Cytochemical parameters of synaptic neurons in rats with different abilities to learn a food-procuring habit.

The characteristics of protein metabolism associated with cognitive activity were studied in neurons of layers III and IV of the sensorimotor cortex of rats, using two groups of Wistar rats. Regardless of the success of learning, information loading was most clearly reflected in the associative neurons of layer III. In rats with poor learning ability, these neurons showed increases in nuclear and cytoplasmic size, along with increases in protein concentration and content. The clearest changes in efferent neurons (layer V) were increases in the area and protein content, occurring only in the cytoplasm. In rats with good learning outcomes, all cytochemical parameters responded to information loading with decreases in layer III and increases in layer V protein contents and concentrations, affecting both the cytoplasm and nucleus. The question of whether the vector of changes in neuronal protein metabolism in response to information loading can be regarded as a measure of the individual features of higher nervous activity is discussed, as is the question of whether the magnitude of these changes is a measure of the complexity of a cognitive task.