UC Berkeley

The ability to utilize stored semantic knowledge in the service of goal-directed behavior is an important component of cognitive control. Though a growing amount of work has been done to characterize the precise role of ventrolateral prefrontal cortex (VLPFC) in memory processing, it is currently unclear whether left VLPFC supports controlled access to long-term memory and/or post-retrieval selection to stimuli outside of the explicitly verbal domain. Furthermore, the precise contribution of left posterior middle temporal gyrus (left pMTG) in supporting goal-relevant knowledge is unclear. More specifically, it is uncertain whether this region represents semantic function knowledge about a stimulus and/or knowledge about how a stimulus moves when it is in motion. The goal of this volume is to further explore the contributions of left VLPFC and left pMTG in accessing and representing goal-relevant knowledge, respectively. Chapter 1 reviews the literature on the involvement of PFC in goal-directed cognition and mnemonic processing, as well as the evidence supporting the role of left pMTG in representing knowledge. Chapter 2 discusses a functional MRI study examining the neural correlates of controlled retrieval and selection using foreign and domestic traffic signs. The results suggest that the anterior portion of left VLPFC is more sensitive to controlled retrieval, the posterior extent is more sensitive to selection demands, and the region intermediate to these two is sensitive to both demands. Chapter 3 describes an fMRI study focusing on the retrieval of distinct types of knowledge relevant to everyday manipulable objects. We found that left anterior VLPFC was driven by semantic retrieval demands, and that a region in left pMTG, previously associated with correctly retrieving the meanings to traffic signs, was most engaged when accessing knowledge about the object's function. To control for other factors (e.g., task difficulty) which may have fueled these results, we replicated this study while better controlling for task demands and difficulty (Chapter 4). In Chapter 5, these findings are synthesized and future directions are discussed. In summary, this work supports the involvement of left VLPFC and left pMTG in the retrieval and representation of stored knowledge that informs our actions.