R.Solomonia
Institute of Chemical Biology, Ilia State University and I.Beritashvili Centre of Experimental Biomedicine
Visual imprinting is a learning process whereby young animals come to prefer a visual stimulus after exposure to it (training). The available evidence indicates that the intermediate medial mesopallium (IMM) in the domestic chick forebrain is a site of memory formation during visual imprinting. Criteria for identifying learning-related changes in a particular brain region have been formulated which allow us to distinguish side-effects of training from the effects which are specific for learning and/or memory. A key criterion for determining whether a protein or RNA level results from learning is correlation with a behavioural measure of learning – in the case of imprinting, a preference score which measures the preference of an animal for the object to which it has become imprinted. However, a correlation can be interpreted in an alternative way, namely that protein/RNA level does not change during learning but reflects a predisposition to learn readily. A series of learning-related molecular changes has been thus identified in the IMM, which are the results of learning. Alongside with these changes certain learning-related correlations were attributable to learn readily. Correlations which reflects a predisposition to learn in the left IMM includes: (i) One hour after training, a positive correlation between the amount phosphorylated tyrosine-416 Src (activated, 416P-Src); (ii) 24h after training negative correlation of micro-RNA ggamiR-130b-3p and positive correlation of aggregated form of cytoplasmic polyadenylation binding protein-3.
One hour after training, in the left IMM, we also observed a positive correlation between the amount of 527P-Src and learning strength that was attributable to learning. The available data indicate that Src is not phosphorylated simultaneously on the 527 and 416 tyrosine residues and that changes in 416P-Src and 527P-Src therefore presumably reflect activated and inhibited forms, respectively, in different pools of Src. These pools could be in different cells of IMM