Attention recruits frontal cortex in human infants

Young infants learn about the world by overtly shifting their attention to
perceptually salient events. In adults, attention recruits several brain
regions spanning the frontal and parietal lobes. However, it is unclear
whether these regions are sufficiently mature in infancy to support
attention and, more generally, how infant attention is supported by the
brain. We used event-related fMRI in 24 sessions from 20 awake behaving
infants 3–12 months old while they performed a child-friendly attentional
cuing task. A target was presented to either the left or right of the
infant's fixation and offline gaze coding was used to measure the
latency with which they saccaded to the target. To manipulate attention, a
brief cue was presented before the target in three conditions: on the same
side as the upcoming target (valid), on the other side (invalid), or on
both sides (neutral). All infants were faster to look at the target on
valid versus invalid trials, with valid faster than neutral and invalid
slower than neutral, indicating that the cues effectively captured
attention. We then compared the fMRI activity evoked by these trial types.
Regions of adult attention networks activated more strongly for invalid
than valid trials, particularly frontal regions. Neither behavioral nor
neural effects varied by infant age within the first year, suggesting that
these regions may function early in development to support the orienting
of attention. Together, this furthers our mechanistic understanding of how
the infant brain controls the allocation of attention.