ORGANIZATION OF NEOCORTICAL PROJECTIONS FROM THE VENTROLATERAL THALAMIC NUCLEUS IN THE BRUSH-TAILED POSSUM, TRICHOSURUS-VULPECULA, AND THE PROBLEM OF MOTOR AND SOMATIC SENSORY CONVERGENCE WITHIN THE MAMMALIAN BRAIN

  • 1 January 1979
    • journal article
    • research article
    • Vol. 129  (DEC) , 673-694
Abstract
The retrograde transport of horseradish peroxidase was used to determine the extent and organizational details of the ventrolateral [VL] neocortical projection in T. vulpecula. The major, or external, part of VL projects homotypically to the anteromedial part of the parietofrontal cortex, overlapping the VP or ventroposterior cortical projection field extensively, but not completely. Overlap between the VL field and SmI (= the VP field) is most extensive in the area of the rear limb and body representation, and decreases considerably in the area of the head representation. A small internal subdivision of VL projects discontinuously to the SmI head region, and appears to project only to portions of the cortical barrel field. The VL cortical projection is much less extensive than that of VP, but does include a small area of cortex which does not receive a VP projection. VL and VP do not display congruent cortical projections. Details of thalamocortical relationships in the motor-sensory system are compared in other marsupials and with placental mammals. The anatomy of the thalamocortical relationship in marsupial and in most placental mammals is quite different.