Cortical connections of the frontoparietal opercular areas in the rhesus monkey

The connections of the frontoparietal opercular areas were studied in rhesu s monkeys by using antero- and retrograde tracer techniques. The rostral op ercular cortex including the gustatory and proisocortical motor (ProM) area s is connected with precentral areas 3, 1, and 2 as well as with the rostra l portion of the opercular area which resembles the second somatosensory ty pe of cortex (area SII) and the ventral portion of area 6. Its distant conn ections are with the ventral portion of prefrontal areas 46, 11, 12, and 13 as well as with the rostral insula and cingulate motor area (CMAr). The mi d opercular region (areas 1 and 2) is connected with pre- and postcentral a reas 3, 1, and 2 as well as SII. Additionally, it is connected with the ven tral portion of area 6, area 44, area ProM, the gustatory area, and the ros tral insula. Its distant connections are with area 4, the ventral portion o f area 46, area 7b, and area POa in the intraparietal sulcus (IPS). The ros tral parietal opercular region is connected with the postcentral portions o f areas 3, 1, and 2; areas 5, 7, and SII; the gustatory area; and the vesti bular area. Its other connections are with area 4, area 44, the ventral por tion of area 46, area ProM, CMAr, and the supplementary motor area (SMA). T he caudal opercular region is connected with the dorsal portion of area 3; areas 2, 5, and 7a; and areas PEa as well as IPd of IPS. It is also connect ed with area SII, insula, and the superior temporal sulcus. Its distant con nections are with area 44; the dorsal portion of area 8 and the ventral por tion of area 46; as well as CMAr, SMA, and the supplementary sensory area. This connectivity suggests that the ventral somatosensory areas are involve d in sensorimotor activities mainly related to head, neck, and face structu res as well as to taste. Additionally, these areas may have a role in front al (working) and temporal (tactile) memory systems. (C) 1999 Wiley-Liss, In c.