Hiroko Ichikawa

Infant brain activity while viewing facial movement of point-light displays as measured by near-infrared spectroscopy (NIRS)☆

Adult observers can quickly identify specific actions performed by an invisible actor from the points of lights attached to the actors head and major joints. Infants are also sensitive to biological motion and prefer to see it depicted by a dynamic point-light display. In detecting biological motion such as whole body and facial movements, neuroimaging studies have demonstrated the involvement of the occipitotemporal cortex, including the superior temporal sulcus (STS). In the present study, we used the point-light display technique and near-infrared spectroscopy (NIRS) to examine infant brain activity while viewing facial biological motion depicted in a point-light display. Dynamic facial point-light displays (PLD) were made from video recordings of three actors making a facial expression of surprise in a dark room. As in Bassilis study, about 80 luminous markers were scattered over the surface of the actors faces. In the experiment, we measured infants hemodynamic responses to these displays using NIRS. We hypothesized that infants would show different neural activity for upright and inverted PLD. The responses were compared to the baseline activation during the presentation of individual still images, which were frames extracted from the dynamic PLD. We found that the concentration of oxy-Hb increased in the right temporal area during the presentation of the upright PLD compared to that of the baseline period. This is the first study to demonstrate that infants brain activity in face processing is induced only by the motion cue of facial movement depicted by dynamic PLD.

Novel method to classify hemodynamic response obtained using multi-channel fNIRS measurements into two groups: exploring the combinations of channels.

Near-infrared spectroscopy (NIRS) in psychiatric studies has widely demonstrated that cerebral hemodynamics differs among psychiatric patients. Recently we found that children with attention-deficit/hyperactivity disorder (ADHD) and children with autism spectrum disorders (ASD) showed different hemodynamic responses to their own mother’s face. Based on this finding, we may be able to classify the hemodynamic data into two those groups and predict to which diagnostic group an unknown participant belongs. In the present study, we proposed a novel statistical method for classifying the hemodynamic data of these two groups. By applying a support vector machine (SVM), we searched the combination of measurement channels at which the hemodynamic response differed between the ADHD and the ASD children. The SVM found the optimal subset of channels in each data set and successfully classified the ADHD data from the ASD data. For the 24-dimensional hemodynamic data, two optimal subsets classified the hemodynamic data with 84% classification accuracy, while the subset contained all 24 channels classified with 62% classification accuracy. These results indicate the potential application of our novel method for classifying the hemodynamic data into two groups and revealing the combinations of channels that efficiently differentiate the two groups.

Hemodynamic response of children with attention-deficit and hyperactive disorder (ADHD) to emotional facial expressions

Children with attention-deficit/hyperactivity disorder (ADHD) have difficulty recognizing facial expressions. They identify angry expressions less accurately than typically developing (TD) children, yet little is known about their atypical neural basis for the recognition of facial expressions. Here, we used near-infrared spectroscopy (NIRS) to examine the distinctive cerebral hemodynamics of ADHD and TD children while they viewed happy and angry expressions. We measured the hemodynamic responses of 13 ADHD boys and 13 TD boys to happy and angry expressions at their bilateral temporal areas, which are sensitive to face processing. The ADHD children showed an increased concentration of oxy-Hb for happy faces but not for angry faces, while TD children showed increased oxy-Hb for both faces. Moreover, the individual peak latency of hemodynamic response in the right temporal area showed significantly greater variance in the ADHD group than in the TD group. Such atypical brain activity observed in ADHD boys may relate to their preserved ability to recognize a happy expression and their difficulty recognizing an angry expression. We firstly demonstrated that NIRS can be used to detect atypical hemodynamic response to facial expressions in ADHD children.

Finding a face in a face-like object.

Humans have the tendency to perceive a face even in a non-living object. Previous studies report that people perceive facial features and even interpret a personality in a car front. Following these findings, we investigated whether the perception of a face in a face-like object is mediated by human face processing, which involves both featural and configural processing. In our experiment, participants were presented with 30 face-like objects and were asked about the existence of facial features, the intensity of typicality/distinctiveness, and the intensity of facial expression. Using multiple regression analysis, which predicts the perception of a face in a face-like object, we found that the existence of eyes was a significant predictor of variance in perceiving a face in a face-like object.

Face Orientation and Motion Differently Affect the Deployment of Visual Attention in Newborns and 4-Month-Old Infants.

Orienting visual attention allows us to properly select relevant visual information from a noisy environment. Despite extensive investigation of the orienting of visual attention in infancy, it is unknown whether and how stimulus characteristics modulate the deployment of attention from birth to 4 months of age, a period in which the efficiency in orienting of attention improves dramatically. The aim of the present study was to compare 4-month-old infants’ and newborns’ ability to orient attention from central to peripheral stimuli that have the same or different attributes. In Experiment 1, all the stimuli were dynamic and the only attribute of the central and peripheral stimuli to be manipulated was face orientation. In Experiment 2, both face orientation and motion of the central and peripheral stimuli were contrasted. The number of valid trials and saccadic latency were measured at both ages. Our results demonstrated that the deployment of attention is mainly influenced by motion at birth, while it is also influenced by face orientation at 4-month of age. These findings provide insight into the development of the orienting visual attention in the first few months of life and suggest that maturation may be not the only factor that determines the developmental change in orienting visual attention from birth to 4 months.

Differences in the Pattern of Hemodynamic Response to Self-Face and Stranger-Face Images in Adolescents with Anorexia Nervosa: A Near-Infrared Spectroscopic Study

There have been no reports concerning the self-face perception in patients with anorexia nervosa (AN). The purpose of this study was to compare the neuronal correlates of viewing self-face images (i.e. images of familiar face) and stranger-face images (i.e. images of an unfamiliar face) in female adolescents with and without AN. We used near-infrared spectroscopy (NIRS) to measure hemodynamic responses while the participants viewed full-color photographs of self-face and stranger-face. Fifteen females with AN (mean age, 13.8 years) and 15 age- and intelligence quotient (IQ)-matched female controls without AN (mean age, 13.1 years) participated in the study. The responses to photographs were compared with the baseline activation (response to white uniform blank). In the AN group, the concentration of oxygenated hemoglobin (oxy-Hb) significantly increased in the right temporal area during the presentation of both the self-face and stranger-face images compared with the baseline level. In contrast, in the control group, the concentration of oxy-Hb significantly increased in the right temporal area only during the presentation of the self-face image. To our knowledge the present study is the first report to assess brain activities during self-face and stranger-face perception among female adolescents with AN. There were different patterns of brain activation in response to the sight of the self-face and stranger-face images in female adolescents with AN and controls.

Infants recognize identity in a dynamic facial animation that simultaneously changes its identity and expression

ABSTRACT Recognition of facial identity and facial expression have been reported to be correlated. Previous studies using static facial photographs reported that identity recognition was not interfered by task-irrelevant change of facial expression but that expression recognition was interfered by task-irrelevant change of facial identity. In this study, we created dynamic morphing animations that simultaneously changes facial identity and expression to investigate the interaction between identity and expression recognition. We tested 7 –8-month-old infants who were around the age at which the recognition of facial expression develops. Using the familiarization–novelty preference procedure, we examined whether infants could learn identity and facial expression from morphing animation. We found that infants learned identity but not expression from the morphing animation. Our results demonstrate that the interaction between identity and expression occurs differently in infancy than in adults when both the dimension of facial identity and the expression vary simultaneously.