The effect of neural adaptation of population coding accuracy

Most neurons in the primary visual cortex initially respond vigorously when a preferred stimulus is presented, but adapt as stimulation continues. The functional consequences of adaptation are unclear. Typically a reduction of firing rate would reduce single neuron accuracy as less spikes are available for decoding, but it has been suggested that on the population level, adaptation increases coding accuracy. This question requires careful analysis as adaptation not only changes the firing rates of neurons, but also the neural variability and correlations between neurons, which affect coding accuracy as well. We calculate the coding accuracy using a computational model that implements two forms of adaptation: spike frequency adaptation and synaptic adaptation in the form of short-term synaptic plasticity. We find that the net effect of adaptation is subtle and heterogeneous. Depending on adaptation mechanism and test stimulus, adaptation can either increase or decrease coding accuracy. We discuss the neurophysiological and psychophysical implications of the findings and relate it to published experimental data.Comment: 35 pages, 8 figure

Recht als probleemoplossing?

De vraag naar de mogelijkheden en beperkingen om het recht meer te laten zijn dan een instrument voor de juridische beslechting van geschillen staat centraal in dit themanummer van Recht der Werkelijkheid

Universal conductance fluctuations in non-integer dimensions

We propose an Ansatz for Universal conductance fluctuations in continuous dimensions from 0 up to 4. The Ansatz agrees with known formulas for integer dimensions 1, 2 and 3, both for hard wall and periodic boundary conditions. The method is based solely on the knowledge of energy spectrum and standard assumptions. We also study numerically the conductance fluctuations in 4D Anderson model, depending on system size L and disorder W. We find a small plateau with a value diverging logarithmically with increasing L. Universality gets lost just in 4D.Comment: 4 pages, 4 figures submitted to Phys. Rev.

Evaluating the effectiveness of the Fit2Learn motor sensory integration programme on children’s capacity to learn

BACKGROUND Many children in the UK are trying to cope with the demands of the schooling system without full sensory integration. The includes: 1. Motor skills: postural control and bi-lateral integration of motor skills, which should be in place by 7 years old, are absent 2. 80% of children under 5 years old experience an inner ear infection (Berman, 1994) which suppresses the inner ear’s ability to process sound. This sound processing abilities are not checked or on the national agenda despite the impact on global development via the vestibular system 3. Binocular vision and visual processing skills are not checked or on anyone’s agenda 4. With the retention of primitive reflexes, a child may never reach their full cognitive potential (Berne, 2006). These are the foundation of proprioception (i.e. the sense of where one is in space) which can increase anxiety and sense of well-being. PURPOSE We worked with a small group of young people in alternative provision and secondary school settings who were recognised to be at risk from poor emotional and mental wellbeing, to improve their development and confidence, and subsequently, their capacity to learn. Within this project, the young people took part in a range of specific activities designed by Fit2Learn in school to help their motor-sensory development. By providing this targeted support to young people, this program was intended to improve their future opportunities by providing them with the readiness to learn, and improve their movement competence, self-confidence and motivation to make more positive life choices, influencing their future education and employment. The Fit 2 Learn program has proven to be successful in supporting children to overcome motor skill deficiencies and improve their sensory system. This has enabled the children to become more functional learners and engage better within a mainstream learning environment. RESEARCH AIMS The research objectives are three-fold: 1. Examine the relationship between completing the Fit2Learn program and children's readiness to learn. 2. Examine how completing the Fit2Learn program influences children's engagement in the classroom. 3. Evaluate the feasibility of the Fit2Learn program being implemented in school by teachers

Event-driven simulations of a plastic, spiking neural network

We consider a fully-connected network of leaky integrate-and-fire neurons with spike-timing-dependent plasticity. The plasticity is controlled by a parameter representing the expected weight of a synapse between neurons that are firing randomly with the same mean frequency. For low values of the plasticity parameter, the activities of the system are dominated by noise, while large values of the plasticity parameter lead to self-sustaining activity in the network. We perform event-driven simulations on finite-size networks with up to 128 neurons to find the stationary synaptic weight conformations for different values of the plasticity parameter. In both the low and high activity regimes, the synaptic weights are narrowly distributed around the plasticity parameter value consistent with the predictions of mean-field theory. However, the distribution broadens in the transition region between the two regimes, representing emergent network structures. Using a pseudophysical approach for visualization, we show that the emergent structures are of "path" or "hub" type, observed at different values of the plasticity parameter in the transition region.Comment: 9 pages, 6 figure