Meta-Analysis of Functional Neuroimaging and Cognitive Control Studies in Schizophrenia: Preliminary Elucidation of a Core Dysfunctional Timing Network

Time discrimination and change detection could share a common brain network: findings of a task-based fMRI study

Introduction

Over the past few years, several studies have described the brain activation pattern related to both time discrimination (TD) and change detection processes. We hypothesize that both processes share a common brain network which may play a significant role in more complex cognitive processes. The main goal of this proof-of-concept study is to describe the pattern of brain activity involved in TD and oddball detection (OD) paradigms, and in processes requiring higher cognitive effort.

Methods

We designed an experimental task, including an auditory test tool to assess TD and OD paradigms, which was conducted under functional magnetic resonance imaging (fMRI) in 14 healthy participants. We added a cognitive control component into both paradigms in our test tool. We used the general linear model (GLM) to analyze the individual fMRI data images and the random effects model for group inference.

Results

We defined the areas of brain activation related to TD and OD paradigms. We performed a conjunction analysis of contrast TD (task > control) and OD (task > control) patterns, finding both similarities and significant differences between them.

Discussion

We conclude that change detection and other cognitive processes requiring an increase in cognitive effort require participation of overlapping functional and neuroanatomical components, suggesting the presence of a common time and change detection network. This is of particular relevance for future research on normal cognitive functioning in the healthy population, as well as for the study of cognitive impairment and clinical manifestations associated with various neuropsychiatric conditions such as schizophrenia.

Cognitive Deficit in Schizophrenia: From Etiology to Novel Treatments

Schizophrenia is a major mental illness characterized by positive and negative symptoms, and by cognitive deficit. Although cognitive impairment is disabling for patients, it has been largely neglected in the treatment of schizophrenia. There are several reasons for this lack of treatments for cognitive deficit, but the complexity of its etiology-in which neuroanatomic, biochemical and genetic factors concur-has contributed to the lack of effective treatments. In the last few years, there have been several attempts to develop novel drugs for the treatment of cognitive impairment in schizophrenia. Despite these efforts, little progress has been made. The latest findings point to the importance of developing personalized treatments for schizophrenia which enhance neuroplasticity, and of combining pharmacological treatments with non-pharmacological measures.

Formalin-induced pain prolongs sub- to supra-second time estimation in rats

Background

Temporal estimation can be influenced by pain, which is a complex psychological and physiological phenomenon. However, the time range in which perception is most sensitive to pain remains unclear.

Methods

In the present study, we explored the effects of acute inflammatory pain on time perception in the sub- to supra-second (0.6–2.4-s) and supra-second (2–8-s) ranges in rats. Plantar formalin injection was used to induce acute inflammatory pain, and a temporal bisection task was used to measure time perception. Task test sessions were held for five consecutive days (one per day): the day before injection (baseline), immediately after injection, and the three post-injection days. The point of subjective equality (PSE, which reflects the subjective duration) and Weber fraction (which reflects temporal sensitivity) were calculated and analysed.

Results

In the 0.6–2.4-s range, the PSE was significantly lower, indicating prolonged subjective duration, in the formalin group relative to the saline group (p = 0.049) immediately after injection. Formalin-induced pain also tended to lengthened time perception in the 0.6–2.4-s range on post-injection days 2 (p = 0.06) and 3 (p = 0.054). In the 2–8-s range, formalin injection did not affect the PSE or Weber fraction.

Conclusions

The enhanced effect of pain on temporal perception in the sub- to supra-second range is observed in this study and this effect is attenuated with the prolongation of estimated time, even in rats.

An fMRI Study Using a Combined Task of Interval Discrimination and Oddball Could Reveal Common Brain Circuits of Cognitive Change

Recent functional neuroimaging studies suggest that the brain networks responsible for time processing are involved during other cognitive processes, leading to a hypothesis that time-related processing is needed to perform a range of tasks across various cognitive functions. To examine this hypothesis, we analyze whether, in healthy subjects, the brain structures activated or deactivated during performance of timing and oddball-detection type tasks coincide. To this end, we conducted two independent signed differential mapping (SDM) meta-analyses of functional magnetic resonance imaging (fMRI) studies assessing the cerebral generators of the responses elicited by tasks based on timing and oddball-detection paradigms. Finally, we undertook a multimodal meta-analysis to detect brain regions common to the findings of the two previous meta-analyses. We found that healthy subjects showed significant activation in cortical areas related to timing and salience networks. The patterns of activation and deactivation corresponding to each task type partially coincided. We hypothesize that there exists a time and change-detection network that serves as a common underlying resource used in a broad range of cognitive processes.

Neural Correlates of Interval Timing Deficits in Schizophrenia

Previous research has shown that schizophrenia (SZ) patients exhibit impairments in interval timing. The cause of timing impairments in SZ remains unknown but may be explained by a dysfunction in the fronto-striatal circuits. Although the current literature includes extensive behavioral data on timing impairments, there is limited focus on the neural correlates of timing in SZ. The neuroimaging literature included in the current review reports hypoactivation in the dorsal-lateral prefrontal cortex (DLPFC), supplementary motor area (SMA) and the basal ganglia (BG). Timing deficits and deficits in attention and working memory (WM) in SZ are likely due to a dysfunction of dopamine (DA) and gamma-aminobutyric acid (GABA) neurotransmission in the cortico-striatal-thalamo-cortical circuits, which are highly implicated in executive functioning and motor preparation.

Aberrant timing and oddball detection in Schizophrenia: findings from a signed differential mapping meta-analysis

Schizophrenia (SZ) is associated with deficits in both temporal and salience processing. The underlying neurological dysfunctions in both processes, which are interrelated and share neuroanatomical bases, remain poorly understood. The principal objective of this study was to elucidate whether there are any brain regions that show abnormal response during timing and oddball tasks in patients with SZ. To this end, we conducted a signed differential mapping (SDM) meta-analysis of functional magnetic resonance imaging (fMRI) studies assessing abnormal responses elicited by tasks based on the oddball paradigm in patients with SZ. We conducted a similar SDM meta-analysis of neuroimaging studies of timing tasks in SZ. Finally, we undertook a multimodal meta-analysis to detect the common findings of the two previous meta-analyses. We found that SZ patients showed hypoactivation in cortical and subcortical areas related to timing. The dysfunction observed during timing tasks partially coincided with deficiencies in change-detection functions (particularly in the case of preattentional processing in the mismatch negativity response). We hypothesize that a dysfunctional timing/change detection network underlies the cognitive impairment observed in SZ.

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.

Slower Time estimation in Post-Traumatic Stress Disorder

Cognitive deficits in Posttraumatic Stress Disorder (PTSD) and dissociative symptoms suggest there may be an underlying and persistent problem with temporal processing in PTSD, but this question has not been systematically examined. We investigated the ability of a group of PTSD participants in estimating the duration of supra-second visual stimuli relative to healthy controls. The data of 59 participants with PTSD and 62 healthy controls, collected from the BRID database, have been examined. Overall, our results indicate that PTSD patients overestimate the duration of the displayed stimuli. Moreover, we found that PTSD are more variable in the time estimation compared to the control group. Finally, we found evidence that working memory and attention impairments were associated with time overestimation in PTSD. The finding of time overestimation in PTSD accords with previous reports of time overestimation during stressful experiences associated with fear and arousal, but extends findings to suggest it remains in chronic PTSD populations processing non-emotional stimuli. The evidence of time overestimation in PTSD suggests the potential relevance of this factor as a cognitive marker in assessing the neuropsychological profile of this clinical population.

Ten simple rules for neuroimaging meta-analysis

Neuroimaging has evolved into a widely used method to investigate the functional neuroanatomy, brain-behaviour relationships, and pathophysiology of brain disorders, yielding a literature of more than 30,000 papers. With such an explosion of data, it is increasingly difficult to sift through the literature and distinguish spurious from replicable findings. Furthermore, due to the large number of studies, it is challenging to keep track of the wealth of findings. A variety of meta-analytical methods (coordinate-based and image-based) have been developed to help summarise and integrate the vast amount of data arising from neuroimaging studies. However, the field lacks specific guidelines for the conduct of such meta-analyses. Based on our combined experience, we propose best-practice recommendations that researchers from multiple disciplines may find helpful. In addition, we provide specific guidelines and a checklist that will hopefully improve the transparency, traceability, replicability and reporting of meta-analytical results of neuroimaging data.

Electrophysiological correlates of visual backward masking in high schizotypic personality traits participants

Visual backward masking is strongly deteriorated in patients with schizophrenia. Masking deficits are associated with strongly reduced amplitudes of the global field power in the EEG. Healthy participants who scored high in cognitive disorganization (a schizotypic trait) were impaired in backward masking compared to participants who scored low. Here, we show that the global field power is also reduced in healthy participants scoring high (n=25) as compared to low (n=20) in cognitive disorganization, though quantitatively less pronounced than in patients (n=10). These results point to similar mechanisms underlying visual backward masking deficits along the schizophrenia spectrum.

Time perception of simultaneous and sequential events in early-onset schizophrenia

Timing disorders in schizophrenia are a well-known phenomenon. However, no studies have yet assessed the role of temporal distortions in early-onset schizophrenia (EOS), despite evidence that distorted time perception may share genetic risk factors with schizophrenia and may be a useful indicator in identifying individuals at risk for schizophrenia. In the present study, we investigated the ability of 10 patients with EOS (mean age = 21.5 years, SD = 6) matched with 20 healthy control participants (mean age = 25.3 years, SD = 4.6) in order to compare the durations of two visual events, presented either sequentially or overlapping in time, along with neuropsychological assessments of attention, working memory, and executive functions. Each participant had to judge a total of 336 stimuli. We found that temporal overlap had a greater negative effect on ability to judge the duration of a pair of stimuli in EOS patients than in healthy control participants. In addition, EOS patients showed impairments in attention and executive functions. Furthermore, in EOS patients, the scores for executive and attentional functions were significantly correlated with accuracy of temporal estimation in the overlap condition (r = 0.31, p < 0.05 and r = 0.57, p < 0.05, respectively). These preliminary results suggest that impairments in neuropsychological functions participate in the deficit in time estimation observed in patients with EOS. These conclusions highlight the importance of testing time perception in patients with EOS and could contribute to the development of cognitive remediation-based therapy for these patients.