Caddoan Ceremonial Sites of the Caddoan Cultural Area of Arkansas, Louisiana, Oklahoma, and Texas: Draft Caddo National Landmark Nomination

Since 1997, we have been working on the development of a National Historic Landmark (NHL) cover nomination for Caddoan ceremonial sites - earthen mounds in the Caddoan cultural area of southwestern Arkansas, northwestern Louisiana, eastern Oklahoma, and northeastern Texas. Such a nomination establishes the historic context within which all similar cultural properties can be evaluated for significance according to the NHL criteria, as it establishes the research and other criteria by which a cultural property may be identified as a significant archeological resource

Evaluation of denoising strategies to address motion-correlated artifacts in resting-state functional magnetic resonance imaging data from the human connectome roject

Like all resting-state functional connectivity data, the data from the Human Connectome Project (HCP) are adversely affected by structured noise artifacts arising from head motion and physiological processes. Functional connectivity estimates (Pearson's correlation coefficients) were inflated for high-motion time points and for high-motion participants. This inflation occurred across the brain, suggesting the presence of globally distributed artifacts. The degree of inflation was further increased for connections between nearby regions compared with distant regions, suggesting the presence of distance-dependent spatially specific artifacts. We evaluated several denoising methods: censoring high-motion time points, motion regression, the FMRIB independent component analysis-based X-noiseifier (FIX), and mean grayordinate time series regression (MGTR; as a proxy for global signal regression). The results suggest that FIX denoising reduced both types of artifacts, but left substantial global artifacts behind. MGTR significantly reduced global artifacts, but left substantial spatially specific artifacts behind. Censoring high-motion time points resulted in a small reduction of distance-dependent and global artifacts, eliminating neither type. All denoising strategies left differences between high- and low-motion participants, but only MGTR substantially reduced those differences. Ultimately, functional connectivity estimates from HCP data showed spatially specific and globally distributed artifacts, and the most effective approach to address both types of motion-correlated artifacts was a combination of FIX and MGTR

Dynamic Construction of Stimulus Values in the Ventromedial Prefrontal Cortex

Signals representing the value assigned to stimuli at the time of choice have been repeatedly observed in ventromedial prefrontal cortex (vmPFC). Yet it remains unknown how these value representations are computed from sensory and memory representations in more posterior brain regions. We used electroencephalography (EEG) while subjects evaluated appetitive and aversive food items to study how event-related responses modulated by stimulus value evolve over time. We found that value-related activity shifted from posterior to anterior, and from parietal to central to frontal sensors, across three major time windows after stimulus onset: 150–250 ms, 400–550 ms, and 700–800 ms. Exploratory localization of the EEG signal revealed a shifting network of activity moving from sensory and memory structures to areas associated with value coding, with stimulus value activity localized to vmPFC only from 400 ms onwards. Consistent with these results, functional connectivity analyses also showed a causal flow of information from temporal cortex to vmPFC. Thus, although value signals are present as early as 150 ms after stimulus onset, the value signals in vmPFC appear relatively late in the choice process, and seem to reflect the integration of incoming information from sensory and memory related regions

Boundary objects, power, and learning: The matter of developing sustainable practice in organizations

This article develops an understanding of the agential role of boundary objects in generating and politicizing learning in organizations, as it emerges from the entangled actions of humans and non-humans. We offer two empirical vignettes in which middle managers seek to develop more sustainable ways of working. Informed by Foucault’s writing on power, our work highlights how power relations enable and foreclose the affordances, or possibilities for action, associated with boundary objects. Our data demonstrate how this impacts the learning that emerges as boundary objects are configured and unraveled over time. In so doing, we illustrate how boundary objects are not fixed entities, but are mutable, relational, and politicized in nature. Connecting boundary objects to affordances within a Foucauldian perspective on power offers a more nuanced understanding of how ‘the material’ plays an agential role in consolidating and disrupting understandings in the accomplishment of learning