Mapping Healthy and Epileptic States in the Centromedian Nucleus Region.

Background: Neuromodulation of the centromedian nucleus (CM) has shown beneficial effects on seizure frequency. The effects of stimulation vary by location within the CM region, and during closed-loop stimulation, different contacts have been used for recording and stimulation. The spatial relationships between anatomy, stimulation efficacy, and recording utility remain unclear.

Materials and methods: Local field potentials were recorded from participants undergoing responsive neurostimulation targeting the CM for the treatment of epilepsy. Spectral features, including periodic power and aperiodic offset, were derived from baseline recordings. Line length and bandpass detector metrics were calculated from device-detected epileptiform activity and compared with baseline. Spectral and detection features were mapped according to channel locations using coordinates in Montreal Neurological Institute space and spatial reconstruction of local field potential sources.

Results: Ten adult participants were studied, including eight with genetic generalized epilepsy, one with Lennox-Gastaut syndrome, and one with multifocal epilepsy. Periodic spectra demonstrated a daytime beta peak and a nighttime alpha/low beta peak. Spatial variation was noted for all spectral and detection features. Daytime aperiodic exponent, daytime periodic beta power, and nighttime periodic alpha power were highest in the medial CM (p < 0.001), with an additional beta spatial maximum in the motor thalamus. Line length detection exhibited a maximum in the posterior CM and was lower near a previously described "sweet spot" for stimulation (p < 0.001). Maximal bandpass detection was observed in the lateral CM (p < 0.001), 3 mm away from the stimulation sweet spot.

Conclusions: Maximal bandpass detection was observed in the lateral CM, near a previously described stimulation sweet spot. Other spectral and detection features were elevated in the medial/posterior CM, which has been described as a functionally distinct subregion. The lateral CM appears to be a favorable region for detection of epileptiform activity.