Changes in effective connectivity of sensorimotor rhythms in thalamocortical circuits during the induction and recovery of anesthesia in mice

The thalamocortical network serves a role in both consciousness and sensorimotor processing. However, little is known regarding how changes in conscious states, via induction of and recovery from anesthesia, affect the processing of sensorimotor information in the thalamocortical network. To address this, we investigated the dynamics of causal interactions among sensorimotor rhythms (SMR; frequency range of 3-12 Hz) across the thalamocortical network during transitions into and out of ketamine-induced unconsciousness. Two local field potentials from the ventral lateral and ventrobasal thalamic nuclei, as well as two intracranial electroencephalography signals from the primary sensory and primary motor regions, were recorded in 10 mice. Spectral Granger causality analysis revealed two distinct frequency-specific patterns in sensorimotor rhythms. For the low-frequency (3-6.5 Hz) SMR, loss of consciousness evoked causal influences directed from the cortex to the thalamus. For the high-frequency (6.5-12 Hz) SMR, causal influences from the primary sensory cortex to other regions during the conscious period were abruptly altered by loss of consciousness and gradually regenerated following recovery of consciousness. The results of the present study indicate that anesthesia alters the flow of sensorimotor information in the thalamocortical network and may provide evidence of the neural basis of loss and recovery of sensorimotor function associated with anesthesia.ope