Self-regulation of slow cortical potentials in completely paralyzed human patients.

The study was intended to answer the question whether self-regulation of brain activity can be operantly learnt when the brain is disconnected from motor periphery. Two neurological patients with nearly complete motor paralysis learned bi-directional control of their slow cortical potentials (SCP) at vertex. After 4-6 weeks training both patients could reliably differentiate between SCP shifts in a negative versus positive direction. With one patient, training has been continued for a subsequent 4 months, which resulted in precise self-control, i.e. the patient was able to produce positive SCP shifts on command with an accuracy of about 95%. This indicates that self-regulation of cortical excitability (as manifested in the SCP) does not require feedback loops from the periphery. Although we cannot rule out that healthy subjects may employ behavioral strategies such as muscle contractions or changes in breathing, obviously humans can also control their SCP without using these strategies.