29 research outputs found
Disorders of compulsivity: a common bias towards learning habits.
Why do we repeat choices that we know are bad for us? Decision making is characterized by the parallel engagement of two distinct systems, goal-directed and habitual, thought to arise from two computational learning mechanisms, model-based and model-free. The habitual system is a candidate source of pathological fixedness. Using a decision task that measures the contribution to learning of either mechanism, we show a bias towards model-free (habit) acquisition in disorders involving both natural (binge eating) and artificial (methamphetamine) rewards, and obsessive-compulsive disorder. This favoring of model-free learning may underlie the repetitive behaviors that ultimately dominate in these disorders. Further, we show that the habit formation bias is associated with lower gray matter volumes in caudate and medial orbitofrontal cortex. Our findings suggest that the dysfunction in a common neurocomputational mechanism may underlie diverse disorders involving compulsion.This study was funded by the WT fellowship grant for VV (093705/Z/
10/Z) and Cambridge NIHR Biomedical Research Centre. VV and NAH are Wellcome
Trust (WT) intermediate Clinical Fellows. YW is supported by the Fyssen Fondation
and MRC Studentships. PD is supported by the Gatsby Charitable Foundation. JEG has
received grants from the National Institute of Drug Abuse and the National Center for
Responsible Gaming. TWR and BJS are supported on a WT Programme Grant
(089589/Z/09/Z). The BCNI is supported by a WT and MRC grant.This is the final published version. It's also available from Molecular Psychiatry at http://www.nature.com/mp/journal/vaop/ncurrent/full/mp201444a.html
Critical Essay: Organizational cognitive neuroscience drives theoretical progress, or: The curious case of the straw man murder:organizational cognitive neuroscience drives theoretical progress, or: The curious case of the straw man murder
In this critical essay, we respond to Lindebaum’s (2016) argument that neuroscientific methodologies and data have been accepted prematurely in proposing novel management theory. We acknowledge that building new management theories requires firm foundations. We also find his distinction between demand and supply side forces helpful as an analytical framework identifying the momentum for the contemporary production of management theory. Nevertheless, some of the arguments Lindebaum (2016) puts forward, on closer inspection, can be contested, especially those related to the supply side of organizational cognitive neuroscience (OCN) research: fMRI data, motherhood statements and ethical concerns. We put forward a more positive case for OCN methodologies and data, as well as clarifying exactly what OCN really means, and its consequences for the development of strong management theory
Multi-messenger observations of a binary neutron star merger
On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta
Cognitive impact after short-term exposure to different proton pump inhibitors: assessment using CANTAB software
The influence of water activity and temperature on germination, growth and sporulation of stachybotrys chartarum strains
The objectives were to determine theinfluence of water activity (aw, 0.997-0.92)
andtemperature (10-37C) and their interactions onconidial germination, mycelial
growth and sporulationof two strains of Stachybotrys chartarum in vitroon a
potato dextrose medium. Studies were carriedout by modifying the medium with
glycerol andeither spread plating with conidia to evaluate germinationand germ
tube extension or centrally inoculatingtreatment media for measuring
mycelialgrowth rates and harvesting whole colonies fordetermining sporulation.
Overall, germination ofconidia was significantly influenced by aw andtemperature
and was fastest at 0.997-0.98 aw between15 and 30C with complete germination
within 24 h.Germ tube extension was found to be most rapid atsimilar aw levels
and 25-30C. Mycelial growth ratesof both strains were optimal at 0.997 aw
between 25and 30C, with very little growth at 37C. Sporulationwas optimum at 30C
at 0.997 aw. However,under drier conditions, this was optimum at 25C.This shows
that there are differences in the ranges ofaw x temperature for germination and
growth and forsporulation. This may help in understanding the roleof this fungal
species in damp buildings and conditionsunder which immune-compromised
patientsmay be at risk when exposed to such contaminantsin the indoor air
environment