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To LFP or to CSD? – That is the question

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Czerwinski M. B., Kowalska M., Chintaluri C. H., Wojcik D. K.

Acta Neurobiologiae Experimentalis

2017

tom 77

nr Suppl.1

INTRODUCTION: Current Source Density (CSD) is spatially smoothed transmembrane activity of the neurons. Local Field Potential (LFP) is the electric potential generated by ionic currents in the neural tissue and it is directly related to the CSD. LFP is relatively easily accessible experimentally but due to the long range of electric field, it is difficult to interpret. CSD needs to be calculated but it reflects the local neural activity directly. Since the currents directly reflect neuronal computations, using electric potentials (LFP’s) to infer performed computation may lead to misinterpretations. AIM(S): 1) Discuss challenges arising in multielectrode LFP and CSD analysis, in particular case where direct analysis of LFPs can lead to misinterpretation. 2) Show that the kernel Current Source Density reconstruction method (kCSD) gives a better insight into the underlying phenomena than the observed potentials, and to show the limits and uncertainties yielded by the method. 3) Present the kCSD-python toolbox for CSD analysis. METHOD(S): All of the modeling and computations was done in Python and tested on model data. Potentials were calculated using assumed physical models of tissue. The kCSD library in Python is available at: https://github.com/ Neuroinflab/kCSD‑python. RESULTS: We show examples where the LFP’s can ‘hide’ more complex underlying CSD patterns and how the kCSD can reconstruct those sources, depending on the number and configuration of recording electrodes. CONCLUSIONS: Complex CSD patterns studied at the resolution of few electrodes can be obscured if only direct LFP analysis is used. The kCSD method can help to recover them. The main limiting factors are the number of recording electrodes and their configuration. FINANCIAL SUPPORT: This work was supported by EC-FP7-PEOPLE sponsored NAMASEN Marie-Curie ITN grant 264872, Polish Ministry for Science and Higher Education grant 2948/7.PR/2013/2, Narodowe Centrum Nauki grants 2013/08/W/NZ4/00691 and 2015/17/B/ ST7/04123.

New insight into kernel current source density reconstruction

100%

Kowalska M., Czerwinski M. B., Chintaluri C. H., Wojcik D. K.

Acta Neurobiologiae Experimentalis

2017

tom 77

nr Suppl.1

INTRODUCTION: The low-frequency part of extracellular potential, called the Local Field Potential (LFP), is a useful measure of neural systems activity. However, a direct interpretation of LFP is problematic as it is not a local measure – each electrode may record activity observed millimeters away from source. Estimation of current source density (CSD), the volume density of net transmembrane currents, has become a convenient way to deal with this problem. AIM(S): The aim of the study is to investigate the properties of kCSD method to develop a procedure which will facilitate optimal usage of the presented method in complicated experimental scenarios, for complex measurement setups etc. METHOD(S): In the study we use kCSD method which estimates the sources in a family of allowed CSD distributions of dimensionality larger than the number of measurements. To identify the parameters of the method leading to optimal source estimation, a statistical technique of cross-validation is used. We perform this study using Python programming language with several types of known (model) reference data and different electrodes setups. We employ singular value decomposition (SVD) method to study the internal properties of kCSD reconstruction. RESULTS: To examine the influence of the measurement setup on the reconstruction capability of the kCSD method we performed simulated study. We present error maps of CSD estimation which give us valuable insight into kCSD reconstruction quality. CONCLUSIONS: The quality of CSD estimation significantly depends on the measurement setup. This study enables the researchers to check how much they can trust the obtained kCSD reconstruction for a given setup and specific collection of recordings. FINANCIAL SUPPORT: This work was supported by EC-FP7-PEOPLE sponsored NAMASEN Marie-Curie ITN grant 264872, Polish Ministry for Science and Higher Education grant 2948/7.PR/2013/2, Narodowe Centrum Nauki grants 2013/08/W/NZ4/00691 and 2015/17/B/ST7/04123.

Ograniczanie wyników

2 Acta Neurobiologiae Experimentalis

2 Chintaluri C. H.

2 Czerwinski M. B.

2 Kowalska M.

2 Wojcik D. K.

2 2017

Wyniki wyszukiwania

To LFP or to CSD? – That is the question

New insight into kernel current source density reconstruction