New fMRI Study Challenges Long-Held Beliefs About Infant Memory Formation

A new functional magnetic resonance imaging (fMRI) study challenges the long-standing belief that infants are incapable of forming memories. Researchers have discovered that by 12 months of age, infants can encode individual memories—suggesting that infantile amnesia, the phenomenon in which people cannot recall early childhood experiences, is more likely due to retrieval failure rather than an inability to form memories in the first place.

Although infancy is a period of rapid learning, most individuals cannot remember events from their first three years of life. This phenomenon, known as infantile amnesia, has puzzled scientists for decades. One prevailing theory attributes it to the incomplete development of the hippocampus—a brain region essential for episodic memory. However, studies in rodents have shown that memory traces do form in the infant hippocampus but become inaccessible over time.

Human infants demonstrate memory through behaviors such as imitation, recognition of familiar stimuli, and conditioned responses. To investigate whether these abilities depend on the hippocampus, researchers used fMRI to scan the brains of infants aged 4 to 25 months while they performed a memory task. The results revealed that by around 12 months of age, the hippocampus is already capable of encoding specific memories, indicating that memory formation begins much earlier than previously assumed.

The researchers suggest that while these early memories may be temporary, the presence of memory encoding mechanisms supports the idea that infantile amnesia primarily results from difficulties in memory retrieval rather than a failure to form memories. These findings align with previous rodent studies, which suggest that early-life memories can persist into adulthood but may remain inaccessible without specific cues or reactivation of hippocampal memory traces.

This study provides new insights into how early memories are stored and forgotten, reshaping our understanding of infant memory capabilities and challenging traditional assumptions in developmental neuroscience.