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PubMed · 10601746

Words without mind.

N Schiff·U Ribary·F Plum·R Llinás
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Abstract

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 resonance imaging (MRI) revealed a mean brain metabolism equivalent to deep anesthesia. Nevertheless, PET imaging demonstrated islands of modestly higher 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 patterns of spontaneous and evoked brain activity in response to sensory stimulation. Specifically, we examined spontaneous gamma-band activity (near 40 Hz) and its reset or modification during early auditory processing, a measure that correlated with human perception of sensory stimuli (Joliot, Ribary, & Llinás, 1994). Evidence of abnormal and incomplete gamma-band responses appeared in the left hemisphere only in response to auditory or somatosensory stimulation. MEG single-dipole reconstructions localized to the auditory cortex in the left hemisphere and overlapped with metabolically active regions identified by FDG-PET. The observation demonstrates that isolated neuronal 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.

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Acoustic StimulationAuditory PathwaysBrainFemaleFingersFluorodeoxyglucose F18HumansMagnetic Resonance ImagingMagnetoencephalographyMiddle AgedPersistent Vegetative StatePhysical StimulationTomography, Emission-ComputedVerbal BehaviorCase ReportsJournal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.

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N Schiff, U Ribary, F Plum, R Llinás. 1999. Words without mind.. https://doi.org/10.1162/089892999563715

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