Memory-related hippocampal activation in the sleeping toddler

Abstract

Nonhuman research has implicated developmental processes within the hippocampus in the emergence and early development of episodic memory, but methodological challenges have hindered assessments of this possibility in humans. Here, we delivered a previously learned song and a novel song to 2-year-old toddlers during natural nocturnal sleep and, using functional magnetic resonance imaging, found that hippocampal activation was stronger for the learned song compared with the novel song. This was true regardless of whether the song was presented intact or backwards. Toddlers who remembered where and in the presence of which toy character they heard the song exhibited stronger hippocampal activation for the song. The results establish that hippocampal activation in toddlers reflects past experiences, persists despite some alteration of the stimulus, and is associated with behavior. This research sheds light on early hippocampal and memory functioning and offers an approach to interrogate the neural substrates of early memory.

Re-imagining fMRI for awake behaving infants

“…Several labs have avoided some of these constraints by performing fMRI experiments with infants or toddlers who are sedated 7 or sleeping 8 – 10 . These studies have found innovative ways to investigate aspects of early cognitive development, such as by cuing previously learned episodes during sleep 9 . There are also now several large-scale projects that seek to understand functional brain development in infants during rest (HEALthy Brain and Child Development Study, UNC/UMN Baby Connectome project 11 and Developmental Human Connectome Project).…”

“…There are many challenges to collecting fMRI data from infants: head and body motion, limited attention span, fussiness, inability to understand or follow instructions, high acoustic noise levels, and a lack of analysis approaches optimized for the infant brain. Several labs have avoided some of these constraints by performing fMRI experiments with infants or toddlers who are sedated 7 or sleeping [8][9][10] . These studies have found innovative ways to investigate aspects of early cognitive development, such as by cuing previously learned episodes during sleep 9 .…”

The Neurophysiological Processing of Music in Children: A Systematic Review With Narrative Synthesis and Considerations for Clinical Practice in Music Therapy

“…The fMRI data included in this age range extend knowledge about global cortical and subcortical hemodynamic responses to musical stimuli. Prabhakar et al ( 2018 ) described increased bilateral hippocampi activation in sleeping toddlers, in response to a previously heard lullaby. This result indicates that music stimulates sub-cortical memory substrates in young children (Prabhakar et al, 2018 ).…”

“…Prabhakar et al ( 2018 ) described increased bilateral hippocampi activation in sleeping toddlers, in response to a previously heard lullaby. This result indicates that music stimulates sub-cortical memory substrates in young children (Prabhakar et al, 2018 ). In slightly older children, activation of the bilateral temporal lobes, frontal lobes, fusiform, and cerebellum were reported in response to music (Overy et al, 2004 ; Guerrero Arenas et al, 2016 ).…”

How to read a baby’s mind: Re-imagining fMRI for awake, behaving infants

“…There are many challenges to collecting fMRI data from infants: head and body motion, limited attention span and fussiness, inability to understand or follow instructions, high acoustic noise levels, and a lack of analysis approaches optimized for the infant brain. Several labs have performed fMRI experiments with infants who are sedated 7 or sleeping [8][9][10] . However, there have been only a handful of successes when infants are awake and behaving during cognitive tasks [11][12][13] .…”