ABSTRACT
Motor performance presents new difficulties. The essential aspects of the hypothesis builds upon the principles depicted. The extension of the original hypothesis for lateralization, concerning side-to-side differences in axonal conduction delays, requires that be integrated with another body of psychobiological theory. Lateralization of manual praxis or spoken language to the left hemisphere applies in a substantially larger proportion of the population than does lateralization of language perception or of other perceptual tasks. A more fundamental consideration is that language expression, unlike language comprehension, is an instrumental function. The start of neural network is derived from consideration of reward-mediated learning. A three-factor rule for synaptic modification was suggested as the fundamental embodiment of the logical structure. Cytoarchitectural data also provide evidence of differences between the sides, and so are relevant to the left-hemisphere specialisation for expression of language.
