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Biomedical subjects

Andrew W Young

Publications and source records attributed to Andrew W Young.

At least 19 recordsLinked to original sources
PubMed2006

Prosopagnosia following nonconvulsive status epilepticus associated with a left fusiform gyrus malformation.

A 67-year-old, right-handed woman became unable to recognize familiar faces following a period of nonconvulsive status epilepticus. Neuropsychological assessment revealed a relatively selective impairment of familiar face recognition in the absence of low-level visual deficits or widespread cognitive impairment. MRI scanning demonstrated an isolated lesion, probably a venous angioma, involving the left fusiform gyrus, mirror-symmetrical to the site typically linked to prosopagnosia. Potential explanations for the patient's prosopagnosia include seizure-related damage to a left fusiform region required for fully competent face recognition and damage to the contralateral fusiform gyrus via interhemispheric connections. Focal neuropsychological deficits in patients with refractory partial epilepsy who develop nonconvulsive status epilepticus may be underdiagnosed.

Aged↗
PubMed2006

Recognition of emotion with temporal lobe epilepsy and asymmetrical amygdala damage.

PURPOSE: Impairments in emotion recognition occur when there is bilateral damage to the amygdala. In this study, ability to recognize auditory and visual expressions of emotion was investigated in people with asymmetrical amygdala damage (AAD) and temporal lobe epilepsy (TLE). METHODS: Recognition of five emotions was tested across three participant groups: those with right AAD and TLE, those with left AAD and TLE, and a comparison group. Four tasks were administered: recognition of emotion from facial expressions, sentences describing emotion-laden situations, nonverbal sounds, and prosody. RESULTS: Accuracy scores for each task and emotion were analysed, and no consistent overall effect of AAD on emotion recognition was found. However, some individual participants with AAD were significantly impaired at recognizing emotions, in both auditory and visual domains. CONCLUSIONS: The findings indicate that a minority of individuals with AAD have impairments in emotion recognition, but no evidence of specific impairments (e.g., visual or auditory) was found.

Adult↗
PubMed2005

A differential pattern of neural response toward sad versus happy facial expressions in major depressive disorder.

BACKGROUND: Accurate recognition of facial expressions is crucial for social functioning. In depressed individuals, implicit and explicit attentional biases away from happy and toward sad stimuli have been demonstrated. These may be associated with the negative cognitions in these individuals. METHODS: Using event-related functional magnetic resonance imaging (fMRI), neural responses to happy and sad facial expressions were measured in 14 healthy individuals and 16 individuals with major depressive disorder. RESULTS: Healthy but not depressed individuals demonstrated linear increases in response in bilateral fusiform gyri and right putamen to expressions of increasing happiness, while depressed individuals demonstrated linear increases in response in left putamen, left parahippocampal gyrus/amygdala, and right fusiform gyrus to expressions of increasing sadness. There was a negative correlation in depressed individuals between depression severity and magnitude of neural response within right fusiform gyrus to happy expressions. CONCLUSIONS: Our findings indicate preferential increases in neural response to sad but not happy facial expressions in neural regions involved in the processing of emotional stimuli in depressed individuals. These findings may be associated with the above pattern of implicit and explicit attentional biases in these individuals and suggest a potential neural basis for the negative cognitions and social dysfunction in major depression.

Adult↗
PubMed2005

Egocentric disorientation following bilateral parietal lobe damage.

Aguirre and D'Esposito (1999) suggested a taxonomy and theoretical framework for understanding topographical disorders. One of the problems they described involved egocentric disorientation, in which deficits are not strictly confined to the topographical sphere but are seen on a wide variety of visuo-spatial paradigms. Here, we report a neuropsychological investigation of MU, a person with egocentric disorientation. To test the usefulness of Aguirre and D'Esposito's framework, we administered tests which were predicted to be easy or difficult for people with egocentric disorientation to show that MU was impaired on tasks sensitive to egocentric disorientation and that he showed adequate performance on tests sensitive to other types of topographical representation. Thus MU showed normal performance on a test of recognition of famous landmarks and he could identify photographs of personally familiar places in his home town, yet he could not say how to get from a recognised building to another place in his environment. His performance fulfils the criteria for egocentric disorientation and fits the predictions derived from Aguirre and D'Esposito's views.

Adult↗
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↗
PubMed2005

Priming of emotion recognition.

Four experiments investigated priming of emotion recognition using a range of emotional stimuli, including facial expressions, words, pictures, and nonverbal sounds. In each experiment, a prime-target paradigm was used with related, neutral, and unrelated pairs. In Experiment 1, facial expression primes preceded word targets in an emotion classification task. A pattern of priming of emotional word targets by related primes with no inhibition of unrelated primes was found. Experiment 2 reversed these primes and targets and found the same pattern of results, demonstrating bidirectional priming between facial expressions and words. Experiment 2 also found priming of facial expression targets by picture primes. Experiment 3 demonstrated that priming occurs not just between pairs of stimuli that have a high co-occurrence in the environment (for example, nonverbal sounds and facial expressions), but with stimuli that co-occur less frequently and are linked mainly by their emotional category (for example, nonverbal sounds and printed words). This shows the importance of the prime and target sharing a common emotional category, rather than their previous co-occurrence. Experiment 4 extended the findings by showing that there are category-based effects as well as valence effects in emotional priming, supporting a categorical view of emotion recognition.

Adolescent↗
PubMed2005

Asymmetric interference between sex and emotion in face perception.

Previous research with speeded-response interference tasks modeled on the Garner paradigm has demonstrated that task-irrelevant variations in either emotional expression or facial speech do not interfere with identity judgments, but irrelevant variations in identity do interfere with expression and facial speech judgments. Sex, like identity, is a relatively invariant aspect of faces. Drawing on a recent model of face processing according to which invariant and changeable aspects of faces are represented in separate neurological systems, we predicted asymmetric interference between sex and emotion classification. The results of Experiment 1, in which the Garner paradigm was employed, confirmed this prediction: Emotion classifications were influenced by the sex of the faces, but sex classifications remained relatively unaffected by facial expression. A second experiment, in which the difficulty of the tasks was equated, corroborated these findings, indicating that differences in processing speed cannot account for the asymmetric relationship between facial emotion and sex processing. A third experiment revealed the same pattern of asymmetric interference through the use of a variant of the Simon paradigm. To the extent that Garner interference and Simon interference indicate interactions at perceptual and response-selection stages of processing, respectively, a challenge for face processing models is to show how the same asymmetric pattern of interference could occur at these different stages. The implications of these findings for the functional independence of the different components of face processing are discussed.

Adolescent↗
PubMed2004

Differential neural responses to overt and covert presentations of facial expressions of fear and disgust.

There is debate in cognitive neuroscience whether conscious versus unconscious processing represents a categorical or a quantitative distinction. The purpose of the study was to explore this matter using functional magnetic resonance imaging (fMRI). We first established objective thresholds of the critical temporal parameters for overt and covert presentations of fear and disgust. Next we applied these stimulus parameters in an fMRI experiment to determine whether non-consciously perceived (covert) facial expressions of fear and disgust show the same double dissociation (amygdala response to fear, insula to disgust) observed with consciously perceived (overt) stimuli. A backward masking paradigm was used. In the psychophysics experiment, the following parameters were established: 30-ms target duration for the covert condition, and 170-ms target duration for the overt condition. Results of the block-design fMRI study indicated substantial differences underlying the perception of fearful and disgusted facial expressions, with significant effects of both emotion and target duration. Findings for the overt condition (170 ms) confirm previous evidence of amygdala activation to fearful faces, and insula activation to disgusted faces, and a double dissociation between these two emotions. In the covert condition (30 ms), the amygdala was not activated to fear, nor was the insula activated to disgust. Overall, findings demonstrate significant differences between the neural responses to fear and to disgust, and between the covert presentations of these two emotions. These results therefore suggest distinct neural correlates of conscious and unconscious emotion perception.

Adult↗
PubMed2004

Recognition accuracy and response bias to happy and sad facial expressions in patients with major depression.

Impaired facial expression recognition has been associated with features of major depression, which could underlie some of the difficulties in social interactions in these patients. Patients with major depressive disorder and age- and gender-matched healthy volunteers judged the emotion of 100 facial stimuli displaying different intensities of sadness and happiness and neutral expressions presented for short (100 ms) and long (2,000 ms) durations. Compared with healthy volunteers, depressed patients demonstrated subtle impairments in discrimination accuracy and a predominant bias away from the identification as happy of mildly happy expressions. The authors suggest that, in depressed patients, the inability to accurately identify subtle changes in facial expression displayed by others in social situations may underlie the impaired interpersonal functioning.

Adult↗
PubMed2004

Emotion perception from dynamic and static body expressions in point-light and full-light displays.

Research on emotion recognition has been dominated by studies of photographs of facial expressions. A full understanding of emotion perception and its neural substrate will require investigations that employ dynamic displays and means of expression other than the face. Our aims were: (i) to develop a set of dynamic and static whole-body expressions of basic emotions for systematic investigations of clinical populations, and for use in functional-imaging studies; (ii) to assess forced-choice emotion-classification performance with these stimuli relative to the results of previous studies; and (iii) to test the hypotheses that more exaggerated whole-body movements would produce (a) more accurate emotion classification and (b) higher ratings of emotional intensity. Ten actors portrayed 5 emotions (anger, disgust, fear, happiness, and sadness) at 3 levels of exaggeration, with their faces covered. Two identical sets of 150 emotion portrayals (full-light and point-light) were created from the same digital footage, along with corresponding static images of the 'peak' of each emotion portrayal. Recognition tasks confirmed previous findings that basic emotions are readily identifiable from body movements, even when static form information is minimised by use of point-light displays, and that full-light and even point-light displays can convey identifiable emotions, though rather less efficiently than dynamic displays. Recognition success differed for individual emotions, corroborating earlier results about the importance of distinguishing differences in movement characteristics for different emotional expressions. The patterns of misclassifications were in keeping with earlier findings on emotional clustering. Exaggeration of body movement (a) enhanced recognition accuracy, especially for the dynamic point-light displays, but notably not for sadness, and (b) produced higher emotional-intensity ratings, regardless of lighting condition, for movies but to a lesser extent for stills, indicating that intensity judgments of body gestures rely more on movement (or form-from-movement) than static form information.

Adolescent↗
PubMed2004

Self-recognition in everyday life.

INTRODUCTION: A sample of everyday difficulties was collected, encompassing errors and unusual experiences participants had encountered when recognising their own faces in everyday life, with the aim of characterising similarities and differences between the reported difficulties and the major forms of self-recognition impairments described in the neuropsychological and neuropsychiatric literatures (prosopagnosia, mirrored-self misidentification, and Capgras delusion). METHOD: A total of 70 participants recalled experiences from memory. Incidents (n = 51) were recorded on questionnaire sheets that were filled out at home. Reports of three categories of incidents were analysed: misidentifications (the participant misidentified her/his own face as being that of another familiar person; n = 5), recognition failures (the participant judged that his/her own face was that of an unfamiliar person; n = 20) and perception of unusual aspects (the participant confidently recognised his/her own face but found that the seen face did not fit well the representation she/he had of his/her own face; n = 26). RESULTS AND DISCUSSION: In the reported incidents, experiences showing some similarities to those of patients with prosopagnosia, Capgras delusion or mirrored-self misidentification were noted. However, across the whole study, no incident involved a failure of reality testing; in contrast to pathological forms of error, in all of the reported incidents from our study the participant realised that a mistake had been made. The importance of decision processes in pathological forms of own-face misrecognition is discussed.

Journal Article↗
PubMed2004

Social cognition and face processing in schizophrenia.

Summary Studies of face processing have begun to elucidate the brain regions involved in social cognition, which include frontal and temporal regions known to be reduced in volume in schizophrenia. In this case-control study participants with schizophrenia (n=20) showed marked deficits in their ability to interpret social cues from faces, and those experiencing positive symptoms were impaired in recognising even basic facial emotions.

Adult↗
PubMed2003

Task instructions modulate neural responses to fearful facial expressions.

BACKGROUND: The amygdala, hippocampus, ventral, and dorsal prefrontal cortices have been demonstrated to be involved in the response to fearful facial expressions. Little is known, however, about the effect of task instructions upon the intensity of responses within these regions to fear-inducing stimuli. METHODS: Using functional magnetic resonance imaging, we examined neural responses to alternating, 30-sec blocks of fearful and neutral expressions in nine right-handed male volunteers during three different 5-min conditions: 1) passive viewing; 2) performance of a gender-decision task, with no explicit judgment of facial emotion; 3) performance of an emotionality judgment task - an explicitly emotional task. RESULTS: There was a significant effect of task upon activation within the left hippocampus and the left inferior occipital gyrus, and upon the magnitude of response within the left hippocampus, with maximal activation in these regions occurring during passive viewing, and minimal during performance of the explicit task. Performance of the gender-decision and explicit tasks, but not passive viewing, was also associated with activation within ventral frontal cortex. CONCLUSIONS: Neural responses to fearful facial expressions are modulated by task instructions.

Amygdala↗
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↗
PubMed2003

A preferential increase in the extrastriate response to signals of danger.

This study examined neural responses in nine right-handed healthy individuals while they viewed mild and intense expressions of four emotions (fear, disgust, happiness, and sadness) contrasted with neutral faces in four event-related functional magnetic resonance imaging experiments. Orthogonal polynomial trend analysis revealed a significant linear increase in the fusiform extrastriate cortical response to increasing intensities of all four emotional expressions, which was significantly greater to increasing intensities of fear and disgust than happiness and sadness, and a significant linear decrease in response to sadness in another extrastriate region. The amygdala was activated by high-intensity fearful expressions, consistent with findings from previous studies, and by low- but not high-intensity sad expressions. Significant linear increases in response to increasing intensities of fear, disgust, and happiness occurred within the hippocampus, anterior insula, and putamen, respectively. Conversely, significant linear decreases in hippocampal and putamen responses occurred to increasing intensities of sadness. We provide the first demonstration of differential increases in extrastriate and limbic responses to signals of increasing danger than to those of other emotions, and significant decreases in these responses to signals of increasing sadness in others. We suggest that this differential pattern of response to different categories of emotional signals allows the preferential direction of visual attention to signals of imminent danger than to other, less-salient emotional stimuli.

Amygdala↗
PubMed2003

A case of paraprosopia and its treatment.

INTRODUCTION: The present case study describes the neuropsychological testing and a cognitive-behavioural treatment for a 45-year-old female with paraprosopia--the experience of seeing faces sometimes distorted in grotesque and threatening ways. METHOD: The treatment focused on relaxation training, exposure, and cognitive restructuring. Ratings of subjective distress, self-reports and mood rating scale data were collected throughout an 8-week treatment period. Follow-up was at 6 weeks and 6 months. RESULTS AND CONCLUSIONS: Both subjective ratings and clinical interview suggested a reduction in the frequency of seeing the face and a substantial reduction in associated distress. Evidence for generalisation was less compelling. Suggestions are made for future psychological treatment of this uncommon disorder.

Journal Article↗