The engagement of mid-ventrolateral prefrontal cortex and posterior brain regions in intentional cognitive activity.

It is now widely recognized that cognitive processes are carried out by a distributed network of brain areas, some of which are involved in perceptual processing of a stimulus, whilst others are involved in cognitive control processes required to carry out certain tasks. In this study, differential contributions of higher visual areas and of an area involved in cognitive control processes were investigated in a task requiring participants to simply look at a stimulus or to look with the intention of remembering. Varying the extent to which intentional cognitive processes were required and the stimulus material in this task allowed the analysis of "top-down" and "bottom-up" influences on these areas, respectively. Significant increases in the mid-ventrolateral prefrontal cortex (mid-VLPFC) were only observed when the stimuli were viewed with an intention in mind, irrespective of the stimulus type. In contrast, activity in the parahippocampal place area and the fusiform face area, was only modulated in conditions requiring intentional control when stimuli were presented that also elicited activity in these regions during passive viewing. These findings help to clarify the complimentary role that the mid-VLPFC and posterior higher visual areas play in controlled and relatively automatic memory processing.