1,222 research outputs found
Correction: Strokova et al. Interaction Mechanisms in «Portland Cement—Functional Polymer Mineral Additives» Binder Produced by Different Methods. Materials 2025, 18, 3178
No full textMikhail Lebedev was not included as an author in the original publication [...
Interfacing to the brain’s motor decisions
No full textInterfacing to the brain’s motor decisions. J
Neurophysiol 117: 1305–1319, 2017. First published December 21, 2016; doi:
10.1152/jn.00051.2016.—It has been long known that neural activity, recorded
with electrophysiological methods, contains rich information about a subject’s
motor intentions, sensory experiences, allocation of attention, action planning, and
even abstract thoughts. All these functions have been the subject of neurophysiological
investigations, with the goal of understanding how neuronal activity
represents behavioral parameters, sensory inputs, and cognitive functions. The field
of brain-machine interfaces (BMIs) strives for a somewhat different goal: it
endeavors to extract information from neural modulations to create a communication
link between the brain and external devices. Although many remarkable
successes have been already achieved in the BMI field, questions remain regarding
the possibility of decoding high-order neural representations, such as decision
making. Could BMIs be employed to decode the neural representations of decisions
underlying goal-directed actions? In this review we lay out a framework that
describes the computations underlying goal-directed actions as a multistep process
performed by multiple cortical and subcortical areas. We then discuss how BMIs
could connect to different decision-making steps and decode the neural processing
ongoing before movements are initiated. Such decision-making BMIs could operate
as a system with prediction that offers many advantages, such as shorter reaction
time, better error processing, and improved unsupervised learning. To present the
current state of the art, we review several recent BMIs incorporating decisionmaking
components
An unwilling officer: the engineer Mikhail Vasilyevich Lebedev in the era of social cataclysms
No full textIn this article, through the prism of the anthropological approach and the theory
of social adaptation, the biography of the representative of the Russian technical
intelligentsia Mikhail Vasilyevich Lebedev is analyzed. He was given an alternate
service in the Russian (imperial) army, the People’s Army of the Committee of the
Members of the Legislative Assembly, the White Siberian Army, the Red Army, and
Soviet institutions. The study was based on a set of unpublished sources from the
funds of the Museum of Urban Life, the Historical Archive of the Omsk Region, and
the archive of the FSB of Russia in the Omsk Region. The author concludes that,
despite belonging to the category of «former people» and repression, the hero of
the story has successfully adapted to the conditions of the Soviet society
Somatosensory cortical neuronal population activity across states of anaesthesia
No full textExperiments were carried out to learn about changes in sensory cortical processing associated with different levels of anaesthesia. Traditionally this question has been addressed by studying single neurons. Because state changes are likely to influence the relationships between neurons, the present experiments were undertaken to investigate the spatial and temporal firing patterns distributed across cortex. Using 5 × 5 or 10 × 10 microelectrode arrays, spontaneous and stimulus-evoked activity of multineuron clusters was recorded from rat somatosensory 'barrel' cortex (the whisker representation) during a light surgical stage of urethane anaesthesia, and after two supplemental doses of urethane which led to intermediate and deep levels of anaesthesia. At all depths of anaesthesia, spontaneously occurring action potentials at a single electrode tended to be clustered into 'bursts.' With increasing anaesthetic depth, bursts became more prominent and rhythmic, and increasingly synchronized between cortical barrel-columns. Burst frequency decreased and fewer spikes occurred outside bursts, leading to a decrease in the overall spontaneous firing rate. The cortical territory engaged by individual whiskers contracted with increasing depth of anaesthesia, leading to the spatial segregation of whisker representations. At all stages of anaesthesia, whisker stimulation produced the maximal cortical response when delivered close to burst onset. These observations show that ongoing spontaneous activity modulates sensory response properties and makes peripheral tactile information accessible to a cortical territory whose size is determined by the phase of burst cycle. The possible significance of the cyclic cortical responsiveness encountered during urethane anaesthesia to cortical processing in awake rats is considered
COVID-19 Dynamics: A Heterogeneous Model
No full textThe mathematical model reported here describes the dynamics of the ongoing coronavirus disease 2019 (COVID-19) epidemic, which is different in many aspects from the previous severe acute respiratory syndrome (SARS) epidemic. We developed this model when the COVID-19 epidemic was at its early phase. We reasoned that, with our model, the effects of different measures could be assessed for infection control. Unlike the homogeneous models, our model accounts for human population heterogeneity, where subpopulations (e.g., age groups) have different infection risks. The heterogeneous model estimates several characteristics of the epidemic more accurately compared to the homogeneous models. According to our analysis, the total number of infections and their peak number are lower compared to the assessment with the homogeneous models. Furthermore, the early-stage infection increase is little changed when population heterogeneity is considered, whereas the late-stage infection decrease slows. The model predicts that the anti-epidemic measures, like the ones undertaken in China and the rest of the world, decrease the basic reproductive number but do not result in the development of a sufficient collective immunity, which poses a risk of a second wave. More recent developments confirmed our conclusion that the epidemic has a high likelihood to restart after the quarantine measures are lifted. © Copyright © 2021 Gerasimov, Lebedev, Lebedev and Semenycheva
Experience-dependent plasticity of rat barrel cortex: Redistribution of activity across barrel-columns
No full textThe redistribution of neuronal activity across rat barrel cortex following an alteration in whisker usage has been investigated. In adult rats, two mystacial vibrissae - D2 and one neighbor, D1 or D3 were left intact while all other vibrissae on that side of the snout were clipped. Neurons in contralateral barrel cortex were sampled with a microelectrode array 3.5 days later. Stimulation of clipped vibrissae produced a narrow spatial distribution of cortical activity, whereas stimulation of intact vibrissae produced a widened spatial distribution. Simultaneous recordings from multiple cortical barrel-columns suggest that changes in the effective connectivity between barrel-columns may partially account for this redistribution of sensory responses. Evidence is also presented for a second mechanism, a release from inhibition in sensory-deprived cortical areas. A model is therefore proposed where these two mechanisms operate together to regulate the cortical distribution of evoked activity
Dazzled by the Mystery of Mentalism: The Cognitive Neuroscience of Mental Athletes
No full textNeural processing bymental athletes (MAs) has received attention fromNeuroscience community,
with several publications examining superior memorizers (Maguire et al., 2003; Bor et al., 2008),
lighting calculators (Pesenti et al., 2001; Fehr et al., 2010), and savants (Treffert, 2009). In this
opinion, we contend that the presumption of extraordinary abilities inMAs is fundamentally flawed
because their demonstrations involve tricks that regular individuals can learn. Since, these tricks
easily escape the scrutiny of investigators, a high standard of rigor should be applied to research
on MAs.
MAs seem to demonstrate abilities—for example, short-term memory and mental
calculations—that by far exceed those of an average person. MAs’ performance is indeed
impressive: for instance, some of them multiply two 20-digits numbers without annotating and the
other memorize thousands of digits of p.Fil: Rieznik, Andrés. CONICET, Buenos Aires, Argentina. El Gato y La Caja, Buenos Aires, Argentina. Universidad Torcuato Di Tella, Escuela de Negocios, Laboratorio de Neurociencia, Buenos Aires, ArgentinaFil: Lebedev, Mikhail. Center for Neuroengineering, Duke University, Durham, NC, United StatesFil: Sigman, Mariano. CONICET, Buenos Aires, Argentina. Universidad Torcuato Di Tella, Escuela de Negocios, Laboratorio de Neurociencia, Buenos Aires, Argentin
Measurement of the time-dependent CP asymmetry in B0 -> J/ψ KS0 decays
No full textThis Letter reports a measurement of the CP violation observables SJ/ψK0S and CJ/ψK0S in the decay channel B0→J/ψK0S performed with 1.0 fb−1 of pp collisions at s√=7 TeV collected by the LHCb experiment. The fit to the data yields SJ/ψK0S=0.73±0.07(stat)±0.04(syst) and CJ/ψK0S=0.03±0.09(stat)±0.01(syst). Both values are consistent with the current world averages and within
expectations from the Standard Model
First observation of Bs → J/ψf0(980) decays
No full textUsing data collected with the LHCb detector in proton–proton collisions at a centre-of-mass energy of 7 TeV, the hadronic decay is observed. This CP eigenstate mode could be used to measure mixing-induced CP violation in the system. Using a fit to the π+π− mass spectrum with interfering resonances gives . In the interval ±90 MeV around 980 MeV, corresponding to approximately two full f0 widths we also find , where in both cases the uncertainties are statistical and systematic, respectively
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