{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,21]],"date-time":"2026-05-21T10:25:07Z","timestamp":1779359107370,"version":"3.51.4"},"reference-count":35,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2022,2,10]],"date-time":"2022-02-10T00:00:00Z","timestamp":1644451200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Parkinson\u2019s disease (PD) is a neurological disorder that mainly affects the motor system. Among other symptoms, hypomimia is considered one of the clinical hallmarks of the disease. Despite its great impact on patients\u2019 quality of life, it remains still under-investigated. The aim of this work is to provide a quantitative index for hypomimia that can distinguish pathological and healthy subjects and that can be used in the classification of emotions. A face tracking algorithm was implemented based on the Facial Action Coding System. A new easy-to-interpret metric (face mobility index, FMI) was defined considering distances between pairs of geometric features and a classification based on this metric was proposed. Comparison was also provided between healthy controls and PD patients. Results of the study suggest that this index can quantify the degree of impairment in PD and can be used in the classification of emotions. Statistically significant differences were observed for all emotions when distances were taken into account, and for happiness and anger when FMI was considered. The best classification results were obtained with Random Forest and kNN according to the AUC metric.<\/jats:p>","DOI":"10.3390\/s22041358","type":"journal-article","created":{"date-parts":[[2022,2,11]],"date-time":"2022-02-11T02:40:17Z","timestamp":1644547217000},"page":"1358","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":22,"title":["Quantitative Evaluation of Hypomimia in Parkinson\u2019s Disease: A Face Tracking Approach"],"prefix":"10.3390","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2443-3663","authenticated-orcid":false,"given":"Elena","family":"Pegolo","sequence":"first","affiliation":[{"name":"Department of Information Engineering, University of Padova, 35131 Padova, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Daniele","family":"Volpe","sequence":"additional","affiliation":[{"name":"Fresco Parkinson Center, Villa Margherita, Santo Stefano Riabilitazione, 36057 Arcugnano, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alberto","family":"Cucca","sequence":"additional","affiliation":[{"name":"Fresco Parkinson Center, Villa Margherita, Santo Stefano Riabilitazione, 36057 Arcugnano, Italy"},{"name":"Department of Life Sciences, University of Trieste, 34127 Trieste, Italy"},{"name":"Department of Neurology, School of Medicine, New York University, New York, NY 10016, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lucia","family":"Ricciardi","sequence":"additional","affiliation":[{"name":"Neurosciences Research Centre, Molecular and Clinical Sciences Research Institute, St. George\u2019s University of London, London SW17 0RE, UK"},{"name":"Medical Research Council Brain Network Dynamics Unit, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2624-5415","authenticated-orcid":false,"given":"Zimi","family":"Sawacha","sequence":"additional","affiliation":[{"name":"Department of Information Engineering, University of Padova, 35131 Padova, Italy"},{"name":"Department of Medicine, University of Padova, 35131 Padova, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,2,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Cacabelos, R. 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