Basic discriminative and semantic processing in patients in the vegetative and minimally conscious state

Helena Erlbeck, Ruben G L Real, Boris Kotchoubey, Donatella Mattia, Jakob Bargak, Andrea Kübler

Research output: Contribution to journalArticlepeer-review

Abstract

Patients who survive injuries to the brain following accidents or diseases often acquire a disorder of consciousness (DOC). Assessment of the state of consciousness in these patients is difficult since they are usually incapable of reproducible motor movements. The application of event-related potentials (ERP) recorded via EEG constitutes one promising approach to complement the assessment of cognitive functions in DOC patients. For these assessments, a hierarchical approach was suggested which means that paradigms aiming at higher order ERPs are only presented if early responses were found. In this study, 19 behaviorally unresponsive or low-responsive DOC patients were presented with three auditory paradigms using passive instructions. The paradigms aimed at eliciting the Mismatch Negativity (MMN) and N400 and were applied at two time points. One oddball paradigm (MMN) and two semantic paradigms (word-pairs: N400 Words; sentences: N400 Sentences) were included. The majority of patients (n=15) did not show any response to the stimulation. In the MMN paradigm, an MMN was identified in two patients, in the N400 Words paradigm, only an N1 was identified in one patient, and in the N400 Sentences paradigm, a late positive complex (LPC) was identified in two patients. These data contradict the hierarchical approach since the LPC was identified in patients who did not exhibit an MMN. They further support the notion that even higher information processing as addressed with the N400 paradigms is preserved in a minority of DOC patients. Thus, in this sample, around 10% of the DOC patients exhibited indicators of preserved consciousness.

Original languageEnglish
Pages (from-to)8-16
Number of pages9
JournalInternational Journal of Psychophysiology
Volume113
DOIs
Publication statusE-pub ahead of print - Dec 30 2016

Keywords

  • Journal Article

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