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Time perception in schizophrenia and bipolar disorder. A case-control study.
No full textBackground: Models of time perception are inherently modular, comprising specialized mechanisms that represent the temporal relationships among events. Humans can perceive time duration through adaptive functions that engage specific neural regions organized according to the duration of stimuli encountered. Time perception relies on the interaction between cortical structures associated with the internal clock and areas involved in specific tasks. It is crucial to revisit foundational concepts that encompass both subjective and intersubjective dimensions of temporality, especially in relation to significant psychiatric conditions. This subject is regarded as original and highly relevant for research. This case-control study aims to investigate disturbances in time perception in individuals with Bipolar Disorder (BD) and Schizophrenia (SZ).
Aims of the study: The study aimed to achieve several goals: first, to characterize sub-second temporal processing abilities in individuals with bipolar disorder and schizophrenia and their correlation with clinical and psychopathological variables. Second, it sought to compare different acquisition methods or tasks. Finally, it focused on characterizing sub-second temporal processing abilities in bipolar disorder and schizophrenia and examining their relationship with cerebello-thalamo-cortical functional connectivity.
Material and Methods: To facilitate the comparison of various task methods, we recruited two populations. A range of psychopathological scales were employed to assess patient symptomatology at the time of testing, including the Hamilton Depression Rating Scale (HAM-D) (Hamilton, 1960), the Young Mania Rating Scale (YMRS) (Young et al., 1978), and the Positive and Negative Syndrome Scale (PANSS) (Kay et al., 1987). The Temporal Order Judgment Task (TOJ) or Ventriloquist Apparatus was used, providing visual, auditory, and vibrotactile stimuli through a custom-designed serial-controlled stimulator measuring 20 mm × 20 mm, securely attached to the back of the dominant hand with transparent film that did not interfere with the stimuli . The visual stimulus consisted of a high-brightness blue LED with a diameter of 1.5 cm, activated for 10 ms. The vibrotactile stimulus produced a continuous pure vibration lasting 10 ms at a frequency of 112 Hz, while the auditory stimulus was a 10 ms burst of a 926 Hz pure tone pulsed at a frequency of 5 Hz. All stimuli were generated and precisely timed using MATLAB with the Psychtoolbox-3 package, with timings verified by an oscilloscope prior to testing. Additionally, we utilized the Antares PsySuite Method, a mobile app designed to deliver multimodal stimuli, including auditory, visual, and tactile inputs. This user-friendly Android application combines the convenience of a common device with the rigorous methods of psychophysics, which studies the quantitative relationships between psychological experiences and physical events. Within PsySuite, a temporal interval discrimination (TID) test was included to assess and enhance temporal skills in both auditory and tactile sensory modalities, employing classical psychophysical methods such as Two-Alternative Forced-Choice (2AFC) tasks. MRI recordings were conducted using a 3-T GE scanner with a standard head coil, utilizing foam pads to minimize head movement and reduce scanner noise. Three-dimensional T1-weighted anatomical images were acquired in a sagittal orientation via a 3D-SPGR sequence, achieving an in-plane resolution of 256x256 and a slice thickness of 1 mm. Functional images were obtained using a gradient echo Echo Planar Imaging (EPI) sequence sensitive to BOLD contrast, capturing whole-brain volumes in 33 contiguous slices, each 4 mm thick. Each participant underwent 6 minutes of fMRI scanning, totaling 150 scans.
Results: This study investigated temporal precision in a Temporal Order Judgment (TOJ) task involving 21 patients with schizophrenia (SZ), 20 with bipolar disorder (BD), and 21 healthy controls (HC). Participants assessed pairs of audio-tactile, visuo-tactile, and audio-visual stimuli with varying stimulus onset asynchronies (SOAs). Results indicated that both SZ and BD patients exhibited significantly poorer temporal precision compared to HC across all conditions. A permutation-based ANOVA revealed a significant main effect of group (F = 4.06, p = 0.02), with significant differences between HC and both BD (t = -5.5, p < 0.001) and SZ (t = -6.1, p < 0.001), but not between the two patient groups. Age was not a significant factor. Furthermore, correlational analyses showed a significant association between individual just noticeable differences (JNDs) and the positive subscale of the PANSS, explaining approximately 47% of the variance in scores. No significant associations were found between medication dosages and temporal precision. These findings highlight the impact of psychiatric conditions on temporal processing and its relationship with symptomatology.
The MRI study examined differences in amplitude of low-frequency fluctuations (ALFF) and fractional ALFF (fALFF) between bipolar disorder (BD) patients and healthy controls (HC) with adjustments for age and gender. A widespread pattern of differences was observed in both ALFF and fALFF measures. No significant differences were noted when analyzing BD patients based on their clinical phase. Additionally, in BD patients, fALFF demonstrated a negative correlation with both the Young Mania Rating Scale (YMRS) and disease duration, while no significant correlations were found for ALFF. Subject-level seed-based functional connectivity (SBFC) analysis was performed, revealing that connectivity from the Crus II region of the cerebellum negatively correlated with YMRS scores in a frontal region (p = 0.04, k = 149, MNI coordinates: -24, 18, 50). This suggests that greater disconnection between the right Crus II and the left frontal region is linked to higher YMRS scores in BD patients. No significant correlations were found from the other seed regions.
Limitations: This study has several limitations. The primary limitation is the absence of longitudinal evaluations, which restricts the generalizability of the results. Additionally, information regarding patients' medication types and dosages prior to the examination was not rigorously collected for all patients, preventing us from correcting for any potential confounding effects.
Discussion: This study replicates previous findings of sub-second timing deficits in schizophrenia (SZ) patients while offering new insights. Both SZ and bipolar disorder (BD) patients exhibited a similarly wider temporal binding window (TBW) compared to healthy controls, contrary to prior studies. The key finding is that alterations in multisensory temporal binding correlate with specific psychotic symptoms, such as delusions and hallucinations, rather than being exclusive to SZ or BD diagnoses. These results support the idea that low-level temporal integration is essential for coherent higher-level perceptions, with impaired temporal binding potentially leading to fragmented perceptions and clinical symptoms.
Furthermore, these findings suggest a continuum between affective and non-affective psychoses, indicating that TBW amplitude may reflect the severity of psychotic symptoms. No significant relationships were found between temporal binding precision and medication dosages. Additionally, reduced functional connectivity between the right cerebellar Crus II and frontal regions was observed in individuals with more severe manic symptoms, highlighting its role in timing thoughts, emotions, and actions. This weakened connection may disrupt the cerebello-thalamo-cortical pathway, impairing the cerebellum's regulatory functions. Overall, the study suggests shared network dysfunction across psychotic disorders, supporting a unified psychosis model.
Conclusion: In conclusion, this study confirms sub-second timing deficits in schizophrenia and reveals that both schizophrenia and bipolar disorder patients have a wider temporal binding window than healthy controls. This suggests shared characteristics rather than distinct diagnoses. Alterations in temporal binding are linked to specific psychotic symptoms, highlighting the role of low-level temporal integration in perception. No significant relationship was found between temporal binding precision and medication, indicating that these effects are not solely pharmacological. The right cerebellar Crus II is vital for temporal perception, with reduced connectivity to frontal regions in individuals with severe manic symptoms.
Future research should explore connections between specific symptoms, subjective time experience, and temporal processing deficits, aiming to enhance understanding and inform treatment strategies for better patient outcomes
Commentary on the study of Roy et al. Amygdala based altered mir-128-3p in conferring susceptibility to depression-like behavior via Wnt signaling
No full textThe study of Roy and colleagues, recently accepted for publication on Int J Neuropsychopharmacol is a very interesting report investigating the role of specific microRNAs (miRNAs) in vulnerability or resistance to major depressive disorder (MDD) in a specific brain region (e.g., amygdala). MiRNAs may act as a mega controller of gene expression being involved in the pathogenesis of major neuropsychiatric conditions. Interestingly, some of the altered miRNAs (e.g., hsa-miR-425-3p, miR-425, miR-674-3p, and miR-873-3p) identified in this study were found to be dysregulated even in existing studies but several methodological issues may hamper the translation of basic research findings in clinical studies. MiRNAs are proposed as possible biomarkers of disease and treatment response to disentangle the biological complexity underlying major affective disorders. The main implications regarding the present findings are discussed
The Role of Inflammation in the Pathophysiology of Depression and Suicidal Behavior: Implications for Treatment
No full text: Depression and suicidal behavior are 2 complex psychiatric conditions of significant public health concerns due to their debilitating nature. The need to enhance contemporary treatments and preventative approaches for these illnesses not only calls for distillation of current views on their pathogenesis but also provides an impetus for further elucidation of their novel etiological determinants. In this regard, inflammation has recently been recognized as a potentially important contributor to the development of depression and suicidal behavior. This review highlights key evidence that supports the presence of dysregulated neurometabolic and immunologic signaling and abnormal interaction with microbial species as putative etiological hallmarks of inflammation in depression as well as their contribution to the development of suicidal behavior. Furthermore, therapeutic insights addressing candidate mechanisms of pathological inflammation in these disorders are proposed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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