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Perceptual disorders are not part of the diagnosis criteria for schizophrenia. Yet, a considerable amount of work has been conducted, especially on visual perception abnormalities, and there is little doubt that visual perception is altered in patients. There are several reasons why such perturbations are of interest in this pathology. They are observed during the prodromal phase of psychosis, they are related to the pathophysiology (clinical disorganization, disorders of the sense of self), and they are associated with neuronal connectivity disorders. Perturbations occur at different levels of processing and likely affect how patients interact and adapt to their surroundings. The literature has become very large, and here we try to summarize different models that have guided the exploration of perception in patients. We also illustrate several lines of research by showing how perception has been investigated and by discussing the interpretation of the results. In addition to discussing domains such as contrast sensitivity, masking, and visual grouping, we develop more recent fields like processing at the level of the retina, and the timing of perception., (© 2022. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

In this commentary I summarize why I started to study timing in schizophrenia, and why I got interested in non-conscious mechanisms. I emphasize the contrast between the multitude of tiny sensory characteristics that need to be processed, mostly non-consciously, and the stability and continuity we experience subjectively. My work suggests this to be true also for timing. Our studies unveiled some of the mechanisms helping us to ignore the tiny signals that may otherwise disrupt our sense of time continuity, and suggest such disruption may occur in individuals with schizophrenia. Given the link between timing and the sense of self, I propose that further studies on timing may help to connect neurobiology, cognitive and clinical disorders in individuals with schizophrenia, thus helping to develop innovative therapeutics., Competing Interests: Declaration of Competing Interest None., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Background: Retinal dysfunction is widely documented in schizophrenia using flash (fERG) and pattern electroretinograms (PERG), but the role of dopamine transmission has seldom been explored., Methods: We explored the role of dopamine transmission by evaluating the spatial location of retinal anomalies using multifocal ERG (mfERG) in photopic condition and the oscillatory potentials (OPs) extracted from fERG measured in scotopic condition in 29 patients with schizophrenia and 29 healthy controls., Results: With the mfERG, our main results revealed reduced amplitudes in the center of the retina: P1 (p < .005) and N2 amplitudes (p < .01) in the <2° region, N1 (p < .0005) and P1 amplitudes (p < .001) in the 2-5° region and P1 amplitude (p < .05) in the 5-10° region. For OPs, our results showed a decrease in the O1 (p < .005), O2 (p < .005), O3 (p < .05) and overall O1, O2, O3 index amplitudes (p < .005) in patients with schizophrenia., Conclusions: Both the central location of retinal dysfunctions of the mfERG and OPs results could reflect a hypodopaminergic effect in patients with schizophrenia. In future studies, OPs should be considered as a measure to evaluate the hypodopaminergy in patients., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Aim: Psychosis can be preceded by a clinical high risk for psychosis (CHR) and visual anomalies are predictors of transition to psychosis. Visual retinal processing is altered in psychosis, but no study has explored the links between visual symptoms and retinal functions in CHR patients. We report here the case of NR, an antipsychotic-naive young adult with CHR and severe visual symptoms in whom we explored the retinal function., Methods: A flash electroretinogram (fERG) and a pattern electroretinogram (pERG) protocol were conducted and we compared NR results to a group of patients with schizophrenia and a group of healthy controls., Results: Despites an overlap between the measures of NR and the two groups, visual analyses revealed that NR showed increased b-wave implicit time (rod response) compared to the control group and NR's response was at an intermediate level between two subgroups of schizophrenia patients regarding presence or absence of visual hallucinations., Discussion: The relevance of retinal dysfunctions as a marker of vulnerability for psychosis is discussed., (© 2020 John Wiley & Sons Australia, Ltd.)

It has been proposed that agency disorders found in schizophrenia rely on aberrant processing of prediction error. Overreactivity to nonpertinent prediction errors may lead to the attribution of one's own actions to an external source. When applied to perception, this could explain hallucinations. However, experiments in motor control or perception have mainly suggested deficient prediction errors. Using a novel approach based on the manipulation of temporal delays, 23 patients with schizophrenia, 18 patients with bipolar disorder, and 22 healthy participants performed a pointing task with a haptic device that provided haptic feedback without or with delays, which were processed consciously (65 ms) or unconsciously (15 ms). The processing of prediction errors was measured via the adaptation of the hand trajectory, that is, the deceleration in anticipation of the surface, and its modulation as a function of recent history (stable or unstable sensory feedback). Agency was evaluated by measuring the participants' feeling of controlling the device. Only patients with schizophrenia reported a decrease in the feeling of control following subliminally delayed haptic feedback and adapted deceleration durations following subliminally delayed haptic feedback. This effect was correlated with positive symptoms. The overreactivity to subliminal delays was present only when delays occurred repeatedly in an unpredictable way, that is, with a volatile distribution. The results suggest that small temporal uncertainties that should be held as negligible, trigger an aberrant overreactivity which could account for hallucinations and alterations of the patients' conscious feeling of control. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Patients with schizophrenia have altered visual cognition and retinal functions. No studies have explored if retinal anomalies are related to visual cognition and the presence of visual hallucinations (VH). We explored functional responses of the retinal ganglion cells in schizophrenia patients with or without VH and conducted a neuropsychological evaluation to explore the links between cognition and retinal function. The VH+ group showed poorer visual cognition and we found correlations between the amplitudes of the P50 and the N95 waves and visual cognition. Our results provide arguments for a link between retinal dysfunction, impaired visual processing and VH in schizophrenia., (Copyright © 2021. Published by Elsevier B.V.)

The electroretinogram has revealed photoreceptor, bipolar cell, and, in one prior study, retinal ganglion cell (RGC) dysfunction in schizophrenia. The structural abnormalities of the RGC are well documented in schizophrenia and such abnormalities have been associated with visual hallucinations (VH) in neurological disorders. The goals of this study were: 1) to examine the functional responses of photoreceptors and RGC in schizophrenia patients in comparison with healthy controls; and 2) to compare the extent of retinal dysfunction in schizophrenia patients with or without VH. We recorded the flash electroretinogram in scotopic and photopic conditions, and the pattern electroretinogram, in schizophrenia patients (n = 29) and healthy controls (n = 29). Schizophrenia patients were divided in two groups: schizophrenia patients with VH (VH group, n = 12) and schizophrenia patients with auditory hallucinations or no hallucinations (AHNH group, n = 17). Our results replicate previous findings regarding photoreceptor dysfunction in schizophrenia. PERG results showed a significant increase of the P50 implicit time in schizophrenia patients compared with controls (t(55) = 2.1, p < .05, d = 0.55) and a significant increase of the N95 implicit time in schizophrenia patients compared with controls (t(55) = 4.2; p < .001, d = 0.66). We found an increased rod b-wave implicit time (dark-adapted 0.01 ERG) in the VH group compared to the AHNH group and to the control group, which was associated with lifetime VH score. Our results demonstrate a slowing of RGC signaling in schizophrenia patients, which could affect the quality of visual information reaching the visual cortex. The implications of the data for understanding VH in schizophrenia are discussed., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Phenomenologists have provided a detailed description of the disorders of the subjective experience associated with minimal-self disorders in patients with schizophrenia. Those patients report a range of distortions of their conscious experiences, including a sense of inner void, confusion between self and others, and, sometimes, a disruption of the sense of time. These reports have been interpreted as distortion of the first-person perspective and a lack of immersion in the world, associated with a breakdown of the temporal structure of consciousness, and especially a disruption of the sense of time continuity. Further, it has been proposed that these disruptions are based on a difficulty to retain past information and to predict future information, that is, the mechanisms that help to relate events with one another and to reach a sense of time continuity. Experimental psychology results seem to converge to similar conclusions, inasmuch as some results in patients with schizophrenia suggest a deficient ability to predict sequences of events at the millisecond level. Several studies have underlined this convergence. Here we reflect on the limits of both the phenomenological and experimental psychology approaches, and of the convergence of their hypotheses. We think that this reflection is necessary to avoid premature conclusions on the mechanisms underlying the impairments in patients, but also to enrich our understanding of schizophrenia., (© 2019 The Institute of Psychology, Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.)

Recent psychiatric research and treatment initiatives have tended to move away from traditional diagnostic categories and have focused instead on transdiagnostic phenomena, such as hallucinations. However, this emphasis on isolated experiences may artificially limit the definition of such phenomena and ignore the rich, complex, and dynamic changes occurring simultaneously in other domains of experience. This article reviews the literature on a range of experiential features associated with psychosis, with a focus on their relevance for hallucinations. Phenomenological research on changes in cognition, perception, selfhood and reality, temporality, interpersonal experience, and embodiment are discussed, along with their implications for traditional conceptualizations of hallucinations. We then discuss several phenomenological and neurocognitive theories, as well as the potential impact of trauma on these phenomena. Hallucinations are suggested to be an equifinal outcome of multiple genetic, neurocognitive, subjective, and social processes; by grouping them together under a single, operationalizable definition, meaningful differences in etiology and phenomenology may be ignored. It is suggested that future research efforts strive to incorporate a broader range of experiential alterations, potentially expanding on traditional definitions of hallucinations. Relevance for clinical practice, including emphasizing phenomenologically responsive techniques and developing targeted new therapies, is discussed.

Patients with schizophrenia have difficulty in making sensory predictions, in the time domain, which have been proposed to be related to self-disorders. However experimental evidence is lacking. We examined both voluntary and automatic forms of temporal prediction in 28 patients and 24 matched controls. A visual cue predicted (temporal cue) or not (neutral cue) the time (400 ms/1000 ms) at which a subsequent target was presented. In both patients and controls, RTs were faster for targets presented after long versus short intervals due to the temporal predictability inherent in the elapse of time ("hazard function"). This RT benefit was correlated with scores on the EASE scale, which measures disorders of the self: patients with a high 'self-awareness and presence' score did not show any significant benefit of the hazard function, whereas this ability was preserved in patients with a low score. Moreover, all patients were abnormally sensitive to the presence of "catch" trials (unexpected absence of a target) within a testing block, with RTs actually becoming slower at long versus short intervals. These results indicate fragility in patients' ability to continuously extract temporally predictive information from the elapsing interval. This deficit might contribute to perturbations of the minimal self in patients.

In recent decades, embodiment has become an influential concept in psychology and cognitive neuroscience. Embodiment denotes the study of the reciprocal (causal) relationships between mind and body, with the mind not only affecting the body but also vice versa. Embodied cognition comes to the fore in sensorimotor coupling, predictive coding, and nonverbal behavior. Additionally, the embodiment of the mind constitutes the basis of social interaction and communication, as evident in research on nonverbal synchrony and mimicry. These theoretical and empirical developments portend a range of implications for schizophrenia research and treatment. Sensorimotor dysfunctions are closely associated with affective and psychotic psychopathology, leading to altered timing in the processing of stimuli and to disordered appraisals of the environment. Problems of social cognition may be newly viewed as disordered embodied communication. The embodiment perspective suggests novel treatment strategies through psychotherapy and body-oriented interventions, and may ultimately provide biomarkers for diagnosis., (© The Author 2017. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Patients with schizophrenia have often been described as insensitive to nociceptive signals, but objective evidence is sparse. We address this question by combining subjective behavioral and objective neurochemical and neurophysiological measures. The present study involved 21 stabilized and mildly symptomatic patients with schizophrenia and 21 control subjects. We applied electrical stimulations below the pain threshold and assessed sensations of pain and unpleasantness with rating scales, and Somatosensory Evoked Potentials (SEPs/EEG). We also measured attention, two neurochemical stress indices (ACTH/cortisol), and subjective VEPs/EEG responses to visual emotional stimuli. Our results revealed that, subjectively, patients' evaluations do not differ from controls. However, the amplitude of EEG evoked potentials was greater in patients than controls as early as 50 ms after electrical stimulations and beyond one second after visual processing of emotional pictures. Such responses could not be linked to the stress induced by the stimulations, since stress hormone levels were stable. Nor was there a difference between patients and controls in respect of attention performance and tactile sensitivity. Taken together, all indices measured in patients in our study were either heightened or equivalent relative to healthy volunteers.

Goal pursuit is known to be impaired in schizophrenia, but nothing much is known in these patients about unconscious affective processes underlying goal pursuit. Evidence suggests that in healthy individuals positive subliminal cues are taken as a signal that goal pursuit is easy and therefore reduce the effort that is mobilized for goal attainment. Patients with schizophrenia and healthy controls were instructed that a long run of successive correct responses in a visual attention task would entitle them to a reward (the goal to attain). Affective pictures were displayed supraliminally or subliminally during each run and electrophysiological activity was recorded. Patients self-assessed the emotional content of the pictures correctly. However, differences between patients and controls emerged during the goal pursuit task. Healthy controls mobilized less effort for the positive than the neutral subliminal pictures, as suggested by increased error rates and the weaker contingent negative variation (CNV). For the patients, no influence of positive subliminal pictures was found on performance and on the CNV. Similarly the influence of positive pictures was absent or abnormal on components which are usually impaired in patients (fronto-central P2 and N2). In contrast, positive pictures influenced normally the parieto-occipital N2, related to a component of visual attention which has been proposed to be preserved in schizophrenia. The present study indicates the difficulties of patients to modulate effort mobilization during goal pursuit in the presence of positive subliminal cues. The results question the role of cognitive deficits on affective influences., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The ability to order events in time plays a pervasive role in cognitive functions, but has only rarely been explored in patients with schizophrenia. Results we obtained recently suggested that patients have difficulties following events over time. However, this impairment concerned implicit responses at very short asynchronies, and it is not known whether it generalizes to subjective temporal order judgments. Here, we make a direct comparison between temporal order judgments and simultaneity/asynchrony discrimination in the same patients. Two squares were displayed on the screen either simultaneously or with an asynchrony of 24 to 96ms. In one session 20 patients and 20 controls made a temporal order judgment and in the other they discriminated between simultaneous and asynchronous stimuli. Controls recorded similar performances in the two tasks at asynchronies above 50ms, whereas patients displayed a sizeable impairment in temporal order judgment selectively. This impairment occurred in the easiest conditions, with the largest SOAs (Stimulus Onset Asynchronies) and only in the temporal order judgment. The results are the first evidence that patients with schizophrenia have a selective difficulty determining temporal order, even for asynchronies producing a clear perception of asynchrony. This impairment may mediate difficulties engaging oneself in everyday life events., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Patients with schizophrenia experience a loss of temporal continuity or subjective fragmentation along the temporal dimension. Here, we develop the hypothesis that impaired temporal awareness results from a perturbed structuring of events in time-i.e., canonical neural dynamics. To address this, 26 patients and their matched controls took part in two psychophysical studies using desynchronized audiovisual speech. Two tasks were used and compared: first, an identification task testing for multisensory binding impairments in which participants reported what they heard while looking at a speaker's face; in a second task, we tested the perceived simultaneity of the same audiovisual speech stimuli. In both tasks, we used McGurk fusion and combination that are classic ecologically valid multisensory illusions. First, and contrary to previous reports, our results show that patients do not significantly differ from controls in their rate of illusory reports. Second, the illusory reports of patients in the identification task were more sensitive to audiovisual speech desynchronies than those of controls. Third, and surprisingly, patients considered audiovisual speech to be synchronized for longer delays than controls. As such, the temporal tolerance profile observed in a temporal judgement task was less of a predictor for sensory binding in schizophrenia than for that obtained in controls. We interpret our results as an impairment of temporal event structuring in schizophrenia which does not specifically affect sensory binding operations but rather, the explicit access to timing information associated here with audiovisual speech processing. Our findings are discussed in the context of curent neurophysiological frameworks for the binding and the structuring of sensory events in time., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

When two visual stimuli occur within 8 to 17 ms of one another, subjects cannot tell they are asynchronous, yet recent results show they are not processed as simultaneous. Two spatially separate squares were presented at an interval ranging from 0 to 92 ms and remained on the screen until subjects responded. Subjects pressed a right or left response key according to the judged simultaneity/asynchrony of the stimuli. We evaluated the Simon effect, i.e., the tendency to press the key on the same side as the stimulus. We found an effect even when the squares were displayed on opposite sides of the screen, with their onsets separated by less than 20 ms. Controls were biased towards the last stimulus, whereas patients with schizophrenia were biased towards the first. We investigate here whether the results are related to spatial or temporal processing. Using the same paradigm, we explored the impact of spatial grouping by comparing connected vs. unconnected stimuli and manipulating the predictability of the second stimulus location. We tested different groups of mildly symptomatic patients and matched controls in two studies. Under 20 ms, when stimuli were connected and the 2nd square location was predictable, patients tended to press the key to the side of the 1st square, whereas controls displayed the opposite tendency. The results suggest that controls put more emphasis on the last occurring event, but not patients with schizophrenia. This impairment is observed when spatial difficulties are removed, suggesting it is related to time rather than space., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

There is evidence for timing dysfunctions in schizophrenia. However, few studies have evaluated the processing of intervals in the hundreds of milliseconds range, despite their role in the timing of speech, music and movements. This study looked into the prediction and estimation mechanisms for intervals in that time range in individuals with schizophrenia and age-matched neurotypical controls. Specifically, we questioned the capacity of the patients to detect a phase shift that requires the processing of a deviation from 'what should happen when' given prior event regularity. The minimum detectable phase shift was estimated from an adaptive staircase procedure with or without the need for sensorimotor synchronization. Results revealed that patients were significantly impaired relative to controls, at each of the tested inter-onset intervals (IOI=300, 600 and 900ms). A control experiment used the method of repeated interval production to show that both groups performed similarly in the production of target intervals (T=500ms and 1000ms). We conclude that schizophrenia is associated with predictive timing deficits, which cannot be attributed directly to a faster or slower running internal clock., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Patients with schizophrenia display an impaired sense of temporal continuity, and we showed that they judge events as being simultaneous even in case of large onset asynchronies. We check here whether this means a fusion of events in time, or on the contrary, a segregation of events and a deficit in coding time-event structure. Subjects decided whether 2 squares were displayed simultaneously or asynchronously on the screen and gave their response by hitting a left or right response key. The implicit processing of asynchrony was explored by means of the Simon effect, which refers to the finding that manual responses are biased to the side of the stimulus. We checked whether responses were biased to the side of the first or second square, when squares were asynchronous and displayed on opposite sides. Results revealed an enlarged time window in patients irrespective of the squares' position (intra- vs interhemispheric presentation). But for asynchronies eliciting "synchronous" judgments, patients' responses were biased to the side of the first square. In contrast, controls were biased in all cases to the side of the second square. The inverse effects observed below thresholds in patients and controls cannot be attributed to a generalized deficit. In controls, elementary predictive mechanisms would allow anticipation of upcoming events, whereas patients appear to process squares as if isolated rather than following each other. Predictive mechanisms would be impaired in patients, who would rather rely on reactive mechanisms in order to perceive asynchrony.

Schizophrenia has been associated to a distorted time clock. By subtracting contact duration from Inter Response Interval, we report evidence for preserved internal clock in schizophrenia, with normal spontaneous tapping tempo. Contact durations were however increased in patients suggesting a specific problem in the fast integration of incoming haptic feedback with outgoing motor efferences. This integration deficit would emerge at an early phase, since Ultra High Risk patients also revealed abnormal tapping stability. Tactile screens revealed to be a simple and low cost apparatus that may constitute a suitable measuring kit for the characterisation of sensory motor deficits in clinical settings., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Background: Patients with schizophrenia are known to be impaired in masking tasks, but the mechanisms underlying their deficits are still elusive. Our study was intended to examine attentional effects, which have a known impact on masking in healthy volunteers but have only rarely been explored in relation to masking in patients., Methods: We compared focused versus divided attention in 18 control subjects and 18 patients using forward and backward masking tasks. In the conventional masking task, subjects had to locate one target among four possible locations. Presentation of one target allows attention to be focused, in contrast with the divided attention task in which two targets were presented either in the same hemifield or different hemifields., Results: Our results reproduce patients' deficits in forward and backward masking tasks but only when one target is presented. We show that control subjects benefit from focused attention, much more so than patients. Furthermore, patients' performance is identical to that of control subjects in backward masking when targets are presented across hemifields. This performance equalization was checked to ensure it was not due solely to the redundancy of signals (two vs. one). We achieved this by comparing performance when two targets were presented in the same vs. across hemifields, the latter yielding a greater redundancy gain., Conclusions: From the results, it is unlikely that redundancy can account for the whole pattern of results, which suggest instead that attention deficits play a role in backward masking impairments in patients., (Copyright © 2012 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.)

Investigations of memory impairment in schizophrenia have frequently revealed a strategic processing deficit at encoding. The authors studied an early encoding process, refreshing (in this case, thinking of a stimulus that has just-previously been presented), and its impact on recognition memory in schizophrenia. Following simultaneous presentation of three words or a single word in the top, middle, or bottom position of the screen, 25 patients with schizophrenia and 25 control participants saw and read a new word (read condition), or a word presented on the previous screen (repeat condition), or saw a dot indicating that they should think of and say the last word to have appeared in that position (refresh condition). Later, on a surprise test, participants were asked to recognize words seen previously and give a Remember, Know, or Guess response according to whether they recognized each on the basis of conscious recollection, familiarity, or guessing. The cognitive operation of refreshing was impaired in schizophrenia: patients were slower on 1-word trials and less accurate on 3-word trials to refresh a word, and their Remember responses did not benefit from refreshing., (Copyright 2009 APA, all rights reserved.)

Clinical observations suggest that the experience of time phenomenology is disturbed in schizophrenia, possibly originating disorders in dynamic cognitive functions such as language or motor planning. We examined the subjective evaluation of temporal structure using an experimental approach involving judgments of simultaneity of simple, visually presented stimuli. We included a priming procedure, ie, a subthreshold presentation of simultaneous or asynchronous stimuli. This allowed us to evaluate the effects of subthreshold synchrony and to check for bias effects, ie, changes in the criteria used by the subjects to rate the stimuli. Primes were adapted to the responses of the subjects. Bias effects were thus expected to yield a change in the efficiency of the prime and to induce a change in the amplitude of the priming effect. Nineteen outpatients with schizophrenia and their individually matched controls participated in the study. In all tests, patients required longer delays between stimuli to detect that they were asynchronous. In other words, they judged stimuli to be synchronous even when their onset was separated by delays of 100 milliseconds and even more in some cases. These results contrasted with preserved effects of subthreshold synchrony. Our findings argue against the hypothesis that the patients' responses were influenced by biases. We conclude that the subjective evaluation of simultaneity/asynchrony is impaired in schizophrenia, thus leading to impairment in the phenomenology of event-structure coding. The method used in the present study provides a novel approach to the assessment of those disturbances related to time in patients with schizophrenia.

The study attempted to distinguish automatic grouping processes from top-down processes in a visual perceptual task in 30 patients with schizophrenia and 30 matched controls. Participants decided whether 7 figures were all different or whether 2 adjacent figures were identical. The distance between figures was manipulated to produce 3 separated pairs of figures, the targets belonging to either the same pair (within-group trials) or different pairs (between-groups trials). As controls, patients benefited from proximity for grouping. Top-down processes were explored by manipulating the proportion of within-group and between-groups trials in 3 experimental blocks. In patients, response times (RTs) decreased for within-group trials when within-group trials were more frequent, indicating that performance was correctly adapted to the type of block. Unlike controls, however, this RT decrease was not accompanied by a cost for between-groups trials. Ocular movement recordings revealed that controls were able to focus on between-groups regions selectively when between-groups trials were more frequent, whereas patients were unable to do so. The authors suggest that top-down processes allowing the construction of a selective representation of between-groups regions are impaired in patients with schizophrenia., ((c) 2008 APA, all rights reserved)

Many everyday activities depend on the capacity to organize and smoothly execute motor sequences. The authors tested the hypothesis that a sequencing deficit is associated with schizophrenia. They used a new method to distinguish between lower and higher order mechanisms for the impairment. The 1st task involved triggered sequences in which sensory information from 1 movement was the cue for initiation of the following movement. Results showed that the motor sequences were performed as fluently in patients as in controls. The 2nd and 3rd tasks involved sequences in which the entire movement sequence could be preplanned. Patients executed the sequences less fluently than controls but only under the condition where action sequences were required. Furthermore, the patients' fluency deficit increased with sequence complexity. The high discrimination power of Task 3 gave the authors a means to control for a potential psychometric confound involving differential discriminating power and to argue in favor of a specific higher order motor fluency deficit in patients with schizophrenia. It is suggested that basic lower order mechanisms that integrate sensory information with outgoing motor commands are preserved in schizophrenia, whereas higher order integrative mechanisms that are required for the smooth coordination of motor sequences are impaired., ((c) 2007 APA, all rights reserved.)

Objective: During object manipulation, grip force must be adjusted in anticipation of destabilizing load forces to prevent the object from slipping. This study used three gripping tasks to assess whether schizophrenia affects the predictive mechanisms required for the scaling, timing, and/or sequencing of motor actions., Method: Sixteen patients with schizophrenia and 16 comparison subjects matched for age, sex, and educational level 1) lifted objects of various mass and texture (lift task) and 2) used a manipulandum to hit (hit task) or resist (resist task) impacts produced by a collision with a pendulum. For an optimized performance, all tasks demanded a predictive increase in grip force and the timing of external events. The fluid sequencing of finger and hand submovements was required for the lift and the hit tasks but not for the resist task., Results: Patients were impaired in the smooth execution of both the lift and the hit tasks but not in the performance of the resist task. In all three tasks, the scaling of grip force was similar for patients and comparison subjects., Conclusions: Schizophrenia is associated with a specific deficit in the sequencing of motor actions rather than with an overall problem in the predictive control of movement.

We tested the ability of 18 patients with schizophrenia and 18 matched controls to filter non-pertinent information in orientation matching tasks. The non-pertinent information consisted of pictures conveying semantic information. The pertinent information consisted of oriented line-segments drawn inside pictures or was represented by the overall orientation of the picture itself. The results showed that non-pertinent information interfered with performance of control subjects in all tasks. In contrast, non-pertinent information interfered with the performance of patients with schizophrenia to the same extent as that of matched controls only when non-pertinent and pertinent information was physically mingled, but not when they were separated. Yet, patients processed non-pertinent information in all experiments, as shown by reversed interference effects when non-pertinent and pertinent information was physically separated. These results suggest a deficit at linking physically distinct visual information in patients with schizophrenia. Additionally, performance was more impaired in patients with schizophrenia than in control subjects when the amount of displayed information increased. The results suggest the coexistence, and a possible relationship between attentional deficits and impairments at linking distinct visual information in patients with schizophrenia.

Delusions of control in schizophrenia may be due to a deficit in the generation of an efference copy, used to distinguish between self generated and externally imposed changes in the environment. This hypothesis was tested using a framework that differentiated automatic and controlled levels of motor behavior. Subjects resisted collisions that were either self or externally imposed. The grip to load force correlation (response accuracy) and the overall grip force level used (response efficiency) were measured. Controls improved both accuracy and efficiency of their grip force responses in self compared to externally imposed collisions. Patients improved accuracy but not efficiency of motor response. There was no difference between patients with and without delusions of control. These results refute the hypothesis of a perturbed efference copy in patients with delusions of control. We rather propose that schizophrenia globally preserves the automatic level but affects the controlled, more voluntary level of motor behavior., (Copyright 2002 Lippincott Williams & Wilkins.)

Ordering events in time is essential for the understanding of causal relationships between successive events. Incorrect causal links can lead to false beliefs and an altered perception of reality. These symptoms belong to psychosis, which is present in schizophrenia (SZ) spectrum and bipolar (BP) disorder. Experimental results show that patients with SZ have an altered perception of temporal order, while there are no data in patients with BP. We investigated the ability of patients with SZ, BP, and controls to judge the order of stimuli with a 100-ms Stimulus Onset Asynchrony (SOA), and how such large asynchronies facilitate temporal order judgments for small asynchronies. Explicit temporal order effects suggest that patients with SZ perform worse at a long SOA (100 ms) as compared to controls, whereas patients with BP show no difference compared to controls or to patients with SZ. Implicit order effects reveal improved performances in case of identical as compared to different relative order between two successive trials for all groups, with no differences between the groups. We replicated explicit order impairments in patients with SZ compared to controls, while implicit effects appear to be preserved. This difficulty for patients to consciously order stimuli in time might be understood under the light of the loosening-of-associations phenomenon well described in SZ. Further, we showed that patients with BP do not reveal such an explicit order impairment which is consistent with phenomenological descriptions, suggesting a difference in time experience in patients with SZ and BP. [ABSTRACT FROM AUTHOR]

The flow of consciousness is disrupted and disorganized in schizophrenia. We explore the hypothesis that this disruption is related to asynchronies not being predicted in advance and standing out instead of being integrated in the flow of events. We recorded EEG continuously during a simultaneity/asynchrony discrimination task, in which subjects decide whether 2 squares are shown simultaneously or with an asynchrony (asynchronies were between 24 and 96 ms). Behavioral data was obtained in 32 patients with schizophrenia and 27 matched controls, and EEG was recorded in a subset of 17 patients vs 15 controls. Two results suggested a lack of asynchrony prediction in patients. Behavioral difficulties at detecting asynchronies increased in patients with schizophrenia relative to controls after a detection of simultaneity, and this effect was correlated with clinical disorganization. Desynchronization of alpha activity observed before the beginning of a trial was larger after asynchronous than simultaneous responses in controls, but not in patients. EEG signals additionally suggested abnormal sensitivity to short asynchronies in patients. The amplitude of early signals around 180 ms after the first square abnormally increased in patients for short asynchronies relative to perfect simultaneity, whereas EEG signals at parietal regions decreased in amplitude in patients relative to controls, in the 400-600 ms interval after the first square. These results reinforce the hypothesis of time prediction and sequencing impairments at the sub-second level and may provide an explanation for the disruption of the patients' consciousness flow. [ABSTRACT FROM AUTHOR]

Cognitive disorders are considered as a core symptom of schizophrenia. Importantly, episodic autobiographical memory deficits are strongly related to patients' social dysfunction. Although the cognitive mechanisms underlying autobiographical memory deficit are highly important to open the door for specific cognitive remediation, they are yet to be understood. The present study focused on event segmentation to check to which extent possible impairments in temporal ordering and segmenting in patients hinder memories construction. Twenty-seven patients with schizophrenia and 27 matched controls took part in an outdoor circuit while wearing a wearable camera. A week later, their memory and the temporal organization of this event have been assessed. Results showed that patients, compared with control participants, reported a reduced amount of details, especially less actions with interaction related to the event. Contrary to our initial hypotheses, event segmentation abilities in patients were not affected. The relationship between event segmentation and memory is discussed. [ABSTRACT FROM AUTHOR]

Objective: Basic temporal dysfunctions have been described in patients with schizophrenia, which may impact their ability to connect and synchronize with the outer world. The present study was conducted with the aim to distinguish between interval timing and synchronization difficulties and more generally the spatial-temporal organization disturbances for voluntary actions. A new sensorimotor synchronization task was developed to test these abilities. Method: Twenty-four chronic schizophrenia patients matched with 27 controls performed a spatial-tapping task in which finger taps were to be produced in synchrony with a regular metronome to six visual targets presented around a virtual circle on a tactile screen. Isochronous (time intervals of 500 ms) and non-isochronous auditory sequences (alternated time intervals of 300/600 ms) were presented. The capacity to produce time intervals accurately versus the ability to synchronize own actions (tap) with external events (tone) were measured. Results: Patients with schizophrenia were able to produce the tapping patterns of both isochronous and non-isochronous auditory sequences as accurately as controls producing inter-response intervals close to the expected interval of 500 and 900 ms, respectively. However, the synchronization performances revealed significantly more positive asynchrony means (but similar variances) in the patient group than in the control group for both types of auditory sequences. Conclusion: The patterns of results suggest that patients with schizophrenia are able to perceive and produce both simple and complex sequences of time intervals but are impaired in the ability to synchronize their actions with external events. These findings suggest a specific deficit in predictive timing, which may be at the core of early symptoms previously described in schizophrenia. [ABSTRACT FROM AUTHOR]

For years, phenomenological psychiatry has proposed that distortions of the temporal structure of consciousness contribute to the abnormal experiences described before schizophrenia emerges, and may relate to basic disturbances in consciousness of the self. However, considering that temporality refers mainly to an implicit aspect of our relationship with the world, disturbances in the temporal structure of consciousness remain difficult to access. Nonetheless, previous studies have shown a correlation between self disorders and the automatic ability to expect an event in time, suggesting timing is a key issue for the psychopathology of schizophrenia. Timing disorders may represent a target for cognitive remediation, but this requires that disorders can be demonstrated at an individual level. Since cognitive impairments in patients with schizophrenia are discrete, and there is no standardized timing exploration, we focused on timing impairments suggested to be related to self disorders. We present the case report of AF, a 22 year old man suffering from schizophrenia, with no antipsychotic intake. Although AF shows few positive and negative symptoms and has a normal neurocognitive assessment, he shows a high level of disturbance of Minimal Self Disorders (SDs) (assessed with the EASE scale). Moreover, AF has a rare ability to describe his self and time difficulties. An objective assessment of timing ability (variable foreperiod task) confirmed that AF had temporal impairments similar to those previously described in patients, i.e., a preserved ability to distinguish time intervals, but a difficulty to benefit from the passage of time to expect a visual stimulus. He presents additional difficulties in benefitting from temporal cues and adapting to changes in time delays. The impairments were ample enough to yield significant effects with analyses at the individual level. Although causal relationships between subjective and objective impairments cannot be established, the results show that exploring timing deficits at the individual level is possible in patients with schizophrenia. Besides, the results are consistent with hypotheses relating minimal self disorders (SDs) to timing difficulties. They suggest that both subjective and objective timing investigations should be developed further so that their use at an individual level can be generalized in clinical practice. [ABSTRACT FROM AUTHOR]

Disorders of consciousness and the self are at the forefront of schizophrenia symptomatology. Patients are impaired in feeling themselves as the authors of their thoughts and actions. In addition, their flow of consciousness is disrupted, and thought fragmentation has been suggested to be involved in the patients' difficulties in feeling as being one unique, unchanging self across time. Both impairments are related to self disorders, and both have been investigated at the experimental level. Here we review evidence that both mechanisms of motor control and the temporal structure of signal processing are impaired in schizophrenia patients. Based on this review, we propose that the sequencing of action and perception plays a key role in the patients' impairments. Furthermore, the millisecond time scale of the disorders, as well as the impaired sequencing, highlights the cooperation between brain networks including the cerebellum, as proposed by Andreasen (1999). We examine this possibility in the light of recent knowledge on the anatomical and physiological properties of the cerebellum, its role in timing, and its involvement in known physiological impairments in patients with schizophrenia, e.g., resting states and brain dynamics. A disruption in communication between networks involving the cerebellum, related to known impairments in dopamine, glutamate and GABA transmission, may help to better explain why patients experience reduced attunement with the external world and possibly with themselves. [ABSTRACT FROM AUTHOR]

Background: The sense of time continuity appears to be disturbed in pathologies like schizophrenia, associated with a disruption of the sense of self, and of the feeling of being immersed in the world. Prediction mechanisms have been proposed to be involved in the sense of time continuity by helping to relate discontinuous events, and our previous studies have suggested that these mechanisms may occur even at the millisecond level. Such mechanisms would be involved in our ability to interact with the outer world, by helping to follow events accurately in both space and time. We explored prediction mechanisms and attention shifts based on recently experienced sequences of visual information (sequential effects). Methods: 26 patients with schizophrenia and 20 matched controls were included in asynchrony discrimination tasks, and assessments of minimal self disorders with the EASE. On each trial, two stimuli are displayed with varying stimulus onset asynchronies (SOA). Subjects decide whether the stimuli are simultaneous or asynchronous and give manual responses. Sequential effects were explored further in several groups of 15 healthy participants. Results: The main finding in controls is a strong accuracy advantage for different- as compared to same-order trials, but only when trial t is with an SOA slightly larger than trial t-1 (advantage of 16% in accuracy), or equivalent (advantage of 10% in accuracy). An advantage for same-vs. different-order trials is observed only when the SOA on the previous trial is large and visible. In patients, there is no advantage for same-order trials. There is a clear advantage for different-order trials (advantage of 16% in accuracy), but this effect disappears, contrary to controls, when SOAs are equivalent on successive trials (1% difference in accuracy). The impairment in the trial-to-trial effects in patients correlates with minimal self disorders (the EASE). Discussion: Further investigations in healthy participants suggest that the sequential effects can be explained in terms of prediction of stimulus sequences from trial to trial, which are accompanied by an attention shift. The first stimulus triggers the onset of the sequence, and attention is then covertly shifted in space and time according to the previous trial, in order to attend to the second stimulus. This explains the advantage for differentorder trials: when order is reversed on the present trial, attention ends up in the location of the first stimulus of the present sequence. This first stimulus is perceived as isolated on the screen if the second stimulus occurs later than on the previous trial, thus facilitating the detection of an asynchrony. The asynchrony is then obvious, explaining the large amplitude of the effect. The fact that the effect extends to the condition in which SOAs are equivalent on successive trials suggests that participants shift their attention in advance, as if anticipating the location of the second stimulus. This is impaired in patients, who replay sequences of events, but do not anticipate the successive events flexibly. This would impair their immersion in the world, where events rarely happen twice at the same time exactly. [ABSTRACT FROM AUTHOR]

Background Mental states in schizophrenia have been proposed to be fragmented, based on phenomenology and experimental psychology, whereas bipolar disorder would be characterized by racing thoughts and rumination. Here, we explore 'mental states' by analyzing configurations of activated brain regions to calculate how long a given mental state lasts, the variability of mental state durations and the recurrence of a given mental state during a long period of time. We present preliminary data for this new type of analysis in healthy volunteers, in patients with schizophrenia and bipolar disorder. Methods We report on 13 healthy volunteers, 6 patients with bipolar disorder and 10 patients with schizophrenia. All were scanned during 15 minutes of open eyes Resting State using a multiband fMRI protocol (TR = 0.5 sec). Functional MRI data were realigned, normalized and smoothed using SPM software. We then performed a group Independent Component Analysis (ICA) to identify functional networks (Group ICA of fMRI Toolbox - GIFT). We classified manually all components into subcortical, auditory, somatomotor, visual, cognitive control, default mode network (DMN), cerebellum, insular and hippocampal complex networks, and we excluded all noise related components. We obtained a total of 251 networks among those 9 categories. In the first mental state analysis, we considered the pattern of activation of all functional networks for each scan, in other words, at a given moment t we took the value of each independent component into account. In this sense, a specific mental state pattern is considered as a pattern of activation at a moment t. The next step was to perform a correlation of the mental state pattern of the moment t with all the subsequent scans (t+1, t+2 ... t+x). A cutoff of 0.5 in the correlation map was used to define mental state similarity. Based on that correlation map (a 0/1 matrix), we were able to calculate how long a given mental state was lasted, the variance of this duration (mental state variability) and the recurrence of a given pattern of activation (mental state recurrence). In the second mental state analysis, we repeated the same methodology but for each network class to explore if the differences observed in general mental state duration, variability and recurrence are related to specific network classes. Results No difference was observed regarding mental state duration among the different groups. However, we found a significantly higher variability of mental state duration in patients with schizophrenia when compared to both, healthy (p=0.037) and bipolar individuals (p=0.032). The results regarding mental states related to specific networks show a higher duration variability of mental states in schizophrenia for subcortical (p=0.044 compared to controls; p=0.022 compared to Bipolar patients), visual (p=0.049 compared to bipolar patients) and insular (p=0.005 compared to controls) networks. Regarding the recurrence of mental states, we observed a significantly higher recurrence of DMN (p=0.042 compared to schizophrenia patients) and insular (p=0.023 compared to controls) networks in patients with bipolar disorder. Discussion The insular network seems to be involved in both pathologies. In patients with schizophrenia it is characterized by an increased variability, and in patients with bipolar disorder by a higher recurrence of mental states. Results are still preliminary, but it is tempting to interpret the difference in mental state variability observed in schizophrenia patients as a correlate of their subjective mental fragmentation. The increased recurrence of mental states observed in patients with bipolar disorder might be related to the rumination observed in patients. [ABSTRACT FROM AUTHOR]

Background: Previous work suggested that patients with Schizophrenia (SZ) and Bipolar disorder (BP) both show anomalies in temporal cognition, although at different temporal scales. Recent results suggest disruptions in the processing of sensory information in time in SZ at the sub-second scale, including temporal order processing (100s ms). On the other hand, BP patients often report tachypsychia or racing thoughts, a subjective acceleration in the production of thoughts, which points towards temporal anomalies at the (supra-)second scale. Methods: To further investigate the proposed temporal abnormalities which differentially affect the two groups, 11 SZ patients, 14 BP patients and 21 healthy controls (HC) performed two tasks. First, subjects’ ability at ordering events in time was evaluated in a Temporal Order Judgment task. Participants were presented two squares separated by either a subthreshold 17ms or a supra-threshold 100 ms asynchrony, or two squares appearing simultaneously on a computer screen. They were instructed to respond, by clicking on one of two response-buttons, to the side of the first stimulus and their accuracy was recorded. In a second task, subjects were presented the ambiguous Necker cube figure and were instructed to report, via button presses, each time their perception of the figure changed between the two possible interpretations. Two attentional conditions were used: a “Spontaneous” condition where subjects reported perceptual changes that occurred spontaneously (without any attentional control), and a “Focus” condition where subjects were asked to focus on and mentally maintain one of the two interpretations of the figure for as long as possible and switch back to it in case of perceptual reversal. Eye movements and manual responses were recorded during this task and were used to compute two measures: “manual windows” based on subject’s explicit responses and reflecting time intervals of stable percepts of the figure, and “ocular windows” based on ocular fixations and reflecting implicit and automatic alternations between the two interpretations of the figure. The rates and durations of the two “windows” were compared in the two attentional conditions. Results: We present preliminary results. In the Temporal Order Judgment task SZ patients’ accuracy was significantly lower than that of HC for visible 100 ms asynchronies. BP patients’ performance had intermediate values and did not differ from the other groups. For sub-threshold 17 ms asynchronies no significant difference was found between groups. In the Necker cube task, similar rates of “manual windows” were found in all three groups, however there was a tendency towards an increased window duration in the Focus condition in BP patients. The rate of “ocular windows” was significantly higher in BP patients compared to HC and SZ patients, with decreased “ocular window” duration in BP patients compared to HC. BP patients’ rate of “ocular windows” increased mainly in the “Focus” condition. Discussion: The findings in the Temporal Order Judgment task replicate results in the literature showing an impaired temporal order processing in SZ patients for supra-threshold asynchronies at the scale of 100s ms. The results of the Necker cube task suggest that BP patients cannot help oscillating between the two interpretations of the Necker cube. Complementary results obtained in a larger group of BP patients suggest a link with tachypsychia. Our present results support the idea that temporal cognition is altered in both SZ and BP patients but at different temporal scales. [ABSTRACT FROM AUTHOR]

Self-disturbances in schizophrenia include symptoms such as depersonalization, fuzzy demarcation between one's own body and others, feelings of body disintegration or dislocation, the feeling of a distance between oneself and the world, and experiences of time fragmentation or disappearance. These are only a few examples of symptoms related to bodily or 'minimal' self-disturbances, which have been described both in patients with prodromal symptoms and chronic schizophrenia. Contrary to agency disorders, the listed symptoms do not imply voluntary actions, and may occur even when one stands still. They are non-verbal manifestations by definition, and thus hard to describe for the patients. Recent phenomenological developments have nonetheless brought these symptoms back to the forefront. However, compared to the exploration of agency disorders, experimental evidence for disorders of body self-perception is still scarce. The aim of the symposium is to bring together the work of four teams that have independently explored this question with distinct experimental psychology approaches. The sense of bodily self and the ability to see the world from one's own first-person perspective relies on the integration of both interoceptive and exteroceptive information. Being 'immersed in the world', the impression of being in direct contact with the environment, relies on the ability to correctly attribute and integrate information from the outer world relative to oneself, and to synchronize oneself with the environment. It is precisely these abilities that are explored by studying the processing of interoceptive and multisensory information or time prediction, and the sensitivity to asynchronies. Lénie Torregrossa explores interoceptive signals in patients with schizophrenia by looking at their ability to accurately report heartbeats, and to precisely localize emotions in their body. Both abilities are affected in patients, and the results represent a unique insight in the alteration of how patients feel their own body. Anne Giersch explores time disorders and shows behavioral and EEG results suggesting that instead of reaching a sense of time continuity, patients with schizophrenia are abnormally sensitive to short asynchronies. She argues that such difficulties may affect the flow of sensory signals, and thus the bodily self. Neeltje van Haren explores body self-perception disorders using the rubber hand illusion, which is based on visuo-tactile stimulation. Patients report that the rubber hand feels like their own hand more than controls, reflecting the fragility of the patients' body boundaries. Interestingly, agency disorders are explored in parallel, and the results allow for discussion of the relative roles of sensorimotor input vs. the cognitive body representation in sensitivity to the illusion. Roy Salomon induces a feeling of presence experimentally, and shows it affects the ability of first episode patients to distinguish between their own voice and the voice of another person. This deficit correlates with resting-state fMRI dysconnectivity in the cortical systems of bodily self-representations. Voice misattributions have been shown in people with auditory hallucinations, these results thus relate body ownership impairments with agency disorders. The presentations, taking different perspectives, provide complementary descriptions of body self-perception disorders and of their underlying mechanisms. The discussant (Steve Silverstein) will integrate these data on body self-perception disorders in schizophrenia and discuss potential mechanistic interpretations and therapeutic implications. [ABSTRACT FROM AUTHOR]