Paul Grobstein

Organization in the Sensorimotor Interface: A Case Study with Increased Resolution

Recent studies on the neuronal organization underlying prey orienting behavior in the frog, Rana pipiens, are reviewed and discussed in the context of more general consideration of the information processing characterstics and nervous system structures involved in the production of directed movements. It is suggested that directed movements in general depend on “activity gated divergence,” a property of some neuronal networks which allows them to associate with a given topographically specified sensory input any of a number of outputs, depending on the character of other relevant neuronal signals. It is further suggested that two important information processing steps occur between midbrain sensory maps involved in directed movement and the actual motor output pattern. The first of these involves the production of a signal related to stimulus location in an abstract coordinate frame, one closely related neither to sensory surfaces nor to movement parameters. The second involves the selection of the particular movement to be generated and the creation of the appropriate motoneuron discharge patterns. The first transformation seems to occur in the ventral midbrain, and the latter in the spinal cord. Both transformations are likely to involve an interaction between signals derived from the initial topographically specified sensory input and signals representing other relevant information, and hence both transformations probably contribute to the overall activity gated divergent character of the network involved in directed movement. The context-dependent nature of the neuronal signals, together with evidence that autonomous central organization is critical to their interpretation, raises new questions about how signals represented in different coordinate frames are combined, and suggests that reflex theories are ceasing to provide an adequate conceptual framework for the analysis of sensorimotor processing.

Directed movement in the frog: a closer look at a central representation of spatial location

The neuronal circuitry underlying directed, ballistic movements in the frog includes a stage in which information about target location is represented in a form which is both experimentally distinguishable from spatial representations closer to the sensory and motor sides of the nervous system, and distinctive in its organization. Three dimensional location is represented in a distributed fashion, in terms of independent orthogonal components Each component appears to be population coded, apparently as the total activity in a particular neuronal structure. These findings are discussed in relation to related findings in other systems, with the objectives of identifying possible generalizations about spatial representations involved in sensorimotor processing and of defining directions for future research based on these.

The Brain as a Learner/Inquirer/Creator: Some Implications of Its Organization for Individual and Social Well Being

At its best, empirical research opens new and fruitful directions for exploring what it means to be human. In this essay. I will describe several aspects of research on the brain that seem to me to have this character, suggesting that we can and should think of ourselves, individually and collectively, as active creators and revisers of meaning, for ourselves and for the world we find ourselves in. I will conclude with several social policy recommendations that follow from this perspective.

Education Is Life Itself: Biological Evolution as a Model for Human Learning

Schooling often rests uneasily on presumed dichotomies between coverage and inquiry, skill development, and creativity. By drawing on the often under-recognized parallels between biological evolution and human learning, this essay argues that formal education needs and ought not to forego the unconscious exploratory processes of informal learning. Rather than posit as natural the cultural story that formal schooling must prepare students to integrate with given cultures and foreknowable futures, the evolutionary perspective shows that education is better thought of as preparing students to create cultures and to change, and foster change, in relation to unknown futures. The properties that distinguish formal from informal learning—conscious reflection and a degree of collective consensus about what constitutes knowledge at any given time—are, we argue, useful not as ends in themselves, but as tools for maximizing, sharing, and extending unconscious, evolutionary learning. Working with them as such offers a way out of some of education’s persistent problems. Two autobiographical case studies provide examples of these evolutionary changes and indicate pathways of inquiry by which to pursue them.