Sleep and centrotemporal spikes: Thalamic BOLD changes related to centrotemporal spikes during the wake-sleep transition

A 13 years-old right-handed boy with centrotemporal spikes (CTS) heightened during NREM sleep and with language difficulties, underwent EEG-fMRI co-registration both during wake and sleep. Scalp EEG was recorded by means of a 32 channels MRI-compatible EEG recording system and MRI was 3T (3 sessions 10 minutes long; TR: 3 sec). EEG offline was analyzed with Brainvision software and processed with Independent Component Analysis (ICA), while EEG source-imaging analysis was conducted through sLORETA software. SPM5 was utilized for functional data. During the "wake session" 47 right CTS were recorded in 10 minutes and were associated to focal cortical signal in the sensory motor cortex: increments in fMRI BOLD signal were recorded bilaterally, while EEG-source imaging showed activation in the ipsilateral sensory-motor cortex. During the "sleep session" 191 right CTS were recorded in 20 minutes: while the EEG source-imaging analysis resulted identical to the "wake session" (activation of right sensory-motor cortex), EEG-fMRI during sleep showed a more widespread activation in a cotical-subcortical network involving thalamus bilaterally, sensory-motor cortex and perisilvian cortex bilaterally. These results confirm the importance of thalamic oscillations in the genesis of CTS. Moreover, in this single case of CTS accentuated during sleep the involvement of a neural network similar to the one previously observed in patients with ESES has been identified.