Does excessive memory load attenuate activation in the prefrontal cortex? Load-dependent processing in single and dual tasks: functional magnetic resonance imaging study. - Susanne M. Jaeggi; Ria Seewer; Arto C. Nirkko; Doris Eckstein; Gerhard Schroth; Rudolf Groner; Klemens Gutbrod (NeuroImage, 2003)