SPLICE : Fully tractable hierarchical extension of ICA with pooling

We present a novel probabilistic framework for a hierarchical extension of independent component analysis (ICA), with a particular motivation in neuroscientific data analysis and modeling. The framework incorporates a general sub-space pooling with linear ICA-like layers stacked recursively. Unlike related previous models, our generative model is fully tractable: both the likelihood and the posterior estimates of latent variables can readily be computed with analytically simple formulae. The model is particularly simple in the case of complex-valued data since the pooling can be reduced to taking the modulus of complex numbers. Experiments on elec-troencephalography (EEG) and natural images demonstrate the validity of the method. Copyright 2017 by the author(s).Peer reviewe

Pain Evaluation During Colonoscopy by the Erythema Index of the Facial Image

[Background] Endoscopy of the digestive tract is useful but is associated with significant pain to the patient. Its safety and tolerability could be improved by an immediate and objective method to evaluate the pain level and give feedback to the examiner. However, under the current circumstances, it is difficult to measure and assess the pain level objectively.[Methods] We previously developed a discomfort assessment device that measures the changes in brain activity caused by changes in the pain level by extracting the changes in the erythema index from facial color data. In this study, to evaluate the usefulness of this discomfort assessment device, the association between the changes in the erythema index of facial images during colonoscopy and the subjective pain level during the examination were evaluated. For the recording of the subjective pain level during the examination, a subjective pain level recording device that we developed to measure grip strength over time was used. The subjective pain level, facial image, and percutaneous venous oxygen saturation during the examination were recorded in 30 patients who underwent colonoscopy at our hospital. [Results] The duration of colonoscopy was divided into the insertion section and the removal section. The subjective pain level was found to be significantly greater during the insertion section than during the removal section, and the changes in the erythema index of the facial images were significantly different between the two groups. [Conclusion] These findings indicate that the erythema index changes on facial images determined by the discomfort assessment device may facilitate objective evaluation of the pain level during colonoscopy

Balancing plasticity and stability of on-line learning based on hierarchical Bayesian adaptation of forgetting factors

An important character of on-line learning is its potential to adapt to changing environments by properly adjusting meta-parameters that control the balance between plasticity and stability of the learning model. In our previous study, we proposed a learning scheme that address changing environments in the framework of an on-line variational Bayes (VB), which is an effective on-line learning scheme based on Bayesian inference. The motivation of that work was, however, its implications for animal learning, and the formulation of the learning model was heuristic and not theoretically justified. In this article, we propose a new approach that balances the plasticity and stability of on-line VB learning in a more theoretically justifiable manner by employing the principle of hierarchical Bayesian inference. We present a new interpretation of on-line VB as a special case of incremental Bayes that al1ows the hierarchical Bayesian setting to balance the plasticity and stability as well as yielding a simple learning rule compared to standard on-line VB. rrhis dynamic on-line VB scheme is applied to probabilistic PCA as an example of probabilistic models involving latent variables. In computer simulations using artificial datasets, the new on-line VB learning shows robust performance to regulate the balance between plasticity and stability, thus adapting to changing environments.http://library.naist.jp/mylimedio/dllimedio/show.cgi?bookid=100048468&oldid=8922