ИСТИНА

Natural learning involves complex stimuli comprising several sensory modalities. Elemental learn-ing theories suggest that each component of a compound signal is encoded and associated sepa-rately. Configural theories predict that a representation of the entire complex signal is formed and is associated with the second event. We developed a mouse model of fear conditioning to a com-pound tone-light cue or its separate components and used it to test these alternative theories. First, we studied the dynamics of memories for compound cue and its separate components and found that they mature over different times after conditioning. We showed that memory about compo-nents matures over different periods after training: memory about the auditory stimulus and the auditory component of CCS is behaviorally manifested immediately after training, while memory about the light stimulus and the light component of CCS matures within three days. The memory of CCS, its components, and discrete conditioned stimuli is preserved for an extended period, up to one month. We found a similar dissociation in extinction experiments. It was shown that when the extinction procedure was started one day after training, memory extinction of one CCS component had no effect on memory about the other CCS component. When the extinction procedure was started seven days after training when the memory was fully mature, the memory extinction of one component of CCS also resulted in the memory extinction of the other component. Next, we per-formed c-Fos imaging of cellular activity in frontal, prelimbic, cingular, retrosplenial, parietal, primary and secondary visual, primary and secondary auditory cortices, and in the hippocampus amygdala after conditioning to the entire compound cue or to its components. We found that com-pound-cue and single-cue conditioning produced distinct patterns of cortical activation - prelimbic and frontal associative cortices were activated by conditioning to compound cue but not to single cues. Third, we showed that only memory retrieval by the entire compound cue but not by single cues activated parietal, primary visual, mediolateral secondary visual cortices, and hippocampal CA1. Fourth, we performed in vivo two-photon imaging of retrieval-induced c-Fos expression in the parietal cortex of fos-EGFP transgenic mice and found at least three neuronal populations with different response specificity to the compound signal and its components. Taken together, our data suggest that complex signals can establish both integral and elemental neuronal representations. These representations can be used separately in behavior and have different long-term memory dynamics. This work was supported by Non-Commercial Foundation for Support of Science and Education "INTELLECT", the Interdisciplinary Scientific and Educational School of Moscow University «Brain, Cognitive Systems, Artificial Intelligence» and RSF project # 23-78-00010, https://rscf.ru/project/23-78-00010/.