Journal of Neuroscience, Vol 7, 4095-4106, Copyright © 1987 by Society for Neuroscience
Differential laminar distribution of corticostriatal neurons in the prefrontal and pericruciate gyri of the dog
D Tanaka Jr
Department of Anatomy, Michigan State University, East Lansing 48824.
This investigation was undertaken to determine whether the laminar
distribution of corticostriatal neurons differs between different
anatomical and functional areas of the frontal lobe. Injections of
lectin-conjugated horseradish peroxidase were made into the lateral,
intermediate, and medial parts of the head of the caudate nucleus. After
injections into the medial part of the caudate, most of the labeled neurons
were found in the proreal and subproreal gyri of the prefrontal region. In
both gyri, the majority of labeled cells were localized within layer V, and
fewer neurons were located in the deeper part of layer III and in layers IV
(proreal gyrus) and VI. No labeled neurons were noted in layer II. This
distribution contrasted with that seen following injections into the
intermediate and lateral parts of the caudate nucleus. In those cases, the
majority of labeled cells were located in the pericruciate region (areas 4
and 6) and on the medial and lateral banks of the presylvian sulcus
(paraorbital and internal composite areas, respectively). In the
paraorbital and internal composite areas, the majority of labeled cells
were still localized within layer V, but a larger percentage of labeled
neurons were also noted in layer III. In areas 4 and 6, the laminar
distribution shifted so that the majority of labeled cells were now located
in layer III, with a widespread distribution of neurons throughout layers
II-VI. These results indicate that corticostriatal neurons in the frontal
lobe have different laminar distributions, depending on the particular
anatomical or functional area in which they are located. The majority of
neurons in the prefrontal region are located in infragranular layers, while
those in the pericruciate region are located in supragranular layers.