1. MEPHunter: Making things
easier for signal visualization
and analysis
Victor Hugo Souza
E-mail: vhosouza@usp.br
Departamento de Física – Universidade de São Paulo
RIBEIRAO PRETO - BRAZIL

2. Objective
Introduce the MEPHunter software considering some technical
details, applications and its applicability,
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1. Introduction
2. Development of MEPHunter
3. Applications
4. Ongoing studies in Biomag Lab
Topics

3. 1. Introduction
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4. Neurophysiological recordings
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Electroencephalography
Electrocardiography
Electromiography
Magnetoencephalography
Intra and extracellular recordings
(e. g. single-unit recording, patch clamp)
http://www.psychologie.uzh.ch/
http://en.wikipedia.org/wiki/Electrocardiography
Gibson et al. (IEEE Sig Proc Mag, 2012)
Baillet et al. (IEEE Sig Proc Mag, 2001)

5. What is “Signal Analysis”?
 Definition: It is the translation of measured data into quantities
to be used as descriptors of certain object of study.
 Wide range of applications: biomedicine, general physics,
engineering, etc.;
 Case specific;
 Intermediated by many commercial and free software.
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6. Example of signal analysis and visualization
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http://caminhodoscristais.blogspot.com.br/
Wikimedia Commons
Clark, et al. (Manual of Remote Sensing, 2001)
Spectroscopy of Rocks

7. What we are used to?
 Commercial software
Practical and easy to use;
Limited communication with hardware and limited applications.
Most of commercial software are expensive considering research environment.
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www.otbioelettronica.it
www.neurosoft.com

8. What we are used to?
 “Home-made” scripts
Good for limited amount of data and limited number of information to be
extracted;
Fast;
Difficult to manipulate data and results;
No graphical user interface.
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DATA
RESULTS
SCRIPT

9. What if we need to fix errors and change selections for
each case?
 Impossible to do that with commercial software!
 Fixing “home-made” scripts require code editing for each case.
 Time-consuming and need of programming knowledge
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Silva et al. (Unpublished data, 2014)

10. SOLUTION!
 Development of a software with the following features:
Free of charge;
Graphical user interface that allows interactions with automatic
calculations;
Easy addition of new features;
Full interpretation of data exported from many hardware.
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11. 2. Development of MEPHunter
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12. MEPHunter
 Development started in 2011;
 Language MATLAB v 7.8 (MathWorks, Natick, USA);
 Main purposes:
 Create a graphical user interface to signal visualization
 Develop algorithms to extract desired information
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13. Development structure
 Object oriented programming
 Independent modules:
 Easy organization
 Simplified structure
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Mód
II
Mód
III
Mód
IV
Mód
V
Mód
...
Mód
I

14. Development structure
 One main interface to group the independent modules:
 Easy to create and embody new modules;
 Easy to fix errors.
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SIMILAR TO A PLUG-IN!

15. MEPHunter Main Interface
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MEPHunter Main
Myosystem
www.datahominis.com.br/myosystem/
OT Bioelettronica
www.otbioelettronica.it
Search Coil
www.chronos-vision.de
Biopac
http://www.usc.es/pcc/en/laboratorio.php

16. Visualization
MEPHunter Main Interface
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Pre-processing
Exporting
Processing
MEPHunter Main

17. 3. Applications
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18. Applications
1. TMS + EMG analysis
2. TMS pulse analyses
3. General EMG studies
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19. sEMG
MEP
Latency
AmplitudeMotor
Cortex
Innervation Zone
Muscle Fibers
Motor Nerve
Propagation of MEPs
TMS Principles
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20. TMS + EMG analysis
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0°
180°
270°
135°
90°
45°
225°
315°
LEFT RIGHT
61 electrodes grid (13 x 5)
8 stimulation angles

21. TMS + EMG analysis
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22. TMS + EMG analysis
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23. TMS + EMG analysis
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24. TMS + EMG analysis
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25. TMS pulse analysis
 Measurement of magnetic pulse generated by TMS coils for
quality control.
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26. TMS pulse analysis
 Measurement of magnetic pulse generated by TMS coils for
quality control.
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27. Other sEMG analysis
 Manual identification of triggers.
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28. Other sEMG analysis
 Manual identification of triggers.
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29. Other sEMG analysis
 Easy manipulation of automated markers selection.
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Silva et al. (Unpublished data, 2014)

30. 4. Ongoing studies in Biomag
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31. InVesalius Navigator
 InVesalius Navigator - neuronavigation software
 Python language, freeware, open-source
 Translated to 8 languages
 Interface for medical images manipulation
 Connection with 4 models of spatial tracker
 3D Instruments tracking
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32. InVesalius Navigator
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 Mapping of stimulation sites;
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33. InVesalius Navigator
 Measurement of distances and mapping of structures with
biomodels;
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34. InVesalius Navigator
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 Registration and tracking of instruments;
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35. InVesalius Navigator
 Accurate spatial localization of stimulation sites
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36. New TMS coils for small animals
 Development of small coils for more focused stimulation in
animals
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37. TMS coil magnetic field mapping
 Development of techniques for a fast magnetic field mapping of
TMS coils
 MRI images?
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38. Funding Agencies
Acknowledgments
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Prof. Dr. Oswaldo Baffa Dr. André Peres Leonardo Rakauskas
InVesalius Navigator Contributors
Dr. Jorge Vicente Lopes Renan Hiroshi
Eduardo Rodrigues Thiago Moraes
Paulo Amorim