Empirical validation of statistical parametric mapping for group imaging of fast neural activity using electrical impedance tomography

Abstract

Electrical impedance tomography (EIT) allows for the reconstruction of internal conductivity from surface measurements. A change in conductivity occurs as ion channels open during neural activity, making EIT a potential tool for functional brain imaging. EIT images can have >10 000 voxels, which means statistical analysis of such images presents a substantial multiple testing problem. One way to optimally correct for these issues and still maintain the flexibility of complicated experimental designs is to use random field theory. This parametric method estimates the distribution of peaks one would expect by chance in a smooth random field of a given size. Random field theory has been used in several other neuroimaging techniques but never validated for EIT images of fast neural activity, such validation can be achieved using non-parametric techniques. Both parametric and non-parametric techniques were used to analyze a set of 22 images collected from 8 rats. Significant group activations were detected using both techniques (corrected p < 0.05). Both parametric and non-parametric analyses yielded similar results, although the latter was less conservative. These results demonstrate the first statistical analysis of such an image set and indicate that such an analysis is an approach for EIT images of neural activity.

A Versatile and Reproducible Multi-Frequency Electrical Impedance Tomography System

“…The baseline noise in these recordings agreed with that observed in previous fast-neural activity experiments which reported noise of 0.18 $\mathsf{\mu }$V ± 0.04 $\mathsf{\mu }$V, using a bandwidth of 250 Hz [16,42] and averaging over 120 repeated stimuli. However, the results presented in these studies were obtained after averaging of only 60 trials, suggesting a decrease in background noise when using the ScouseTom system.…”

Applications of Electrical Impedance Tomography in Neurology

“…EIT utilized to perform surface measurements for the reconstruction of the conductivity distribution of a cross-section is performed by passing a fixed current through some electrodes, placed on the target surface. The fixed current induces a change in the voltages across the topography of the surface (Figure1), which is primarily utilized to identify the inherent conductivity variations (Bayford, 2006;Packham et al, 2016).…”