ORGANIZATION OF NEOCORTICAL PROJECTIONS FROM VENTROPOSTERIOR THALAMIC COMPLEX IN MARSUPIAL BRUSH-TAILED POSSUM, TRICHOSURUS-VULPECULA - HORSERADISH-PEROXIDASE STUDY

  • 1 January 1978
    • journal article
    • research article
    • Vol. 126  (AUG) , 459-485
Abstract
Retrograde transport of horseradish peroxidase was used to determine the extent and organizational details of the cortical projection of the ventroposterior [VP] thalamic complex. The cortical projection field of VP is coincident with SI and would appear not to fully overlap the primary motor cortex, indicating that the motor and somatic sensory cortical areas are not fully congruent in Trichosurus. Each division of VP projects discretely, in a non-overlapping manner, to various regions within S1 [sacal]. The ventrolateral division (VPL) projects medially and in a strict homotypic manner, though the proportion of VPL cells projecting to cortex is subject to a large amount of variation. The dorsomedial division of VP, or VPM projects uniformly to cortex from all areas of that subnucleus, but the strict homotypy characteristic of VPL''s projection was not as apparent. VPM also projects to 2 distinct regions within its cortical field. The posteromedial division of VP, or VPP, projects to an area of cortex that receives no other VP input but which, on the basis of cortical mapping studies, appears to belong to SI. Projections from VPL (and presumably from VPM) to a small area of cortex in the extreme posterolateral part of the VP cortical field correspond to the position expected for, and electrophysiologically confirmed to be, SII.