Differential development of cortical taste areas in granular and dysgranular insular cortices in rats

Recordings were made from taste neurons in granular and dysgranular areas of the insular cortex of anesthetized SD-rats from the age of 4 days to over 90 days (adults). Almost all of the taste neurons were detected in the dysgranular area prior to weaning, but the number in the granular area increased with age and exceeded the number in the dysgranular area after the age of 50 days. In the dysgranular area, most taste neurons, irrespective of the postnatal age, were located at layer 5. However, in the granular area they were found at a deeper layer, with the advance in age; e.g. layer 2-3 at 14-20 days to layer 5 in adults. Thus, taste afferents in granular and dysgranular areas of the insular cortex differ with advance in age.