Impaired Representation of Time in Schizophrenia Is Linked to Positive Symptoms and Cognitive Demand

The Photic Stimulation Has an Impact on the Reproduction of 10 s Intervals Only in Healthy Controls but Not in Patients with Schizophrenia: The EEG Study

Schizophrenia is a mental disorder characterized by both abnormal time perception and atypical relationships with external factors. Here we compare the influence of external photic stimulation on time production between healthy subjects (n = 24) and patients with schizophrenia (n = 22). To delve into neuropsychological mechanisms of such a relationship, the EEG was recorded during variable conditions: during production of 10 s intervals; during photic stimulation of 4, 9, 16, and 25 Hz; and during combinations of these conditions. We found that the higher frequency of photic stimulation influenced the production of time intervals in healthy volunteers, which became significantly longer and were accompanied by corresponding EEG changes. The impact of photic stimulation was absent in patients with schizophrenia. In addition, the time production was characterized by less accuracy and the absence of EEG dynamics typical for healthy controls that included an increase in alpha2 power and envelope frequency. Our findings indicated that the time perception was not adjusted by external factors in patients with schizophrenia and might have involved cognitive and mental processes different from those of healthy volunteers.

It's About Time: The Circadian Network as Time-Keeper for Cognitive Functioning, Locomotor Activity and Mental Health

A variety of organisms including mammals have evolved a 24h, self-sustained timekeeping machinery known as the circadian clock (biological clock), which enables to anticipate, respond, and adapt to environmental influences such as the daily light and dark cycles. Proper functioning of the clock plays a pivotal role in the temporal regulation of a wide range of cellular, physiological, and behavioural processes. The disruption of circadian rhythms was found to be associated with the onset and progression of several pathologies including sleep and mental disorders, cancer, and neurodegeneration. Thus, the role of the circadian clock in health and disease, and its clinical applications, have gained increasing attention, but the exact mechanisms underlying temporal regulation require further work and the integration of evidence from different research fields. In this review, we address the current knowledge regarding the functioning of molecular circuits as generators of circadian rhythms and the essential role of circadian synchrony in a healthy organism. In particular, we discuss the role of circadian regulation in the context of behaviour and cognitive functioning, delineating how the loss of this tight interplay is linked to pathological development with a focus on mental disorders and neurodegeneration. We further describe emerging new aspects on the link between the circadian clock and physical exercise-induced cognitive functioning, and its current usage as circadian activator with a positive impact in delaying the progression of certain pathologies including neurodegeneration and brain-related disorders. Finally, we discuss recent epidemiological evidence pointing to an important role of the circadian clock in mental health.

Dopamine and the interdependency of time perception and reward

Time is a fundamental dimension of our perception of the world and is therefore of critical importance to the organization of human behavior. A corpus of work - including recent optogenetic evidence - implicates striatal dopamine as a crucial factor influencing the perception of time. Another stream of literature implicates dopamine in reward and motivation processes. However, these two domains of research have remained largely separated, despite neurobiological overlap and the apothegmatic notion that "time flies when you're having fun". This article constitutes a review of the literature linking time perception and reward, including neurobiological and behavioral studies. Together, these provide compelling support for the idea that time perception and reward processing interact via a common dopaminergic mechanism.

Impaired memory for temporal context in schizophrenia patients with hallucinations and thought disorganisation

INTRODUCTION

Context processing deficiencies have been established in patients with schizophrenia and it has been proposed that these deficiencies are involved in the formation of positive symptoms.

METHOD

We administered a temporal context discrimination task to 60 schizophrenia patients and 60 healthy individuals. Pictures were presented in two sessions separated by half an hour and the participants were required to remember afterwards whether the pictures had been presented in the first or the second session.

RESULTS

The number of temporal context errors was significantly increased in the patient group. More specifically, it was highly significantly increased in a subgroup of patients presenting hallucinations, while the patients without hallucinations were equivalent to the healthy individuals. Regression analyses revealed that, independently of memory of the pictures themselves, verbal and visual hallucinations, as well as thought disorganisation, were associated with more temporal context errors. In contrast, affective flattening and anhedonia were associated with fewer of these errors.

CONCLUSION

Inability to process or remember the temporal context of production of events might be a mechanism underlying both hallucinations and thought disorganisation.

Time estimation in a case of Tourette's syndrome: Effect of antipsychotic medications

Aims

Dopamine (DA) hyperactivity causes overestimation of time, whereas DA hypoactivity produces its underestimation. DA activity also provides neurochemical substrates pertinent to several psychiatric conditions, such as schizophrenia and Tourette's syndrome. The overestimation of time sometimes exists in patients with Tourette's syndrome, but no reports have addressed time perception in relation to antipsychotic medications which typically act as DA receptor antagonists. We herein report a case of Tourette's syndrome, in which time estimation was differentially affected by risperidone (a DA antagonist) and aripiprazole (a DA partial agonist).

Case

A 27‐year‐old man who suffered from verbal and motor tics was treated with risperidone. His tic symptoms disappeared; however, he began to experience a strange feeling that “time is going too fast.” For example, “people walk more quickly compared to a normal pace.” These complaints were thought to represent underestimation of time. Then, risperidone was switched to oral aripiprazole to optimize DA transmissions, which resulted in the amelioration of these subjective feelings.

Conclusion

Our observations indicate that the underestimation of time may occur in patients with Tourette's syndrome who receive antipsychotic drugs with high DA D₂ receptor blocking potency. This may support the concept that the estimation of time is influenced by DA activity.

Estimation of time in patients with Tourette's syndrome is affected by actions of antipsychotic drugs on dopamine type 2 receptors.

Gesture impairments in schizophrenia are linked to increased movement and prolonged motor planning and execution

Schizophrenia patients present with a variety of impaired nonverbal communication skills. Performance of hand gestures is frequently impaired and associated with ratings of motor abnormalities. However, the impact of motor abnormalities to gesture performance remains unclear. To test the association between quantitative measures of motor behavior and qualitative ratings of gesture performance, we quantified movement parameters semi-automatically in videotaped recordings of gesture assessment. Thirty-one patients with schizophrenia (77.4%), schizophreniform (19.4%) or schizoaffective disorder (3.2%) and 32 healthy controls matched for age, gender and education underwent clinical assessment. Performance of the test of upper limb apraxia (TULIA) was video-taped in all subjects. The videos were analyzed with motion energy analysis software (MEA) to determine motion and time parameters. Patients and controls differed significantly in quantitative gesture performance: patients required more movement and more time to complete the tasks. Differences increased in patients with qualitatively impaired gesture production ratings (p<0.01). Group differences were most pronounced in the pantomime domain, when gestures are performed following verbal instruction. In patients, ratings of motor abnormalities correlated with duration of movement, while behavioral disorganization correlated with the amount of movements during gesture performance. Disorder related motor symptoms, aberrant action observation, planning and monitoring as well as internal clock abnormalities may explain the poor performance of hand gestures in schizophrenia. Quantitative video analysis offers a unique possibility to analyze movement patterns as a direct functional output of the motor system. In the future, it may assist monitoring, staging and prognosis in schizophrenia.

Positive symptoms and time perception in schizophrenia: A meta-analysis

Positive symptoms of schizophrenia may be related to distortions in time perception. To examine this issue, we conducted a meta-analysis to determine whether positive symptoms are associated with deficits in time processing performance. MEDLINE and Web of Science were searched from January 1980 through March 2017, and all related articles and their references were scrutinized to find relevant studies. Studies were selected if they included participants with a diagnosis of schizophrenia, and reported data from behavioral measures of interval timing (e.g. duration discrimination and temporal order judgement). The results indicated that positive symptoms of schizophrenia are related with overestimation of interval timing (i.e., acceleration of the “internal clock”), and suggest that time perception may be associated with psychosis.

Correlations between exploratory eye movement, hallucination, and cortical gray matter volume in people with schizophrenia

BACKGROUND

Widespread cortical gray matter alternations in people with schizophrenia are correlated with both psychotic symptoms and cognitive/behavioral abnormalities, including the impairments of exploratory eye movement (EEM). Particularly, the loss of gray matter density is specifically related to deficits of the responsive search score (RSS) of EEM in schizophrenia. It is unknown, however, whether the schizophrenia-related RSS deficits are associated with certain psychotic symptoms, such as hallucinations.

METHODS

In 33 participants with schizophrenia, the measurement of EEM, assessment of the hallucination severity using Positive and Negative Syndrome Scale (PANSS) and a voxel-based morphometric analysis of cortical gray matter volume (GMV) were conducted to investigate the relationships between the RSS of EEM, symptom severity, and GMV. In 29 matched healthy controls, the measurement of EEM and a voxel-based morphometric analysis of cortical GMV were also conducted to investigate the relationship between the RSS of EEM and GMV.

RESULTS

In participants with schizophrenia, the hallucination severity was significantly negatively correlated with both the RSS and the GMV of a large number of brain regions in the frontal, temporal, parietal, orbitofrontal, calcarine, cingulate, and insular cortices, and rolandic operculum, hippocampus, parahippocampal gyrus, and thalamus. Also in participants with schizophrenia, the RSS was significantly positively correlated with the GMV in the left supplementary motor area (SMA), left superior frontal cortex (SFG), bilateral precentral gyri, bilateral postcentral gyri, and bilateral middle frontal cortices. More importantly, the GMV of the SMA, SFG, and precentral gyrus in the left hemisphere was not only significantly negatively correlated with the hallucination severity but also significantly positively correlated with the RSS. No significant correlation could be revealed between the RSS and the GMV of any brain regions in healthy controls.

CONCLUSIONS

There was a significantly negative association between the hallucination severity and the RSS of EEM, suggesting that the RSS may be a potential biomarker for predicting the hallucination severity of schizophrenia. Also, the GMV of the left SMA, SFG, and precentral gyrus may be the common substrates underlying both hallucination induction and the RSS in people with schizophrenia.

Predictive timing disturbance is a precise marker of schizophrenia

Timing disturbances have being proposed as a key component of schizophrenia pathogenesis. However, the contribution of cognitive impairment to such disorders has not been clarified. Here, we investigated duration estimation and predictive timing in 30 patients with DSM-5 diagnosis of schizophrenia (SZ) compared to 30 healthy controls (HC). Duration estimation was examined in a temporal and colour discrimination task, fully controlled for working memory (WM) and attention requirements, and by more traditional temporal production and temporal bisection tasks. Predictive timing was measured in a temporal and spatial orienting of attention task. Expectations about stimulus onset (temporal condition) or location (spatial condition) were induced by valid and invalid symbolic cues. Results showed that discrimination of temporal and colour stimulus attributes was equally impaired in SZ. This, taken with the positive correlation between temporal bisection performance and neuropsychological measures of WM, indicates that duration estimation impairments in SZ are underpinned by WM dysfunction. Conversely, we found dissociation in temporal and spatial predictive ability in SZ. Unlike controls, patients were selectively unperturbed by events appearing at an unexpected moment in time, though were perturbed by targets appearing at an unexpected location. Moreover, patients were able to generate temporal expectations more implicitly, as their performance was influenced by the predictive nature of the flow of time itself. Our findings shed new light on the debate over the specificity of timing distortions in SZ, providing evidence that predictive timing is a precise marker of SZ, more sensitive than duration estimation, serving as a valid heuristic for studying the pathophysiology of the disorder.

Dopamine, time perception, and future time perspective

RATIONALE

Impairment in time perception, a critical component of decision-making, represents a risk factor for psychiatric conditions including substance abuse. A therapeutic that ameliorates this impairment could be advantageous in the treatment of impulsivity and decision-making disorders.

OBJECTIVES

Here we hypothesize that the catechol-O-methyltransferase (COMT) inhibitor tolcapone, which increases dopamine tone in frontal cortex (Ceravolo et al Synapse 43:201-207, 2002), improves time perception, with predictive behavioral, genetic, and neurobiological components.

METHODS

Subjects (n = 66) completed a duration estimation task and other behavioral testing in each of two sessions after receiving a single oral dose of tolcapone (200 mg) or placebo in randomized, double-blind, counterbalanced, crossover fashion. Resting state fMRI data were obtained in a subset of subjects (n = 40). Subjects were also genotyped for the COMT (rs4680) polymorphism.

RESULTS

Time perception was significantly improved across four proximal time points ranging from 5 to 60 s (T(524) = 2.04, p = 0.042). The degree of this improvement positively correlated with subjective measures of stress, depression, and alcohol consumption and was most robust in carriers of the COMT Val158 allele. Using seed regions defined by a previous meta-analysis (Wiener et al Neuroimage 49:1728-1740, 2010), we found not only that a connection from right inferior frontal gyrus (RIFG) to right putamen decreases in strength on tolcapone versus placebo (p < 0.05, corrected), but also that the strength of this decrease correlates inversely with the increase in duration estimation on tolcapone versus placebo (r = - 0.37, p = 0.02).

CONCLUSIONS

Compressed time perception can be ameliorated by administration of tolcapone. Additional studies should be conducted to determine whether COMT inhibitors may be effective in treating decision-making disorders and addictive behaviors.

Meta-analysis of functional magnetic resonance imaging studies of timing and cognitive control in schizophrenia and bipolar disorder: Evidence of a primary time deficit

Schizophrenia (SZ) and Bipolar Disorder (BD) are associated with deficits in both timing and cognitive control functions. However, the underlying neurological dysfunctions remain poorly understood. The main goal of this study was to identify brain structures activated both by increases in cognitive activity and during timing tasks in patients with SZ and BD relative to controls. We conducted two signed differential mapping (SDM) meta-analyses of functional magnetic resonance imaging studies assessing the brain response to increasing levels of cognitive difficulty: one concerned SZ, and the other BD patients. We conducted a similar SDM meta-analysis on neuroimaging of timing in SZ (no studies in BD could be included). Finally, we carried out a multimodal meta-analysis to identify common brain regions in the findings of the two previous meta-analyses. We found that SZ patients showed hypoactivation in timing-related cortical-subcortical areas. The dysfunction observed during timing partially coincided with deficits for cognitive control functions. We hypothesize that a dysfunctional temporal/cognitive control network underlies the persistent cognitive impairment observed in SZ.

Sleep state misperception in schizophrenia: Are negative symptoms at work?

OBJECTIVE

This study investigates subjective and objective sleep quality to ascertain whether there is a sleep state misperception in schizophrenia patients, as well as analyze potential effect factors.

METHODS

A total of 148 inpatients with schizophrenia admitted to Beijing HuiLongGuan Hospital were enrolled in this study. The quality of objective sleep was assessed by polysomnography (PSG). On the second day after the successful completion of the PSG evaluation, an interview was arranged to collect patients' recorded subjective evaluation on sleep time, sleep latency, and wake times. Demographic information was collected from an interview, medical records were reviewed, and psychiatric symptoms were assessed using the Positive And Negative Symptom Scale (PANSS).

RESULTS

The main finding of this study was that schizophrenic patients exhibited sleep state misperception with a pattern of overestimation of total sleep time (TST) as well as sleep efficiency (SE), and an underestimation of sleep onset latency (SOL). Regarding the ±standard deviation of the differences between subjective and objective TST as a clinical acceptable range, the patients were divided into three groups: the overestimate group, the normal group, and the underestimate group. The differences of total PANSS score, especially the PANSS-N score in the overestimate group, the normal group and the underestimate group were significant, and there were significant differences between the overestimate group and the other groups.

CONCLUSION

A comprehensive evaluation of the subjective and objective sleep quality in patients with schizophrenia is needed, especially when negative symptoms are severe.

Explicit Time Deficit in Schizophrenia: Systematic Review and Meta-Analysis Indicate It Is Primary and Not Domain Specific

Although timing deficits are a robust finding in schizophrenia (SZ), the notion of a genuine time perception disorder in SZ is still being debated because distortions in timing might depend on neuropsychological deficits that are characteristics of the illness. Here we used meta-analytic methods to summarize the evidence of timing deficits in SZ and moderator analyses to determine whether defective timing in SZ arises from nontemporal sources or from defective time perception. PubMed Services, PsycNET, and Scopus were searched through March 2015, and all references in articles were investigated to find other relevant studies. Studies were selected if they included subjects with a primary diagnosis of SZ compared to a healthy control (HC) group and if they reported behavioral measures of duration estimation (perceptual and motor explicit timing). Data from 24 studies published from 1956 to 2015, which comprised 747 SZ individuals and 808 HC, were included. Results indicate that SZ individuals are less accurate than HC in estimating time duration across a wide range of tasks. Subgroup analyses showed that the fundamental timing deficit in SZ is independent from the length of the to-be-timed duration (automatic and cognitively controlled timing) and from methods of stimuli estimation (perceptual and motor timing). Thus, time perception per se is disturbed in SZ (not just task-specific timing processes) and this perturbation is independent from more generalized cognitive impairments. Behavioral evidence of disturbed automatic timing should be more thoroughly investigated with the aim of defining it as a cognitive phenotype for more homogeneous diagnostic subgrouping.

Psychopathology of Lived Time: Abnormal Time Experience in Persons With Schizophrenia

Abnormal time experience (ATE) in schizophrenia is a long-standing theme of phenomenological psychopathology. This is because temporality constitutes the bedrock of any experience and its integrity is fundamental for the sense of coherence and continuity of selfhood and personal identity. To characterize ATE in schizophrenia patients as compared to major depressives we interviewed, in a clinical setting over a period of 15 years, 550 consecutive patients affected by schizophrenic and affective disorders. Clinical files were analyzed by means of Consensual Qualitative Research (CQR), an inductive method suited to research that requires rich descriptions of inner experiences. Of the whole sample, 109 persons affected by schizophrenic (n = 95 acute, n = 14 chronic) and 37 by major depression reported at least 1 ATE. ATE are more represented in acute (N = 109 out of 198; 55%) than in chronic schizophrenic patients (N = 14 out of 103; 13%). The main feature of ATE in people with schizophrenia is the fragmentation of time experience (71 out of 109 patients), an impairment of the automatic and prereflexive synthesis of primal impression-retention-protention. This includes 4 subcategories: disruption of time flowing, déjà vu/vecu, premonitions about oneself and the external world. We contrasted ATE in schizophrenia and in major depression, finding relevant differences: in major depressives there is no disarticulation of time experience, rather timelessness because time lacks duration, not articulation. These core features of the schizophrenic pheno-phenotype may be related to self-disorders and to the manifold of characteristic schizophrenic symptoms, including so called bizarre delusions and verbal-acoustic hallucinations.

Losing track of time through delayed body representations

The ability to keep track of time is perceived as crucial in most human societies. However, to lose track of time may also serve an important social role, associated with recreational purpose. To this end a number of social technologies are employed, some of which may relate to a manipulation of time perception through a modulation of body representation. Here, we investigated an influence of real-time or delayed videos of own-body representations on time perception in an experimental setup with virtual mirrors. Seventy participants were asked to either stay in the installation until they thought that a defined time (90 s) had passed, or they were encouraged to stay in the installation as long as they wanted and after exiting were asked to estimate the duration of their stay. Results show that a modulation of body representation by time-delayed representations of the mirror-video displays influenced time perception. Furthermore, these time-delayed conditions were associated with a greater sense of arousal and intoxication. We suggest that feeding in references to the immediate past into working memory could be the underlying mental mechanism mediating the observed modulation of time perception. We argue that such an influence on time perception would probably not only be achieved visually, but might also work with acoustic references to the immediate past (e.g., with music).

Processing of sub- and supra-second intervals in the primate brain results from the calibration of neuronal oscillators via sensory, motor, and feedback processes

The processing of time intervals in the sub- to supra-second range by the brain is critical for the interaction of primates with their surroundings in activities, such as foraging and hunting. For an accurate processing of time intervals by the brain, representation of physical time within neuronal circuits is necessary. I propose that time dimension of the physical surrounding is represented in the brain by different types of neuronal oscillators, generating spikes or spike bursts at regular intervals. The proposed oscillators include the pacemaker neurons, tonic inputs, and synchronized excitation and inhibition of inter-connected neurons. Oscillators, which are built inside various circuits of brain, help to form modular clocks, processing time intervals or other temporal characteristics specific to functions of a circuit. Relative or absolute duration is represented within neuronal oscillators by "neural temporal unit," defined as the interval between regularly occurring spikes or spike bursts. Oscillator output is processed to produce changes in activities of neurons, named frequency modulator neuron, wired within a separate module, represented by the rate of change in frequency, and frequency of activities, proposed to encode time intervals. Inbuilt oscillators are calibrated by (a) feedback processes, (b) input of time intervals resulting from rhythmic external sensory stimulation, and (c) synchronous effects of feedback processes and evoked sensory activity. A single active clock is proposed per circuit, which is calibrated by one or more mechanisms. Multiple calibration mechanisms, inbuilt oscillators, and the presence of modular connections prevent a complete loss of interval timing functions of the brain.