Inelastic Dark Matter and the SABRE Experiment

We present here the sensitivity of the SABRE (Sodium iodide with Active Background REjection) experiment to benchmark proto-philic, spin dependent, Inelastic Dark Matter models previously proposed due to their lowered tension with existing experimental results. We perform fits to cross section, mass, and mass splitting values to find the best fit to DAMA/LIBRA data for these models. In this analysis, we consider the Standard Halo Model (SHM), as well as an interesting extension upon it, the SHM+Stream distribution, to investigate the influence of the Dark Matter velocity distribution upon experimental sensitivity and whether or not its consideration may be able to help relieve the present experimental tension. Based on our analysis, SABRE should be sensitive to all the three benchmark models within 3-5 years of data taking.Comment: Adjusted for full DAMA run 1+2 efficiency. Updated to match published versio

Modelling impairment of evoked gamma range oscillations in schizophrenia

© 2015 Metzner et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.Abnormal oscillatory activity in schizophrenia has been found in a wide range of experimental paradigms [1]. For example, schizophrenic patients show reduced evoked gamma activity, which has been associated with negative symptoms, and increased spontaneous gamma activity, which has been associated with positive symptoms [2]. However, the underlying mechanisms remain elusive. Here we investigated the impact of circuit abnormalities on oscillatory activity in the gamma range (> 30 Hz) by simulating auditory entrainment in an established computational model of the primary auditory cortex [3]. Auditory click entrainment experiments showed that for schizophrenic patients EEG/MEG power decreased at 40 Hz and increased at 20 Hz in response to 40 Hz drive but no differences between were visible in response to 30 Hz drive [4, 5]. Here we used the primary auditory cortex model from Beeman [3] and simulated click train stimulation at 40 Hz, to investigate gamma entrainment deficits, and at 30 Hz as a control condition. Without alterations the model entrained at the driving frequency of 30 and 40 Hz, respectively. Similar to previous approaches [6], however, focusing on evoked rather than spontaneous activity, we next explored the effects of (1) connectivity disturbances (reduced (a) recurrent excitation, (b) pyramidal cell input and (c) total connectivity), (2) prolonged GABAergic decay time constant, and (3) reduced inhibitory output. All three interventions in connectivity (1a-c) led to an increase in 40 Hz power for 40 Hz drive, contrary to human EEG/MEG experiments. A prolonged GABAergic decay time constant produced a reduction of power at 40 Hz and an increase in power at 20 Hz, for the 40 Hz drive, which concurs with [4, 5]. Furthermore, for the 30 Hz drive, no differences to the standard model were observed. Reduction of inhibitory output led to decreases in power at 40 Hz for 40 Hz drive but no increases at 20 Hz. In the 30 Hz drive condition, a decrease was visible, in contrast to experimental data [4, 5]. In conclusion, only prolonged GABAergic decay time constants (2), but not interventions (1) and (3) led to changes in entrainment comparable to experimental evidence in agreement with previous modeling approaches [5]. Our simulations suggest that prolonged time constants at GABAergic synapses might play a key role in abnormal evoked gamma rhythms in schizophrenia. However, since we only investigated one intervention at a time, further studies are needed to investigate the complex interactions of these circuit abnormalities. Furthermore, it remains unclear if the same mechanism also underlies increased spontaneous gamma activity in schizophrenia.Peer reviewe

Center-surround interactions in a network model of layer 4Cα of primary visual cortex

© 2013 Metzner et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly citedContext integration is an ubiquitious principle in cortical processing underlying many perceptual and cognitive functions. Several neuropsychiatric disorders have been associated with an impairment of integration of context information, particularly schizophrenia. One way to investigate the mechanisms underlying context processing and its impairments, is to look at context integration in the well-understood visual system. Center-surround interactions (CSI), i.e. the mutual influencing of stimuli presented in the center and in the surround of the visual or receptive field, respectively, are well established, both in animal neurophysiology and human psychophysical and neuroimaging studiesPeer reviewe

Computational multifactoriality in a detailed neural network model resembling centre-surround suppression deficits in schizophrenia

© 2014 Metzner et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise statedPeer reviewe

Lecture Recital: MaryClaire Zurowski

Kemp Recital HallApril 24, 2016Sunday Evening5:00 p.m

Dark Matter at ICRC 2023

This proceedings summarises the dark matter presentations at ICRC 2023. It aims to not only act as a reference document reporting the various results and projections, but also compares the different search methods and attempts to assess the complementarity of the experimental methods discussed.Comment: 24 pages, 7 figures, rapporteur proceedings for ICRC202

Senior Recital: MaryClaire Zurowski

Kemp Recital HallNovember 7, 2015Saturday Evening5:00 p.m