Immediate Interpersonal and Intermanual Referral of Sensations Following Anesthetic Block of One Arm

OBJECTIVES: To explore whether interpersonal and intermanual sensory referral occurs following anesthetic block of a limb and to test theories of disinhibition of mirror neuron activity and transcallosal referral. DESIGN: Case series. SETTING: Outpatient surgery at the University of California San Diego Medical Center. PATIENTS: Six patients who underwent orthopedic surgery. MAIN OUTCOME MEASURES: Patient verbal ratings. RESULTS: Patients with brachial plexus blocks experienced touch sensations in the anesthetized arm when watching another person's arm being touched or when the contralateral intact hand was touched. CONCLUSIONS: To our knowledge, this is the first demonstration of rapid reorganization of functional connectivity in the adult human brain, most likely in S2 neurons. This finding suggests that conscious perception of touch results from fluctuating mosaics of cortical excitation and inhibition between different regions within the patient's own S2 neurons and, more remarkably, from viewing others' sensations.