Objective:

The objective of this study is to investigate the effects of centromedian thalamus stimulation on vigilance and its subsequent impact on cognitive functions.

Background:

Arousal, regulated by the Reticular Activating System, allocates mental processing resources. Vigilance, linked to fronto-parietal (FPN) and cingulo-opercular (CON) networks, enhances cognition. Preclinical studies show that improving arousal boosts vigilance and cognitive functions, with the centromedian nucleus serving as a key connection hub.

Design/Methods:

We recorded a 10-minute baseline of simultaneous scalp and thalamic EEG. Seven patients underwent stimulation at 100Hz, 2mA, with 20 trials of short train (0.1s) or long burst (5s). For local thalamic effects, we analyzed power-spectra post-stimulation, comparing short and long bursts using multi-taper spectral analysis. Simultaneous cortical changes were examined using dSPM, focusing on percentage differences in gamma power between long (5s) and short bursts (0.1s) in CON and FPN networks.

Results:

Thalamic Effects: Long burst (5s) CM stimulation reduced delta power and increased alpha to high gamma power within a 4-second post-stimulation period (FDRp< 0.002). Notably, 100Hz long bursts induced a surge in narrowband gamma power across both low (p < 0.001) and high gamma frequencies (p=0.005), correlating with clinical arousal from heightened wakefulness and increased heart rate. Cortical Effects: Thalamic-induced arousal during prolonged burst (5s) was associated with a significant rise in broadband power in CON and FPN networks. This increase translated to a mean spectral power surge of 357% in CON and 297% in FPN. 

Conclusions:

 CM stimulation at 100Hz with a 5-second burst activates the arousal network, including cingulo-opercular and frontoparietal networks crucial for sustained attention tasks.