Joni N. Saby

The Utility of EEG Band Power Analysis in the Study of Infancy and Early Childhood

Research employing electroencephalographic (EEG) techniques with infants and young children has flourished in recent years due to increased interest in understanding the neural processes involved in early social and cognitive development. This review focuses on the functional characteristics of the alpha, theta, and gamma frequency bands in the developing EEG. Examples of how analyses of EEG band power have been applied to specific lines of developmental research are also discussed. These examples include recent work on the infant mu rhythm and action processing, frontal alpha asymmetry and approach–withdrawal tendencies, and EEG power measures in the study of early psychosocial adversity.

Neural correlates of being imitated: An EEG study in preverbal infants

A foundational aspect of early social–emotional development is the ability to detect and respond to the actions of others who are coordinating their behavior with that of the self. Behavioral work in this area has found that infants show particular preferences for adults who are imitating them rather than adults who are carrying out noncontingent or mismatching actions. Here, we explore the neural processes related to this tendency of infants to prefer others who act like the self. Electroencephalographic (EEG) signals were recorded from 14-month-old infants while they were observing actions that either matched or mismatched the action the infant had just executed. Desynchronization of the EEG mu rhythm was greater when infants observed an action that matched their own most recently executed action. This effect was strongest immediately prior to the culmination of the goal of the observed action, which is consistent with recent ideas about the predictive nature of brain responses during action observation.

Infants' somatotopic neural responses to seeing human actions: I've got you under my skin.

Human infants rapidly learn new skills and customs via imitation, but the neural linkages between action perception and production are not well understood. Neuroscience studies in adults suggest that a key component of imitation–identifying the corresponding body part used in the acts of self and other–has an organized neural signature. In adults, perceiving someone using a specific body part (e.g., hand vs. foot) is associated with activation of the corresponding area of the sensory and/or motor strip in the observer’s brain–a phenomenon called neural somatotopy. Here we examine whether preverbal infants also exhibit somatotopic neural responses during the observation of others’ actions. 14-month-old infants were randomly assigned to watch an adult reach towards and touch an object using either her hand or her foot. The scalp electroencephalogram (EEG) was recorded and event-related changes in the sensorimotor mu rhythm were analyzed. Mu rhythm desynchronization was greater over hand areas of sensorimotor cortex during observation of hand actions and was greater over the foot area for observation of foot actions. This provides the first evidence that infants’ observation of someone else using a particular body part activates the corresponding areas of sensorimotor cortex. We hypothesize that this somatotopic organization in the developing brain supports imitation and cultural learning. The findings connect developmental cognitive neuroscience, adult neuroscience, action representation, and behavioral imitation.

An investigation of the determinants of motor contagion in preschool children.

The influence of action perception on action execution has been demonstrated by studies of motor contagion in which the observation of an action interferes with the concurrent execution of a different action. The current study extends prior work on the extent of motor contagion in early childhood, a period of development when the effects of action observation on action execution may be particularly salient. During a classroom story reading, children (mean age 4.8 years) were familiarized with two different-colored bears, one of which was used as a seemingly animate hand puppet while the other bear remained lifeless and inanimate. Children then completed a task in which they were instructed to move a stylus on a graphics tablet in the presence of background videos of each bear making horizontal arm movements which had biological (human-moved) or non-biological (machine-moved) origins. Motor contagion was assessed as the variability of stylus movements in the horizontal axis when children were instructed to produce vertical stylus movements. Significant levels of motor contagion were seen when children observed the previously animate bear in the non-biological motion condition and when they observed the previously inanimate bear in the biological motion condition. For future studies of social perception, this finding points to the potential importance of examining mismatches between prior experience with (or knowledge about) a particular agent and the subsequent behavior of that agent in a different context.

Exploring potential social influences on brain potentials during anticipation of tactile stimulation

This study explored interpersonal influences on electrophysiological responses during the anticipation of tactile stimulation. It is well-known that broad, negative-going potentials are present in the event-related potential (ERP) between a forewarning cue and a tactile stimulus. It has also been shown that the alpha-range mu rhythm shows a lateralized desynchronization over central electrode sites during anticipation of tactile stimulation of the hand. The current study used a tactile discrimination task in which a visual cue signaled that an upcoming stimulus would either be delivered 1500ms later to the participants hand, to a task partners hand, or to neither person. For the condition in which participants anticipated the tactile stimulation to their own hand, a negative potential (contingent negative variation, CNV) was observed in the ERP at central sites in the 1000ms prior to the tactile stimulus. Significant mu rhythm desynchronization was also present in the same time window. The magnitudes of the ERPs and of the mu desynchronization were greater in the contralateral than in the ipsilateral hemisphere prior to right hand stimulation. Similar ERP and EEG changes were not present when the visual cue indicated that stimulation would be delivered to the task partner or to neither person. The absence of social influences during anticipation of tactile stimulation, and the relationship between the two brain signatures of anticipatory attention (CNV and mu rhythm) are discussed.

Beyond the N1: A review of late somatosensory evoked responses in human infants

Somatosensory evoked potentials (SEPs) have been used for decades to study the development of somatosensory processing in human infants. Research on infant SEPs has focused on the initial cortical component (N1) and its clinical utility for predicting neurological outcome in at-risk infants. However, recent studies suggest that examining the later components in the infant somatosensory evoked response will greatly advance our understanding of somatosensory processing in infancy. The purpose of this review is to synthesize the existing electroencephalography (EEG) and magnetoencephalography (MEG) studies on late somatosensory evoked responses in infants. We describe the late responses that have been reported and discuss the utility of such responses for illuminating key aspects of somatosensory processing in typical and atypical development.

Neural representations of the body in 60‐day‐old human infants

The organization of body representations in the adult brain has been well documented. Little is understood about this aspect of brain organization in human infancy. The current study employed electroencephalography (EEG) with 60-day-old infants to test the distribution of brain responses to tactile stimulation of three different body parts: hand, foot, and lip. Analyses focused on a prominent positive response occurring at 150-200 ms in the somatosensory evoked potential at central and parietal electrode sites. The results show differential electrophysiological signatures for touch of these three body parts. Stimulation of the left hand was associated with greater positive amplitude over the lateral central region contralateral to the side stimulated. Left foot stimulation was associated with greater positivity over the midline parietal site. Stimulation of the midline of the upper lip was associated with a strong bilateral response over the central region. These findings provide new insights into the neural representation of the body in infancy and shed light on research and theories about the involvement of somatosensory cortex in infant imitation and social perception.