Somaesthetic pathways in the marsupial phalanger, Trichosurus vulpecula.

Abstract

SUMMARYSpinal afferent pathways corresponding to the classical somaesthetic projections, medial lemniscus and anterolateral column system, have been described for the marsupial phalanger, Trichosurus vulpecula, using potentials evoked by limb stimulation.Potentials were also evoked within the central tegmental fasciculus and central grey which are considered to be phylogenetically older somaesthetic systems. These projections are relatively conspicuous in comparison with the classical paths, particularly the medial lemniscus. It is considered that the marsupial somaesthetic systems, with a dominance of medical indirect somaesthetic sensory paths, represent a step between the reptilian condition, where such paths predominate, and the full development of more direct spinothalamic projections in the higher mammals.