Lifelong consequences of early nutritional conditions on learning performance in zebra finches (Taeniopygia guttata)

Long-term effects of early developmental conditions on physiological and behavioural traits are common in animals. Yet, such lifelong effects of early life conditions on learning skills received relatively less attention, even though they are expected to have strong fitness effects. To test the lifelong impact of the early environment on associative and reversal learning performance, we tested zebra finches (Taeniopygia guttata) in a reversal learning task about five years after they were raised either under low or high quality food treatments in their first month of life. The early nutritional treatment and its respective growth patterns significantly influenced learning performance: Zebra finches who received a high-quality nutrition early in life gained more weight during the treatment period but needed more trials to associate a cue with a reward. The early growth rate during the treatment phase was linked to how fast the birds detected the food at the onset of training in our learning task as well as to their associative learning performance. However, in the reversal learning step of the task testing for behavioural flexibility, no differences with respect to early nutritional treatments or related growth rates were apparent. We show that early life conditions directly affect the approach to our task and learning abilities over an entire lifetime, emphasizing how crucial the early environment is for understanding adult behaviour throughout life.