Neural criticality from effective latent variables

Observations of power laws in neural activity data have raised the intriguing notion that brains may operate in a critical state. One example of this critical state is "avalanche criticality," which has been observed in a range of systems, including cultured neurons, zebrafish, and human EEG. More recently, power laws have also been observed in neural populations in the mouse under a coarse-graining procedure, and they were explained as a consequence of the neural activity being coupled to multiple latent dynamical variables. An intriguing possibility is that avalanche criticality emerges due to a similar mechanism. Here, we determine the conditions under which dynamical latent variables give rise to avalanche criticality. We find that a single, quasi-static latent variable can generate critical avalanches, but that multiple latent variables lead to critical behavior in a broader parameter range. We identify two regimes of avalanches, both of which are critical, but differ in the amount of information carried about the latent variable. Our results suggest that avalanche criticality arises in neural systems in which there is an emergent dynamical variable or shared inputs creating an effective latent dynamical variable, and when this variable can be inferred from the population activity.Comment: 18 pages, 5 figure

The dark side of bright traits: How context cues misdirect facets of conscientiousness

© 2020, Emerald Publishing Limited. Purpose: The authors test the proposition that there are dark sides to conscientiousness that are revealed when examining lower-level facets. The authors propose that potentially dysfunctional behavior is triggered by context cues that are relevant to duty versus achievement striving. Design/methodology/approach: The authors conducted two laboratory experiments designed to test how context cues that are specific to duty and achievement striving influence the relationship between these facets and quality versus quantity dimensions of task performance. Findings: In Study 1, the authors found that normative quality cues led to a stronger relationship between duty and discretionary quality performance. In Study 2, achievement striving was associated with lower levels of quality performance in the presence of competitive feedback cues. Research limitations/implications: The findings illustrate that the dark side of duty and achievement striving emerges in two ways. First, when there is normative pressure for quality, dutiful individuals are apt to sacrifice efficiency. Second, when there is competitive feedback, achievement striving individuals focus on performance standards at the detriment of quality. Practical implications: The findings point to the importance of precision and specificity when using personality measures for staffing. Equally important is the informational content of cues conveyed by the social, task and organizational context, in leveraging the impact of personality in the workplace. Originality/value: This paper clarifies the dark side and bright side contradiction of conscientiousness, adding to the growing literature on unique and often competing consequences of duty and achievement striving. The authors also draw attention to the importance of the content of contextual cues, in trait activation of personality

Academic Reading and Writing in Stream Four: A Multi-Pronged Proposal for Change

The purpose of this paper is to disseminate information to all ELA staff about a multi-pronged proposal for suggested changes to the ARW course for Stream Four, the stream in which students with TOEFL scores of 350-450 are placed. The proposal is primarily curricular in nature and scope, and involves considering significant changes to the current in-house materials: The ELA Reader and The Student Guide to Writing in the ELA. In addition, we propose reformulating the learning outcomes and indicators guiding the curriculum so that they follow The Common European Framework of Reference for Languages (CEFR), and developing lesson plans based on a Content and Language Integrated Learning (CLIL) approach to accompany the piloted reading and writing materials. Making course content available to students online is also discussed. Finally, student assessment will be looked at, followed by a proposal to develop tools for evaluating the efficacy of the piloted materials and the other changes that are being proposed

English-medium Instruction Across Majors at ICU (2008-2011):Opportunities and Constraints

This paper looks at the extent and distribution of English-medium instruction atInternational Christian University (ICU) from 2008 to 2011. This time periodrepresents the first four years following a major academic reform in the College ofLiberal Arts (CLA) at ICU, and a time when the administration aimed to increase thepercentage of courses taught in English to 45%. The two main questions addressed inthe paper were, in 2008-2011, (a) how close did ICU get to this 45% target, and (b)what constraints limited the availability of English-medium instruction? This type ofinformation, which both students and their advisers need to know, has not beenprovided by the ICU administration in the past, nor for the period considered in thispaper. Our results show an increase in “E-course” offerings (an ICU designation forcourses in which English is used primarily) from 15.2% in 1997-2000, to 21% in 2008-2011. Inconsistent availability of English-medium instruction was found across majors,and involved the major prerequisite courses, 100-level courses, and General Education(GE) courses. Scheduling patterns which further constrained the availability ofEnglish-medium courses for some students were found. Finally, we found that thepercentage of senior theses written in English by March graduates had dropped to 28%.Based on our findings, we suggest some questions for future discussion at ICU

DU Undergraduate Showcase: Research, Scholarship, and Creative Works: Abstracts

Abstracts from the DU Undergraduate Showcase

Photometry of the Didymos System across the DART Impact Apparition

On 2022 September 26, the Double Asteroid Redirection Test (DART) spacecraft impacted Dimorphos, the satellite of binary near-Earth asteroid (65803) Didymos. This demonstrated the efficacy of a kinetic impactor for planetary defense by changing the orbital period of Dimorphos by 33 minutes. Measuring the period change relied heavily on a coordinated campaign of lightcurve photometry designed to detect mutual events (occultations and eclipses) as a direct probe of the satellite’s orbital period. A total of 28 telescopes contributed 224 individual lightcurves during the impact apparition from 2022 July to 2023 February. We focus here on decomposable lightcurves, i.e., those from which mutual events could be extracted. We describe our process of lightcurve decomposition and use that to release the full data set for future analysis. We leverage these data to place constraints on the postimpact evolution of ejecta. The measured depths of mutual events relative to models showed that the ejecta became optically thin within the first ∼1 day after impact and then faded with a decay time of about 25 days. The bulk magnitude of the system showed that ejecta no longer contributed measurable brightness enhancement after about 20 days postimpact. This bulk photometric behavior was not well represented by an HG photometric model. An HG 1 G 2 model did fit the data well across a wide range of phase angles. Lastly, we note the presence of an ejecta tail through at least 2023 March. Its persistence implied ongoing escape of ejecta from the system many months after DART impact

Bi-allelic Loss-of-Function CACNA1B Mutations in Progressive Epilepsy-Dyskinesia.

The occurrence of non-epileptic hyperkinetic movements in the context of developmental epileptic encephalopathies is an increasingly recognized phenomenon. Identification of causative mutations provides an important insight into common pathogenic mechanisms that cause both seizures and abnormal motor control. We report bi-allelic loss-of-function CACNA1B variants in six children from three unrelated families whose affected members present with a complex and progressive neurological syndrome. All affected individuals presented with epileptic encephalopathy, severe neurodevelopmental delay (often with regression), and a hyperkinetic movement disorder. Additional neurological features included postnatal microcephaly and hypotonia. Five children died in childhood or adolescence (mean age of death: 9 years), mainly as a result of secondary respiratory complications. CACNA1B encodes the pore-forming subunit of the pre-synaptic neuronal voltage-gated calcium channel Cav2.2/N-type, crucial for SNARE-mediated neurotransmission, particularly in the early postnatal period. Bi-allelic loss-of-function variants in CACNA1B are predicted to cause disruption of Ca2+ influx, leading to impaired synaptic neurotransmission. The resultant effect on neuronal function is likely to be important in the development of involuntary movements and epilepsy. Overall, our findings provide further evidence for the key role of Cav2.2 in normal human neurodevelopment.MAK is funded by an NIHR Research Professorship and receives funding from the Wellcome Trust, Great Ormond Street Children's Hospital Charity, and Rosetrees Trust. E.M. received funding from the Rosetrees Trust (CD-A53) and Great Ormond Street Hospital Children's Charity. K.G. received funding from Temple Street Foundation. A.M. is funded by Great Ormond Street Hospital, the National Institute for Health Research (NIHR), and Biomedical Research Centre. F.L.R. and D.G. are funded by Cambridge Biomedical Research Centre. K.C. and A.S.J. are funded by NIHR Bioresource for Rare Diseases. The DDD Study presents independent research commissioned by the Health Innovation Challenge Fund (grant number HICF-1009-003), a parallel funding partnership between the Wellcome Trust and the Department of Health, and the Wellcome Trust Sanger Institute (grant number WT098051). We acknowledge support from the UK Department of Health via the NIHR comprehensive Biomedical Research Centre award to Guy's and St. Thomas' National Health Service (NHS) Foundation Trust in partnership with King's College London. This research was also supported by the NIHR Great Ormond Street Hospital Biomedical Research Centre. J.H.C. is in receipt of an NIHR Senior Investigator Award. The research team acknowledges the support of the NIHR through the Comprehensive Clinical Research Network. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR, Department of Health, or Wellcome Trust. E.R.M. acknowledges support from NIHR Cambridge Biomedical Research Centre, an NIHR Senior Investigator Award, and the University of Cambridge has received salary support in respect of E.R.M. from the NHS in the East of England through the Clinical Academic Reserve. I.E.S. is supported by the National Health and Medical Research Council of Australia (Program Grant and Practitioner Fellowship)