The role of the agranular insular cortex in working memory for food rewardvalue and allocentric space in rats

The present experiment examined the effects of quinolinic acid (125 mM) les ions of the agranular insular area on working memory for food reward value and working memory for spatial locations. In both tasks a go/no-go procedur e was used. Working memory for food reward value was assessed using a delay ed conditional discrimination in which either a 20% or 45% sugar content ce real was associated with a reinforcement and the other cereal was not. In t he spatial locations task, rats were allowed to enter 12 arms in a radial m aze for a food reinforcement. Of the 12 arm presentations, three or four ar ms were presented for a second time in a session which did not contain a re inforcement. The number of trials between the 1st and 2nd presentation of a n arm ranged from 0 to 6 (lags). Working memory was assessed by the latency to enter an arm during the 2nd presentation. In the food reward value task , agranular insular lesions produced memory deficits in a delay-dependent m anner. In contrast, agranular insular lesions did not impair working memory for spatial locations. These results add to accumulating evidence suggesti ng that different types of working memory are distributed across separate p refrontal subregions. (C) 1999 Elsevier Science B.V. All rights reserved.