This volume is an attempt to relate neuroscience research to cognitive metaphors (e.g., auditory loop, Universal Grammar [UG], fossilization) used by SLA researchers and psycholinguists to describe language acquisition. The volume consists of six chapters, originally master's theses and PhD qualifying papers, and an introduction and conclusion by Schumann. The chapters review literature that pertains to the neurobiology of six subtopics: aptitude, motivation, procedural memory, declarative memory, memory consolidation, and attention. In the preface, Schumann suggests that the purpose of the volume is “to promote a neurobiology of language that starts with the brain and moves to behavior” (p. xi), although he acknowledges one page later that “empirical research on the hypothesized mechanisms may be some time off” (p. xii). The volume aims to convince the intended readership, SLA researchers who might know little or no neurobiology, that investing time in the study of the neuroscience of learning is critical to the field's progression.
The volume's arguments rest on the assumption that an understanding of the neuroscience of learning (e.g., what increases oxygen consumption in specific parts of the brain, which behaviors are affected when certain parts of the brain are nonfunctioning) should constrain theories of SLA. Although I will not disagree with the underlying belief—that cognition is ultimately a function of the brain and that to fully understand cognitive processes, we need to understand the neural activation and cellular processes supporting that function—I do not believe that our current (limited) understanding of neurobiology can productively constrain SLA theories. Although we can observe changes in the brain, such as increased blood flow to particular brain structures, we do not know how to interpret that blood flow. Given that we do not know how various components of the brain interact to perform unique functions, placing limits on theories of SLA based only on our crude understanding of the neurobiology of cognition seems premature.
A major thesis of the volume (and a thread through all of the chapters) is that language acquisition (SLA and also, possibly, the acquisition of a first language) is facilitated by “a domain-general learning mechanism in the brain that is used not only for language but also for motor and other cognitive learning” (p. 43). This idea rests on the questionable assumption that specific brain activation patterns uniquely identify specific cognitive processes. Moreover, many of the studies that indicate similar patterns of brain activation for language learning and general learning cited in this text compare nonlinguistic tasks with tasks that are only partially linguistic (e.g., pp. 60, 62, 99, 127, and 135). It is not surprising, therefore, that the researchers find similar patterns of activation, so one cannot conclude that those similar patterns of activation necessarily represent identical cognitive processes.
More problematic is the bold use of neuroscience research and the conclusions that the authors draw from those studies—conclusions that most neuroscientists would report only in context and definitely more cautiously. Many of the studies are presented in insufficient detail for readers to evaluate critically (e.g., pp. 39, 51, 94, 124, and 169), and other studies seem to support multiple models of language acquisition—some counter to the volume's argument that language acquisition does not require language-specific learning mechanisms (e.g., pp. 2, 67, 99, and 107).
It is difficult to make disciplinary knowledge accessible to a wide audience, and some chapters in the volume explain the neuroscience better than others. The vocabulary used in some sections is intimidating or even off-putting. For example, readers with only a basic background in neurobiology might be surprised to read about the role of “spiny neurons in the striasomes of the striatum” (p. 33), an unnecessarily detailed description. In other parts of the volume, concepts are presented in such a simplified way that important exceptions to the generalizations made in the text are ignored.
Although the volume's assumptions and the conclusions the authors draw from the empirical studies that they cite are sometimes questionable, the volume makes an important contribution to the field of SLA. A complete understanding of language acquisition cannot exist independently of an understanding of its neural instantiation, and it would benefit the field of SLA to inform and be informed by the neuroscience of learning and memory.
This volume takes the difficult but important step of trying to relate current knowledge in the fields of neuroscience and SLA, and its authors should be commended for this. It can only serve as a basic starting point, though. Future work needs to more critically evaluate research both from neuroscience and from SLA and to interpret such work cautiously. Although I do not agree with the authors that our current understanding of brain biology should constrain SLA theories, I agree that it should inform them. That will only be the case when the fields of SLA and neurobiology contribute to each other, recognizing their interdisciplinary nature. This volume represents an important step in that direction.
