Information processing deficits in head injury assessed with ERPs reflecting early and late processing stages

ERPs provide informative measures of slowed information processing in head injury. While several studies have reported changes in long latency ERPs (N2, P3) in head injury, the data on early ERP components related to attention selection are inconclusive. The problem may be partly methodological because the standard oddball paradigm does not give an adequate basis for discriminating components contributing to the N1 and P2 waveforms. Following a suggestion by Garcia-Larrea et al. [10: Garcia-Larrea L, Lukasziewicz A-C, Maugière F. Revisiting the oddball paradigm. Non-target vs neutral stimuli and the evaluation of ERP attention effects. Neuropsychologia 1992;30:723-741] we used an extended oddball paradigm to study measures of early processing (N1-average, P250) as well as conventional cognitive ERPs (N1, P2, N2, P3) in a group of head injured patients and controls. We found evidence of deficits in early processing of neutral and non-target stimuli in the patient group, and interpret the findings as an indication that the patients are less efficient in terminating processing of irrelevant stimuli. The results further indicate that processing deviations affect both target and non-target stimuli in the oddball paradigm and thus the allocation of attention in the task as a whole.