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present, novel memory can bypass the hippocampus and be rapidly acquired via the neocortex. Tse et al. (Tse et al., 2007) used a paired associate learning task and trained rats to associate different food flavors with variable spatial locations. The constancy of paired flavor-location association became the schema, which took about a month-long repetitive training for the rats to learn effectively. Once having acquired the schema, the rats could rapidly learn, in a single- trial exposure, a novel flavor-location pair, without memory interference with concurrently trained paired associates. Critically, experimentally induced neurotoxic hippocampal lesions did not impair the ability for rapid (neocortical) learning of novel flavor-location pairs if the lesions occurred following schema acquisition. The authors concluded that what the learner brings to the table, i.e. a consistent schema, can permit rapid neocortical memory consolidation without interfering with remote memory, suggesting a revision to the notion of the neocortex as a slow learner. In a subsequent study, Tse et al (Tse et al., 2011) demonstrated that rapid neocortical learning of a novel paired associate consistent with a preexisting schema was associated with expression of immediate-early genes (IEGs) in the rat peri-limbic medial prefrontal cortex. The latter effect which more directly established a neocortical region involved in rapid neocortical memory consolidation, was exclusively present when the novel paired associate learning occurred in the presence of a consistent schema.

Mechanisms similar to the schema-dependent learning have since been demonstrated in human subjects. The phenomenon dubbed fast mapping is a learning mechanism that is thought

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to underlie word learning, particularly as occurs during early vocabulary development. Similar to the schema-based learning, the idea behind fast mapping is to train a novel word in the context of retrieval of an already known concept. Retrieving the meaning of the already known word, and then ruling it out allows the learner to infer that the new word to be learned refers to a novel item. Similar to how an existing schema can scaffold the acquisition and rapid

neocortical integration of a novel memory, the retrieval of an already familiar concept can act as a similar scaffold for acquiring a new word. As described below, a fast-mapping approach to novel word learning is argued to lead to hippocampus-independent rapid neocortical learning.

Coutanche and Thompson-Schill (Coutanche & Thompson-Schill, 2014) demonstrated that words acquired using a fast mapping approach (in contrast to an approach they termed episodic encoding, which asked participants to “remember the XXX”) result in rapid integration into lexical networks. Lexical integration was assessed via lexical competition effects as done previously (Bowers et al., 2005). If the newly learned word (e.g. “torato”) is lexically integrated, it is expected to compete with the lexical representation, and hence slow down lexical decisions to its orthographic neighbor (i.e. “tomato”, which now has “torato” as its only neighbor), relative to lexical decisions for control hermit words. Lexical integration effects, which typically take multiple days of consolidation to emerge (M. H. Davis et al., 2009; Gaskell & Dumay, 2003), were demonstrated both 10 minutes after training as well as on the following day. The same publication also demonstrated preliminary evidence for semantic priming effects, using the novel words as primes for related concepts. The above behavioral demonstration was forwarded as evidence that fast mapping results in rapid

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neocortical representations, thought to underlie lexical integration (Coutanche & Thompson- Schill, 2014).

More direct evidence for the possibility of rapid hippocampus-independent neocortical learning comes from demonstrations of word learning via fast mapping, in bilateral

hippocampal amnesics (Sharon, Moscovitch, & Gilboa, 2011). Four severely amnesic patients were taught arbitrary word-picture associations using a fast mapping paradigm. Despite exhibiting strong impairment in a standard associative memory task, the patients were able to acquire the word-picture associations over a few trials, and were able to retain the knowledge when tested a week later. On the contrary, patients with damage to the left anterior temporal lobe were impaired in the fast mapping task. The potentially critical importance of the left anterior temporal lobe for rapid cortical learning was corroborated in a subsequent publication from the same group (Atir-Sharon et al., 2015). In that publication, the group demonstrated in healthy adults that subsequent memory performance following fast mapping vs. standard explicit encoding training was best predicted by anterior temporal lobe and hippocampal voxels, respectively.

The aforementioned findings by Tse et al (Tse et al., 2007, 2011) seemed, at first glance, to counter prior models of novel memory acquisition and consolidation (McClelland et al., 1995; Nadel & Moscovitch, 1997). The schema-based learning account seemingly

contradicted the position taken by predating computational models in two accounts. First, unlike the schema-based account, the models considered the hippocampus as the exclusive gateway for novel declarative memory acquisition and retrieval. Second, unlike the rapid

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neocortical schema-based learning, the computational models posited that neocortical declarative memory consolidation is an obligatorily slow (on the order of weeks or longer) process if it is to avoid interference with prior memory. To address the apparent discrepancies in schema-based learning, McClelland (McClelland, 2013) ran another simulation of the Complementary Learning Systems model, with an exclusive focus on the consistency of the new learning with prior knowledge. The relevant findings were that, given consistency with prior knowledge, the model’s simulated neocortical network was able to rapidly acquire new information, without interfering with prior knowledge, similar to schema-based learning. The latter finding provides an important validation for a critical finding about schema-dependent memory acquisition and consolidation that has profound implications, an example of which would be the faculty of education.

4.4 Functional Neuroanatomy of Memory Retrieval – Current