Words without mind

A woman (LR), unconscious for 20 years, spontaneously produces infrequent, isolated words unrelated to any environmental context. Fluorodeoxy-glucose- positron emission tomography (FDG-PET) imaging coregistered with magnetic r esonance imaging (MRI) revealed a mean brain metabolism equivalent to deep anesthesia. Nevertheless, PET imaging demonstrated islands of modestly high er metabolism that included Broca's and Wernicke's areas. Functional brain imaging with magnetoencephalographic (MEG) imaging, a technique providing a temporal resolution of better than 1 msec, identified preserved dynamic pa tterns of spontaneous and evoked brain activity in response to sensory stim ulation. Specifically, we examined spontaneous gamma-band activity (near 40 Hz) and its reset or modification during early auditory processing, a meas ure that correlates with human perception of sensory stimuli Joliot, Ribary , Sr Llinas, 1994). Evidence of abnormal and incomplete gamma-band response s appeared in the left hemisphere only in response to auditory or somatosen sory stimulation. MEG single-dipole reconstructions localized to the audito ry cortex in the left hemisphere and overlapped with metabolically active r egions identified by FDG-PET. The observation demonstrates that isolated ne uronal groups may express well-defined fragments of activity in a severely damaged, unconscious brain. The motor fixed-action pattern character of her expressed words supports the notion of brain modularity in word generation .