The Autonomous Brain: A Neural Theory of Attention and Learning

The Autonomous Brain: A Neural Theory of Attention and Learning

The Autonomous Brain: A Neural Theory of Attention and Learning

The Autonomous Brain: A Neural Theory of Attention and Learning

Synopsis

The behaviorist credo that animals are devices for translating sensory input into appropriate responses dies hard. The thesis of this pathbreaking book is that the brain is innately constructed to initiate behaviors likely to promote the survival of the species, and to sensitize sensory systems to stimuli required for those behaviors. Animals attend innately to vital stimuli (reinforcers) and the more advanced animals learn to attend to related stimuli as well. Thus, the centrifugal attentional components of sensory systems are as important for learned behavior as the more conventional paths. It is hypothesized that the basal ganglia are an important source of response plans and attentional signals.

This reversal of traditional learning theory, along with the rapid expansion of knowledge about the brain, especially that acquired by improved techniques for recording neural activity in behaving animals and people, makes it possible to re-examine some long standing psychological problems. One such problem is how the intention to perform an act selects sensory input from relevant objects and ensures that it alone is delivered to the motor system to control the intended response. This is an aspect of what is sometimes known as the binding problem: how the different features of an observed object are integrated into a unified percept. Another problem that has never been satisfactorily addressed is how the brain stores information concerning temporal order, a requirement for the production of most learned responses, including pronouncing and writing words.

A fundamental process, the association between brain activities representing external events, is surprisingly poorly understood at the neural level. Most concepts have multiple associations but the concept is not unduly corrupted by them, and usually only a single appropriate association is aroused at a time. Furthermore, any arbitrary pair of concepts can be instantly associated, apparently requiring an impossibly high degree of neural interconnection. The author suggests a substitute for the reverberating closed neuronal loop as an explanation for the engram (active memory trace or working memory), which may go some way to resolving these difficulties.

Shedding new light on enduring questions, The Autonomous Brain will be welcomed by a broad audience of behavioral and brain scientists.

Excerpt

Nearly half a century ago Sperry urged what he called a motor approach to behavior, claiming that it "immediately helps us to view the brain objectively for what it is, namely, a mechanism for governing motor activity" (Sperry, 1952. P. 297). His arguments in favor of viewing perceptual activity as being closely related to the response mechanisms made a lasting impression on me, though they had little apparent effect on the direction of neuropsychological research at the time.

During the last few years, improvement in the quality and quantity of information about the motor system, and the dorsal sensory pathways that feed it, have made it easier to heed Sperry's urging. Increased interest in "thinking" robots also has tended to redress the imbalance between investigations of the output and input mechanisms of behaving organisms. For too long the observer monopolised our attention, it is time the actor took his proper place at center-stage.

The primary goal of this book is to chronicle, and perhaps hasten, the switch in emphasis from sensory systems to sensory-motor integration, but it is also intended as a tribute to Karl Lashley and Donald Hebb, two of the most creative and influential physiological psychologists of the 20th century. Both men saw clearly that the popular notion of the brain as a collection of conditionable reflexes could not begin to explain the subtleties of mammalian behavior, and both tried to find alternatives, Lashley by discounting the influence of individual neural connections, and Hebb by postulating a more complex array of connections that permitted the brain to be active independently of sensory input.

Seventy years have passed since Lashley (1929) published his monograph Brain Mechanisms and Intelligence and 50 since Hebb's (1949) Organization of Behavior appeared. Pavlovian learning theorists were not seriously shaken by Lashley's account of his failure to find specific deficits in learned behavior after brain lesions in the rat. Their response was to deny the value of brain research for psychological theory. Nevertheless, Lashley's data were frequently cited by neurologists opposed to the theory of cerebral localization.

Hebb's primary message that feedback connections provide the brain with endogenous sources of activity also was ignored for a number of years by learning theorists, whereas his postulates concerning the mechanism of synaptic change were adopted by connectionist modelers (mostly of stimulus-response theories) and neurophysiologists.

Both Lashley and Hebb tackled interesting and difficult problems that other psychologists were inclined to bypass, but their quests for neural mechanisms were . . .

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