Event-related alpha synchronization/desynchronization in a memory-search task in adolescent survivors of childhood cancer

Objectives: Event-related desynchronization (ERD) and synchronization (ERS) of the 8-10 and 10-12 Hz frequency bands of the background EEG were studie d in 19 adolescent survivors of childhood cancer (11 leukemias, 8 solid tum ors) and in 10 healthy control subjects performing an auditory memory task. Methods: The stimuli were auditory Finnish words presented as a Sternberg-t ype memory-scanning paradigm. Each trial started with the presentation of a 4 word set for memorization whereafter a probe word was presented to be id entified by the subject as belonging or not belonging to the memorized set. Results: Encoding of the memory set elicited ERS and retrieval ERD at both frequency bands. However, in the survivors of leukemia, ERS was turned to E RD during encoding at the lower alpha frequency band. ERD was lasting longe r at the lower frequency band than at the higher frequency band, in each st udy group. At both frequency bands, the maximum of ERD was achieved later i n the cancer survivors than in the control group. Conclusion: The previously reported type of ERD/ERS during an auditory memo ry task was reproducible also in the survivors of childhood cancer, at diff erent alpha frequency bands. However, the temporal deviance in ERD/ERS magn itudes, in the cancer survivors, was interpreted to indicate that both surv ivor groups had prolonged information processing time and/or they used inef fective cognitive strategies. This finding was more pronounced in the group of leukemia survivors, at the lower alpha frequency band, suggesting that the main problem of this patient group might be in the held of attention. ( C) 1999 Elsevier Science Ireland Ltd. All rights reserved.