Ketamine Increases Human Motor Cortex Excitability to Transcranial Magnetic Stimulation
The Journal of Physiology March 1, 2003 Vincenzo Di Lazzaro, Antonio Oliviero, Paolo Profice et al. 255 citations
Subanesthetic doses of the NMDA antagonist ketamine enhance the excitability of the human motor cortex, as shown by progressive reductions in resting and active motor thresholds and increased muscle response amplitudes to transcranial magnetic stimulation. Before ketamine, mean resting motor threshold was 49% of maximum stimulator output; at the highest infusion level it fell to 42.6%. Active motor threshold dropped from 38% to 33%. Responses to electric stimulation were unchanged, indicating that ketamine specifically boosts excitatory cortical networks by increasing glutamatergic transmission at non-NMDA receptors, likely AMPA receptors, facilitating repetitive discharge of pyramidal neurons.