Motion Perception In Schizophrenia Research Articles

Oscillatory Activities in Multiple Frequency Bands in Patients with Schizophrenia During Motion Perception.

Patients with schizophrenia show impairment in binding stimulus features into coherent objects, which are reflected in disturbed oscillatory activities. This study aimed to identify disturbances in multiple oscillatory bands during perceptual organization of motion perception in patients with schizophrenia. EEG was recorded from healthy controls and patients with schizophrenia during continuous presentation of a motion stimulus which induces reversals between two exogenously generated perceptions. This stimulus was used to investigate differences in motion binding processes between healthy controls and patients with schizophrenia. EEG signals were transformed into frequency components by means of the Morlet wavelet transformation in order to analyse inter-trial coherences (ITC) in the delta (1-4 Hz), theta (4-7 Hz), alpha (8-12 Hz), and gamma (28-48 Hz) frequency bands during exogenous motion binding. Patients showed decreased delta-ITC in occipital and theta-ITC in central and parietal areas, while no significant differences were found for neither alpha nor gamma-ITCs. The present study provides one of the first insights on the oscillatory synchronizations related with the motion perception in schizophrenia. The ITC differences revealed alterations in the consistency of large-scale integration and transfer functions in patients with schizophrenia.

Impaired Motion Processing in Schizophrenia and the Attenuated Psychosis Syndrome: Etiological and Clinical Implications.

The ability to perceive the motion of biological objects, such as faces, is a critical component of daily function and correlates with the ability to successfully navigate social situations (social cognition). Deficits in motion perception in schizophrenia were first demonstrated about 20 years ago but remain understudied, especially in the early, potentially prodromal, stages of the illness. The authors examined the neural bases of visual sensory processing impairments, including motion, in patients with schizophrenia (N=63) and attenuated psychosis (clinical high risk) (N=32) compared with age-matched healthy control subjects (N=67). Electrophysiological recordings during stimulus and motion processing were analyzed using oscillatory (time frequency) approaches that differentiated motion-onset-evoked activity from stimulus-onset sensory-evoked responses. These were compared with functional MRI (fMRI) measures of motion processing. Significant deficits in motion processing were observed across the two patient groups, and these deficits predicted impairments in both face-emotion recognition and cognitive function. In contrast to motion processing, sensory-evoked stimulus-onset responses were intact in patients with attenuated psychosis, and, further, the relative deficit in motion-onset responses compared with stimulus-onset responses predicted transition to schizophrenia. In patients with schizophrenia, motion detection deficits mapped to impaired activation in motion-sensitive visual cortex during fMRI. Additional visual impairments in patients with schizophrenia, not present in patients with attenuated psychosis, implicated other visual regions, including the middle occipital gyrus and pulvinar thalamic nucleus. The study findings emphasize the importance of sensory-level visual dysfunction in the etiology of schizophrenia and in the personal experience of individuals with the disorder and demonstrate that motion-processing deficits may predate illness onset and contribute to impaired function even in patients with attenuated psychosis.

Seeing the World as it is: Mimicking Veridical Motion Perception in Schizophrenia Using Non-invasive Brain Stimulation in Healthy Participants

Schizophrenia (Sz) is a mental health disorder characterized by severe cognitive, emotional, social, and perceptual deficits. Visual deficits are found in tasks relying on the magnocellular/dorsal stream. In our first experiment we established deficits in global motion processing in Sz patients compared to healthy controls. We used a novel task in which background optic flow produces a distortion of the apparent trajectory of a moving stimulus, leading control participants to provide biased estimates of the true motion trajectory under conditions of global stimulation. Sz patients were significantly less affected by the global background motion, and reported trajectories that were more veridically accurate than those of controls. In order to study the mechanism of this effect, we performed a second experiment where we applied transcranial electrical stimulation over area MT+ to selectively modify global motion processing of optic flow displays in healthy participants. Cathodal and high frequency random noise stimulation had opposite effects on trajectory perception in optic flow. The brain stimulation over a control site and in a control task revealed that the effect of stimulation was specific for global motion processing in area MT+. These findings both support prior studies of impaired early visual processing in Sz and provide novel approaches for measurement and manipulation of the underlying circuits.

Seeing the world as it is: veridical motion perception in schizophrenia and effects of non-invasive transcranial electric stimulation

Seeing the world as it is: veridical motion perception in schizophrenia and effects of non-invasive transcranial electric stimulation

The neurophysiology of biological motion perception in schizophrenia.

IntroductionThe ability to recognize human biological motion is a fundamental aspect of social cognition that is impaired in people with schizophrenia. However, little is known about the neural substrates of impaired biological motion perception in schizophrenia. In the current study, we assessed event-related potentials (ERPs) to human and nonhuman movement in schizophrenia.MethodsTwenty-four subjects with schizophrenia and 18 healthy controls completed a biological motion task while their electroencephalography (EEG) was simultaneously recorded. Subjects watched clips of point-light animations containing 100%, 85%, or 70% biological motion, and were asked to decide whether the clip resembled human or nonhuman movement. Three ERPs were examined: P1, N1, and the late positive potential (LPP).ResultsBehaviorally, schizophrenia subjects identified significantly fewer stimuli as human movement compared to healthy controls in the 100% and 85% conditions. At the neural level, P1 was reduced in the schizophrenia group but did not differ among conditions in either group. There were no group differences in N1 but both groups had the largest N1 in the 70% condition. There was a condition × group interaction for the LPP: Healthy controls had a larger LPP to 100% versus 85% and 70% biological motion; there was no difference among conditions in schizophrenia subjects.ConclusionsConsistent with previous findings, schizophrenia subjects were impaired in their ability to recognize biological motion. The EEG results showed that biological motion did not influence the earliest stage of visual processing (P1). Although schizophrenia subjects showed the same pattern of N1 results relative to healthy controls, they were impaired at a later stage (LPP), reflecting a dysfunction in the identification of human form in biological versus nonbiological motion stimuli.

Visual processing and social cognition in schizophrenia: Relationships among eye movements, biological motion perception, and empathy

Schizophrenia patients have impairments at several levels of cognition including visual attention (eye movements), perception, and social cognition. However, it remains unclear how lower-level cognitive deficits influence higher-level cognition. To elucidate the hierarchical path linking deficient cognitions, we focused on biological motion perception, which is involved in both the early stage of visual perception (attention) and higher social cognition, and is impaired in schizophrenia. Seventeen schizophrenia patients and 18 healthy controls participated in the study. Using point-light walker stimuli, we examined eye movements during biological motion perception in schizophrenia. We assessed relationships among eye movements, biological motion perception and empathy. In the biological motion detection task, schizophrenia patients showed lower accuracy and fixated longer than healthy controls. As opposed to controls, patients exhibiting longer fixation durations and fewer numbers of fixations demonstrated higher accuracy. Additionally, in the patient group, the correlations between accuracy and affective empathy index and between eye movement index and affective empathy index were significant. The altered gaze patterns in patients indicate that top-down attention compensates for impaired bottom-up attention. Furthermore, aberrant eye movements might lead to deficits in biological motion perception and finally link to social cognitive impairments. The current findings merit further investigation for understanding the mechanism of social cognitive training and its development.

An asymmetry of translational biological motion perception in schizophrenia

Background: Biological motion perception is served by a network of regions in the occipital, posterior temporal, and parietal lobe, overlapping areas of reduced cortical volume in schizophrenia. The atrophy in these regions is assumed to account for deficits in biological motion perception described in schizophrenia but it is unknown whether the asymmetry of atrophy found in previous studies has a perceptual correlate. Here we look for possible differences in sensitivity to leftward and rightward translation of point-light biological motion in data collected for a previous study and explore its underlying neurobiology using functional imaging.Methods: n = 64 patients with schizophrenia and n = 64 controls performed a task requiring the detection of leftward or rightward biological motion using a standard psychophysical staircase procedure. six control subjects took part in the functional imaging experiment.Results: We found a deficit of leftward but not rightward biological motion (leftward biological motion % accuracy patients = 57.9% ± 14.3; controls = 63.6% ± 11.3 p = 0.01; rightward biological motion patients = 62.7% ± 12.4; controls = 64.1% ± 11.7; p > 0.05). The deficit reflected differences in distribution of leftward and rightward accuracy bias in the two populations. Directional bias correlated with functional outcome as measured by the Role Functioning Scale in the patient group when co-varying for negative symptoms (r = -0.272, p = 0.016). Cortical regions with preferential activation for leftward or rightward translation were identified in both hemispheres suggesting the psychophysical findings could not be accounted for by selective atrophy or functional change in one hemisphere alone.Conclusion: The findings point to translational direction as a novel functional probe to help understand the underlying neural mechanisms of wider cognitive dysfunction in schizophrenia.

Deficient biological motion perception in schizophrenia: results from a motion noise paradigm

Background: Schizophrenia patients exhibit deficient processing of perceptual and cognitive information. However, it is not well-understood how basic perceptual deficits contribute to higher level cognitive problems in this mental disorder. Perception of biological motion, a motion-based cognitive recognition task, relies on both basic visual motion processing and social cognitive processing, thus providing a useful paradigm to evaluate the potentially hierarchical relationship between these two levels of information processing.Methods: In this study, we designed a biological motion paradigm in which basic visual motion signals were manipulated systematically by incorporating different levels of motion noise. We measured the performances of schizophrenia patients (n = 21) and healthy controls (n = 22) in this biological motion perception task, as well as in coherent motion detection, theory of mind, and a widely used biological motion recognition task.Results: Schizophrenia patients performed the biological motion perception task with significantly lower accuracy than healthy controls when perceptual signals were moderately degraded by noise. A more substantial degradation of perceptual signals, through using additional noise, impaired biological motion perception in both groups. Performance levels on biological motion recognition, coherent motion detection and theory of mind tasks were also reduced in patients.Conclusion: The results from the motion-noise biological motion paradigm indicate that in the presence of visual motion noise, the processing of biological motion information in schizophrenia is deficient. Combined with the results of poor basic visual motion perception (coherent motion task) and biological motion recognition, the association between basic motion signals and biological motion perception suggests a need to incorporate the improvement of visual motion perception in social cognitive remediation.

Perceptual training strongly improves visual motion perception in schizophrenia

Schizophrenia patients exhibit perceptual and cognitive deficits, including in visual motion processing. Given that cognitive systems depend upon perceptual inputs, improving patients’ perceptual abilities may be an effective means of cognitive intervention. In healthy people, motion perception can be enhanced through perceptual learning, but it is unknown whether this perceptual plasticity remains in schizophrenia patients. The present study examined the degree to which patients’ performance on visual motion discrimination can be improved, using a perceptual learning procedure. While both schizophrenia patients and healthy controls showed decreased direction discrimination thresholds (improved performance) with training, the magnitude of the improvement was greater in patients (47% improvement) than in controls (21% improvement). Both groups also improved moderately but non-significantly on an untrained task—speed discrimination. The large perceptual training effect in patients on the trained task suggests that perceptual plasticity is robust in schizophrenia and can be applied to develop bottom-up behavioral interventions.

Differential activation patterns of occipital and prefrontal cortices during motion processing: Evidence from normal and schizophrenic brains

Visual motion perception is normally mediated by neural processing in the posterior cortex. Focal damage to the middle temporal area (MT), a posterior extrastriate region, induces motion perception impairment. It is unclear, however, how more broadly distributed cortical dysfunction affects this visual behavior and its neural substrates. Schizophrenia manifests itself in a variety of behavioral and perceptual abnormalities that have proved difficult to understand through a dysfunction of any single brain system. One of these perceptual abnormalities involves impaired motion perception. Motion processing provides an opportunity to clarify the roles of multiple cortical networks in both healthy and schizophrenic brains. Using fMRI, we measured cortical activation while participants performed two visual motion tasks (direction discrimination and speed discrimination) and one nonmotion task (contrast discrimination). Normal controls showed robust cortical activation (BOLD signal changes) in MT during the direction and speed discrimination tasks, documenting primary processing of sensory input in this posterior region. In patients with schizophrenia, cortical activation was significantly reduced in MT and significantly increased in the inferior convexity of the prefrontal cortex, an area that is normally involved in higher level cognitive processing. This shift in cortical responses from posterior to prefrontal regions suggests that motion perception in schizophrenia is associated with both deficient sensory processing and compensatory cognitive processing. Furthermore, this result provides evidence that in the context of broadly distributed cortical dysfunction, the usual functional specificity of the cortex becomes modified, even across the domains of sensory and cognitive processing.

Compromised speed discrimination among schizophrenia patients when viewing smooth pursuit targets

Schizophrenia subjects' smooth pursuit abnormalities may reflect a problem with perception of motion, although evidence comes primarily from reports using stimuli that differ from standard smooth pursuit stimuli (i.e. moving gratings or coherent dots). This study presented schizophrenia and healthy subjects with a forced-choice speed discrimination paradigm using smooth pursuit-like stimuli. The schizophrenia subject's motion processing was impaired, as evidenced by their significantly higher speed discrimination thresholds (a difference that was 1.7 larger for the patient group). Abnormalities of motion perception in schizophrenia, even for simple stimuli, suggest a problem with motion processing in area MT.

Eye movement and visual motion perception in schizophrenia I: Apparent motion evoked smooth pursuit eye movement reveals a hidden dysfunction in smooth pursuit eye movement in schizophrenia

To date, smooth pursuit eye movement in schizophrenia has only been investigated using a target stimulus in continuous motion. However, smooth pursuit can also be evoked by an oscillating jumping dot that appears to be in apparent motion and although there is no continuous motion on the retinal surface this apparently moving stimulus can effortlessly elicit smooth-pursuit eye movement. In the first of two experiments smooth pursuit eye movement was evoked by target stimuli in continuous (real) motion at seven target velocities from 5.0 to 35.0 deg/s, and in a second experiment it was measured in response to an oscillating jumping dot in apparent motion at eight target velocities from 5.0 to 25.0 deg/s in a group with mixed-symptoms in schizophrenia and in a control group. The results of Experiment 1 provided no evidence for a dysfunction in continuous motion evoked smooth pursuit eye movement in the group with schizophrenia. However, following the removal of saccadic eye movements in smooth pursuit, the group with schizophrenia showed significantly lower smooth pursuit eye velocity at target velocities from 20.0 to 35.0 deg/s. The results of Experiment 2 revealed that apparent motion evoked smooth pursuit eye velocity in the group with schizophrenia was significantly lower in comparison with normal observers at all target velocities up to 25.0 deg/s with the inclusion or exclusion of saccadic eye movements. The findings demonstrate that overall smooth pursuit eye movement evoked in response to a continuous (real) motion target in the group with schizophrenia may nevertheless contain a hidden temporal resolution and integration dysfunction that is revealed when smooth pursuit eye movement is evoked in response to an oscillating jumping dot in apparent motion. The findings also demonstrate that normal smooth pursuit eye movement in normal observers can be made to resemble the dysfunctional smooth pursuit eye movement that is naturally found in some people with schizophrenia by using a target stimulus in apparent motion.

Eye movement and visual motion perception in schizophrenia II: global coherent motion as a function of target velocity and stimulus density

Coherent global motion is a compelling illusion of visual motion that is seen as the result of spatially and successively presented stimuli that are, in fact, stationary. In the present study the threshold perception of global coherent motion was measured using random-dot kinematograms in a group of normal observers and a group with mixed symptoms in schizophrenia who also participated in a companion study on smooth pursuit eye movement (Slaghuis et al. in Exp Brain Res, 2007). The velocity of coherent motion target stimuli was produced by varying the spatial step-size (Deltas) between dots to create three target velocities (6.0, 12.0 and 24.0 deg/s) which were measured at three target stimulus densities (100, 200, and 400 dots/deg(2)). A staircase procedure was used to determine the threshold for the number of target dots that was needed to move in the same direction to detect the direction of motion and which were plotted amongst a field of randomly moving visual noise dots. The findings demonstrate that in comparison with normal observers, the threshold for the perception of coherent motion in the group with schizophrenia was significantly higher at the lowest target velocity of 6.0 deg/s but not at target velocities of 12.0 and 24.0 deg/s. Stimulus density was found to have a significant effect on the perception of coherent motion, but it had no differential effect on performance in the groups. An examination of relationships between coherent motion and smooth pursuit eye movement in the companion study (Slaghuis et al. in Exp Brain Res, 2007) revealed significant, negative, correlations between coherent motion and apparent motion smooth pursuit eye velocity at target velocities of 6.0, 12.0 and 24.0 deg/s in the group with schizophrenia, but no such relationship was found in normal observers. It was concluded that the significant reduction in sensitivity for the perception of coherent motion at the lowest target velocity of 6.0 deg/s in the group with schizophrenia is consistent with an impairment in the detection of visual motion at a local level and in parallel for all parts of the image at striate and extrastiate levels of visual processing.

Theory of Mind and Motion Perception in Schizophrenia.

This study investigated the relationship between theory of mind (ToM) deficits and visual perception in patients with schizophrenia (N=52; 17 remitted and unmedicated) compared with healthy controls (N=30). ToM was assessed with the Eyes Test, which asked participants to choose which of 4 words best described the mental state of a person whose eyes were depicted in a photograph. Visual perception was evaluated with form and motion coherence threshold measurements. Results revealed that patients with schizophrenia (both remitted and nonremitted) showed deficits on the Eyes Test and the motion coherence task. ToM dysfunctions were associated with higher motion coherence thresholds and more severe negative symptoms. This suggests that ToM deficits are related to motion perception dysfunctions, which indicates a possible role of motion-sensitive areas in the pathophysiology of schizophrenia.