title: Analysis of facial expressions in parkinson's disease through video-based automatic methods.
abstract: BACKGROUND
  The automatic analysis of facial expressions is an evolving field that finds several clinical applications. One of these applications is the study of facial bradykinesia in Parkinson's disease (PD), which is a major motor sign of this neurodegenerative illness. Facial bradykinesia consists in the reduction/loss of facial movements and emotional facial expressions called hypomimia.
  
  
  METHODS
  In this work we propose an automatic method for studying facial expressions in PD patients relying on video-based METHODS: 17 Parkinsonian patients and 17 healthy control subjects were asked to show basic facial expressions, upon request of the clinician and after the imitation of a visual cue on a screen. Through an existing face tracker, the Euclidean distance of the facial model from a neutral baseline was computed in order to quantify the changes in facial expressivity during the tasks. Moreover, an automatic facial expressions recognition algorithm was trained in order to study how PD expressions differed from the standard expressions.
  
  
  RESULTS
  Results show that control subjects reported on average higher distances than PD patients along the tasks.
  
  
  METHODS
  This confirms that control subjects show larger movements during both posed and imitated facial expressions. Moreover, our results demonstrate that anger and disgust are the two most impaired expressions in PD patients.
  
  
  CONCLUSIONS
  Contactless video-based systems can be important techniques for analyzing facial expressions also in rehabilitation, in particular speech therapy, where patients could get a definite advantage from a real-time feedback about the proper facial expressions/movements to perform.
authors.affiliation: Department of Information Engineering, Università degli Studi di Firenze, Via di S. Marta 3, 50139 Firenze, Italy; Department of Electrical, Electronic and Information Engineering (DEI) "Guglielmo Marconi", Università di Bologna, Viale del Risorgimento 2, 40136, Bologna, Italy. Electronic address: andrea.bandini@uhn.ca.
authors.forename: Andrea
authors.initials: A
authors.lastname: Bandini
authors.affiliation: Department of Information Engineering, Università degli Studi di Firenze, Via di S. Marta 3, 50139 Firenze, Italy. Electronic address: silvia.orlandi@unifi.it.
authors.forename: Silvia
authors.initials: S
authors.lastname: Orlandi
authors.affiliation: Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE), Computer Science Department, Luis Enrique Erro No. 1, Tonantzintla, Puebla 72840, Mexico. Electronic address: hugojair@inaoep.mx.
authors.forename: Hugo Jair
authors.initials: HJ
authors.lastname: Escalante
authors.affiliation: Unit of Neurology, Florence Health Autority, Ospedale "Nuovo San Giovanni di Dio", Via Torregalli 3, Firenze, Italy. Electronic address: fabio.giovannelli@unifi.it.
authors.forename: Fabio
authors.initials: F
authors.lastname: Giovannelli
authors.affiliation: Unit of Neurology, Florence Health Autority, Ospedale "Nuovo San Giovanni di Dio", Via Torregalli 3, Firenze, Italy. Electronic address: massimo.cincotta@uslcentro.toscana.it.
authors.forename: Massimo
authors.initials: M
authors.lastname: Cincotta
authors.affiliation: Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE), Computer Science Department, Luis Enrique Erro No. 1, Tonantzintla, Puebla 72840, Mexico. Electronic address: kargaxxi@inaoep.mx.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Reyes-Garcia
authors.affiliation: Unit of Neurology, Florence Health Autority, Ospedale "Nuovo San Giovanni di Dio", Via Torregalli 3, Firenze, Italy. Electronic address: paola.vanni@uslcentro.toscana.it.
authors.forename: Paola
authors.initials: P
authors.lastname: Vanni
authors.affiliation: Unit of Neurology, Florence Health Autority, Ospedale "Nuovo San Giovanni di Dio", Via Torregalli 3, Firenze, Italy. Electronic address: gaetano.zaccara@uslcentro.toscana.it.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Zaccara
authors.affiliation: Department of Information Engineering, Università degli Studi di Firenze, Via di S. Marta 3, 50139 Firenze, Italy. Electronic address: claudia.manfredi@unifi.it.
authors.forename: Claudia
authors.initials: C
authors.lastname: Manfredi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D004644:Emotions; D005149:Facial Expression; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007100:Imitative Behavior; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000145:classification / Q000175:diagnosis / Q000503:physiopathology; D060388:Support Vector Machine; D014741:Video Recording / Q000379:methods*
keywords: Automatic facial expression recognition; Contactless; Facial mimicry; Hypomimia; Parkinson's disease; Video-based