Cognitive control and discourse comprehension in schizophrenia.

Cognitive deficits across a wide range of domains have been consistently observed in schizophrenia and are linked to poor functional outcome (Green, 1996; Carter, 2006). Language abnormalities are among the most salient and include disorganized speech as well as deficits in comprehension. In this review, we aim to evaluate impairments of language processing in schizophrenia in relation to a domain-general control deficit. We first provide an overview of language comprehension in the healthy human brain, stressing the role of cognitive control processes, especially during discourse comprehension. We then discuss cognitive control deficits in schizophrenia, before turning to evidence suggesting that schizophrenia patients are particularly impaired at processing meaningful discourse as a result of deficits in control functions. We conclude that domain-general control mechanisms are impaired in schizophrenia and that during language comprehension this is most likely to result in difficulties during the processing of discourse-level context, which involves integrating and maintaining multiple levels of meaning. Finally, we predict that language comprehension in schizophrenia patients will be most impaired during discourse processing. We further suggest that discourse comprehension problems in schizophrenia might be mitigated when conflicting information is absent and strong relations amongst individual words are present in the discourse context."There is no "centre of Speech" in the brain any more than there is a faculty of Speech in the mind.The entire brain, more or less, is at work in a man who uses language"William JamesFrom The Principles of Psychology, 1890"The mind in dementia praecox is like an orchestra without a conductor"Kraepelin, 1919

Potential oviposition attractants of Culiseta melanura, the principal vector of eastern equine encephalitis

Olfactory cues emanating from oviposition sites have strong potential as management tools for insect pests. The mosquito Culiseta melanura is the principal vector of eastern equine encephalitis (EEE) and utilizes regionally specific oviposition sites. In the Northeast, these are usually red maple crypts . Volatile organic compounds were collected from red-maple crypts occupied by C. melanura. In the laboratory, these volatiles were then assessed in a behavioral bioassay to determine attraction of female C. melanura. Thirty-seven percent of C. melanura test subjects responded positively to volatiles, none responded to controls, and the other eighty-percent were unresponsive. These results suggest an olfactory role in oviposition site selection in C. melanura; however further testing with more robust sample sizes should be conducted. The threat of EEE transmission from this vector to mammalian hosts including humans is serious and control measures based on environmentally benign semiochemicals rather than insecticides should be developed

Altered brainstem responses to modafinil in schizophrenia: implications for adjunctive treatment of cognition.

Candidate pro-cognitive drugs for schizophrenia targeting several neurochemical systems have consistently failed to demonstrate robust efficacy. It remains untested whether concurrent antipsychotic medications exert pharmacodynamic interactions that mitigate pro-cognitive action in patients. We used functional MRI (fMRI) in a randomized, double-blind, placebo-controlled within-subject crossover test of single-dose modafinil effects in 27 medicated schizophrenia patients, interrogating brainstem regions where catecholamine systems arise to innervate the cortex, to link cellular and systems-level models of cognitive control. Modafinil effects were evaluated both within this patient group and compared to a healthy subject group. Modafinil modulated activity in the locus coeruleus (LC) and ventral tegmental area (VTA) in the patient group. However, compared to the healthy comparison group, these effects were altered as a function of task demands: the control-independent drug effect on deactivation was relatively attenuated (shallower) in the LC and exaggerated (deeper) in the VTA; in contrast, again compared to the comparison group, the control-related drug effects on positive activation were attenuated in LC, VTA and the cortical cognitive control network. These altered effects in the LC and VTA were significantly and specifically associated with the degree of antagonism of alpha-2 adrenergic and dopamine-2 receptors, respectively, by concurrently prescribed antipsychotics. These sources of evidence suggest interacting effects on catecholamine neurons of chronic antipsychotic treatment, which respectively increase and decrease sustained neuronal activity in LC and VTA. This is the first direct evidence in a clinical population to suggest that antipsychotic medications alter catecholamine neuronal activity to mitigate pro-cognitive drug action on cortical circuits

Surface differential rotation and prominences of the Lupus post T Tauri star RX J1508.6-4423

We present in this paper a spectroscopic monitoring of the Lupus post T Tauri star RX J1508.6-4423 carried out at two closely separated epochs (1998 May 06 and 10) with the UCL Echelle Spectrograph on the 3.9-m Anglo-Australian Telescope. Applying least-squares convolution and maximum entropy image reconstruction techniques to our sets of spectra, we demonstrate that this star features on its surface a large cool polar cap with several appendages extending to lower latitudes, as well as one spot close to the equator. The images reconstructed at both epochs are in good overall agreement, except for a photospheric shear that we interpret in terms of latitudinal differential rotation. Given the spot distribution at the epoch of our observations, differential rotation could only be investigated between latitudes 15° and 60°. We find in particular that the observed differential rotation is compatible with a solar-like law (i.e., with rotation rate decreasing towards high latitudes proportionally to sin 2l, where l denotes the latitude) in this particular latitude range. Assuming that such a law can be extrapolated to all latitudes, we find that the equator of RX J1508.6-4423 does one more rotational cycle than the pole every 50 ±10 d, implying a photospheric shear 2 to 3 times stronger than that of the Sun. We also discover that the Hα emission profile of RX J1508.6-4423 is most of the time double-peaked and strongly modulated with the rotation period of the star. We interpret this rotationally modulated emission as being caused by a dense and complex prominence system, the circumstellar distribution of which is obtained through maximum entropy Doppler tomography. These maps show in particular that prominences form a complete and inhomogeneous ring around the star, precisely at the corotation radius. We use the total Hα and Hβ emission flux to estimate that the mass of the whole prominence system is about 10 20g. From our observation that the whole cloud system surrounding the star is regenerated in less than 4 d, we conclude that the braking time-scale of RX J1508.6-4423 is shorter than 1 Gyr, and that prominence expulsion is thus likely to contribute significantly to the rotational spindown of young low-mass stars

A Proposed Mechanism to Adolescent Cannabis Induced Psychosis

As the rate of cannabis induced psychosis increases in many parts of the world, it is important to understand the pathophysiology of this disorder. In this review we will attempt to connect cannabis induced physiological changes with new PET data on CB1receptors in patients with schizophrenia to provide a theoretical mechanisms of cannabis-induced psychosis in adolescence. Wepropose that adolescent cannabis induced psychosis is possibly induced by chronic usage of cannabis during an important neurodevelopmental timeframe. This induces CB1 receptor down regulation due to tolerance, a similar pathophysiological state seenin patients with schizophrenia. The risk of developing cannabis induced psychosis is proposed to be a combination of whencannabis use is first initiated, potency of cannabis, frequency of usage and genetic predisposition. After reviewing these steadilyincreasing data, we propose future studies and policy changes to further understand this mechanism and decrease the incidence ofadolescent cannabis induced psychosis

Two-fluid models of superfluid neutron star cores

Both relativistic and non-relativistic two-fluid models of neutron star cores are constructed, using the constrained variational formalism developed by Brandon Carter and co-workers. We consider a mixture of superfluid neutrons and superconducting protons at zero temperature, taking into account mutual entrainment effects. Leptons, which affect the interior composition of the neutron star and contribute to the pressure, are also included. We provide the analytic expression of the Lagrangian density of the system, the so-called master function, from which the dynamical equations can be obtained. All the microscopic parameters of the models are calculated consistently using the non-relativistic nuclear energy density functional theory. For comparison, we have also considered relativistic mean field models. The correspondence between relativistic and non-relativistic hydrodynamical models is discussed in the framework of the recently developed 4D covariant formalism of Newtonian multi-fluid hydrodynamics. We have shown that entrainment effects can be interpreted in terms of dynamical effective masses that are larger in the relativistic case than in the Newtonian case. With the nuclear models considered in this work, we have found that the neutron relativistic effective mass is even greater than the bare neutron mass in the liquid core of neutron stars.Comment: 24 pages, 15 figures, accepted for publication in MNRA

Non-Suicidal Self-Injury and Suicidal Behaviour in Children and Adolescents Accessing Residential or Intensive Home-Based Mental Health Services

Objective: There is a dearth of Canadian research with clinical samples of youth who self-harm, and no studies could be located on self-harm in children and youth accessing residential or intensive home-based treatment. The purposes of this report were to explore the proportion and characteristics of children and youth identified as self-harming at admission by clinicians compared to youth not identified as self-harming, compare self-harming children to adolescents, and to compare caregiver ratings of self-harm at intake to clinician ratings at admission. Method: This report was developed from a larger longitudinal, observational study involving 210 children and youth accessing residential and home-based treatment and their caregivers in partnership with five mental health treatment centres in southwestern Ontario. Agency data were gleaned from files, and caregivers reported on symptom severity at 12 to 18 months and 36 to 40 months post-discharge. Results: Fifty-seven (34%) children and youth were identified as self-harming at admission. The mean age was 11.57 (SD 2.75). There were statistically significant differences on symptom severity at intake between those identified as self-harming and those not so identified; most of these differences were no longer present at follow up. Children were reported to have higher severity of conduct disorder symptoms than adolescents at intake, and there was some consistency between caregiver-rated and clinician-rated self-harm. Children were reported to engage in a wide range of self-harming behaviours. Conclusion: These findings suggest that youth who were identified as self-harming at admission have elevated scores of symptom severity, self-harm can occur in young children and while many improve, there remains a concern for several children and youth who did not improve by the end of service. Children engage in some of the same types of self-harm behaviours as adolescents, and they also engage in behaviours unique to children