CIFRE support (2011-2014): Electrodes for Multiscale Electrophysological Recordings in Human

OBJECTIVES

We propose in this thesis to design new types of electrodes, which will meet the challenges posed by simultaneous recordings at multiple scales in humans.

In a first project, we will adapt dry electrodes small, already used for multisite recordings on the auditory cortex in animals (Takahashi 2003), single site on the cochlear nerve during surgery of the skull base (Schmerber 2004) and polysomnographic recordings (SENSATION project). The dry electrodes can indeed good quality recordings for a very long time. A fixation system should be flexible mesh developed for the rapid installation of a large number of electrodes (64) during the operation. The appearance of more flexible will avoid asking too near places electrodes as the electrodes of SEEG. Tests will be performed in healthy subjects, on conventional EEG recordings (evoked potentials) and in patients during implantation.

We also study the electrodes based on conductive polymers. Besides the fact that these materials are compatible, naturally, with flexible substrates, they demonstrated an ability to decrease the impedance of the electrodes and improve the quality of recordings of neuronal activity (Abidian 2009). We will work on polythiophenes commercially available, deposited from solutions which patterns are formed either by photolithograpie either by inkjets. We will optimize the morphology of designs by varying the deposition conditions to minimize impedance and maximize the signal to noise ratio of our recordings.

In a second project, we will design a modified version of SEEG electrodes. These electrodes incorporate small contacts (

In parallel, mathematical analysis of multi-signals collected will be addressed in two forms. The first is the signal processing (locating sources and measures of partial correlation) to quantify the relationship between the signals and map depth (SEEG) regions visible on the surface (EEG, MEG). The second form, which is complementary, is computational modeling to understand the link between dynamic effects visible on Multiunit neuronal populations (Hervé 1990) or mean-field (Francis 2000) and of those induced to the signals above level.

 

REFERENCES:

Abidian,M.R., Ludwig, K.A., Marzullo, T.C., Martin, D.C., Kipke, D.R., Adv. Mater. 21, 3764 (2009).

Bartolomei, F., Chauvel, P., Wendling, F., 2008. Epileptogenicity of brain structures in human temporal lobe epilepsy: a quantified study from intracerebral EEG. Brain 131, 1818-1830.

Bénar, C.G., Grova, C., Kobayashi, E., Bagshaw, A.P., Aghakhani, Y., Dubeau, F., Gotman, J., 2006. EEG-fMRI of epileptic spikes: concordance with EEG source localization and intracranial EEG. Neuroimage 30, 1161-1170.

François, O., Horikawa, J., Abdallahi, M., Taniguchi, I., Hervé, T., 2000. Statistical procedures for spatiotemporal neuronal data and application to optical recording of auditory cortex, Neural Comput. , 12(8):1821-38.

 François, O., Larota C., Horikawa, J., Hervé, T., 2000. Diffusion and innovation rates for multidimensional  neuronal data with large covariances,  Network : Comput.  Neural Syst. 11., 211-220

Gavaret, M., Badier, J.M., Marquis, P., Bartolomei, F., Chauvel, P., 2004. Electric source imaging in temporal lobe epilepsy. J Clin Neurophysiol 21, 267-282.

Hervé, T., Dolmazon, J.M., & Demongeot, J., Random field and neural information Proc. Natl. Acad. Sc., 1990: 87, 806-810.

Lopes da Silva, F.H., Van Rotterdam, A., 2005. Biophysical Aspects of EEG and Magnetoencephalogram Generation In: Niedermeyer, E., Lopes da Silva, F.H. (Eds.), Electroencephalography: Basic Principles, Clinical Applications, and Related Fields. Lippincott Williams Wilkins, Baltimore.

Michel, C.M., Murray, M.M., Lantz, G., Gonzalez, S., Spinelli, L., Grave de Peralta, R., 2004. EEG source imaging. Clin Neurophysiol 115, 2195-2222.

Schmerber S, Lavieille JP, Dumas G, Herve T., 2004. Intraoperative auditory monitoring in vestibular schwannoma surgery: new trends. Acta Otolaryngol.  Jan;124(1):53-61.

Takahashi H, Ejiri T, Nakao M, Nakamura N, Kaga K, Hervé T.,2003. Microelectrode array on  folding polyimide ribbon for epidural mapping of functional evoked potentials.IEEE Trans Biomed Eng. Apr;50(4):510-6.

Urrestarazu, E., Chander, R., Dubeau, F., Gotman, J., 2007. Interictal high-frequency oscillations (100-500 Hz) in the intracerebral EEG of epileptic patients. Brain 130, 2354-2366.