Visuospatial task-related prefrontal activity is correlated with negative symptoms in schizophrenia

The two-back task leads to activity in the left dorsolateral prefrontal cortex in schizophrenia patients with predominant negative symptoms: a fNIRS study and its implication for tDCS

Transcranial direct current stimulation (tDCS) over left dorsolateral prefrontal cortex (DLPFC) has shown some potential as an adjunctive intervention for ameliorating negative symptoms of schizophrenia, but its efficacy requires optimization. Recently, 'functional targeting' of stimulation holds promise for advancing tDCS efficacy by coupling tDCS with a cognitive task where the target brain regions are activated by that task and further specifically polarized by tDCS.The study used 48-channel functional near infra-red spectroscopy (fNIRS) aiming to determine a cognitive task that can effectively induce a cortical activation of the left DLPFC in schizophrenia patients with predominant negative symptoms before running a tDCS trial. Sixty schizophrenia patients with predominant negative symptoms completed measures of clinical and psychosocial functioning characteristics and assessments across cognitive domains. Hemodynamic changes during n-back working memory tasks with different cognitive loads (1-back and 2-back) and verbal fluency test (VFT) were measured using fNIRS. For n-back tasks, greater signal changes were found when the task required elevated cognitive load. One sample t-test revealed that only 2-back task elicited significant activation in left DLPFC (t = 4.23, FDR-corrected p = 0.0007). During VFT, patients failed to show significant task-related activity in left DLPFC (one sample t-test, t = -0.25, FDR-corrected p > 0.05). Our study implies that 2-back task can effectively activate left DLPFC in schizophrenia patients with predominant negative symptoms. This neurophysiologically-validated task is considered highly potential to be executed in conjunction with high-definition tDCS for "functional targeting" of the left DLPFC to treat negative symptoms in a double-blind randomized sham-control trial, registered on ClinicalTrials.gov Registry (ID: NCT05582980).

Altered dynamic functional connectivity of the thalamus subregions in patients with schizophrenia

BACKGROUND

Previous neuroimaging studies indicated that patients with schizophrenia showed impaired thalamus and thalamo-cortical circuits. However, the dynamic functional connectivity (dFC) patterns of the thalamus remain unclear. In this study, we explored the dFC of the thalamus in SZ patients and whether clinical features are correlated with altered dFC.

METHODS

Forty-three patients with schizophrenia and 31 healthy controls underwent 3.0 T rs-fMRI. Based on the human Brainnetome atlas, the thalamus is divided into 8 subregions. Subsequently, we performed flexible least squares method to calculate the dFC of each thalamus subregions.

RESULTS

Compared with healthy controls, patients with schizophrenia exhibited increased dFC between the thalamus and cerebellar, visual-related cortex, sensorimotor-related cortex, and frontal lobe. In addition, we found that the dFC of the thalamus and the right fusiform gyrus was negatively associated with age of onset.

CONCLUSIONS

Our findings demonstrated that the dFC of specific thalamus sub-regions is altered in patients with schizophrenia. Our results further suggested the dysconnectivity of thalamus plays an important role in the pathophysiology of schizophrenia.

An fNIRS investigation of novel expressed emotion stimulations in schizophrenia

Living in high expressed emotion (EE) environments tends to increase the relapse rate in schizophrenia (SZ). At present, the neural substrates responsible for high EE in SZ remain poorly understood. Functional near-infrared spectroscopy (fNIRS) may be of great use to quantitatively assess cortical hemodynamics and elucidate the pathophysiology of psychiatric disorders. In this study, we designed novel low- (positivity and warmth) and high-EE (criticism, negative emotion, and hostility) stimulations, in the form of audio, to investigate cortical hemodynamics. We used fNIRS to measure hemodynamic signals while participants listened to the recorded audio. Healthy controls (HCs, [Formula: see text]) showed increased hemodynamic activation in the major language centers across EE stimulations, with stronger activation in Wernicke's area during the processing of negative emotional language. Compared to HCs, people with SZ ([Formula: see text]) exhibited smaller hemodynamic activation in the major language centers across EE stimulations. In addition, people with SZ showed weaker or insignificant hemodynamic deactivation in the medial prefrontal cortex. Notably, hemodynamic activation in SZ was found to be negatively correlated with the negative syndrome scale score at high EE. Our findings suggest that the neural mechanisms in SZ are altered and disrupted, especially during negative emotional language processing. This supports the feasibility of using the designed EE stimulations to assess people who are vulnerable to high-EE environments, such as SZ. Furthermore, our findings provide preliminary evidence for future research on functional neuroimaging biomarkers for people with psychiatric disorders.

Static and temporal dynamic changes of intrinsic brain activity in pediatric and adults OCD

Epidemiological and clinical age differences in obsessive-compulsive disorder (OCD) have been reported in clinical symptoms and morphometry changes; however, age differences in amplitude of low-frequency fluctuation and the relationship between ALFF imaging and clinical symptoms has not been thoroughly studied in OCD. Age may be an important feature associated with distinct subtypes of OCD. To examine the effect of age on OCD, the current study enrolled 92 OCD patients (32 pediatrics and 60 adults) and matched HCs (33 pediatrics and 84 adults), undergoing resting-state functional magnetic resonance imaging. The spontaneous brain activity was measured by static and dynamic amplitude of low-frequency fluctuation (ALFF) followed by two-way ANOVA. In pediatric OCD patients versus adult patients, we observed a significantly higher ALFF in the default mode network (DMN), including posterior cingulate, precuneus and superior frontal gyrus, and extending to cuneus, lingual gyrus. Additionally, the increased ALFF and dynamic ALFF in the precentral gyrus were found in pediatric patients. In OCD patients compared with controls, we found a significantly increased ALFF in hippocampal gyrus, cerebellum network (CN), and the dALFF in middle and inferior occipital gyrus, bilateral paracentral lobule and sensorimotor network. The findings emphasized the different patterns of static and dynamic intrinsic brain activity alterations associated with pediatric and adult OCD patients. These results provide unique insights into constructing evidenced-based distinct OCD subtypes based on brain activity and point the need of specified management for pediatric and adult OCD patients in clinical setting.

Efficacy of metacognitive training on symptom severity, neurocognition and social cognition in patients with schizophrenia: A single-blind randomized controlled trial

Over the past decades, a number of complementary treatments for schizophrenia have emerged. One of these is metacognitive training (MCT), which combines the principles of cognitive‐behavioral therapies, cognitive remediation, and psychoeducation into a hybrid approach placing emphasis on increasing metacognitive awareness. The aim of our study was to investigate the efficacy of MCT on symptom severity, and neurocognitive and social cognitive functioning in schizophrenia; also, attention was paid to the assessment of subjective acceptability. Forty‐six patients diagnosed with schizophrenia were included in our single‐blind randomized controlled trial, who were assigned to the intervention or control group. The intervention group was provided standard MCT, while the control group received treatment as usual. We assessed symptom severity and cognitive functions before and after the training, as well as after a 6‐month follow‐up period. Compared to the control group, the intervention group showed improvement in overall symptom severity, and positive and disorganized symptoms. Training participans showed further improvement at the follow‐up assessment. Regarding neurocognitive functions, improvement in visuospatial functions was observed between pre‐ and post‐intervention assessments compared to the control group. Patients showed excellent adherence, and evaluated the training as useful and interesting. In line with the results of previous studies, our results demonstrate the efficacy of MCT on symptom severity in schizophrenia. Improvements in cognitive functions that are closely related to the onset and prevalence of symptoms of schizophrenia were also found.

Fronto-parietal network function during cued visual search in the first-episode schizophrenia spectrum

Cognitive impairments account for significant morbidity in schizophrenia and are present at disease onset. Controlled processes are particularly susceptible and may contribute to pervasive selective attention deficits. The present study assessed fronto-parietal attention network (FPAN) functioning during cue presentation on a visual search task in first-episode schizophrenia spectrum patients (FE) and its relation to symptom burden and community functioning. Brain activity was recorded with magnetoencephalography from 38 FE and 38 healthy controls (HC) during blocks of pop-out and serial search target detection. Activity during cue presentation was compared between groups across bilateral FPAN regions (frontal eye fields (FEF), inferior frontal gyrus (IFG), midcingulate cortex (MCC), and intraparietal sulcus (IPS)). FE exhibited greater right hemisphere IFG activity despite worse performance relative to HC. Performance and FPAN activity were not correlated in HC. Among FE, however, stronger activity within right hemisphere FEF and IFG was associated with faster responses. Stronger right IPS and left IFG activity in patients was also associated with reduced negative symptoms and improved community functioning, respectively. Increased reliance on the FPAN for task completion suggests an inefficient cognitive control network and might reflect a compensation for impaired attentional deployment during target detection, a strategy employed by those with less severe illness. These findings represent a critical step towards identifying the neural substrates of negative symptoms and impaired neurocognition at disease onset.

Memory-Guided Saccades in Psychosis: Effects of Medication and Stimulus Location

The memory-guided saccade task requires the remembrance of a peripheral target location, whilst inhibiting the urge to make a saccade ahead of an auditory cue. The literature has explored the endophenotypic deficits associated with differences in target laterality, but less is known about target amplitude. The data presented came from Crawford et al. (1995), employing a memory-guided saccade task among neuroleptically medicated and non-medicated patients with schizophrenia (n = 31, n = 12), neuroleptically medicated and non-medicated bipolar affective disorder (n = 12, n = 17), and neurotypical controls (n = 30). The current analyses explore the relationships between memory-guided saccades toward targets with different eccentricities (7.5° and 15°), the discernible behaviour exhibited amongst diagnostic groups, and cohorts distinguished based on psychotic symptomatology. Saccade gain control and final eye position were reduced among medicated-schizophrenia patients. These metrics were reduced further among targets with greater amplitudes (15°), indicating greater deficit. The medicated cohort exhibited reduced gain control and final eye positions in both amplitudes compared to the non-medicated cohort, with deficits markedly observed for the furthest targets. No group differences in symptomatology (positive and negative) were reported, however, a greater deficit was observed toward the larger amplitude. This suggests that within the memory-guided saccade paradigm, diagnostic classification is more prominent in characterising disparities in saccade performance than symptomatology.

Multi-dimensional predictions of psychotic symptoms via machine learning

The diagnostic criteria for schizophrenia comprise a diverse range of heterogeneous symptoms. As a result, individuals each present a distinct set of symptoms despite having the same overall diagnosis. Whilst previous machine learning studies have primarily focused on dichotomous patient-control classification, we predict the severity of each individual symptom on a continuum. We applied machine learning regression within a multi-modal fusion framework to fMRI and behavioural data acquired during an auditory oddball task in 80 schizophrenia patients. Brain activity was highly predictive of some, but not all symptoms, namely hallucinations, avolition, anhedonia and attention. Critically, each of these symptoms was associated with specific functional alterations across different brain regions. We also found that modelling symptoms as an ensemble of subscales was more accurate, specific and informative than models which predict compound scores directly. In principle, this approach is transferrable to any psychiatric condition or multi-dimensional diagnosis.

Functional Near-Infrared Spectroscopy Indicates That Asymmetric Right Hemispheric Activation in Mental Rotation of a Jigsaw Puzzle Decreases With Task Difficulty

Mental rotation (MR) is a cognitive skill whose neural dynamics are still a matter of debate as previous neuroimaging studies have produced controversial results. In order to investigate the underlying neurophysiology of MR, hemodynamic responses from the prefrontal cortex of 14 healthy subjects were recorded with functional near-infrared spectroscopy (fNIRS) during a novel MR task that had three categorical difficulty levels. Hemodynamic activity strength (HAS) parameter, which reflects the ratio of brain activation during the task to the baseline activation level, was used to assess the prefrontal cortex activation localization and strength. Behavioral data indicated that the MR requiring conditions are more difficult than the condition that did not require MR. The right dorsolateral prefrontal cortex (DLPFC) was found to be active in all conditions and to be the dominant region in the easiest task while more complex tasks showed widespread bilateral prefrontal activation. A significant increase in left DLPFC activation was observed with increasing task difficulty. Significantly higher right DLPFC activation was observed when the incongruent trials were contrasted against the congruent trials, which implied the possibility of a robust error or conflict-monitoring process during the incongruent trials. Our results showed that the right DLPFC is a core region for the processing of MR tasks regardless of the task complexity and that the left DLPFC is involved to a greater extent with increasing task complexity, which is consistent with the previous neuroimaging literature.