INDIVIDUAL RELIABILITY OF AMPLITUDE DISTRIBUTION IN TOPOGRAPHICAL MAPPING OF EEG

Whilst there is an accumulation of evidence suggesting that many quant itative EEG parameters show good stability and reliability, no previou s study has considered whether the spatial distribution of EEG amplitu de is reliable over time within a session. This study reports on the s patio-temporal reliability of EEG using data recorded from 24 subjects in a baseline condition with eyes open and also whilst performing a s imple motor task. Both the internal stability and test-retest reliabil ity for electrode parameters were comparable to previously published d ata. For most individuals, amplitude distribution was stable within ea ch recording condition. but the test-retest reliability after 40 min w as less good with the poorest reliability in the delta frequency band. Most subjects showed spatio-temporal reliability of less than 0.7 in at least one frequency band. In contrast, spatio-temporal reliability for the group average was good and exceeded 0.88 in all frequency band s. It is argued that the results indicate that reliability is insuffic ient to allow topographical comparisons for a single individual, but i s more than adequate to allow group comparisons.