The main question raised by Sarà and colleagues is whether the activation that we observed in our patient when we asked her to perform mental imagery tasks in the functional magnetic resonance imaging scanner could have reflected an “implicit preconscious neural response.” For this to be a plausible alternative explanation, Sarà and colleagues would need to provide empirical evidence of the following: (1) the word tennis can produce a statistically significant change in activity in the supplementary motor cortex of a single individual who is not consciously aware; (2) the word house can produce a statistically significant change in activity in anatomically different regions of the brain, including the parietal lobe and the parahippocampal cortices, in the same unconscious individual; and (3) in both cases, these responses are sustained for up to 30 seconds and then stop when the (unconscious) participant is presented with another word (eg, rest). The article1 they cited in support of their argument provides no such evidence; indeed, that study demonstrates only that emotional words can produce changes in skin conductance in the absence of conscious awareness, which, although interesting in its own right, is not directly relevant to the anatomically specific, temporally sustained functional magnetic resonance imaging responses to specific (nonemotional) words that we observed in our patient who was diagnosed as vegetative. In fact, we know of no data supporting the inference that such stimuli do unconsciously elicit sustained hemodynamic responses in these regions of the brain, but considerable data exist to suggest that they would not (eg, in the study by Davis et al2).
Owen AM, Coleman MR, Boly M, Davis MH, Laureys S, Pickard JD. The Consciousness Dilemma: Feel or Feel of Feeling?—Reply. Arch Neurol. 2008;65(3):418-419. doi:10.1001/archneur.65.3.418-b