Neuronal Specificity and Development of Neuronal Projection Maps
During the 17th century science was at first concerned only with fonnulating mechanical and mathematical models to explain natural phenomena. Philosophy retained its traditional role of explaining how it is possible for a person to perceive objects in the physical world. During the seventeenth and eighteenth centuries a mechanistic picture of the physical universe was gradually extended to include the sense organs and nervous system of the perceiving subject. At first this extension was limited to the direct actions of physical stimuli on the sense organs. These were regarded as the boundary between the physical world and vital processes which were believed to be properties uniquely belonging to living beings. The interactions could be conceived as a penetration of atoms into the sense organs resulting in movements of vital spirits in the nerves of sensation. Descartes conceived of these nervous spirits as material atoms or particles whose movements in the nerves were governed by their physical properties and by purely mechanical processes. The boundary between the external world, conceived as mechanism, and the psyche, conceived as a vital agent, was moved progressively more deeply into the nervous system, until, according to Descartes, the interaction between physical and psychical occurs in the pineal gland.
KeywordsNeuronal Specificity Retinal Ganglion Cell Optic Tectum Ocular Dominance Monocular Deprivation
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