Biomedical subjects

Evian Gordon

Publications and source records attributed to Evian Gordon.

78 records · Page 5Linked to original sources

PubMed2002

Schizophrenia and affective disorder show different visual scanning behavior for faces: a trait versus state-based distinction?

BACKGROUND: Abnormal visual scanpaths to faces and facial expressions in schizophrenia may underlie schizophrenic subjects' disturbed interpersonal communication. This study is the first to examine the specificity of these impairments to schizophrenia, by including an affective disorder psychiatric control group. METHODS: The visual scanpath performance of 65 schizophrenia, 52 affective disordered, and 61 control subjects were compared in two experiments. In the "face recognition" experiment, subjects viewed four identifiable (non-degraded) neutral faces versus four matched non-identifiable (degraded) control faces. In the "facial affect recognition" experiment, subjects viewed positive (happy), negative (sad), and neutral (control) facial emotion stimuli. Concurrent behavioral tasks were face matching (face recognition) and expression matching (facial affect recognition), each under two multiple-choice conditions (7 or 3 options). RESULTS: Scanpath disturbances were most apparent in schizophrenia subjects, who maintained a comparatively "restricted" scanpath style to all face stimuli. Schizophrenics subjects also showed the greatest recognition difficulties, particularly for neutral and happy faces. Scanpath parameters for affective disorder subjects differed only from the schizophrenia (but not the control) group, except for attention to facial features where they generally avoided facial features in all expressions and showed the greatest attentional problems of all groups for degraded faces. CONCLUSIONS: Our results suggest that a global restriction of visual scanpaths is specific to schizophrenic psychosis and might be a trait marker for this disorder, whereas scanpath abnormalities in affective disorder might instead reflect severe state-based (or discrete) attentional disturbances.

Adult↗

PubMed2002

Visual scanpaths to positive and negative facial emotions in an outpatient schizophrenia sample.

We used a psychophysiological marker of visual attention (visual scanpath) to investigate facial emotion processing in schizophrenia (n= 65) and healthy control (n = 61) groups. Visual scanpaths to 'happy', *sad' and 'neutral' faces (two exposures each) were recorded using video-oculography. Emotion recognition accuracy was assessed under both 'difficult' (exposure 1) and 'limited choice' (exposure 2) conditions. Compared to controls, schizophrenia subjects showed 'restricted' scanning and reduced attention to salient facial features (eyes, nose, mouth), that was particularly apparent for happy and neutral faces: accuracy was correspondingly reduced for the 'difficult' condition. The schizophrenia deficit in positive emotion perception may reflect a failure to integrate salient features due to dysfunctions in local processing of detailed, relevant information (fewer fixations, less attention to facial features), and in the networks that synchronise local and global processing of biologically-relevant face stimuli (generally restricted scanning style).

Adult↗

PubMed2002

Event-related potential dysfunction in posttraumatic stress disorder: the role of numbing.

The purpose of this study was to examine the relationship between disturbance in event-related potentials (ERPs) and symptom clusters in posttraumatic stress disorder (PTSD). ERPs were recorded in 17 unmedicated civilian PTSD patients and 17 age- and sex-matched controls during a conventional auditory oddball task. PTSD symptom clusters (re-experiencing, active avoidance, numbing, hyperarousal) were correlated with ERP measures. The PTSD group showed ERP disturbances to target stimuli (reduced P200 and P300 and increased N200 amplitude, increased N200 and P300 latency) and reduced P200 amplitude to common stimuli compared to the control group. A significant negative correlation was found between the intensity of numbing symptoms and parietal P300 amplitude. This study replicates findings of disturbed N200 and P300 components in PTSD, reflecting impairments in stimulus discrimination and attention. The finding that numbing was associated with reduced attention processing (P300) is consistent with models positing a relationship between disordered arousal and attention in PTSD.

Acoustic Stimulation↗

PubMed2002

Is 'gamma' (40 Hz) synchronous activity disturbed in patients with traumatic brain injury?

OBJECTIVES: The objective of this work is to determine whether Gamma (40 Hz) synchronous activity has disturbed patients with severe traumatic brain injury (TBI). METHODS: Using a conventional auditory oddball paradigm, the extent of Gamma synchrony across multiple scalp sites in specific frequency bands as a function of time was examined in 15 patients with severe TBI and 15 age- and sex-matched controls. Averaged Gamma synchrony was analyzed using within and between group multiple analyses of variance with region (left versus right hemisphere, anterior versus posterior region) as the within factor. RESULTS: Compared to controls, subjects with TBI displayed significantly delayed early Gamma latency (from -150 to 150 ms) (F((1,28))=10.28, P<0.003) across all sites in addition to other specific regional disturbances. For late Gamma synchrony, subjects with TBI displayed delayed Gamma latency at the left hemisphere (from 200 to 450 ms) (F((1,28))=8.71, P<0.006) and posterior region (F((1,28))=9.18, P<0.006) in comparison to controls. CONCLUSIONS: Impaired integration of spatially distributed brain activity ('40 Hz' electroencephalogram rhythms) may be an important marker of deficits of cortical network binding postulated to be abnormal in people who have survived TBI.

Adult↗

PubMed2002

Neuroimaging in neuropsychiatry.

Advances in physics, computing, and signal processing have provided a range of computerized brain imaging technologies that facilitate examination of the brain as a dynamical system. This article provides a review of brain imaging advances and their application in neuropsychiatry. The review encompasses (1) a description of the imaging technologies used in neuropsychiatry; (2) an outline of their temporospatial complementarity; (3) application to clinical applications; and (4) suggested future directions including an "integrative neuroscience" approach to neuropsychiatry (in which theoretical models, data and information concerning mechanisms are integrated). In the absence of a unified theory of the brain, an integrated approach is presented as one means of exploring converging brain-imaging evidence in relation to neuropsychiatric disorders.

Brain↗

PubMedDate not supplied

Clinical profiles, scope and general findings of the Western Sydney First Episode Psychosis Project.

OBJECTIVE: To examine the clinical profile, treatment and social functioning of a community-based sample of young people presenting with their first episode of psychosis. METHODS: Over a 2-year period, young people with their first episode of psychosis referred to early intervention services in two area mental health services in western Sydney were assessed with a battery of clinical, neuropsychological, psychophysiological and neuroanatomical measures. This paper reports the clinical results of the baseline section of the study. RESULTS: Of the 224 referrals to the project, 94 subjects meet inclusion criteria and agreed to take part. Subjects were divided into three diagnostic groups--'Schizophrenia', 'Mood Disorders' and 'Mixed Psychosis', the latter principally comprised of substance induced psychotic disorders. Subjects from the 'Schizophrenia' group differed significantly from the other two groups in that they had higher levels of negative symptoms and general psychopathology, and were less likely to be employed or engaged in study. They had poorer overall social functioning. Subjects with 'Mixed Psychosis' were similar to those from the 'Schizophrenia' group in that they were older and male, but they did not have the same burden of negative symptoms as the 'Schizophrenia' group. The 'Mood Disorders' group was younger, female and had overall a higher level of psychosocial functioning than the other two groups. Subjects from the 'Mood Disorders' group were more likely to be managed with mood stabilisers and multiple drug therapies. The use of atypical antipsychotic medication was almost universal. CONCLUSIONS: Even shortly after the time of presentation to mental health services young people with a schizophrenia spectrum diagnosis have a heavier burden of symptoms and are significantly more impaired by them than young people with other psychotic illnesses. This and their symptom profile differentiated them from young people with other psychotic disorders.

Activities of Daily Living↗