Interictal cortical spikes are followed by thalamic responses that are not reliably larger for SOZ spikes

We tested whether interictal spikes in seizure-onset-zone (SOZ) bipolar pairs produce a larger time-locked response in ipsilateral thalamic pairs than spikes in ipsilateral non-SOZ grey-matter pairs. Using OpenNeuro ds007445 v1.0.4, we analyzed up to 120 s before a seizure in each patient; the plan was written before signal inspection. A simple 10–60 Hz envelope detector identified spikes, and we compared thalamic 10–60 Hz envelope response from 0 to 250 ms after SOZ and control spikes, with patient as the unit. In the first-seizure analysis (15 patients), SOZ-minus-control response was +0.34 robust-z (11/15 positive; 95% CI −0.05 to 0.77; sign-flip p = 0.17). Spike co-occurrence was +0.088 (13/15 positive; raw p = 0.039; Holm p = 0.077). Both SOZ and control spikes were followed by responses above random-time levels (13/15 positive for each; p < 0.001). Pure SOZ events, without a control spike within 200 ms, had a smaller response than control events (−0.22; 3/12 positive; p = 0.070); trigger amplitude did not differ (p = 0.95). In the second-seizure replication (10 patients; the sub-007 run was incomplete), the SOZ-control differences were not significant (response p = 0.21; co-occurrence p = 0.17), while SOZ and control responses exceeded random-time levels in 10/10 patients (p = 0.002). The findings support a time-locked thalamic high-frequency response after cortical spikes, but do not show a reliably larger response for SOZ spikes. The response may be related to spike spread. Limitations include a simple detector without visual validation, no electrode coordinates or distance control, a 120 s window, and pooling 200 Hz and 2000 Hz recordings at 200 Hz, so activity above 60 Hz was not measured.

interictal spikes · thalamus · stereoelectroencephalography · SEEG · seizure-onset zone · epilepsy · spike-triggered response · OpenNeuro · ds007445