98 research outputs found
Information in small neuronal ensemble activity in the hippocampal CA1 during delayed non-matching to sample performance in rats
<p>Abstract</p> <p>Background</p> <p>The matrix-like organization of the hippocampus, with its several inputs and outputs, has given rise to several theories related to hippocampal information processing. Single-cell electrophysiological studies and studies of lesions or genetically altered animals using recognition memory tasks such as delayed non-matching-to-sample (DNMS) tasks support the theories. However, a complete understanding of hippocampal function necessitates knowledge of the encoding of information by multiple neurons in a single trial. The role of neuronal ensembles in the hippocampal CA1 for a DNMS task was assessed quantitatively in this study using multi-neuronal recordings and an artificial neural network classifier as a decoder.</p> <p>Results</p> <p>The activity of small neuronal ensembles (6-18 cells) over brief time intervals (2-50 ms) contains accurate information specifically related to the matching/non-matching of continuously presented stimuli (stimulus comparison). The accuracy of the combination of neurons pooled over all the ensembles was markedly lower than those of the ensembles over all examined time intervals.</p> <p>Conclusion</p> <p>The results show that the spatiotemporal patterns of spiking activity among cells in the small neuronal ensemble contain much information that is specifically useful for the stimulus comparison. Small neuronal networks in the hippocampal CA1 might therefore act as a comparator during recognition memory tasks.</p
Attenuation of the effects of d-amphetamine on interval timing behavior by central 5-hydroxytryptamine depletion
Neural Correlates of Visual Motion Prediction
Predicting the trajectories of moving objects in our surroundings is important for many life scenarios, such as driving, walking, reaching, hunting and combat. We determined human subjectsâ performance and task-related brain activity in a motion trajectory prediction task. The task required spatial and motion working memory as well as the ability to extrapolate motion information in time to predict future object locations. We showed that the neural circuits associated with motion prediction included frontal, parietal and insular cortex, as well as the thalamus and the visual cortex. Interestingly, deactivation of many of these regions seemed to be more closely related to task performance. The differential activity during motion prediction vs. direct observation was also correlated with task performance. The neural networks involved in our visual motion prediction task are significantly different from those that underlie visual motion memory and imagery. Our results set the stage for the examination of the effects of deficiencies in these networks, such as those caused by aging and mental disorders, on visual motion prediction and its consequences on mobility related daily activities
Pharmacokinetic-Pharmacodynamic Modeling in Pediatric Drug Development, and the Importance of Standardized Scaling of Clearance.
Pharmacokinetic/pharmacodynamic (PKPD) modeling is important in the design and conduct of clinical pharmacology research in children. During drug development, PKPD modeling and simulation should underpin rational trial design and facilitate extrapolation to investigate efficacy and safety. The application of PKPD modeling to optimize dosing recommendations and therapeutic drug monitoring is also increasing, and PKPD model-based dose individualization will become a core feature of personalized medicine. Following extensive progress on pediatric PK modeling, a greater emphasis now needs to be placed on PD modeling to understand age-related changes in drug effects. This paper discusses the principles of PKPD modeling in the context of pediatric drug development, summarizing how important PK parameters, such as clearance (CL), are scaled with size and age, and highlights a standardized method for CL scaling in children. One standard scaling method would facilitate comparison of PK parameters across multiple studies, thus increasing the utility of existing PK models and facilitating optimal design of new studies
Updated measurements of exclusive J/Ï and Ï(2S) production cross-sections in pp collisions at âs = 7 TeV
The differential cross-section as a function of rapidity has been measured for the exclusive production of J/Ï and Ï(2S) mesons in protonâproton collisions at âs = 7 TeV, using data collected by the LHCb experiment, corresponding to an integrated luminosity of 930 pbâ1. The cross-sections times branching fractions to two muons having pseudorapidities between 2.0 and 4.5 are measured to be where the first uncertainty is statistical and the second is systematic. The measurements agree with next-to-leading order QCD predictions as well as with models that include saturation effects
Measurement of indirect CP asymmetries in D 0 â K â K + and D 0 â Ï â Ï + decays using semileptonic B decays
No abstract available
The molecular logic of endocannabinoid signalling
The endocannabinoids are a family of lipid messengers that engage the cell surface receptors that are targeted by Î9-tetrahydrocannabinol, the active principle in marijuana (Cannabis). They are made on demand through cleavage of membrane precursors and are involved in various short-range signalling processes. In the brain, they combine with CB1 cannabinoid receptors on axon terminals to regulate ion channel activity and neurotransmitter release. Their ability to modulate synaptic efficacy has a wide range of functional consequences and provides unique therapeutic possibilities. © 2003, Nature Publishing Group. All rights reserved
Is procrastination a vulnerability factor for hypertension and cardiovascular disease? Testing an extension of the procrastinationâhealth model
Personality is an important epidemiological factor for understanding health outcomes. This study investigated the associations of trait procrastination with hypertension and cardiovascular disease (HT/CVD) and maladaptive coping by testing an extension of the procrastinationâhealth model among individuals with and without HT/CVD. Individuals with self-reported HT/CVD (NÂ =Â 182) and healthy controls (NÂ =Â 564), from a community sample, completed an online survey including measures of personality, coping, and health outcomes. Logistic regression analysis controlling for demographic and higher order personality factors found that older age, lower education level and higher procrastination scores were associated with HT/CVD. Moderated mediation analyses with bootstrapping revealed that procrastination was more strongly associated with maladaptive coping behaviours in participants with HT/CVD than the healthy controls, and the indirect effects on stress through maladaptive coping were larger for the HT/CVD sample. Results suggest procrastination is a vulnerability factor for poor adjustment to and management of HT/CVD
Studies of beauty baryon decays to D0phâ and Î+châ final states
Decays of beauty baryons to the D0phâ and Î+châ final states (where h indicates a pion or a kaon) are studied using a data sample of pp collisions, corresponding to an integrated luminosity of 1.0ââfbâ1, collected by the LHCb detector. The Cabibbo-suppressed decays Î0bâD0pKâ and Î0bâÎ+cKâ are observed, and their branching fractions are measured with respect to the decays Î0bâD0pÏâ and Î0bâÎ+cÏâ. In addition, the first observation is reported of the decay of the neutral beauty-strange baryon Î0b to the D0pKâ final state, and a measurement of the Î0b mass is performed. Evidence of the Î0bâÎ+cKâ decay is also reported
Measurement of indirect CP asymmetries in D-0 -> K-K+ and D-0 -> pi(-)pi(+) decays using semileptonic B decays
Time-dependent asymmetries in the decay rates of the singly
Cabibbo-suppressed decays and are measured in collision data corresponding to an integrated
luminosity of 3.0 fb collected by the LHCb experiment. The mesons
are produced in semileptonic -hadron decays, where the charge of the
accompanying muon is used to determine the initial state as or
. The asymmetries in effective lifetimes between and
decays, which are sensitive to indirect violation, are
determined to be \begin{align*}
A_{\Gamma}(K^-K^+) = (-0.134 \pm 0.077 \; {}^{+0.026}_{-0.034})\% \,
A_{\Gamma}(\pi^-\pi^+) = (-0.092\pm 0.145 \; {}^{+0.025}_{-0.033})\% \,
\end{align*} where the first uncertainties are statistical and the second
systematic. This result is in agreement with previous measurements and with the
hypothesis of no indirect violation in decays.Comment: 20 pages, 4 figure
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