Implicit statistical learning (ISL) allows for the learning of environmental patterns and is thought to be important for many aspects of perception, cognition, and language development. However, very little is known about the development of the underlying neural mechanisms that support ISL. To explore the neurodevelopment of ISL, we investigated the event-related potential (ERP) correlates of learning in adults, older children (aged 9-12), and younger children (aged 6-9) using a novel predictor-target paradigm. In this task, which was a modification of the standard oddball paradigm, participants were instructed to view a serial input stream of visual stimuli and to respond with a button press when a particular target appeared. Unbeknownst to the participants, covert statistical probabilities were embedded in the task such that the target was predicted to varying degrees by different predictor stimuli. The results were similar across all three age groups: a P300 component that was elicited by the high predictor stimulus after sufficient exposure to the statistical probabilities. These neurophysiological findings provide evidence for developmental invariance in ISL, with adult-like competence reached by at least age 6.

Cortical reorganization of function due to the growth of an adjacent brain tumor has clearly been demonstrated in a number of surgically proven cases. Such cases demonstrate the unmistakable implications for the neurosurgical treatment of brain tumors, as the cortical function may not reside where one may initially suspect based solely on the anatomical magnetic resonance imaging (MRI). Consequently, preoperative localization of eloquent areas adjacent to a brain tumor is necessary, as this may demonstrate unexpected organization, which may affect the neurosurgical approach to the lesion. However, in interpreting functional MRI studies, the interpreting physician must be cognizant of artifacts, which may limit the accuracy of functional MRI in the setting of brain tumors.

The birth of the statistical learning literature is often traced back to Reberʼs (1967) seminal study on implicit learning using an artificial grammar learning paradigm. However, to fully understand the relationship between such early implicit learning studies and the current notion of statistical learning, it is important also to consider its conception. The theory of perceptual learning by J. J. Gibson and Gibson (1955) paved the way for accounts of learning with a basis in sensory experience. In the Gibsonsʼ theory of perceptual learning, which has close parallels to current ideas about entrenchment (Schmid, 2007), repeated experience with a percept enhances oneʼs ability to discriminate between it and other percepts. This chapter argues that a communicative system characterized by entrenchment, as posited in this volume, likely relies to a considerable extent on the ability to track, learn, and use underlying associative relationships between linguistic elements and structures in comprehension and production. When considering the origin of statistical learning as a theoretical construct, it is also important to consider the early work of Miller and Selfridge (1950), who thought that a reliance on transitional probabilities may be similar to the way in which grammar is learned. Other research informed by both Millerʼs work and the theory of perceptual learning espoused by J. J. Gibson and Gibson (1955) demonstrated that frequent co-occurrence due to underlying structure improved participantsʼ recall of letter sequences (Miller, 1958) and that learning the positional relationships between linguistic units (i.e., morphemes) occurs as an experiential process of familiarization with the temporal positions in which such units are frequently encountered (Braine, 1963). This laid the foundation for future research investigating the close relationship between frequent co-occurrence and the strength and automaticity of recall at various levels of linguistic analysis. From the beginning, research on implicit learning related to language was focused on the way(s) in which units of linguistic information are formed. Some of the early explanations for the ways in which this learning happened relied on experiencebased accounts, as just described. However, experience-independent theories of language acquisition quickly became the dominant perspective primarily because of the widespread acceptance of the "poverty of the stimulus" argument (Chomsky, 1965; Crain, 1991). Saffran, Aslin, and Newportʼs (1996) research gave the psychology of

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