Connectionist Approaches
B.J. MacLennan, in International Encyclopedia of the Social & Behavioral Sciences, 2001
5.4 Relation to Biological Neural Networks
Connectionist networks are often called ‘neural networks’ and described in terms of (artificial) neurons connected by (artificial) synapses, but is this more than a metaphor? Generally, connectionist models have reflected the contemporary understanding of neurons. For example, McCulloch and Pitts focused on the ‘all or nothing’ character of neuron firing, and modeled neurons as digital logic gates. Newer connectionist models have had a more analog focus, and so the activity level of a unit is often identified with the instantaneous firing rate of a neuron. However, these models still ignore many important properties of real neurons, which may be relevant to neural information processing (Rumelhart et al., 1986′, vol. 2, Chap. 20). As a consequence neuroscientists have stressed the differences between biological neurons and the simple units in connectionist networks; the relation between the two remains an open problem. Nevertheless, it is much easier to envision neural implementations of connectionist networks than of symbol-processing architectures.
See Churchland (1986) and Quinlan (1991) for an introduction to connectionist approaches in philosophy and psychology. See Connectionist Models of Concept Learning; Connectionist Models of Development.
==