Comment on "Preserved feedforward but impaired top-down processes in the vegetative state"

Abstract

Boly et al. (Reports, 13 May 2011, p. 858) investigated cortical connectivity patterns in patients suffering from a disorder of consciousness, using electroencephalography in an auditory oddball paradigm. We point to several inconsistencies in their data, including a failure to replicate the classical mismatch negativity. Data quality, source reconstruction, and statistics would need to be improved to support their conclusions.

Fig. 1

MMN topography in patients with disorders of consciousness and in healthy controls. The figure shows a comparison of (A) t test maps from Boly et al. (1) for the MMN (comparison of deviant and standard trials) with (B) similar maps obtained from 120 recordings collected in the past three years in Lionel Naccache’s laboratory, Hôpital de la Salpêtrière, Paris [intermediate results published in (5, 7)]. Note that we kept the uneven temporal spaces from figure 2 in Boly et al. (1). The higher-resolution data and larger numbers of patients lead to a quiescent period (up to ~100 ms) followed by a classical frontocentral MMN (~100 to 200 ms) and P3a (~200 to 300 ms), with similar topography in all groups.