The neural correlates of orienting to walking direction in 6‐month‐old infants: An ERP study

Abstract

The ability to detect social signals represents a first step to enter our social world. Behavioral evidence has demonstrated that 6‐month‐old infants are able to orient their attention toward the position indicated by walking direction, showing faster orienting responses toward stimuli cued by the direction of motion than toward uncued stimuli. The present study investigated the neural mechanisms underpinning this attentional priming effect by using a spatial cueing paradigm and recording EEG (Geodesic System 128 channels) from 6‐month‐old infants. Infants were presented with a central point‐light walker followed by a single peripheral target. The target appeared randomly at a position either congruent or incongruent with the walking direction of the cue. We examined infants' target‐locked event‐related potential (ERP) responses and we used cortical source analysis to explore which brain regions gave rise to the ERP responses. The P1 component and saccade latencies toward the peripheral target were modulated by the congruency between the walking direction of the cue and the position of the target. Infants' saccade latencies were faster in response to targets appearing at congruent spatial locations. The P1 component was larger in response to congruent than to incongruent targets and a similar congruency effect was found with cortical source analysis in the parahippocampal gyrus and the anterior fusiform gyrus. Overall, these findings suggest that a type of biological motion like the one of a vertebrate walking on the legs can trigger covert orienting of attention in 6‐month‐old infants, enabling enhancement of neural activity related to visual processing of potentially relevant information as well as a facilitation of oculomotor responses to stimuli appearing at the attended location.

Electrophysiological Evidence of Space‐Number Associations in 9‐Month‐Old Infants

“…This finding replicates and extends earlier demonstrations of a validity effect at the level of the occipital P1 in response to peripheral targets appearing soon after a peripheral cue (Richards, 2005), or a dynamic central cue whose movement is spatially informative with respect to the target position (Lunghi et al, 2019(Lunghi et al, , 2020Natale et al, 2017). Critically, the current results extend these earlier demonstrations by showing that even spatially noninformative central cues are capable of orient infants' visual attention toward the left or right side of space.…”

“…In these studies, ERP responses to peripheral target objects were modulated by the congruent versus incongruent relation between the directionality (leftward or rightward) of the dynamic social cue and the position of the target object. In particular, Lunghi et al (2019) reported a larger P1 amplitude over occipital-parietal sites in response to peripheral targets appearing at locations congruent with the walking direction of the point-light displays, indicating the enhancement of information processing at the attended location induced by the central cue.…”

“…In particular, Lunghi et al. ( 2019 ) reported a larger P1 amplitude over occipital‐parietal sites in response to peripheral targets appearing at locations congruent with the walking direction of the point‐light displays, indicating the enhancement of information processing at the attended location induced by the central cue.…”

“…In these studies, the P1 validity effect resulted from the cue‐target spatial relation, as both the cue and the target were presented at a peripheral location. However, more recently two studies with 6‐month‐old infants have shown that ERP correlates of visuospatial attention to peripheral targets can also be modulated by central directional social cues, such as hand grasping gestures (Natale et al., 2017 ) or point‐light displays of a human walker (Lunghi, Di Giorgio, Benavides‐Varela, & Simion, 2020 ; Lunghi, Piccardi, Richards, & Simion, 2019 ). In these studies, ERP responses to peripheral target objects were modulated by the congruent versus incongruent relation between the directionality (leftward or rightward) of the dynamic social cue and the position of the target object.…”

Structural templates for imaging EEG cortical sources in infants

“…Source estimation has not been frequently reported in the infant EEG literature, with the notable exception of a few research groups that used volumetric approaches such as CDR with realistic head models built from MRIs of head-size-matched individuals ( Xie and Richards, 2017 ) or from age-matched MRI averages ( Lunghi et al, 2019 ), or using ECD with a four-shell ellipsoidal head model ( Ortiz-Mantilla et al, 2019 ). Source imaging is more frequently used in magnetoencephalography (MEG) ( Kao and Zhang, 2019 ), but it generally relies on over simplistic spherical models to overcome the absence of realistic head models ( Imada et al, 2006 ; Kuhl et al, 2014 ) or it uses custom-built subject-specific head models that are not reusable by the research community ( Ramírez et al, 2017 ; Travis et al, 2011 ).…”