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Pupillometry in rats with schizophrenia-like alterations

Partners: 

Faculty of Medicine, Department of Physiology (Alexandra Büki, Gabriella Kékesi, Gyöngyi Horváth)

Lifetime from: 
2016
Short description: 

The research focuses on investigating the pupillary light reflex to reveal the nervous system changes  in rats with schizophrenia-like alterations.

Description: 

Patients with schizophrenia, besides the well-known behavioral symptoms, also show autonomic dysregulation, including impaired pupillary function, which is a sensitive and reliable source of information about the function of the nervous system.

Pupillometry is a simple, non-invasive technique for the assessment of the autonomic nervous system function by testing the pupillary light reflex (PLR), meaning the contraction of the pupil in response to light. During the test, the changes of the pupil diameter are recorded and the size of the pupil is measured offline in each video frame.

Our study investigates the PLR to reveal the schizophrenia-related autonomic alterations in WISKET rats. The main challenges of the project are the following:

  • Management of the experiments: sedation, camera and light impulse synchronization
  • Video processing: accurate, automated measurement of the pupil in each frame
  • Signal processing: Feature extraction from pupillogram
  • Data analysis: Statistical analysis, classification

We implemented a novel method [1] to detect and measure the pupil in each frame, which is a challenging task since the videos are blurry and the signal-to-noise ratio is very low (low contrast difference between pupil and iris in albino rats). The method achieves around 3% measurement error. Figure 1. shows a set of input frames and the resulting outputs respectively.

We published the results of data analysis in [2] and [3].

 

 

Figure 1: Results of the pupil detection and measurement algorithm.

 

Publications: 
[1] Image processing-based automatic pupillometry on infrared videos., Kalmár, G, Büki A, Kekesi G, Horváth G, and Nyúl LG , Acta Cybernetica, 2017, Volume 23, Issue 2, Szeged, p.599-613, (2017)
[2] Impaired pupillary control in “schizophrenia-like” WISKET rats. Autonomic Neuroscience: Basic and Clinical., Büki, A, Kalmár G, Kekesi G, Benedek G, Nyúl LG, and Horváth G , Autonomic Neuroscience: Basic and Clinical, 2018 September, Volume 213, p.34-42, (2018)
[3] Feature extraction and classification for pupillary images of rats, Kalrmár, G, Büki A, Kekesi G, Horváth G, and Nyúl LG , The 11th Conference of PhD Students in Computer Science. Volume of short papers., Szeged, Hungary, p.88--91, (2018)
Kategória: 
Medical Applications