*R. LAMPRECHT1, S. ASSOUN2, S. DRACHEVA3, J. LEDOUX4;
1Dept Neurol and Ethology, Fac of Sci. and Sci. Ed, Mount Carmel, Israel; 2Univ. Pierre et Marie Curie, Paris, France; 3Mount Sinai Sch. of Med., New York, NY; 4New York Univ., New York, NY

Long-term memory (LTM) formation requires gene expression. The lateral nucleus of the amygdala has been implicated in the formation of LTM for stimuli associated with danger through associative fear conditioning. The current study aimed to detect the pattern of gene expression in the lateral amygdala (LA) following associative fear conditioning. Rats were trained with one of three conditions: paired training (5 pairings of a tone conditioned stimulus, CS, that co-terminated with a footshock unconditioned stimulus, US); unpaired training (5 presentations of the CS and US in a non-overlapping manner); and no stimulation (naive animals placed in the chamber but without the CS or US presentations). Because the paired procedure consistently leads to fear memory formation, whereas unpaired or no stimulation does not, pairing is said to induce associative learning. The brains were removed 30 minutes or 5 hours after training, the LA was dissected using laser capture microdissection, RNA was extracted and analyzed using the rat genechip 230 A (Affymetrix). Thirty minutes after training, changes in gene expression levels occurred in LA for immediate early genes (e.g. c-fos) when the paired or unpaired groups were compared to the naive group. When the paired group was compared to the unpaired group, the expression of several genes was increased while the expression of other genes was decreased in LA. These differentially expressed genes encode proteins involved in key cellular functions including transcription regulation, intracellular signal transduction, and neuronal communication. Five hours after training an increase in expression of late response genes was detected in LA in paired group in comparison to the unpaired group. Most of these differentially expressed genes code for adaptor or chaperon proteins involved in protein stability and translocation, suggesting that these cellular functions are important at later stages of memory consolidation. A unique pattern of expression was detected in an additional set of genes which were expressed at lower levels at 30 minutes after training but at higher level at 5 hours after training when the paired group was compared to the unpaired group. These results show that the pattern of gene expression in LA depends on the CS-US relation and time following training.

Support Contributed By: NIH grant R01 MH46516; NIH grant R37 MH38774; NIH grant K05 MH067048; NIH grant; P50 MH58911; NSF grant IBN-0131433

Program No. 307.8/BBB21
Poster presentation:Sunday, Nov 04, 2007, 4:00 PM - 5:00 PM
Location: San Diego Convention Center: Halls B-H