Abnormal Visual Processing Research Articles

Abnormal visual processing and increased seizure susceptibility result from developmental exposure to the biocide methylisothiazolinone

Methylisothiazolinone (MIT) is a commonly used biocide known to be neurotoxic in vitro. Brief exposure of cortical neurons in culture to MIT results in increased neurodegeneration, whereas chronic exposure of developing neurons in culture to low concentrations of MIT has been shown to interfere with normal neurite outgrowth. However, the effects of chronic MIT exposure on the developing nervous system have not been tested in vivo. Here we expose Xenopus laevis tadpoles to sub-lethal concentrations of MIT during a critical period in neural development. We find that MIT exposure results in deficits in visually mediated avoidance behavior and increased susceptibility to seizures, as well electrophysiological abnormalities in optic tectal function, without any effects on overall morphology, gross anatomy of the visual projections, overall visual function, and swimming ability. These effects indicate that chronic exposure to low levels of MIT results in neural circuit-level deficits that result in abnormal neurological function without causing increased mortality or even gross anatomical defects. Our findings, combined with the fact that the long-term neurological impacts of environmental exposure to MIT have not been determined, suggest a need for a closer evaluation of the safety of MIT in commercial and industrial products.

Fixational saccadic eye movements are altered in anisometropic amblyopia

Amblyopia develops during a critical period in early visual development and is characterized by reduced visual sensory functions and structural reorganization of the brain. However, little is known about oculomotor functions in amblyopes despite the special role of eye movements in visual perception, task execution and fixation. Therefore, we studied the relationship of visual deficits in anisometropic amblyopia and fixational saccadic eye movements. We recruited twenty-eight anisometropic amblyopes and twenty-eight age-matched control subjects. Using a high-speed eye-tracker, fixational eye-movements of both eyes were recorded. A computerized fixational saccadic component analysis of eye-movement waveforms was developed to quantify the parameters of fixational saccades (FSs) and a simulation model was developed to help explain the FS performances. Amblyopic eyes, but not control eyes, showed fewer FSs, but these had increased amplitudes, increased peak velocities, and longer inter-saccadic intervals. The reduced FSs occurred mainly in the 0- to 0.6-degree amplitude range, and the probability of FSs with larger amplitudes and longer inter-saccadic intervals was significantly higher than in controls. A new simulation model analysis suggests that an excitatory-inhibitory activity imbalance in superior colliculus may explain these FSs changes. We propose that the abnormal visual processing and circuitry reorganization in anisometropic amblyopia has an impact on the fixational saccade generation. We see two possible interpretations: (i) altered FSs may be an attempt of the visual system to adapt to the deficit, trying to capture more information from a broader spatial domain of the visual world so as to enhance the contrast sensitivity to low spatial frequencies viewed by the amblyopic eye, or (ii) it may be the cause of amblyopia or a contributing factor to the original deficit that aggravates the early deprivation.

Regional grey and white matter volumetric changes in myalgic encephalomyelitis (chronic fatigue syndrome): a voxel-based morphometry 3 T MRI study

It is not established whether myalgic encephalomyelitis/chronic fatigue syndrome (CFS) is associated with structural brain changes. The aim of this study was to investigate this by conducting the largest voxel-based morphometry study to date in CFS. High-resolution structural 3 T cerebral MRI scanning was carried out in 26 patients with CFS and 26 age- and gender-matched healthy volunteers. Voxel-wise generalised linear modelling was applied to the processed MR data using permutation-based non-parametric testing, forming clusters at t>2.3 and testing clusters for significance at p<0.05, corrected for multiple comparisons across space. Significant voxels (p<0.05, corrected for multiple comparisons) depicting reduced grey matter volume in the CFS group were noted in the occipital lobes (right and left occipital poles; left lateral occipital cortex, superior division; and left supracalcrine cortex), the right angular gyrus and the posterior division of the left parahippocampal gyrus. Significant voxels (p<0.05, corrected for multiple comparisons) depicting reduced white matter volume in the CFS group were also noted in the left occipital lobe. These data support the hypothesis that significant neuroanatomical changes occur in CFS, and are consistent with the complaint of impaired memory that is common in this illness; they also suggest that subtle abnormalities in visual processing, and discrepancies between intended actions and consequent movements, may occur in CFS.

Contextual Modulation of Contour Detection is Altered in Schizophrenia

Contour detection is an important step in early visual processing that facilitates figure-ground segmentation and object recognition. Patients with schizophrenia show abnormalities in early visual processing, and contour detection deficits have been observed in those with this disorder. It has recently been shown that during contour detection, nearby elements that are not part of a contour can influence detection thresholds, an effect referred to here as contextual modulation. The valence of this modulation depends on the relative orientation between contour elements and flankers, and agrees with known orientation selective surround suppression (OSSS) effects. It has also been shown that the OSSS effect is diminished in subjects with schizophrenia. However, is it currently unknown how deficits in OSSS in schizophrenia may influence contextual modulation by flanking elements during contour detection. Therefore, we measured contour detection thresholds in healthy adults and those with schizophrenia in a psychophysics experiment. Stimuli consisted of an array of Gabor elements with a vertically oriented group of elements forming a target contour to the left or right of fixation. Thresholds were obtained by determining a subject's tolerance to jitter in the orientation of target elements. Stimulus context differed between conditions, and was defined by the relative orientation between contour elements and flankers (5 Gabors flanking left & right of both possible target locations). Within subject groups, thresholds for randomly or orthogonally oriented flankers are significantly higher than for parallel flankers. In general, subjects with schizophrenia performed better on the task than healthy controls, with a significant increase in performance in the orthogonal condition, relative to randomly oriented flankers, that was not observed in controls. Increased performance in the orthogonal condition constitutes a context-specific visual processing abnormality during contour detection, and suggests broader tuning of orientation-dependent lateral masking effects in schizophrenia.

New visual information processing abnormality biomarkers for the diagnosis of schizophrenia

INTRODUCTION: Schizophrenia is currently diagnosed on the basis of patient reports and clinical observations. A diagnosis based on aetiology is inherently more reliable due to being closer to the disease process than the overt clinical manifestations. Accordingly, recent research in schizophrenia has focused on the development of biomarkers in a bit to improve the reliability and neurobiological relevance of the diagnosis. Visual information processing is one of these promising fields of recent biomarker research. AREAS COVERED: This article provides an overview of the available literature regarding deficits in schizophrenia detectable through psychophysical (contrast and motion sensitivity, visual backward-masking), ERP (P1 and N1 visual evoked potentials) and oscillatory (signal power and phase-locking factor of evoked oscilations) measures and their validity as trait or state biomarkers of the disease. The methodology included a search on articles related to visual information processing in schizophrenia on the PubMed database. EXPERT OPINION: Biomarker research in schizophrenia is a rapidly expanding area. Evidence exists to suggest that both psychotic and manic symptoms are associated with visual processing abnormalities. A specific impairment confined to the magnocellular component of the visual system might be a trait biomarker of schizophrenia.

Abnormalities of object visual processing in body dysmorphic disorder

Individuals with body dysmorphic disorder (BDD) may have perceptual distortions for their appearance. Previous studies suggest imbalances in detailed relative to configural/holistic visual processing when viewing faces. No study has investigated the neural correlates of processing non-symptom-related stimuli. The objective of this study was to determine whether individuals with BDD have abnormal patterns of brain activation when viewing non-face/non-body object stimuli. Fourteen medication-free participants with DSM-IV BDD and 14 healthy controls participated. We performed functional magnetic resonance imaging (fMRI) while participants matched photographs of houses that were unaltered, contained only high spatial frequency (HSF, high detail) information or only low spatial frequency (LSF, low detail) information. The primary outcome was group differences in blood oxygen level-dependent (BOLD) signal changes. The BDD group showed lower activity in the parahippocampal gyrus, lingual gyrus and precuneus for LSF images. There were greater activations in medial prefrontal regions for HSF images, although no significant differences when compared to a low-level baseline. Greater symptom severity was associated with lower activity in the dorsal occipital cortex and ventrolateral prefrontal cortex for normal spatial frequency (NSF) and HSF images. Individuals with BDD have abnormal brain activation patterns when viewing objects. Hypoactivity in visual association areas for configural and holistic (low detail) elements and abnormal allocation of prefrontal systems for details are consistent with a model of imbalances in global versus local processing. This may occur not only for appearance but also for general stimuli unrelated to their symptoms.

Altered directional connectivity in Parkinson's disease during performance of a visually guided task

Recent animal studies have suggested that cortical areas may play a greater role in the modulation of abnormal oscillatory activity in Parkinson's disease (PD) than previously recognized. We investigated task and medication-dependent, EEG-based directional cortical connectivity in the θ (4–7Hz), α (8–12Hz), β (13–30Hz) and low γ (31–50Hz) frequency bands in 10 PD subjects and 10 age-matched controls. All subjects performed a visually guided task previously shown to modulate abnormal oscillatory activity in PD subjects. We examined the connectivity in the simultaneously-recorded EEG between 5 electrode regions of interest (fronto-central, left and right sensorimotor, central and occipital) using a sparse, multivariate, autoregressive-based partial directed coherence method. For comparison, we utilized traditional Fourier analysis to evaluate task-dependent frequency spectra modulation in these same regions. While the spectral analysis revealed some overall differences between PD and control subjects, it demonstrated relatively modest changes between regions. In contrast, the partial directed coherence-based analysis revealed multifaceted, regionally and directionally-dependent alterations of connectivity in PD subjects during both movement preparation and execution. Connectivity was particularly altered posteriorly, suggesting abnormalities in visual and visuo-motor processing in PD. Moreover, connectivity measures in the α, β and low γ frequency ranges correlated with motor Unified Parkinson's Disease Rating Scores in PD subjects withdrawn from medication. Levodopa administration only partially restored connectivity, and in some cases resulted in further exacerbation of abnormalities. Our results support the notion that PD is associated with significant alterations in connectivity between brain regions, and that these changes can be non-invasively detected in the EEG using partial directed coherence methods. Thus, the role of EEG to monitor PD may need to be further expanded.

Changes in neuronal correlates of body image processing by means of cognitive-behavioural body image therapy for eating disorders: a randomized controlled fMRI study

Previous neuroimaging studies have demonstrated abnormalities in visual body image processing in anorexia and bulimia nervosa, possibly underlying body image disturbance in these disorders. Although cognitive behavioural interventions have been shown to be successful in improving body image disturbance in eating disorders, no randomized controlled study has yet analysed treatment-induced changes in neuronal correlates of visual body image processing. Altogether, 32 females with eating disorders were randomly assigned either to a manualized cognitive behavioural body image therapy consisting of 10 group sessions, or to a waiting list control condition. Using functional magnetic resonance imaging, brain responses to viewing photographs of one's own and another female's body taken from 16 standardized perspectives while participants were wearing a uniform bikini were acquired before and after the intervention and the waiting time, respectively. Data indicate a general blood oxygen level dependent signal enhancement in response to looking at photographs of one's own body from pre- to post-treatment, whereas exclusively in the control group activation decreases from pre- to post-waiting time were observed. Focused activation increases from pre- to post-treatment were found in the left middle temporal gyrus covering the coordinates of the extrastriate body area and in bilateral frontal structures including the middle frontal gyrus. Results point to a more intense neuronal processing of one's own body after the cognitive behavioural body image therapy in cortical regions that are responsible for the visual processing of the human body and for self-awareness.

The McCollough Effect and Facial Emotion Discrimination in Patients With Schizophrenia and Their Unaffected Relatives

Abnormalities in visual processing have been found consistently in schizophrenia patients, including deficits in early visual processing, perceptual organization, and facial emotion recognition. There is however no consensus as to whether these abnormalities represent heritable illness traits and what their contribution is to psychopathology. Fifty patients with schizophrenia, 61 of their first-degree healthy relatives, and 50 psychiatrically healthy volunteers were tested with regard to facial affect (FA) discrimination and susceptibility to develop the color-contingent illusion [the McCollough Effect (ME)]. Both patients and relatives demonstrated significantly lower accuracy in FA discrimination compared with controls. There was also a significant effect of familiality: Participants from the same families had more similar accuracy scores than those who belonged to different families. Experiments with the ME showed that schizophrenia patients required longer time to develop the illusion than relatives and controls, which indicated poor visual adaptation in schizophrenia. Relatives were marginally slower than controls. There was no significant association between the measures of FA discrimination accuracy and ME in any of the participant groups. Facial emotion discrimination was associated with the degree of interpersonal problems, as measured by the Schizotypal Personality Questionnaire in relatives and healthy volunteers, whereas the ME was associated with the perceptual-cognitive symptoms of schizotypy and positive symptoms of schizophrenia. Our results support the heritability of FA discrimination deficits as a trait and indicate visual adaptation abnormalities in schizophrenia, which are symptom related.

Abnormal Microstructure of the Atrophic Thalamus in Preterm Survivors with Periventricular Leukomalacia

The neuroanatomic substrate of cognitive deficits in long-term survivors of prematurity with PVL is poorly understood. The thalamus is critically involved in cognition via extensive interconnections with the cerebral cortex. We hypothesized that the thalamus is atrophic (reduced in volume) in childhood survivors of prematurity with neuroimaging evidence of PVL and that the atrophy is associated with selective microstructural abnormalities within its subdivisions. We performed quantitative volumetric and DTI measurements of the thalamus in 17 children with neuroimaging evidence of PVL (mean postconceptional age, 5.6 ± 4.0 years) who were born prematurely and compared these with 74 term control children (5.7 ± 3.4 years). The major findings were the following: 1) a significant reduction in the overall volume of the thalamus in patients with PVL compared with controls (P < .0001), which also correlated with the severity of PVL (P = .001); 2) significantly decreased FA (P = .003) and increased λ(⊥) (P = .02) in the thalamus overall and increased axial, radial, and mean diffusivities in the pulvinar (P < .03), suggesting injury to afferent and efferent myelinated axons; and 3) a positive correlation of pulvinar abnormalities with those of the parieto-occipital white matter in periventricular leukomalacia, suggesting that the pulvinar abnormalities reflect secondary effects of damaged interconnections between the pulvinar and parieto-occipital cortices in the cognitive visual network. There are volumetric and microstructural abnormalities of the thalamus in preterm children with PVL, very likely reflecting neuronal loss and myelinated axonal injury. The selective microstructural damage in the pulvinar very likely contributes to abnormal cognitive visual processing known to occur in such survivors.

Basic Abnormalities in Visual Processing Affect Face Processing at an Early Age in Autism Spectrum Disorder

A detailed visual processing style has been noted in autism spectrum disorder (ASD); this contributes to problems in face processing and has been directly related to abnormal processing of spatial frequencies (SFs). Little is known about the early development of face processing in ASD and the relation with abnormal SF processing. We investigated whether young ASD children show abnormalities in low spatial frequency (LSF, global) and high spatial frequency (HSF, detailed) processing and explored whether these are crucially involved in the early development of face processing. Three- to 4-year-old children with ASD (n = 22) were compared with developmentally delayed children without ASD (n = 17). Spatial frequency processing was studied by recording visual evoked potentials from visual brain areas while children passively viewed gratings (HSF/LSF). In addition, children watched face stimuli with different expressions, filtered to include only HSF or LSF. Enhanced activity in visual brain areas was found in response to HSF versus LSF information in children with ASD, in contrast to control subjects. Furthermore, facial-expression processing was also primarily driven by detail in ASD. Enhanced visual processing of detailed (HSF) information is present early in ASD and occurs for neutral (gratings), as well as for socially relevant stimuli (facial expressions). These data indicate that there is a general abnormality in visual SF processing in early ASD and are in agreement with suggestions that a fast LSF subcortical face processing route might be affected in ASD. This could suggest that abnormal visual processing is causative in the development of social problems in ASD.

Ophthalmological, cognitive, electrophysiological and MRI assessment of visual processing in preterm children without major neuromotor impairment

Many studies report chronic deficits in visual processing in children born preterm. We investigated whether functional abnormalities in visual processing exist in children born preterm but without major neuromotor impairment (i.e. cerebral palsy). Twelve such children (< 33 weeks gestation or birthweight < 1000 g) without major neuromotor impairment and 12 born full-term controls were assessed at 8-12 years of age by means of ophthalmological assessment (visual acuity, colour vision, stereopsis, stereoacuity, visual fields, ocular motility, motor fusion), cognitive tests of visual-motor, visual-perceptual and visual-spatial skills and pattern-reversal visual evoked potentials (PR-VEPs). All participants also underwent magnetic resonance imaging (MRI) of the brain and neuromotor assessments. No significant differences were found between the groups on the ophthalmological, visual cognitive, neurological, neuromotor or MRI measures. The P100 component of the PR-VEP showed a significantly shorter latency in the preterm compared with the full-term participants. Whilst this P100 finding suggests that subtle abnormalities may exist at the neurophysiological level, we conclude that visual dysfunction is not systematically associated with preterm birth in the context of normal neurological status.

P.3.a.010 Visual processing abnormalities as biomarker for schizophrenia: an EEG study in the schizophrenia spectrum

P.3.a.010 Visual processing abnormalities as biomarker for schizophrenia: an EEG study in the schizophrenia spectrum

Magnocellular visual evoked potential delay with high autism spectrum quotient yields a neural mechanism for altered perception

Everyone has autistic characteristics to a greater or lesser degree, encapsulated in the Autism Spectrum Quotient, a scale that measures the degree to which an adult of normal intelligence displays traits associated with autism spectrum disorders. Recent psychophysical analyses of autism spectrum disorders point to superior local processing, and impaired or ignored global and contextual processing. The aim of this study was to test whether low- and high-scoring individuals on the Autism Spectrum Quotient differ on a measure of local and global processing, motion processing and visual pathway integrity. Fifteen low-scoring individuals and 14 high-scoring individuals derived from a normal population participated in the study. The results indicate that the initial cortical response to the magnocellular afferents is weaker at low contrast in the high autistic tendency group and that a second-order response, reflecting magnocellular activity, demonstrated a delay for high versus low scorers when the parvocellular pathway was also active in response to a high contrast stimulus. High-scoring individuals also demonstrated difficulty in identifying the global components of locally salient hierarchical Navon figures. Furthermore, cross-validated discriminant analysis, using four physiologically and three psychophysically derived parameters, correctly classified 83% of individuals who scored either high or low on the Autism Spectrum Quotient. These findings in the group scoring high on the Autism Spectrum Quotient indicate that a delay in primary visual/prestriate cortical processing of magnocellular input diminishes the advantage of its early arrival to primary visual cortex. This appears to be associated with impaired global visual perception, predicting with high accuracy behavioural tendencies associated with autism spectrum disorders. It has been proposed that perceptual impairment in autism may be attributed to a dysfunction of horizontal connections within early visual areas, presumably parvocellular in nature. However, the timing of such form processing aberrations is much later than the timing of abnormal magnocellular visual processing measured directly here. Thus it is proposed that a magnocellular processing delay decreases the ability of autistic individuals to benefit perceptually from feedback normally associated with the magnocellular advantage.

Center-Surround Visual Motion Processing in Migraine

It has been proposed that reduced cortical inhibition might be a key feature of migraine. Here the authors compared migraine and control group performance for two visual motion tasks in which performance was considered to reflect center-surround inhibitory processes. These tasks use the observations that healthy young observers require longer stimulus durations to detect the direction of motion of larger higher contrast stimuli, and these stimuli also elicit weaker motion aftereffect (MAE) strength. Both observations are considered to arise from center-surround inhibition. The authors measured stimulus duration thresholds for detecting the direction of motion of stimuli of different sizes and contrasts, and also examined motion aftereffect strength for similar stimuli presented for longer durations in 20 control participants and 30 people with migraine (15 with aura). The migraine group was assessed between migraines while they were asymptomatic. For the motion direction task, a significant interaction existed between experimental group and contrast for large stimuli (F((3.96, 190.01)) = 2.95; P < 0.05); however, the interaction was in the opposite direction from that expected from reduced inhibition. Similarly, the MAE data demonstrated a significant interaction between stimulus size and group, but it was in the opposite direction from that predicted (F((1, 48)) = 4.13; P < 0.05). Consistent with previous studies, the migraine group in this study demonstrated abnormal visual motion processing. However, the data from both the motion direction detection and the motion aftereffect tasks do not support a theory of reduced cortical inhibition.

Impaired identity recognition of faces with emotional expressions in body dysmorphic disorder

Individuals with body dysmorphic disorder (BDD) are preoccupied with perceived physical defects or flaws, often facial features, which may be due to distorted perception. Previous studies have demonstrated abnormalities in visual processing of faces and figures, and misinterpretations of emotional expressions. The objective of this study was to determine in BDD how viewing faces with emotional expressions affects perception on an identity-matching task. Twelve BDD subjects and 11 healthy controls matched identities of faces with emotional expressions, neutral expressions, and a control task of ovals and circles. The BDD group made twice as many errors relative to controls for identity-matching of faces with emotional expressions but not for neutral faces or ovals/circles. Mean reaction times were slower for the BDD relative to the control group for emotional faces in general, but there was no effect of specific emotion type. These data suggest that individuals with BDD have abnormalities in facial identification for faces with emotional expressions. This could reflect fundamental abnormalities in visual information processing that are more pronounced for emotional expressions in general, and may relate to their perceptual disturbances.

Inverted face processing in body dysmorphic disorder

Individuals with body dysmorphic disorder (BDD) are preoccupied with perceived defects in appearance. Preliminary evidence suggests abnormalities in global and local visual information processing. The objective of this study was to compare global and local processing in BDD subjects and healthy controls by testing the face inversion effect, in which inverted (upside–down) faces are recognized more slowly and less accurately relative to upright faces. Eighteen medication-free subjects with BDD and 17 matched, healthy controls performed a recognition task with sets of upright and inverted faces on a computer screen that were either presented for short duration (500 ms) or long duration (5000 ms). Response time and accuracy rates were analyzed using linear and logistic mixed effects models, respectively. Results indicated that the inversion effect for response time was smaller in BDD subjects than controls during the long duration stimuli, but was not significantly different during the short duration stimuli. Inversion effect on accuracy rates did not differ significantly between groups during either of the two durations. Lesser inversion effect in BDD subjects may be due to greater detail-oriented and piecemeal processing for long duration stimuli. Similar results between groups for short duration stimuli suggest that they may be normally engaging configural and holistic processing for brief presentations. Abnormal visual information processing in BDD may contribute to distorted perception of appearance; this may not be limited to their own faces, but to others’ faces as well.

Abnormalities of Visual Processing and Frontostriatal Systems in Body Dysmorphic Disorder

Body dysmorphic disorder (BDD) is a psychiatric disorder in which individuals are preoccupied with perceived defects in their appearance, often related to their face. Little is known about its pathophysiology, although early research provides evidence of abnormal visual processing. To determine whether patients with BDD have abnormal patterns of brain activation when visually processing their own face with high, low, or normal spatial resolution. Case-control study. A university hospital. Seventeen right-handed medication-free subjects with BDD and 16 matched healthy control subjects. Intervention Functional magnetic resonance imaging while viewing photographs of face stimuli. Stimuli were neutral-expression photographs of the patient's own face and a familiar face (control stimuli) that were unaltered, altered to include only high spatial frequency (fine spatial resolution), or altered to include only low spatial frequency (low spatial resolution). Blood oxygen level-dependent signal changes in the BDD and control groups during each stimulus type. Subjects with BDD showed relative hyperactivity in the left orbitofrontal cortex and bilateral head of the caudate for the unaltered own-face vs familiar-face condition. They showed relative hypoactivity in the left occipital cortex for the low spatial frequency faces. Differences in activity in frontostriatal systems but not visual cortex covaried with aversiveness ratings of the faces. Severity of BDD symptoms correlated with activity in frontostriatal systems and visual cortex. These results suggest abnormalities in visual processing and frontostriatal systems in BDD. Hypoactivation in the occipital cortex for low spatial frequency faces may indicate either primary visual system abnormalities for configural face elements or top-down modulation of visual processing. Frontostriatal hyperactivity may be associated both with aversion and with symptoms of obsessive thoughts and compulsive behaviors.

Early-stage visual processing abnormalities in high-functioning autism spectrum disorder (ASD)

It has been reported that individuals with autism spectrum disorder (ASD) have abnormal responses to the sensory environment. For these individuals sensory overload can impair functioning, raise physiological stress, and adversely affect social interaction. Early-stage (i.e. within 200ms of stimulus onset) auditory processing abnormalities have been widely examined in ASD using event-related potentials (ERP), while ERP studies investigating early-stage visual processing in ASD are less frequent. We wanted to test the hypothesis of early-stage visual processing abnormalities in ASD by investigating ERPs elicited in a visual oddball task using illusory figures. Our results indicate that individuals with ASD have abnormally large cortical responses to task irrelevant stimuli over both parieto-occipital and frontal regions-of-interest (ROI) during early stages of visual processing compared to the control group. Furthermore, ASD patients showed signs of an overall disruption in stimulus discrimination, and had a significantly higher rate of motor response errors.

PW01-173 - Object visual processing in body dysmorphic disorder

IntroductionBody dysmorphic disorder (BDD) is characterized by a preoccupation with misperceived defects in appearance. Neuropsychological studies and neuroimaging studies of face perception suggests visual processing abnormalities in individuals with BDD, which may involve focus on details at the expense of configural elements.ObjectiveThe objective of the current functional magnetic resonance imaging (fMRI) study was to determine whether individuals with BDD have abnormal patterns of brain activation when visually processing non-face objects (houses).MethodsFourteen medication-free subjects with BDD and fourteen matched healthy controls engaged in a matching task of photographs of houses that werea)unaltered,b)high spatial frequency (high detail elements only), orc)low spatial frequency (low detail elements only).The main outcome measure was group differences in blood oxygen level-dependent fMRI signal changes.ResultsBDD subjects demonstrated lesser activity relative to controls in left parahippocampal gyrus, left lingual gyrus, and bilateral precuneus for low spatial frequency images and relatively greater activity in the frontal pole, left superior frontal gyrus, bilateral anterior cingulate gyrus, and bilateral paracingulate gyrus for high spatial frequency images (Figure 1).ConclusionsIndividuals with BDD have abnormal brain activation patterns when viewing houses for both detailed and configural/holistic visual elements. These results suggest general abnormalities in higher- and lower-order visual processing in individuals with BDD, beyond that for appearance-related stimuli.