Complex dendritic fields of pyramidal cells in the frontal eye field of the macaque monkey: comparison with parietal areas 7a and LIP

LAYER III pyramidal neurones were injected with Lucifer Yellow in cortical slices taken from the medial subdivision of the frontal eye field (FEF) of the macaque monkey. The average area covered by basal dendritic fields, in the dimension parallel to the cortical layers, was 115.1+/-2.9x10(3) mu m(2), significantly larger than that observed among layer III cells in eye movement-related visual areas of the parietal lobe. Furthermore, the dendritic fields of pyramidal cells in the FEF were considerably more complex than those of their counterparts in the parietal lobe, as evaluated by Shell analysis. Spine density varied along the basal dendritic tree, reaching a maximum of 8.5+/-0.8 spines/10 mu m at a distance of 70-90 mu m from the centre of the cell body. Such highly complex basal dendritic fields of layer III pyramidal neurones in the FEF may enable the integration of a diverse set of inputs from visual, motor, polysensory and memory-related periprincipal cortical areas.