Steven M. Platek

Neural substrates for functionally discriminating self-face from personally familiar faces

Understanding the neurobiological substrates of self‐recognition yields important insight into socially and clinically critical cognitive functions such as theory of mind. Experimental evidence suggests that right frontal and parietal lobes preferentially process self‐referent information. Recognition of ones own face is an important parameter of self‐recognition, but well‐controlled experimental data on the brain substrates of self‐face recognition is limited. The goal of this study was to characterize the activation specific to self‐face in comparison with control conditions of two levels of familiarity: unknown unfamiliar face and the more stringent control of a personally familiar face. We studied 12 healthy volunteers who made “unknown,” “familiar,” and “self” judgments about photographs of three types of faces: six different novel faces, a personally familiar face (participants fraternity brother), and their own face during an event‐related functional MRI (fMRI) experiment. Contrasting unknown faces with baseline showed activation of the inferior occipital lobe, which supports previous findings suggesting the presence of a generalized face‐processing area within the inferior occipital‐temporal region. Activation in response to a familiar face, when contrasted with an unknown face, invoked insula, middle temporal, inferior parietal, and medial frontal lobe activation, which is consistent with an existing hypothesis suggesting familiar face recognition taps neural substrates that are different from those involved in general facial processing. Brain response to self‐face, when contrasted with familiar face, revealed activation in the right superior frontal gyrus, medial frontal and inferior parietal lobes, and left middle temporal gyrus. The contrast familiar vs. self produced activation only in the anterior cingulate gyrus. Our results support the existence of a bilateral network for both perceptual and executive aspects of self‐face processing that cannot be accounted for by a simple hemispheric dominance model. This network is similar to those implicated in social cognition, mirror neuron matching, and face‐name matching. Our findings also show that some regions of the medial frontal and parietal lobes are specifically activated by familiar faces but not unknown or self‐faces, indicating that these regions may serve as markers of face familiarity and that the differences between activation associated with self‐face recognition and familiar face recognition are subtle and appear to be localized to lateral frontal, parietal, and temporal regions. Hum. Brain Mapping, 2005.

Functional Near Infrared Spectroscopy (fNIRS): An Emerging Neuroimaging Technology with Important Applications for the Study of Brain Disorders

Functional near-infrared spectroscopy (fNIRS) is an emerging functional neuroimaging technology offering a relatively non-invasive, safe, portable, and low-cost method of indirect and direct monitoring of brain activity. Most exciting is its potential to allow more ecologically valid investigations that can translate laboratory work into more realistic everyday settings and clinical environments. Our aim is to acquaint clinicians and researchers with the unique and beneficial characteristics of fNIRS by reviewing its relative merits and limitations vis-à-vis other brain-imaging technologies such as functional magnetic resonance imaging (fMRI). We review cross-validation work between fMRI and fNIRS, and discuss possible reservations about its deployment in clinical research and practice. Finally, because there is no comprehensive review of applications of fNIRS to brain disorders, we also review findings from the few studies utilizing fNIRS to investigate neurocognitive processes associated with neurological (Alzheimers disease, Parkinsons disease, epilepsy, traumatic brain injury) and psychiatric disorders (schizophrenia, mood disorders, anxiety disorders).

Contagious yawning: the role of self-awareness and mental state attribution.

Contagious yawning is a common, but poorly understood phenomenon. We hypothesized that contagious yawning is part of a more general phenomenon known as mental state attribution (i.e. the ability to inferentially model the mental states of others). To test this hypothesis we compared susceptibility to contagiously yawn with performance on a self-face recognition task, several theory of mind stories, and on a measure of schizotypal personality traits. Consistent with the hypothesis, susceptibility to contagiously yawn was positively related to performance on self-face recognition and faux pas theory of mind stories, and negatively related to schizotypal personality traits. These data suggest that contagious yawning may be associated with empathic aspects of mental state attribution and are negatively affected by increases in schizotypal personality traits much like other self-processing related tasks.

Reactions to children's faces: Resemblance affects males more than females

Abstract Since cuckoldry risk is asymmetrical, we hypothesized that parental investment would be more affected by paternal than maternal resemblance. To test this hypothesis, we asked subjects hypothetical questions about investing in children under conditions in which their faces or those of other people had been morphed with photographs of children. Males were more likely to choose a face they had been morphed with as the most attractive, the child they were most likely to adopt, the child they would like to spend the most time with, the child they would spend US

Neural correlates of self-face recognition: an effect-location meta-analysis.

50 on, and the child they would least resent having to pay child support for. Reactions to childrens faces by females were much less affected by resemblance.

How much paternal resemblance is enough? Sex differences in hypothetical investment decisions but not in the detection of resemblance

Recent evidence from neuropsychological patients with focalized lesions and functional brain imaging studies indicate that processing of self is distinguishable from processing of information about others (e.g., recognizing a familiar face). Here, we conduct an effect-location meta-analysis (Fox et al., 1998) of 9 functional neuroimaging studies of self-face recognition. The evidence provides support for a right-dominated, but largely bilaterally distributed model for self-face processing. Four areas are consistently activated: the left fusiform gyrus, bilateral middle and inferior frontal gyri, and right precuneus. The evidence is interpreted in light of a developing model of self-face recognition as part of a larger social cognitive stream of processing.

Self-face recognition is affected by schizotypal personality traits

Abstract Subjects presented with an array of childrens faces, which had been morphed to resemble the subject to varying degrees, were asked to make hypothetical investment decisions. Although females were relatively indifferent to resemblance, males reacted favorably towards childrens faces that contained 25% or more of their characteristics. This difference was not a byproduct of differences in the detection of resemblance since males were no better than females at matching child faces with adult faces.

Is family special to the brain? An event-related fMRI study of familiar, familial, and self-face recognition

The right cortical hemisphere appears to be important for processing self-face images and we have hypothesized that self-face processing is compromised in schizophrenia. As a way of testing this hypothesis, we investigated how reaction times to ones own face varied as a function of scores on the Schizotypal Personality Questionnaire (SPQ). Left-hand reaction times to self-face images were positively correlated to scores on the SPQ. In addition, people who scored 20 or below on the SPQ showed shorter reaction times to self-face images than stranger faces when responding with their left-hand, whereas those who scored 21 or above on the SPQ showed a left-hand disadvantage. These results imply that self-face processing in the right hemisphere is impaired in individuals with schizotypal traits. Our data are the first to show that traits associated with a schizophrenic spectrum disorder in a non-clinical population may compromise self-face recognition.

Brain activation in restrained and unrestrained eaters: an fMRI study.

The face-processing network has evolved to respond differentially to different classes of faces depending on their relevance to the perceiver. For example, self-, familiar, and unknown faces are associated with activation in different neural substrates. Family should represent a special class of face stimuli that is of high relevance to individuals, because incorrect assignment of kinship can have dire consequences (e.g., incest, cuckoldry). Therefore evolution should have favored redundant mechanisms for detection of kin. We used fMRI to investigate the neural substrates associated with viewing faces of kin compared to other classes of faces (e.g., self-face, familiar face, and unknown face), and to examine the degree to which self-facial resemblance activated similar neural substrates. Contrasting kin faces with unknown faces activated substrates associated with self-face recognition, while comparing kin faces to friend faces activated posterior cingulate and cuneus. Similar posterior medial substrates were recruited when contrasting self-resembling faces with morphed faces of kin, suggesting these regions potentially represent computational processing about facial familiarity and identity. On the other hand, discrimination of self-resembling faces from familiar morphs activated anterior medial substrates (anterior cingulate cortex, ACC, medial prefrontal cortex, MPFC). These findings, and a region of interest (ROI) analysis, highlight the role of the extended face-processing network for discrimination of kin from familiar non-kin members of ones social group based on self-referent phenotypic cues.

In-group and out-group membership mediates anterior cingulate activation to social exclusion.

Restraint theory has been used to model the process that produces binge eating. However, there is no satisfactory explanation for the tendency of restrained eaters (REs) to engage in counterregulatory eating, an ostensible analogue of binge eating. Using functional magnetic resonance imaging (fMRI), the authors investigated brain activation of normal weight REs (N = 9) and unrestrained eaters (UREs; N = 10) when fasted and fed and viewing pictures of highly and moderately palatable foods and neutral objects. When fasted and viewing highly palatable foods, UREs showed widespread bilateral activation in areas associated with hunger and motivation, whereas REs showed activation only in the cerebellum, an area previously implicated in low-level processing of appetitive stimuli. When fed and viewing high palatability foods, UREs showed activation in areas related to satiation and memory, whereas REs showed activation in areas implicated in desire, expectation of reward, and goal-defined behavior. These findings parallel those from behavioral research. The authors propose that the counterintuitive findings from preload studies and the present study are due to the fact that REs are less hungry than UREs when fasted and find palatable food more appealing than UREs when fed.