MAPPING THE MIDSAGITTAL CORPUS CALLOSUM IN THE RAT:
TOPOGRAPHICAL CORRESPONDENCE OF CALLOSAL REGIONS WITH CORTICAL SUBDIVISIONS.
M. Noonan, M.A. Sanfilippo, D.J. Chmiel, Jr., M.A.
Presented at the Society for Neuroscience, Washington, D.C., USA,
The location in the midsagittal plane of fibers within the corpus
callosum of the rat are mapped in correspondence with cortical region. Results are
reported from both HRP and silver-staining following localized cortical treatments.
A detailed map is presented delineating the callosal regions
corresponding to each Zilles subdivision. Fibers corresponding to most cortical areas are
segregated and distinctly bundled in their passage through the callosum at the midline.
However, the fibers of some subdivisions overlap and intermingle extensively. In general,
there is an anterior-posterior correspondence relating cortical area and callosal locale.
Additionally, there is a tendency for fibers associated with medially-located cortical
regions to cross in dorsal layers of the callosum and more laterally-located regions to
cross in ventral layers. The genu of the callosum consists of fibers corresponding to
medial prefrontal cortex (e.g., DPC, IL, MO, VO, Cg3), the trunk includes fibers
corresponding to frontal and parietal cortex (e.g., FR1&2 and PAR1&2), and the
splenium consists largely of occipital and retrosplenial fibers (e.g., OC2L, RSA, RSG).
The results are expected to guide future callosotomy studies in
which only selected regions of the cortex are disconnected.
Supported by NSF: RUI-9209551.