Acquired equivalence (AE) is a form of feedback-based associative learning where two or more stimuli are mapped to the same outcomes or responses. The performance on this task has previously been demonstrated to strongly depend on the functions of basal ganglia and the hippocampi. These structures and related functions have a distinct developmental trajectory: basal ganglia associated implicit memory functions mature early, while hippocampus-linked explicit memory functions show development late into adolescence. While several studies examined how various neurological and psychiatric conditions influence AE performance, studies dealing with the development of this function are scarce, and no study made an attempt to plot the development of this form of learning from early childhood to adulthood so far. Furthermore the basal ganglia and hippocampus are known to be affected in migraine, however there is no information available whether these alterations, described with imaging techniques also manifest on a functional level.
Therefore we assessed 265 healthy subjects aged 3 to 52 with the modified and Hungarian form of the computer based Rutger Acquired Equivalence Test (RAET), to examine the healthy development of AE performance (Study #1). The same test was used to measure the learning performance of 22 patients with migraine without aura, and an age- and sex-matched control group, to assess if migraine affects performance on this task (Study #2). RAET assesses three main aspects of AE: the efficiency of pair learning, the efficiency of the retrieval of acquired pairs, and the ability to generalise previous knowledge to a new stimulus.
In study #1 both pair learning and retrieval were found to exhibit development, with kindergarten children having significantly higher (p