The invention relates to the use of glutamine, preferably in the form of free amino acids, dipeptides and/or tripeptides, in the manufacture of a nutritional composition for improving exploratory behavior, memory performance, particularly spatial memory performance, and/or social interaction in an infant or toddler and/or treating or preventing impaired or decreased exploratory behavior, memory performance, particularly spatial memory performance, and/or social interaction in an infant or toddler.