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Andrew J Calder

Publications and source records attributed to Andrew J Calder.

11 recordsLinked to original sources
PubMed2007

Separate coding of different gaze directions in the superior temporal sulcus and inferior parietal lobule.

Electrophysiological recording in the anterior superior temporal sulcus (STS) of monkeys has demonstrated separate cell populations responsive to direct and averted gaze. Human functional imaging has demonstrated posterior STS activation in gaze processing, particularly in coding the intentions conveyed by gaze, but to date has provided no evidence of dissociable coding of different gaze directions. Because the spatial resolution typical of group-based fMRI studies (approximately 6-10 mm) exceeds the size of cellular patches sensitive to different facial characteristics (1-4 mm in monkeys), a more sensitive technique may be required. We therefore used fMRI adaptation, which is considered to offer superior resolution, to investigate whether the human anterior STS contains representations of different gaze directions, as suggested by non-human primate research. Subjects viewed probe faces gazing left, directly ahead, or right. Adapting to leftward gaze produced a reduction in BOLD response to left relative to right (and direct) gaze probes in the anterior STS and inferior parietal cortex; rightward gaze adaptation produced a corresponding reduction to right gaze probes. Consistent with these findings, averted gaze in the adapted direction was misidentified as direct. Our study provides the first human evidence of dissociable neural systems for left and right gaze.

Adaptation, Physiological↗
PubMed2006

Individual differences in reward drive predict neural responses to images of food.

A network of interconnected brain regions, including orbitofrontal, ventral striatal, amygdala, and midbrain areas, has been widely implicated in a number of aspects of food reward. However, in humans, sensitivity to reward can vary significantly from one person to the next. Individuals high in this trait experience more frequent and intense food cravings and are more likely to be overweight or develop eating disorders associated with excessive food intake. Using functional magnetic resonance imaging, we report that individual variation in trait reward sensitivity (as measured by the Behavioral Activation Scale) is highly correlated with activation to images of appetizing foods (e.g., chocolate cake, pizza) in a fronto-striatal-amygdala-midbrain network. Our findings demonstrate that there is considerable personality-linked variability in the neural response to food cues in healthy participants and provide important insight into the neurobiological factors underlying vulnerability to certain eating problems (e.g., hyperphagic obesity).

Adult↗
PubMed2006

I thought you were looking at me: direction-specific aftereffects in gaze perception.

Gaze direction is an important social signal in humans and other primates. In this study, we used an adaptation paradigm to investigate the functional organization of gaze perception in humans. Adaptation to consistent leftward or rightward gaze produced a powerful illusion that virtually eliminated observers' perception of gaze in the adapted direction; gaze to that side was seen as pointing straight ahead, though perception of gaze to the opposite side was unimpaired. This striking dissociation held even when retinotopic mapping between adaptation and test stimuli was disrupted by changes in size or head orientation, suggesting that our findings do not reflect adaptation to low-level visual properties. Moreover, adaptation to averted gaze did not affect judgments of line bisection, illustrating that our findings do not reflect a general spatial bias. Our findings provide evidence that humans have distinct populations of neurons that are selectively responsive to particular directions of seen gaze.

Adolescent↗
PubMed2005

Understanding the recognition of facial identity and facial expression.

Faces convey a wealth of social signals. A dominant view in face-perception research has been that the recognition of facial identity and facial expression involves separable visual pathways at the functional and neural levels, and data from experimental, neuropsychological, functional imaging and cell-recording studies are commonly interpreted within this framework. However, the existing evidence supports this model less strongly than is often assumed. Alongside this two-pathway framework, other possible models of facial identity and expression recognition, including one that has emerged from principal component analysis techniques, should be considered.

Face↗
PubMed2004

Impaired recognition of anger following damage to the ventral striatum.

Comparative neuropsychology has identified a role for the ventral striatum (VS) in certain forms of aggression. To address whether the homologous region in humans also contributes to the emotion anger, we studied a case series of four human subjects with focal lesions affecting the VS. All four demonstrated a disproportionate impairment in recognizing human signals of aggression. By contrast, a control group of individuals with damage to more dorsal basal ganglia (BG) regions showed no evidence of an anger impairment. Our findings demonstrate that the VS makes a significant contribution to coding signals of aggression in humans, and emphasize the importance of an approach to human affective neuroscience based on cross-species homologies. The results are discussed in relation to the ventral striatal dopamine system's role in the pursuit of biological resources in general. We propose that the role of the VS in the recognition of human signals of anger may reflect a more general role in the coordination of behaviour relevant to the acquisition and protection of valued resources, including detection of signals of conspecific challenge (anger).

Adult↗
PubMed2003

Facial expression recognition across the adult life span.

We report three experiments investigating the recognition of emotion from facial expressions across the adult life span. Increasing age produced a progressive reduction in the recognition of fear and, to a lesser extent, anger. In contrast, older participants showed no reduction in recognition of disgust, rather there was some evidence of an improvement. The results are discussed in terms of studies from the neuropsychological and functional imaging literature that indicate that separate brain regions may underlie the emotions fear and disgust. We suggest that the dissociable effects found for fear and disgust are consistent with the differential effects of ageing on brain regions involved in these emotions.

Adolescent↗
PubMed2002

Selective disruption of the recognition of facial expressions of anger.

Appetitive aggression occurs in the context of resource/dominance disputes in a wide variety of species. Hence, the possibility arises that a specific neural system may have evolved to detect and coordinate responses to this specific form of challenge or threat. The dopamine system has been implicated in the processing of signals of aggression in social-agonistic encounters in several species. Here we report that dopaminergic antagonism in healthy male volunteers, following acute administration of the dopamine D2-class receptor antagonist sulpiride, leads to a selective disruption in the recognition of facial expressions of anger (signals of appetitive aggression in humans), but leaves intact recognition of other emotions and the matching of unfamiliar faces.

Adult↗
PubMed2002

Face and emotion processing in frontal variant frontotemporal dementia.

Lavenu et al. [Alzheimer Dis. Assoc. Disorder 5 (1999) 96] have shown that patients with frontotemporal dementia (FTD) show impaired recognition of facial expressions. It is not clear, however, whether these deficits arise from an impairment affecting face processing generally, emotion processing generally, or facial expression recognition alone. We address this issue by testing six patients with frontal variant frontotemporal dementia (fvFTD) on a series of face perception tasks (including facial identity and facial expression recognition), and a test of vocal emotion recognition. In general, the fvFTD participants showed impaired recognition of facial expressions in the context of preserved recognition of facial identity. In addition, however, deficits were also observed for the vocal emotion recognition task. These results are consistent with the idea that fvFTD affects the recognition of emotional signals from multiple modalities rather than facial expression processing alone. It is plausible that the emotion recognition impairments observed contribute to the abnormal social behaviour that is characteristic of this condition.

Dementia↗
PubMed2002

Reading the mind from eye gaze.

Baron-Cohen [Mindblindness: an essay on autism and theory of mind. Cambridge, MA: MIT Press, 1997] has suggested that the interpretation of gaze plays an important role in a normal functioning theory of mind (ToM) system. Consistent with this suggestion, functional imaging research has shown that both ToM tasks and eye gaze processing engage a similar region of the posterior superior temporal sulcus (STS). However, a second brain region associated with ToM, the medial prefrontal (MPF) cortex, has not been identified by previous eye gaze studies. We discuss the methodological issues that may account for the absence of MPF activation in these experiments and present a PET study that controls for these factors. Our experiment included three conditions in which the proportions of faces gazing at, and away from, the participant, were as follows: 100% direct [0% averted], 50% direct-50% averted, and 100% horizontally averted [0% direct]. Two control conditions were also included in which the faces' gaze were averted down, or their eyes were closed. Contrasts comparing the gaze conditions with each of the control conditions revealed medial frontal involvement. Parametric analyses showed a significant linear relationship between increasing proportions of horizontally averted gaze and increased rCBF in the MPF cortex. The opposite parametric analysis (increasing proportions of direct gaze) was associated with increased rCBF in a number of areas including the superior and medial temporal gyri. Additional subtraction contrasts largely confirmed these patterns. Our results demonstrate a considerable degree of overlap between the medial frontal areas involved in eye gaze processing and theory of mind tasks.

Arousal↗
PubMed2002

Anxiety-related bias in the classification of emotionally ambiguous facial expressions.

High- and low-trait socially anxious individuals classified the emotional expressions of photographic quality continua of interpolated ("morphed") facial images that were derived from combining 6 basic prototype emotional expressions to various degrees, with the 2 adjacent emotions arranged in an emotion hexagon. When fear was 1 of the 2 component emotions, the high-trait group displayed enhanced sensitivity for fear. In a 2nd experiment where a mood manipulation was incorporated, again, the high-trait group exhibited enhanced sensitivity for fear. The low-trait group was sensitive for happiness in the control condition. The mood-manipulated group had increased sensitivity for anger expressions, and trait anxiety did not moderate these effects. Interpretations of the results related to the classification of fearful expressions are discussed.

Adolescent↗