It shows multijoint synergies stabilizing head trajectory in space. In contrast, there was no synergy between head and eye rotations during saccades that would achieve a relatively invariant gaze trajectory.

Nine participants stood quietly for 30 s while the activity of the soleus, biceps femoris, lumbar erector spinae, tibialis anterior, rectus femoris, and rectus abdominis muscles were recorded using surface electrodes. Intermuscular (EMG-EMG) coherence was estimated for 12 muscle pairs formed by these muscles, including pairs formed solely by either posterior, anterior, or mixed (one posterior and one anterior) muscles. Intermuscular coherence was only found to be significant for muscle pairs formed solely by either posterior or anterior muscles, and no significant coherence was found for mixed muscle pairs. Significant intermuscular coherence was only found within a distinct frequency interval bounded between 1 and 10 Hz when visual input was available (OEs trials). The strength of correlated neural inputs was similar across muscle pairs located in different joints but executing a similar function (pushing body either backward or forward) suggesting that synergistic postural groups are likely formed based on their functional role instead of their anatomical location. Absence of visual information caused a significant decrease in intermuscular coherence. These findings are consistent with the hypothesis that correlated neural inputs are a mechanism used by the CNS to assemble synergistic muscle groups. Further, this mechanism is affected by interruption of visual input.