Patterns of increased metabolic activity in somatosensory cortex of monkeys Macaca fascicularis, subjected to controlled cutaneous stimulation: A 2-deoxyglucose study

Six cynomolgus monkeys were used in a [¹⁴C]2-deoxyglucose (2-DG) investigation to determine the global pattern of metabolic (functional) activity in the postcentral gyrus. The animals were subjected to unilateral somatic stimulation on their upper extremities. To a lesser extent, the pattern of labeling in the posterior parietal cortex, the superior and inferior banks of the lateral fissure, and the anterior and posterior banks of the superior temporal sulcus was evaluated in the same animals. In the contralateral postcentral gyrus of all animals, labeling consisted of columnlike patches. The label commonly extended from laminae II to V, and reached its greatest tangential extent in basal lamina III and lamina IV. The labeling within a given patch was most dense in lower lamina III and lamina IV. In areas 3a and 3b, the patches were superimposed on a continuous band of label in basal lamina III and lamina IV. Surface reconstructions of the contralateral postcentral gyrus were formed by aligning individual adjacent sections; they indicated that the labeled patches consistently arranged to mediolaterally oriented strips. A three-dimensional rendering of the pattern of 2-DG labeling demonstrated that the individual strips have undulating borders, due to label extending to varying degrees in the cortical laminae. The striplike 2-DG labeling pattern observed in the postcentral gyrus reflects the body locus of a somatosensory stimulus in a reproducible manner and is consistent with the topographical organization described within this cortical region by prior neurophysiological studies conducted in the absence of general anesthesia. The columnlike patches of 2-DG label found in the other cytoarchitectural zones demonstrated characteristic differences from those in the postcentral gyrus. In general, the patches found outside the postcentral gyrus were more varied in their width, shape, and spatial distribution. It is concluded that the patches of 2-DG label share features in common with the functional unit known as the cortical column. Their formation into mediolateral strips may provide a pictorial image of the distribution of functional activity in the postcentral gyrus.