Preparing Laboratory and Real-World EEG Data for Large-Scale Analysis: A Containerized Approach.

Large-scale analysis of EEG and other physiological measures promises new insights into brain processes and more accurate and robust brain-computer interface models. However, the absence of standardized vocabularies for annotating events in a machine understandable manner, the welter of collection-specific data organizations, the difficulty in moving data across processing platforms, and the unavailability of agreed-upon standards for preprocessing have prevented large-scale analyses of EEG. Here we describe a "containerized" approach and freely available tools we have developed to facilitate the process of annotating, packaging, and preprocessing EEG data collections to enable data sharing, archiving, large-scale machine learning/data mining and (meta-)analysis. The EEG Study Schema (ESS) comprises three data "Levels," each with its own XML-document schema and file/folder convention, plus a standardized (PREP) pipeline to move raw (Data Level 1) data to a basic preprocessed state (Data Level 2) suitable for application of a large class of EEG analysis methods. Researchers can ship a study as a single unit and operate on its data using a standardized interface. ESS does not require a central database and provides all the metadata data necessary to execute a wide variety of EEG processing pipelines. The primary focus of ESS is automated in-depth analysis and meta-analysis EEG studies. However, ESS can also encapsulate meta-information for the other modalities such as eye tracking, that are increasingly used in both laboratory and real-world neuroimaging. ESS schema and tools are freely available at www.eegstudy.org and a central catalog of over 850 GB of existing data in ESS format is available at studycatalog.org. These tools and resources are part of a larger effort to enable data sharing at sufficient scale for researchers to engage in truly large-scale EEG analysis and data mining (BigEEG.org)

Hierarchical Event Descriptors (HED): Semi-Structured Tagging for Real-World Events in Large-Scale EEG.

Real-world brain imaging by EEG requires accurate annotation of complex subject-environment interactions in event-rich tasks and paradigms. This paper describes the evolution of the Hierarchical Event Descriptor (HED) system for systematically describing both laboratory and real-world events. HED version 2, first described here, provides the semantic capability of describing a variety of subject and environmental states. HED descriptions can include stimulus presentation events on screen or in virtual worlds, experimental or spontaneous events occurring in the real world environment, and events experienced via one or multiple sensory modalities. Furthermore, HED 2 can distinguish between the mere presence of an object and its actual (or putative) perception by a subject. Although the HED framework has implicit ontological and linked data representations, the user-interface for HED annotation is more intuitive than traditional ontological annotation. We believe that hiding the formal representations allows for a more user-friendly interface, making consistent, detailed tagging of experimental, and real-world events possible for research users. HED is extensible while retaining the advantages of having an enforced common core vocabulary. We have developed a collection of tools to support HED tag assignment and validation; these are available at hedtags.org. A plug-in for EEGLAB (sccn.ucsd.edu/eeglab), CTAGGER, is also available to speed the process of tagging existing studies

Retrieval Failure Contributes to Gist-Based False Recognition

People often falsely recognize items that are similar to previously encountered items. This robust memory error is referred to as gist-based false recognition. A widely held view is that this error occurs because the details fade rapidly from our memory. Contrary to this view, an initial experiment revealed that, following the same encoding conditions that produce high rates of gist-based false recognition, participants overwhelmingly chose the correct target rather than its related foil when given the option to do so. A second experiment showed that this result is due to increased access to stored details provided by reinstatement of the originally encoded photograph, rather than to increased attention to the details. Collectively, these results suggest that details needed for accurate recognition are, to a large extent, still stored in memory and that a critical factor determining whether false recognition will occur is whether these details can be accessed during retrieval.Psycholog

Latin America 2060: consolidation or crisis?

This repository item contains a single issue of the Pardee Center Task Force Reports, a publication series that began publishing in 2009 by the Boston University Frederick S. Pardee Center for the Study of the Longer-Range Future.Latin America has produced vigorous ideas throughout its history, expressed in narratives about its struggles and successes, or its weaknesses and failures. Together, these have shaped a multi-faceted vision of the region and its peoples. Some of its expositors, finding the story to be neither complete nor precise, work toward reformulations, some quite radical. Such generation of knowledge in different fields seems destined to yield a variety of distinct outcomes, at least in part because some of the emerging social and cultural movements are not yet very well structured. This Task Force Report project seeks to harness ideas about the region’s future into a coherent and policy useful discourse. A Workshop and a Task Force meeting was held at Boston University on November 18-19, 2010. A select group of invited experts – a mix of academic scholars and practitioners – were asked to turn their ideas into short ‘Think Pieces’ essays. Each Think Piece focuses on a specific topical issue for the region as a whole, instead of looking only at particular countries. These Think Piece essays are compiled and edited by the Task Force coordinator and published by the Pardee Center as a Task Force Report

Designing for democracy: Bulk data and authoritarianism

Transparency is important for liberal democracies; however, the value of transparency is difficult to articulate. In this article we articulate transparency as an instrumental value for providing what we call ensurance and assurance to liberal democratic citizens. Ensurance refers to the property of liberal democracies which prevents it from sliding into authoritarianism and assurance is the property whereby citizens are assured that ensurance exists. Looking at the rise of bulk data collection and use afforded by information communication technologies, this paper focuses on the way that technologies disrupt relations between the state and its citizens, and suggests Value Sensitive Design as a methodology to protect key aspects of liberal democracies. Bulk data collection makes the achieving of ensurance and assurance more difficult due to two types of opacity which arise as a result of the practice: technical opacity-the difficulty for citizens to understand the technology behind bulk data collection; and, algorithmic opacity-opacity which results from properties inherent to algorithms which guide the collection and processing of bulk data. Design requirements will be suggested to respond to the disruptions caused by ICTs between liberal democracies and their citizens which threaten the necessary value for liberal democracies of representativeness

Interactions Between Visual Attention and Episodic Retrieval: Dissociable Contributions of Parietal Regions During Gist-Based False Recognition

The interaction between episodic retrieval and visual attention is relatively unexplored. Given that systems mediating attention and episodic memory appear to be segregated, and perhaps even in competition, it is unclear how visual attention is recruited during episodic retrieval. We investigated the recruitment of visual attention during the suppression of gist-based false recognition, the tendency to falsely recognize items that are similar to previously encountered items. Recruitment of visual attention was associated with activity in the dorsal attention network. The inferior parietal lobule, often implicated in episodic retrieval, tracked veridical retrieval of perceptual detail and showed reduced activity during the engagement of visual attention, consistent with a competitive relationship with the dorsal attention network. These findings suggest that the contribution of the parietal cortex to interactions between visual attention and episodic retrieval entails distinct systems that contribute to different components of the task while also suppressing each other.Psycholog

Evaluation of bio-optical inversion of spectral irradiance measured from an autonomous underwater vehicle

Autonomous underwater vehicles (AUVs) can map water conditions at high spatial (horizontal and vertical) and temporal resolution, including under cloudy conditions when satellite and airborne remote sensing are not feasible. As part of the RADYO program, we deployed a passive radiometer on an AUV in the Santa Barbara Channel and off the coast of Hawaii to apply existing bio-optical algorithms for characterizing the optical constituents of coastal seawater (i.e., dissolved organic material, algal biomass, and other particles). The spectral differences between attenuation coefficients were computed from ratios of downwelling irradiance measured at depth and used to provide estimates of the in-water optical constituents. There was generally good agreement between derived values of absorption and concurrent measurements of this inherent optical property in Santa Barbara Channel. Wave focusing, cloud cover, and low attenuation coefficients influenced results off the coast of Hawaii and are used to evaluate the larger-scale application of these methods in the near surface coastal oceans

Modelling the effect of time varying organ deformations in head and neck cancer using a PCA model

Throughout the radiotherapy treatment process, geometrical changes in the patient often occur, e.g. organs differing in shape from that of the planning CT scan (pCT). This organ deformation leads to uncertainties in the dose distribution throughout the treatment course. We present a method to statistically model the time dependent effect of organ deformation on organ at risk (OAR) dose, with the aim of later incorporating it into advanced treatment planning methods i.e. probabilistic planning

Short Duration Waveforms Recorded Extracellularly from Freely Moving Rats are Representative of Axonal Activity

While extracellular somatic action potentials from freely moving rats have been well characterized, axonal activity has not. We report direct extracellular tetrode recordings of putative axons whose principal feature is a short duration waveform (SDW) with an average peak-trough length less than 179 μs. While SDW recordings using tetrodes have previously been treated as questionable or classified as cells, we hypothesize that they are representative of axonal activity. These waveforms have significantly shorter duration than somatic action potentials, are triphasic and are therefore similar to classic descriptions of microelectrode recordings in white matter and of in vitro action potential propagation along axons. We describe SDWs recorded from pure white-matter tracts including the alveus and corpus callosum. Recordings of several SDWs in the alveus exhibit grid-like firing patterns suggesting these axons carry spatial information from entorhinal cortical neurons. Finally, we locally injected the GABAA agonist Muscimol into layer CA1 of the hippocampus while simultaneously recording somatic activity and SDWs on the same tetrodes. The persistent activity of SDWs during Muscimol inactivation of somatic action potentials indicates that SDWs are representative of action potential propagation along axons projecting from more distal somata. This characterization is important as it illustrates the dangers of exclusively using spike duration as the sole determinant of unit type, particularly in the case of interneurons whose peak-trough times overlap with SDWs. It may also allow future studies to explore how axonal projections from disparate brain regions integrate spatial information in the hippocampus, and provide a basis for studying the effects of pharmaceutical agents on signal transmission in axons, and ultimately to aid in defining the potential role of axons in cognition