Inter-channel variations in P300 amplitudes-an advocacy for multichannel recording

• Published in: Journal of Advanced Clinical and Research Insights 2015-05, Vol.2 (3), p.116-119
• Main Authors: Anupriya, J., Prakash, Ravi, Kumar, Arun, Roopakala, M. S.
• Format: Article
• Language: English
• Subjects: Electrodes; Generators
• ISSN: 2393-8625; 2393-8625
• DOI: 10.15713/ins.jcri.58

For long, the controversy has prevailed regarding the number of channels that should be involved in recording the P300 waveform or other long-latency event-related potentials (ERPs). There are several theoretical reasons which favor the technique of using multiple channels for ERP over a single channel. Most important is the possibility of, asymmetries in generator activity of a particular waveform. If there are asymmetries of the generator activity, it will result in topographical deviations of the P300 peak from the midline. Here, we provide support for multiple channel recording on the basis of our study results. This was a cross-sectional case-control study. 17 normal individuals were recruited for the study. The auditory ERP data were collected using the auditory oddball P300 paradigm. The peak amplitudes obtained in CZ was compared with independent samples t-test with the peak amplitudes in all other electrodes. There were significant differences between the amplitudes of P300 as recorded from CZ compared to the amplitudes of other electrodes. In line with the idea popular in literature, the maximum amplitude was found in the midline region which was however located at the parietal regions rather than the central region. Our results show two important findings which should be taken into account while interpreting the active electrode as the major source of P300 recording. The first and foremost seems to be that the standard deviations and variances of the amplitude values that we observed were very high, sometimes even more than the mean values. Second, there are irregularities in the localizations of maximum amplitudes in between individuals. On the basis of these findings, we recommend multiple channel recording for P300 ERPs.