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

Public summary

• Thalamic spike analyses are conducted in 29 patients with disorders of consciousness.

• Thalamic tonic and burst firing modes distinctly signal consciousness level and recovery.

• Burst firing reflects consciousness; minimally conscious ones show shorter, stable bursts.

• Tonic firing in centromedian/parafascicular nuclei predicts deep brain stimulation outcome.

Abstract

Patients with disorders of consciousness suffer from severe impairments in arousal and awareness alongside anomalous brain connections and aberrant neuronal activities. The thalamus, a crucial hub in the brain connectome, has been empirically inferred to maintain consciousness and wakefulness. Here, we investigated thalamic spiking, brain connectivity, consciousness states, and recovery outcomes following deep brain stimulation in 29 patients. Our study reveals that thalamic neuronal activity serves as a marker of consciousness state. Patients diagnosed with vegetative state/unresponsive wakefulness syndrome exhibited less-active neurons, with longer and more variable burst discharges, than those in a minimally conscious state. Furthermore, neuronal profiles in the intralaminar thalamus, the direct stimulation site, predicted whether electrostimulation here improved recovery. Stronger tonic firing was correlated with enhanced thalamocortical connectivity 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.