Introduction The aim was to compare evoked potentials (EP) from the P300 paradigm against mismatch negativity (MMN) paradigm, both recorded in the subthalamic nucleus (STN), internal globus pallidus (GPi) and thalamus (Th) and thus electrophysiologically isolate conscious cognition component in these structures.
Methods We included 8 patients in Deep brain stimulation program and recorded EP (patients with Parkinson's disease, Generalized dystonia, Essential tremor, Epilepsy). The two four-contacts intracerebral electrodes were implanted into the left and right STN, GPi or Th bilaterally. We computed local potentials on the left and right electrode and we studied the latency of cognitive response (from 200 to 400 ms).
Results In the comparison of infrequent stimuli related P300 and MMN a significant difference was found in 14 from 16 electrodes. Comparing frequent answers we found significant difference in 13 from 16 electrodes.
Conclusion The difference between evoked potentials of MMN and P300 protocols in 200–400 ms latency suggests that STN, GPi and Th are involved in conscious cognitive processes at the time of stimuli application.