How old knowledge begets new knowledge: strategic regulation of neocortical knowledge modules and learning-induced neocortical plasticity

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Cognitive and educational psychology have long identified the influential role of prior knowledge on encoding and retrieval of new knowledge, with particular focus on the roles of conceptual knowledge and schemas. Schemas have only recently generated interest in both the animal and human neurobiological literature, whereas more is known about the cognitive neuroscience of categories. In the present research program I will build on recent and exciting findings on the neurobiology of schemas in the memory domain. Importantly our research program is geared towards elucidating the use of the term schema and delineating its relationship to other related terms- most notably concepts, but also scripts, gist, extracted probabilities and so forth. In these studies we rely on data from patients with neurological damage (confabulation and amnesia), and neuroimaging (fMRI, MEG and ERP's). Neuroanatomically, we propose that the same principle of representational hubs that bind together isolated neural modules into multi-modal ensembles operate for conceptual knowledge, with the anterior temporal lobe (ATL) as the hub, and for schemas, with the ventromedial prefrontal cortex (vmPFC) as hub. Facilitation of encoding of new information by prior schemas can be mediated by hippocampal-vmPFC interaction with posterior neocortex. The vmPFC supports schema-related memory functions by “schema instantiation”: biasing and actively maintaining online contextually relevant schemas that serve as scaffold for information assimilation. Using ERP's and MEG we will test cortico-cortical interactions between vmPFC and lateral posterior neocortical structures when patients and controls perform schema instantiation tasks. We expect that healthy controls' successful performance would depend on frequency coherence primarily in the theta range and that these will be missing in patients. We will compare these signals to the ones derived from analogous conceptual knowledge tasks (i.e. categories such as mammals or arthropods). We expect to find that rather than vmPFC, the ATL would play a coordinating role for posterior neocortical activity. We will also continue our investigations of how conceptual knowledge may support direct neocortical learning. We have previously demonstrated that the ATL is key for learning novel label-picture associations, independently of the hippocampus. Others who followed our lead, confirming our prediction that this learning depends on activation of related semantics during encoding of the novel associations; this presumably leads to activation of neocortical networks and this network activity enables its modification and integration of novel information. Using MEG and a Bayesian model which we developed we plan to investigate the manner in which neocortical activity facilitates conceptual learning at the neocortical level, as well as the boundaries of such learning**