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Updated: May 24, 2026
Neural Activity Propagation in an Unfolded Hippocampal Preparation with a Penetrating Micro-electrode Array
Published on: March 27, 2015
Propagation concordance index reflects spatial proximity to the spike generator by linking interictal spikes with
Takumi Mitsuhashi1, Hiroharu Suzuki1, Kazuki Nishioka1
1Department of Neurosurgery, Juntendo University, Tokyo 1138421, Japan; Epilepsy Center, Juntendo University Hospital, Tokyo 1130033, Japan.
Objective:
To develop and validate a novel biomarker, termed the propagation concordance index (PCI), for estimating proximity to the spike generator by quantifying the similarity between the spatiotemporal propagation dynamics of interictal spikes and cortico-cortical spectral responses (CCSRs).
Methods:
Twelve patients with drug-resistant focal epilepsy underwent stereoelectroencephalography followed by resection or disconnection surgery. For interictal spikes and CCSRs, percent amplitude changes were quantified within 10-50 ms after spike or stimulation onset. These changes were projected onto a 5-mm three-dimensional intracerebral grid using Gaussian-weighted interpolation. PCI was defined as the mean Pearson correlation between spike- and stimulation-related spatial distributions of amplitude changes across the window. We evaluated (i) the relationship between PCI and the distance between the spike-leading site and the stimulation site, (ii) the effect of incomplete electrode sampling by systematically excluding electrode contacts within 5-20 mm of the spike-leading site, and (iii) the association between resection of high-PCI regions and outcomes.
Results:
PCI decreased with increasing distance from the spike-leading site (mixed model estimate -0.0061, p < 0.001). Under simulated incomplete sampling, PCI at the resulting apparent leading sites decreased with increasing exclusion radius (estimate -5.44, p < 0.001). A PCI threshold of 0.78 identified high-PCI sites, and higher resection ratios of these sites were associated with better outcomes (ρ = -0.796, p = 0.002).
Conclusions:
PCI reflects spatial proximity to the spike generator based on propagation dynamics.
Significance:
PCI may assist in identifying candidate regions for resection within and beyond electrode coverage.
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