Functional decortication in the CS-US interval decrease efficiency of taste aversive learning

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Conditioned taste aversion was studied in 160 rats with the cortical spreading depression (CSD) technique. Water-deprived animals had 15-min access to water on the familiarization Days 1 and 2. On Day 3 they were offered saccharin (0.1%, CS) followed after 30–300 min by intraperitoneal LiCI injection (0.14 M, 2% body wt, US). Saccharin intake on Day 4 increased proportionally to the duration of CS-US interval from 40% (30 min) to 86% (240 min) and 103% (300 min) of Day 3 consumption. Bilateral CSD evoked 15 min after CS termination and maintained during the rest of the CS-US interval impaired the taste aversion conditioning with 120- and 180-min delays (85% and 89%) but not with 30- and 60-min delays (32% and 50%). Gustatory experience acquired during unilateral CSD on Day 3 yielded strong conditioned aversion with 20- and 60-min CS-US delays (40% and 43%). When bilateral CSD was induced 10 min after hemidecorticate exposure to saccharin, significant aversion was found with the 20- and 40-min delays (38% and 53%) but not with 50- and 60-min delays (95% and 87%). It is concluded that CSD interferes with the short-term storage of the gustatory information acquired with the intact brain.