TOWARDS A PHYSIOLOGICAL THEORY OF ABSTRACT LEARNING

H. REY, D. A. GUTNISKY, B. S. ZANUTTO

Italia

Congreso; 39th Annual European Brain and Behaviour Society; 2007

European Brain and Behaviour Society

The capacity to conceptualize contingencies abstractly is an efficient way to save memory resources. In the past, Same/Different (SD) discrimination, the simplest form of abstract learning, was thought to have language training as a necessary condition. However, experimental evidence have shown that this task cannot only be solved by humans, but also by chimpanzees, rhesus and capuchin monkeys, and pigeons. In addition, recent neurophysiological data suggests that neurons in prefrontal cortex of rhesus monkey code abstract rules. Despite these evidence, how neural networks are able to learn abstract rules is largely unknown. We propose a minimal model that is able to learn the SD task. The model is composed of an input layer, working memory cells, SD cells and response neurons. Working memory cells are connected to SD cells through depressing synapses. Each different stimulus activates a defined subset of working memory cells. The synapses impinging on the SD cells that correspond to activated working memory cells become depressed. A further presentation of the same stimulus will elicit a lower response from these cells indicating that the same stimulus was presented, irrespective to its particular features. In contrast when the stimulus are different, the synapses are not depressed, and the SD cells response are not attenuated. Response neurons pool these neurons to provide the correct response. The model is minimal in the sense that all its components are already described in the literature, although without explicit mention to its relevance for this task. The model provides also a basic building block upon more complicated abstract tasks can be accomplished, such as conceptual matching to sample, learning sequences of stimuli, etc.