Thalamic burst and tonic firing selectively indicate patients’ consciousness level and recovery

Patients with disorders of consciousness exhibit severe declines in arousal and awareness, alongside anomalous functional brain connections and aberrant neuronal activities ^1–4 . Yet, the diagnostic error of patients’ consciousness states can reach up to forty percent ^5,6 , resulting in a worse prognosis. Neuronal mechanisms underlying the disorders are indispensable for identifying objective and intrinsic markers of consciousness. As the principal relay station between the brainstem arousal nuclei and the cerebral cortex, the thalamus has been empirically inferred to maintain consciousness and wakefulness within the brain connectome ^7–12 . Here, we investigated thalamic spiking, brain connections, consciousness states, and outcomes following deep brain stimulation in 29 patients. Our study reveals that thalamic activities can signal their consciousness states. Patients diagnosed with vegetative state/unresponsive wakefulness syndrome exhibited less active neurons with longer and more variable burst discharges compared to those in a minimally conscious state. Furthermore, as a direct deep brain stimulation site, neuronal profiles in the centromedian/parafascicular complex of the thalamus indicated whether electrostimulation here improved outcomes. Stronger tonic firing was associated with enhanced thalamocortical connections and better recovery outcomes in patients. These findings suggest that thalamic spiking signatures, including single-neuron burst discharge and tonic firing, selectively indicate the representation and alteration of consciousness. These findings provide direct neuronal and clinical evidence for understanding of thalamic contributions to disorders of consciousness.