The molecular mechanisms underlying memory formation in vertebrates are not well understood, despite their paramount importance to neuroscience and their potential clinical implications for neurodegenerative diseases. The present project aims at further investigating of molecular mechanisms of memory during a visual imprinting in domestic chicks.
Visual imprinting is a learning process whereby young animals come to prefer a visual stimulus after exposure to it (training). The intermediate medial mesopallium (IMM) in the chick forebrain is critical for visual imprinting and contributes to molecular regulation of memory formation. It is possible to measure the strength of learning and memory and criteria for the learning-relatedness of molecular changes have been formulated by us and published. Available evidence indicates that learning-related molecular changes occur in the IMM after imprinting in a progression from transient/labile to trophic neural modifications, culminating in stable recognition memory. According to our data, this process is associated with learning-related changes in gene expression, however on a wide scale these changes were never assigned to individual cell types in IMM.  Only in one study learning-related increase in the early-immediate gene-Fos was localized to gamma-aminobutiric acid (GABA) and parvalbumin expressing neurons. We have applied single-nuclei RNA sequencing technology to study this problem. IMMs from two groups of chicks were compared, 24h after training: one group developed a good memory of the imprinting stimulus where the second one comprised untrained chicks. In glutamate decarboxylase (GABA synthesizing enzyme) and parvalbumin expressing nuclei the analysis shows  approximately 100 highly significant changed genes. Another series of RNA-SEQ studies revealed  5 circular-RNAs that are differentially expressed in a highly significant way. However, all these differences may not be learning-related, but reflecting side-effects of training. Further validation is necessary for ensuring that these differences are learning-related. The  project is aimed for: (1) bioinformatics analysis for differentially expressed genes in  known types of IMM cells and  also to define new groups of IMM cells according to the gene expression patterns; (2) further evaluation of the detected molecular differences for mRNA and circular-RNA by strong quantitative approaches according to experimental and statistical criteria for identifying imprinting-related changes; and (3) localiზation of memory related molecular changes in cell types by in situ hybridization and immunocytochemical methods.
The expected outcomes of the project are extraordinary: memory related molecular changes in individual cell types of a brain region that is known to be a key player in memory formation and storage.