AFFERENT CONNECTIONS OF THE CAUDOLATERAL ORBITOFRONTAL CORTEX TASTE AREA OF THE PRIMATE

A cortical taste region has recently been identified in the caudolateral orbitofrontal cortex of the macaque. The afferents to this region were investigated by means of retrograde tracing, using six injections of wheatgerm-conjugated horseradish peroxidase. The area of taste cortex was first identified physiologically in all the monkeys used in this anatomical study. The four injections into the middle and posterior part of this region resulted in large numbers of labelled cell bodies in the insular-opercular primary taste cortex. Following the two more anterior injections, label was found predominantly in the caudal part of the cardolateral orbitofrontal cortex itself. None of the injections resulted in labelled cells in the gustatory thalamic nucleus ventralis posterior medialis, pars parvocellularis, although all injections resulted in label of the mediodorsal nucleus of the thalamus. Afferents were also seen from more anterior parts of the orbitofrontal taste cortex, which may represent backprojections from subsequent taste areas. These results suggest that the caudolateral orbitofrontal cortex contains a higher-order taste cortex.