Effect of Mental Workload on Breathing Pattern and Heart Rate for a Working Memory Task: A Pilot Study.

Mental workload or cognitive load is the total amount of mental resources required while doing a task. Apart from qualitative measures, various physiological signals are being used for assessment of mental workload. However, very limited research has been done on assessment of cognitive load from respiratory signals. In the present study, we have tried to analyze the cognitive load mainly based on respiratory features. n-back memory test has been modified to impart low and high cognitive load. The peripheral blood volume signal (PPG) collected while executing the task is used to reconstruct the breathing pattern signal. A number of morphological as well as statistical features are calculated from this reconstructed signal. Finally a classifier is used for classifying the low and high cognitive load. Results show that a classification accuracy of 76.8% is obtained while using respiratory features only. A maximum accuracy of 81.80% is obtained if we combine time domain PPG features with respiratory features. The features finally selected can also be used to study the habituation effect.

Reckoning respiratory signals to affectively decipher mental state.

Recognizing mental states from physiological signal is a concern not only for medical diagnostics, but also for cognitive science, behavioral studies as well as brain machine interfaces. This study employs an unique approach of solely utilizing the respiration signals in order to decipher mental states. A public dataset, Affective Pacman, is considered for this study, where the various physiological signals are acquired during normal and frustrated mental states. An efficient way to remove the non-linear baseline drifts in the signal is implemented to extract the respiratory features in most effective way. Another major adversity is the presence of class imbalance, which is effectively rectified using Synthetic Minority Oversampling TEchnique (SMOTE). Application of SMOTE algorithm to resolve class imbalance problem, not only increased the classification accuracy, but also reduced the classifier bias towards the majority class, which in turn exceedingly enhanced the classifier sensitivity. The multilayer perceptron classifier performed best with SMOTE generated feature set, with classification accuracy (CA), true positive rate (TPR) and true negative rate (TNR) of 97.9%, 92.6% and 99.3% respectively. The current approach is found to perform better compared to relevant literature.

Early Detection of Mild Cognitive Impairment using Pervasive Sensing.

Aging in place and independent living for the elderly has gained importance, and so has instrumented homes for ambient assisted living (AAL). In this paper we explore the feasibility of using passive sensors to provide insights into the cognitive and physical well-being of the subject. We derive a novel clustering based tactics to check heterogeneity in terms of movement behaviour among patients, and then provide our feasibility study on detection of mild cognitive impairment based on the results of the clustering.

A Novel Approach to the Identification of Compromised Pulmonary Systems in Smokers by Exploiting Tidal Breathing Patterns.

Smoking causes unalterable physiological abnormalities in the pulmonary system. This is emerging as a serious threat worldwide. Unlike spirometry, tidal breathing does not require subjects to undergo forceful breathing maneuvers and is progressing as a new direction towards pulmonary health assessment. The aim of the paper is to evaluate whether tidal breathing signatures can indicate deteriorating adult lung condition in an otherwise healthy person. If successful, such a system can be used as a pre-screening tool for all people before some of them need to undergo a thorough clinical checkup. This work presents a novel systematic approach to identify compromised pulmonary systems in smokers from acquired tidal breathing patterns. Tidal breathing patterns are acquired during restful breathing of adult participants. Thereafter, physiological attributes are extracted from the acquired tidal breathing signals. Finally, a unique classification approach of locally weighted learning with ridge regression (LWL-ridge) is implemented, which handles the subjective variations in tidal breathing data without performing feature normalization. The LWL-ridge classifier recognized compromised pulmonary systems in smokers with an average classification accuracy of 86.17% along with a sensitivity of 80% and a specificity of 92%. The implemented approach outperformed other variants of LWL as well as other standard classifiers and generated comparable results when applied on an external cohort. This end-to-end automated system is suitable for pre-screening people routinely for early detection of lung ailments as a preventive measure in an infrastructure-agnostic way.