A biophysical framework needed to interpret electrophysiological data recorded at multiple spatial scales of brain tissue is developed. Micro current sources at membrane surfaces produce local field potentials, electrocorticography, and electroencephalography (EEG). We categorize multi-scale sources as genuine, equivalent, or representative. Genuine sources occur at the micro scale of cell surfaces. Equivalent sources provide identical experimental outcomes over a range of scales and applications. In contrast, each representative source distribution is just one of many possible source distributions that yield similar experimental outcomes. Macro sources ("dipoles") may be defined at the macrocolumn (mm) scale and depend on several features of the micro sources-magnitudes, micro synchrony within columns, and distribution through the cortical depths. These micro source properties are determined by brain dynamics and the columnar structure of cortical tissue. The number of representative sources underlying EEG data depends on the spatial scale of neural tissue under study. EEG inverse solutions (e.g. dipole localization) and high resolution estimates (e.g. Laplacian, dura imaging) have both strengths and limitations that depend on experimental conditions. The proposed theoretical framework informs studies of EEG source localization, source characterization, and low pass filtering. It also facilitates interpretations of brain dynamics and cognition, including measures of synchrony, functional connections between cortical locations, and other aspects of brain complexity.

This music score was submitted for the Kaleidoscope 2020 Call for Scores, an open access collaboration with the UCLA Music Library.

This music score was submitted for the Kaleidoscope 2020 Call for Scores, an open access collaboration with the UCLA Music Library.

Increasing evidence reveals the rather massive transcription of non-coding RNA (ncRNA) transcripts in mammalian cells, including bidirectional transcripts at enhancer sites, referred to as eRNAs; however, it has remained unclear whether these eRNAs are functional, or merely a reflection of altered enhancer chromatin. Here, we report that estrogen receptor [alpha] (ER[alpha]) causes an upregulation of eRNAs on ER[alpha]-bound activated enhancers that is required both for specific enhancer:promoter looping, and for activation of E₂- regulated coding target genes. Estrogen regulated recruitment of the cohesin complex to enhancers, the ER[alpha] mediated relocation of induced target genes from the repressive environment of the polycomb body to the activating environment of the interchromatin granule, and the enhanced strength of specific enhancer:promoter looping, are all eRNA dependent events. Enhancer functions involve the ability of eRNAs to interact with WDR82 (a component of the COMPASS complex), as well as reading the H3K4me3 mark. Our data suggest that eRNAS are likely to exert important functions in many regulated programs of gene expression, ultimately based on their roles in altering long range chromatin interactions and the location of regulated transcription units between functionally-distinct subnuclear architectural structures

This music score was submitted for the Kaleidoscope 2020 Call for Scores, an open access collaboration with the UCLA Music Library.

Throughout history the concept of infinity has played an important role in almost every branch of human knowledge Paradoxically, very little effort has been made by the various theoretical schools in Cognitive Science to study this fascinating aspect of human mental activity. The study of subdivision offers an interesting subject matter to address the question of how the idea of infinity in the small emerge in our minds. 32 students, aged 8, 10, 12 and 14 (high and low intellectual-academic performers), participated in this study, in which a version of one of Zeno's paradoxes was analyzed by means of individual interviews. Results suggest that between ages 10 and 12, a certain intuition of the entailments of subdivision emerges, remaining very labile afterwards and being very influenced by the context. 66 % of the 12- and 14-year-old children said that the process involved in the paradox comes to an end. Less than 25 % considered (with deep hesitations) the possibility that the process might continue endlessly. This suggests that the classic piagetian view that the indefinite subdivision is mastered at the period of formal operations must be reassessed. Some epistemological consequences based on an embodiedcognition oriented perspective are discussed.

The brain is treated as a nested hierarchical complex system with substantial interactions across spatial scales. Local networks are pictured as embedded within global fields of synaptic action and action potentials. Global fields may act top-down on multiple networks, acting to bind remote networks. Because of scale-dependent properties, experimental electrophysiology requires both local and global models that match observational scales. Multiple local alpha rhythms are embedded in a global alpha rhythm. Global models are outlined in which cm-scale dynamic behaviors result largely from propagation delays in cortico-cortical axons and cortical background excitation level, controlled by neuromodulators on long time scales. The idealized global models ignore the bottom-up influences of local networks on global fields so as to employ relatively simple mathematics. The resulting models are transparently related to several EEG and steady state visually evoked potentials correlated with cognitive states, including estimates of neocortical coherence structure, traveling waves, and standing waves. The global models suggest that global oscillatory behavior of self-sustained (limit-cycle) modes lower than about 20 Hz may easily occur in neocortical/white matter systems provided: Background cortical excitability is sufficiently high; the strength of long cortico-cortical axon systems is sufficiently high; and the bottom-up influence of local networks on the global dynamic field is sufficiently weak. The global models provide “entry points” to more detailed studies of global top-down influences, including binding of weakly connected networks, modulation of gamma oscillations by theta or alpha rhythms, and the effects of white matter deficits.

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