In 1935 Jacobsen reported that monkeys with bilateral frontal lesions involving the sulcus principalis, a putative analogue of human dorsolateral prefrontal cortex (Brodmann areas 9 and 46: Rajkowska and Goldman-Rakic, 1995a and Rajkowska and Goldman-Rakic, 1995b; see Fig. 1), were severely impaired at delayed response tasks. In delayed response tasks, subjects are initially presented with [...]