Statistical Learning in the Hippocampus and Neocortical Regions: Evidence From Intracranial Neural Entrainment

Statistical learning (SL) is a fundamental learning mechanism, but its neural underpinnings are not well understood. Modality-specific sensory regions are known to be involved in SL, but some studies suggest that the hippocampus may also support this process. However, direct neural evidence for engagement of the hippocampus in speech-based SL is scarce. In our study, 13 epilepsy patients with intracranial electrodes listened to a continuous speech stream containing embedded trisyllabic words. Neural entrainment at the frequency of words was used as a neural marker of learning, along with implicit and explicit behavioral measures. We found neural evidence of SL mainly in temporal cortex, insula, parietal, and frontal regions, but not the hippocampus. Behaviorally, we found robust evidence of SL on our implicit measure. Our results suggest that SL engages a widespread brain network that may not involve the hippocampus, but further research is needed to elucidate its role in SL.