Elaborations of Hebb’s Cell Assembly Theory
Donald Olding Hebb · 2018
Activity of a first-order assembly theoretically is a very specific perception, of a horizontal line in the visual field, for example, or a vowel sound, or a sensation of roughness. Activity of a second-order assembly is more generalized, as perception of the line anywhere in the field, or the phoneme at a higher or lower pitch, or roughnesses at different loci. Perception of an object or a word would be a still higher level, an assembly of the third or fourth order. The significance lies in the fact that electrical stimulation of speech-area cortex does not produce speech but impairs or prevents it. The transmission in the cerebrum is largely via divergent pathways with no automatic provision of summation at the synapse, such as is provided by the overlapping axon collaterals at each synaptic junction in the great afferent and efferent tracts, which are organized in parallel.