Different patterns of local field potentials from limbic DBS targets in patients with major depressive and obsessive compulsive disorder

Unser Verständnis über die Regulation von Emotionen in limbischen Hirnarealen wurde bisher hauptsächlich aus nicht-invasiven bildgebenden Verfahren gewonnen. Die Wiederentdeckung der funktionellen Neurochirurgie als therapeutisches Verfahren in der Behandlung psychiatrischer Erkrankungen wie der therapierefraktären Depression (TRD) ermöglicht durch Implantation von tiefen Hirnelektroden die perioperative Ableitung subkortikaler Nervenzellpopulationsaktivität. In dieser Studie untersuchen wir die Hypothese, dass charakteristische oszillatorische Muster lokaler Feldpotentiale (LFP) im menschlichen limbischen System die Symptomschwere der Depression reflektieren. Über die zur tiefen Hirnstimulation implantierten Elektroden wurden LFPs aus dem subgenualem cingulären Kortex bei 7 Patienten mit Depression (Brodmann Area 25; CG25; 7 TRD Patienten) und bei weiteren 7 Patienten mit Depression aus dem Nucleus striae terminalis (BNST, 7 TRD Patienten) abgeleitet und mit LFPs aus dem BNST von 5 Patienten mit Zwangsstörung verglichen. Im direkten Vergleich zeigten die Patienten mit Depression signifikant höhere oszillatorische Alpha-Aktivität im BNST (8-14 Hz;p<0.01) als Patienten mit Zwangserkrankung. Die im CG25 Zielgebiet operierten Depressionspatienten zeigten ein ähnliches oszillatorisches Muster wie die TRD-BNST Patienten. Die mittlere Alpha-Aktivität korrelierte signifikant mit den depressiven Symptomen der Patienten (Beck Depressions Inventar; n=14, r=0.55, p = 0.042), nicht aber mit den Symptomen der Zwangsstörung. Unsere Ergebnisse deuten darauf hin, dass Alpha-Aktivität im limbischen System ein Korrelat der Symptomschwere bei Patienten mit Depression ist und als potentieller Biomarker für moderne Stimulationsverfahren wie der bedarfsgerechten (closed-loop) tiefen Hirnstimulation verwendet werden könnte.The role of distinct limbic areas in emotion regulation has been largely inferred from neuroimaging studies. Recently, the opportunity for intracranial recordings from limbic areas has arisen in patients undergoing deep brain stimulation (DBS) for neuropsychiatric disorders including major depressive disorder (MDD) and obsessive compulsive disorder (OCD). Here we test the hypothesis that distinct temporal patterns of local field potential (LFP) activity in the human limbic system reflect disease state and symptom severity in MDD and OCD patients. To this end, we recorded LFPs via implanted DBS electrodes from the bed nucleus of stria terminalis (BNST area) in 12 patients (5 OCD, 7 MDD) and from the subgenual cingulate cortex in 7 MDD patients (CG25 area). We found a distinct pattern of oscillatory activity with significantly higher α-power in MDD compared with OCD in the BNST area (broad α-band 8–14 Hz; P = 0.01) and a similar level of α-activity in the CG25 area as in the BNST area in MDD patients. The mean α-power correlated with severity of depressive symptoms as assessed by the Beck depression inventory in MDD (n = 14, r = 0.55, P = 0.042) but not with severity of obsessive compulsive symptoms in OCD. Here we show larger α-band activity in MDD patients compared with OCD recorded from intracranial DBS targets. Our results suggest that α-activity in the limbic system may be a signature of symptom severity in MDD and may serve as a potential state biomarker for closed loop DBS in MDD

Visibility of Young's interference fringes: Scattered light from small ion crystals

We observe interference in the light scattered from trapped $^{40}$Ca$^+$ ion crystals. By varying the intensity of the excitation laser, we study the influence of elastic and inelastic scattering on the visibility of the fringe pattern and discriminate its effect from that of the ion temperature and wave-packet localization. In this way we determine the complex degree of coherence and the mutual coherence of light fields produced by individual atoms. We obtain interference fringes from crystals consisting of two, three and four ions in a harmonic trap. Control of the trapping potential allows for the adjustment of the interatomic distances and thus the formation of linear arrays of atoms serving as a regular grating of microscopic scatterers.Comment: Main text: 5 pages, 4 figures. Supplemental Material: 2pages, 1 figur

IT’S NOT ABOUT WHAT, IT’S ABOUT WHO YOU KNOW: SOCIAL MEDIA-USE IN ORGANISATIONS (8)

This paper investigates the impact of social media-use on communication processes within organisations. Findings from three qualitative comparative case studies are analysed through the lens of the resource based view of organisations. The analysis follows comparative logic focusing on similarities and differences in case-settings and outcomes. Each of the cases represents an organisation with workforces of similar size, composition and distribution but with qualitatively different approaches to social media-use and, as expected, different effects of social media on processes and capabilities. The findings suggest, that the value of social media in contrast to other IT technologies is derived from its use for relationship-building (who the users are connected to and how) rather than information storage and dissemination (what do the users know and where they find it)

Towards understanding of value co-creation on web 2.0 platforms: an assessment methodology

Web 2.0 technologies and social media can be used as a platform for value creation. While some firms are successful in engaging with external audiences on social media, others are less so. Many of these firms have equal access to web 2.0 platforms and operate in similar or same conditions, the resource based view (RBV) offers an explanation for disparities in performance of these organisations: the differences are due to firm internal, valuable, immutable and rare resources. Comparing high- and low-performers in a comparative case study helps to identify and highlight firm internal idiosyncratic resources that result in better sustained performances. In-depth studies inside the organisations answer the questions how and why some firms on the same platform can attract higher engagement levels than others. The problem is how to recognise best and worst performance to conduct in-depth case studies? This paper introduces ALIAS – a methodology for identification of the relative firm performance within a population, and selection of theoretically relevant cases to conduct comparative case studies through the lens of RBV. The proposed methodology is a five step process and utilises the DART framework of value co-creation for identification and assessment of performance criteria

Theoretical Sampling – ALIAS: a Case Selection Framework for Research on Social Media Engagement

Web 2.0 is a platform that supports value co-creation. Firms engage with a variety of audiences to generate additional value. The study presented in this paper looks at employer/employee engagement and identifies high-and low-performers. By comparing successful and less successful firms, the firm specific idiosyncratic relationships are uncovered and firm specific resources as sources of superior performance identified. This paper introduces ALIAS – a methodology for identification of the relative firm performance within a population, and selection of theoretically relevant cases to conduct comparative case studies through the lens of RBV. The proposed methodology is a five step process and utilises the DART framework of value co-creation for identification and assessment of performance criteria

The Role Of Social Media In Human Resource Management

The impact of Social Media (SM) on Human Resource Management (HRM) strategies and practices is increasing and has not been fully explored yet. This research focuses on understanding the role of SM in HRM, specifically the contribution of SM utilization to the strength of HRM. Viewing SM as a User Generated Information System and HRM as a Communications System, the presented theoretical framework allows (1) understanding of SM utilization within HRM and (2) assessment of vertical and horizontal alignment of HRM practices which emerge through utilization of SM. Two pilot case studies demonstrate the application of this framework in a PhD research project

Social Media? What Social Media?

This developmental paper is flagging up the issue of insufficiently clear definition of two contemporary concepts: social media and enterprise social media. Drawing on the findings from empirical case studies, differences in users’ perceptions of what is and is not social media are highlighted. These are juxtaposed with extant definitions from IS literature. The concept of “in-house” or “enterprise” social media is introduced from the literature and its clarity and necessity is challenged based on the data from the case studies. The aim of this early research paper is to evaluate whether a re-definition of “social media”, for example through performative lens is meaningful, necessary and helpful

Social media use in HR management; rule making, rule breaking and workarounds: a sociomaterial view

Employees use alternative tools and technologies to modify existing routines such that shortcomings in organisational processes can be overcome by deviating from prescribed procedures. These practices are referred to as “workarounds” and present a recognised yet under-researched phenomenon. Our study investigates how employees use social media as tools for compensating for shortcomings of existing information technologies and the effects of these workarounds on the strength of the HR communication process. We present a multiple case study to demonstrate workarounds in large UK organisations and to describes the intended outcomes and undesired side-effects. We further suggest an extension to the established structurational model of technology to incorporate effects of workarounds and conclude with an outlook for further research. The findings further offer practical application in the HR field by demonstrating how social media can be adopted into the existing HR processes