Brain, Alexandre Gramfort

Alexandre Gramfort translates our brain waves with algorithms

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Alexandre Gramfort is a young researcher at Télécom ParisTech and just received an ERC starting grant. This prestigious European prize and support acknowledges his research efforts in signal processing and machine learning. For the last eight years, Alexandre Gramfort has worked on mathematical tools to better extract, analyze and visualize brain signals, essentially using electroencephalograms and magnetoencephalograms.

 

In order to study the brain in a non-invasive way with a good temporal resolution, electroencephalogram (EEG) and magnetoencephalogram (MEG) are standard techniques. They respectively measure the electrical activity of our neurones and the magnetic fields that this activity creates. For a patient, the EEG examination consists in nothing more than wearing a helmet with multiple electrodes on the head. The practitioner then visualizes signals and 3D models of the patient’s brain, in which coloured areas indicate the neuronal activity. As described here, everything seems simple…

But in fact, a whole crucial aspect of the imaging technique has been forgotten: signal processing. Indeed, to convert raw measurements into a dynamic visualization of the brain, mathematical and algorithmic tools are required. This step is at the heart of the research work done by Alexandre Gramfort at the LTCI — a mixed research unit Télécom ParisTech and CNRS.

The young researcher has been developing this subject for eight years. First during his PhD thesis at Inria on cerebral activity detection, completed in 2009. Then during his post-docs (CEA Neurospin, Harvard), and today in the “Audio, acoustic and waves” team at the LTCI. Alexandre Gramfort’s works in functional neuroimaging have been highlighted by the development of an open-source software: MNE. Now used in several places over the world, it allows its users to process EEG and MEG signals, from raw data to the visualization of active brain regions. MNE takes care of many aspects of the analysis of such signals, including machine learning.

 

Alexandre Gramfort, ERC Grant

MEG and EEG measurements and their localization inside the brain (red spot).

Laureate of an ERC starting grant

The quality of Alexandre Gramfort’s research has recently been acknowledged by the European Research Council (ERC) with a starting grant. Being worth 1.5 million euros, delivered over five years, these grants not only award works achieved by young researchers, they also encourage them to build their own teams. The Télécom ParisTech laureate thereby announced that he will recruit six PhD students or post-docs and one engineer.

“A huge part of the work lies in mathematical developments, algorithms and software, Alexandre Gramfort explains. In this research field, one has to deal with a large amount of data, and it is almost impossible to do it alone”. Thus, the increased workforce will allow the researcher to build up a team to address the data analysis challenges. Alexandre Gramfort is looking for different profiles, in order to cover the diversity of the required expertises, from data mining to software development.

Thanks to these new resources, research topics will be further explored. One challenge is to process data that are not currently useable due to spurious signals, called noise. “Noise can come from sensors, but also from patient’s brains” Alexandre Gramfort tells us. “When you measure the neuronal signal created by someone’s thought or action, there is not only one part of the brain that activates: everything else keeps working”.

When we asked about potential impact of his research, Alexandre Gramfort answered that “this type of research is very important for everyone working on acquiring and processing data”. Behind the algorithms lies the objective for neuroscientists to better understand brain mechanisms. In their sight: pathologies like epilepsy or autism. But Alexandre Gramfort prefers to temper the expectations: “functional brain imaging is essentially oriented towards diagnosis, not treatment. It is mostly about identifying biomarkers that could help to detect pathologies as early as possible”.

Source localization of continuous Magnetoencephalography (MEG) data

Additive manufacturing, a process for the industry of the future

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As a major component of the Industry of the Future project, additive manufacturing — or 3D printing — is leading to ever-increasing research on materials. Researchers at Mines Douai seized on the opportunity to explore this line of research a little over two years ago. Today, the many requests the school has received for research partnerships show the importance of issues surrounding additive manufacturing.

 

“Additive manufacturing probably constitutes the most promising market in the materials sector,” assures Jérémie Soulestin, a researcher at Mines Douai. According to this polymers specialist, it is a “mature” field, but is “still rarely addressed by plastics manufacturers.” The Polymer and Composite Technology & Mechanical Engineering Department (TPCIM), where Jérémie Soulestin works, has seized the opportunity offered by this field. For two years, additive manufacturing has been the focus of the research carried out by the department’s teams. Of course, 3D printing processes for materials are no longer new. “Other colleagues have been addressing the issue by using laser sintering for some years now,” admits Jérémie Soulestin. But the innovation lies in the new combinations of materials and processes.

Laser sintering uses dry powders that are melted by a laser in specific places. The drops that form remain malleable for a few moments before cooling down, making it possible to create the desired shapes. Additive manufacturing via laser sintering was one of the first 3D printing processes to emerge, and today it produces good results for metals and certain plastics, specifically polyamides. However, it cannot be used for all available materials. Therefore, scientists have chosen to seek other processes, in order to expand the range of possibilities.

 

A wide range of stakeholderss

Jérémie Soulestin explains that the TPCIM department is “ahead of the game, particularly in terms of machines.” In support of this claim, he mentions the recent acquisition of the Arburg freeformer. Theoretically, this 3D printer is capable of using a large range of plastic materials used in plastics processes. “This tool uses an approach that is at odds with other manufacturers offering machines adapted to a limited range of associated materials,” the researcher explains. This approach is also better adapted to the work of Mines Douai scientists, which has traditionally focused on injection processes. Unlike laser sintering, this new additive manufacturing technique is within the researchers’ field of expertise. It is also a very popular field of expertise as reflected by the many industrial collaboration projects, which have continued to increase in line with the new work on additive manufacturing.

“We work with partners with a wide range of profiles,” explains Jérémie Soulestin. And for good reason, since the new processes interest industrial stakeholders at different levels of maturity, who all recognize the increasingly important role additive manufacturing will play in the industry of the future. “Some companies come to us for business development purposes: they know this is important, without truly understanding the issues,” admits the scientist. However, he adds, “Others, like major companies, come to us with very specific subjects.” All sectors are concerned, such as aeronautics for the small-series production of part.

 

La freeformer d'Arburg offre, en théorie, une palette de matériaux bien plus large que les autres imprimantes 3D.

The Arburg freeformer offers, in theory, a much wider range of materials than other 3D printers. Credits: Arburg.


Additive manufacturing: added value

The reluctance expressed in the past — particularly regarding durability — is no longer valid today. Companies see additive manufacturing as representing “real added value” in comparison with other traditional processes (such as machining). “We no longer have the technological barriers we had a few years ago,” confirms Jérémie Soulestin. The technology, with its layer-by-layer concept, does have its limitations, “but the choice of materials and certain optimization concepts have made it possible to overcome these limitations,” the researcher stresses.

Today, the prospects for improving the processes lie essentially in expanding the range of useable materials. In plastics processes, the key issue is to be able to use a larger range than for polyamides, which form a large percentage of the available polymers. Another opportunity for research is in semi-crystalline polymers, which present more challenges in terms of mastering the solidification. The target seems clear: in the future, it should be possible to manufacture every part using an additive manufacturing process.

 

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Conference on Polymer materials for additive manufacturing

What are the prospects for additive manufacturing technology in the field of polymer materials? This is the question researchers and industrial stakeholders will be trying to answer at the conference on “Polymer materials for additive manufacturing – reality and prospects.” The conference, organized by the French Society of Plastics Engineers (SFIP), Mines Douai, and the French Society of Automotive Engineers (SIA), will take place on March 23 and 24 in Villeurbanne on the INSA Lyon campus, which is also a partner of this event.

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