Recognizing a mother's voice in the persistent vegetative state

We studied an 8-year-old boy after a near-drowning left him in a vegetative state (VS) for 4 years before the study. Findings fulfilled all clinical criteria for the diagnosis of VS. The purpose of this study was to investigate whether there was significant differential activation of the brain in response to hearing his mother's voice compared with the voices of unknown women. The data were assessed using quantitative electric tomography (QEEGt), a technique that combines anatomical information of the brain by MRI with EEG patterns to estimate the sources of the EEG within the brain. We found significant differences for EEG frequencies from 14-58 Hz, with a peak at 33.2 Hz (gamma band). The 3D reconstruction showed that these statistical differences were localized in the lateral and posterior regions of the left hemisphere. No significant differences were found between unknown women vs. basal conditions. These results demonstrate recognition of the mother's voice and indicate high-level residual linguistic processing in a patient meeting clinical criteria for VS. These findings launch new ethical and practical implications for the management of VS patients.