Brain oscillatory 4-30 Hz electroencephalogram responses in adolescents during a visual memory task.

Brain oscillatory responses of the 4-30 Hz electroencephalogram frequencies were assessed in 12 adolescents (mean age 14 years) during a visual N-back task with four memory load conditions (0-back, 1-back, 2-back, and 3-back). Theta frequency range (approximately 4-6 Hz) responses were elicited in all memory load conditions. The magnitude and duration of alpha frequency range (approximately 8-12 Hz) responses varied as a function of memory load. Beta frequency range (approximately 15-20 Hz) responses were modulated by both task difficulty and cognitive strategy. The differences between the memory load conditions were most prominent between the 0-back and 1-back conditions in the approximately 10 and 20 Hz electroencephalogram frequencies. Dynamic alpha and beta rhythm brain oscillatory responses are related to the cognitive processes in adolescence.