Infantile amnesia, the inability to recall early childhood memories, is explored in a recent study revealing that infants form memories despite their inaccessibility later in life. Researchers used innovative techniques to study brain activity in infants, discovering that the hippocampus engages in memory encoding by around 12 months. While some memories may fade by age three, ongoing research aims to uncover whether these memories can be reactivated later, deepening our understanding of memory development.
The Enigma of Infantile Amnesia
The early years of life are filled with remarkable learning opportunities, yet most individuals find that they cannot recall these formative experiences due to a phenomenon known as infantile amnesia. A groundbreaking study recently published in the journal Science reveals that infants do indeed create memories. However, the lingering question is why these memories become so elusive as we grow older. Nick Turk-Browne, a psychology professor at Yale and the study’s lead author, expressed his intrigue regarding this puzzling gap in our personal narratives.
By the time they reach their first birthday, children exhibit exceptional learning abilities. They master language, begin to walk, identify objects, and develop social connections. Yet, despite these milestones, we often cannot retrieve any memories from this period. Sigmund Freud, the renowned psychoanalyst, posited that early memories are pushed out of conscious awareness through repression. In contrast, contemporary theories suggest that the hippocampus, a crucial brain region responsible for episodic memory, is still maturing during early childhood, making memory access challenging.
Innovative Research Techniques Unveiled
Previous behavioral studies have indicated that infants, despite their inability to articulate their memories, tend to gaze longer at familiar objects, demonstrating recognition. Recent research involving brain activity in young rats further supports this idea, showing that memory storage, or engrams, develops in young creatures but may become inaccessible as they grow.
Until now, studying infant brain activity using functional magnetic resonance imaging (fMRI) has proven difficult, primarily because infants are often restless. To overcome this hurdle, Turk-Browne’s team employed innovative strategies, including the use of pacifiers, stuffed animals, and engaging visuals to capture the babies’ attention. Their extensive research included hundreds of scanning sessions, even when faced with challenges such as blurry images.
In total, 26 infants participated in the study, divided into two groups: those under one year old and those over one year old. The researchers assessed their brain activity by presenting familiar and new images. “We tracked the duration of time spent focusing on known images, which serves as a measure of their memory,” explained Turk-Browne.
The findings revealed that the hippocampus was indeed active in encoding memories from a young age, with significant activity observed in 11 of the 13 participants over one year old, while those under one year did not show similar brain responses. Notably, infants who excelled in memory tasks exhibited heightened hippocampal activity. “Our study indicates that by around 12 months, babies can encode episodic memories in the hippocampus,” Turk-Browne emphasized.
While the research sheds light on the memory encoding capabilities of infants, the fate of these early memories remains unclear. They may never fully transition to long-term storage or could exist but become inaccessible over time. Turk-Browne leans toward the latter and is currently leading a follow-up study to explore whether infants and young children can recognize images they have seen before. Initial findings suggest that memories may linger until around the age of three before beginning to fade. The researcher is eager to determine whether these memory fragments can be reactivated later in life.