| 1. |
- Leiva, Victor, et al.
(author)
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Modeling neural activity with cumulative damage distributions
- 2015
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In: Biological Cybernetics. - : Springer Science and Business Media LLC. - 0340-1200 .- 1432-0770. ; 109:4-5, s. 421-433
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Journal article (peer-reviewed)abstract
- Neurons transmit information as action potentials or spikes. Due to the inherent randomness of the inter-spike intervals (ISIs), probabilistic models are often used for their description. Cumulative damage (CD) distributions are a family of probabilistic models that has been widely considered for describing time-related cumulative processes. This family allows us to consider certain deterministic principles for modeling ISIs from a probabilistic viewpoint and to link its parameters to values with biological interpretation. The CD family includes the Birnbaum-Saunders and inverse Gaussian distributions, which possess distinctive properties and theoretical arguments useful for ISI description. We expand the use of CD distributions to the modeling of neural spiking behavior, mainly by testing the suitability of the Birnbaum-Saunders distribution, which has not been studied in the setting of neural activity. We validate this expansion with original experimental and simulated electrophysiological data.
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| 2. |
- Lowe, Robert, et al.
(author)
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Affective-associative two-process theory: a neurocomputational account of partial reinforcement extinction effects
- 2017
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In: Biological Cybernetics. - : Springer Science and Business Media LLC. - 0340-1200 .- 1432-0770. ; 111:5-6, s. 365-388
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Journal article (peer-reviewed)abstract
- The partial reinforcement extinction effect (PREE) is an experimentally established phenomenon: behavioural response to a given stimulus is more persistent when previously inconsistently rewarded than when consistently rewarded. This phenomenon is, however, controversial in animal/human learning theory. Contradictory findings exist regarding when the PREE occurs. One body of research has found a within-subjects PREE, while another has found a within-subjects reversed PREE (RPREE). These opposing findings constitute what is considered the most important problem of PREE for theoreticians to explain. Here, we provide a neurocomputational account of the PREE, which helps to reconcile these seemingly contradictory findings of within-subjects experimental conditions. The performance of our model demonstrates how omission expectancy, learned according to low probability reward, comes to control response choice following discontinuation of reward presentation (extinction). We find that a PREE will occur when multiple responses become controlled by omission expectation in extinction, but not when only one omission-mediated response is available. Our model exploits the affective states of reward acquisition and reward omission expectancy in order to differentially classify stimuli and differentially mediate response choice. We demonstrate that stimulus-response (retrospective) and stimulus-expectation-response (prospective) routes are required to provide a necessary and sufficient explanation of the PREE versus RPREE data and that Omission representation is key for explaining the nonlinear nature of extinction data.
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| 3. |
- Pchelkin, Stepan, et al.
(author)
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A dynamic human motion : coordination analysis
- 2015
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In: Biological Cybernetics. - : Springer Science and Business Media LLC. - 0340-1200 .- 1432-0770. ; 109:1, s. 47-62
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Journal article (peer-reviewed)abstract
- This article is concerned with the generic structure of the motion coordination system resulting from the application of the method of virtual holonomic constraints (VHCs) to the problem of the generation and robust execution of a dynamic humanlike motion by a humanoid robot. The motion coordination developed using VHCs is based on a motion generator equation, which is a scalar nonlinear differential equation of second order. It can be considered equivalent in function to a central pattern generator in living organisms. The relative time evolution of the degrees of freedom of a humanoid robot during a typical motion are specified by a set of coordination functions that uniquely define the overall pattern of the motion. This is comparable to a hypothesis on the existence of motion patterns in biomechanics. A robust control is derived based on a transverse linearization along the configuration manifold defined by the coordination functions. It is shown that the derived coordination and control architecture possesses excellent robustness properties. The analysis is performed on an example of a real human motion recorded in test experiments.
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| 4. |
- Bramberg, Elisabeth Bjork, et al.
(author)
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Development of evidence-based practice in occupational health services in Sweden : a 3-year follow-up of attitudes, barriers and facilitators
- 2017
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In: International Archives of Occupational and Environmental Health. - : Springer. - 0340-0131 .- 1432-1246. ; 90:4, s. 335-348
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Journal article (peer-reviewed)abstract
- The Swedish government initiated an investigation of how to secure and develop the competence of the occupational health services. The primary aim of the present study was to investigate whether the development of evidence-based practice (EBP) in the Swedish occupational health services in relation to attitudes, knowledge and use improved during the first 3 years of the government's initiative. The study has a mixed methods design combining questionnaires and interviews with data collection at baseline and at 3-year follow-up. The response rate was 66% at baseline and 63% at follow-up. The results show that practitioners' knowledge of EBP was moderate at baseline and improved at follow-up (p = 0.002; 95% CI 0.01; 0.21). Practitioners experienced lower levels of organizational and managerial support for EBP at follow-up (p < 0.001; 95% CI 0.18; 0.38). The results revealed that managers viewed responsibility for implementing EBP as a matter for individual practitioners rather than as an organizational issue. Occupational health service managers and practitioners are generally positive to EBP. However, the findings emphasize the need to educate managers in how to support EBP at the organizational level by creating an infrastructure for EBP in the OHS.
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