Brain Networks Communicate Through Theta Oscillations to Encode High Load in a Visuospatial Working Memory Task: An EEG Connectivity Study.

The encoding of visuospatial information is the foremost and indispensable step which determines the outcome in a visuospatial working memory (VSWM) task. It is considered to play a crucial role in limiting our ability to attend and process only 3-5 integrated items of information. Despite its importance in determining VSWM performance, the neural mechanisms underlying VSWM encoding have not been clearly differentiated from those involved during VSWM retention, manipulation and/or retrieval. The high temporal resolution of electroencephalography (EEG) and improved spatial resolution with dense array data acquisition makes it an ideal tool to study the dynamics in the functional brain connectivity during a cognitive task. In the present study, the changes in the functional brain connectivity due to memory load during VSWM encoding were studied using 128-channel EEG. Lagged linear coherence (LagR) was computed between 84 regions of interest (ROIs) defined according to the Brodmann areas for seven EEG frequency bands: delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13 Hz), beta 1 (13-20 Hz), beta 2 (20-30 Hz), and gamma (30-45 Hz). Interestingly, out of seven EEG frequency bands investigated in the current study, LagR of only theta band varied significantly in 13 brain connections due to memory load during VSWM encoding. LagR of theta band increased significantly at high memory load when compared to low memory load in twelve brain connections with the maximum change observed between right cuneus and right middle temporal gyrus (Cohen's d = 0.836), indicating the integration of brain processes to confront the increase in memory demands. Theta LagR decreased significantly between left postcentral gyrus and right precentral gyrus at high memory load as compared to low memory load, which might have a role for sustaining attention during encoding. Change in the LagR values due to memory load between fusiform gyrus and lingual gyrus in the right hemisphere had a positive correlation (r = 0.464, p = 0.003) with the error rate, signifying the crucial role played by these two regions in predicting the performance. The current study has not only identified the neural connections that are responsible for the formation of working memory traces during VSWM encoding, but also support the notion that encoding is a rate-limiting process underlying our memory capacity limit.

Cingulate oscillatory activity reflects the quality of memory representations in visuospatial working memory.

The human brain has the high likelihood for committing errors when confronted by a day-to-day situation that demands to process more than four integrated items in working memory, for example driving a car to a new destination in high traffic. However, neural mechanisms underlying the response outcome in working memory is still unclear. High temporal resolution and improved spatial resolution of dense array electroencephalogram (EEG) make it an ideal tool to investigate the dynamics of brain networks. In the present study, the brain activity of twenty healthy male volunteers was investigated during correct and error trials of visuospatial working memory task using dense array EEG. Independent brain components were identified using independent component analysis (ICA). Event-related spectral perturbations (ERSP) were computed for each independent component using Morlet wavelet transform for the frequency range of 3-70 Hz. ERSP of independent component clusters identified using K-means algorithm were statistically compared between correct and error trials. Delta and theta power increased in the component cluster located at cingulate gyrus before the error response of visuospatial working memory task. The current study findings suggest that cingulate oscillatory activity might reflect the quality of memory representation and intensity of target uncertainty during the visuospatial search.

Effect of controlled deep breathing on psychomotor and higher mental functions in normal individuals.

OBJECTIVE: The present study was conducted to assess the effect of controlled deep breathing on psychomotor and higher mental functions. METHODS: 100 normal healthy subjects (52 females and 48 males, age range - 18 to 25 years) participated in the study. Each subject acted as his or her own control. Six weeks course of controlled deep breathing i.e. 5 seconds of maximal inhalation followed by 5 seconds of maximal exhalation, once a day for ten minutes, six days a week was arranged. (i) Letter cancellation test (ii) Rapid fire arithmetic deviation test and (iii) Playing card test were conducted before and after six weeks of controlled deep breathing practice for evaluating psychomotor and higher mental functions. RESULTS: No significant gender difference was observed on comparing baseline readings between female and male subjects. After six weeks of controlled deep breathing practice letter cancellation test time significantly reduced (P<0.001), rapid fire arithmetic deviation test and playing card test scores (P<0.001) significantly improved. Letter cancellation test score didn't show improvement. CONCLUSION: The results suggest that a short, simple breathing practice can be helpful in improving cognitive processes.

Correction: Altered Heart Rate Variability During Rest in Schizophrenia: A State Marker.

[This corrects the article DOI: 10.7759/cureus.44145.].

Altered Heart Rate Variability During Rest in Schizophrenia: A State Marker.

BACKGROUND: Autonomic nervous system (ANS) imbalance has been reported in a number of psychiatric disorders such as depression, schizophrenia, panic disorder, etc. Autonomic dysfunction in schizophrenia has been associated with the symptoms and manifestation of psychosis. Heart rate variability (HRV) as a tool has been widely used to assess ANS activity and the effect of disease on the sympathovagal balance. Therefore, in the present study, HRV derived from electrocardiogram (ECG) lead II at rest was investigated in order to understand the changes in frequency domain measures in patients with schizophrenia and their first-degree relatives compared to healthy controls. METHODS: Twenty-five patients with schizophrenia, 24 first-degree relatives of patients, and 24 healthy controls (Diagnostic and Statistical Manual of Mental Disorders (DSM)-5; 18-45 years) were included in the study. HRV of the subjects was measured after five minutes of rest. ECG lead II was recorded for five minutes and HRV was analysed in the frequency domain: low frequency (LF), high frequency (HF), total power, and LF/HF ratio. HRV parameters and heart rate were statistically analysed for group comparisons using general linear model multivariate analysis. RESULTS: Patients had significantly higher minimum heart rate and lower HF (normalized units (nu)) compared to their first-degree relatives. A trend was observed in HF (nu) with the lowest in patients followed by healthy controls and first-degree relatives and LF/HF ratio was the highest in patients followed by healthy controls and first-degree relatives, although not statistically significant. No significant difference was found between first-degree relatives and healthy controls. CONCLUSION: The alteration of HRV in schizophrenia could be attributed to reduction in vagal tone and sympathetic dominance, which in turn could serve as state markers of schizophrenia.

Spectral perturbations of cortical dipoles during a dynamic visuo-spatial working memory task in schizophrenia.

Altered neural oscillations during prestimulus-task conditions have been reported to be associated with aberrant information processing in schizophrenia. Spectral perturbations induced by visuo-spatial working memory (VSWM) task were investigated in patients and their first-degree relatives in order to study the biomarkers in schizophrenia. EEG was recorded using 128-channel during VSWM task in 28 patients, 27 first-degree relatives and 25 controls. After pre-processing and ICA, current dipole was estimated for each IC. Total of 1609 independent and localizable EEG components across all groups were used to compute ERSP during different events of task. Patients deactivated DMN, RSN, auditory cortex more compared to controls during search period to perform VSWM task. Relatives showed altered activation of right medial and inferior frontal gyri during different events and loads of task in lower frequencies compared to controls. Relatives also showed hyperactivity in right cingulate and parahippocampal gyri compared to controls. This is suggestive of genetic predisposition in schizophrenia and could act as vulnerability markers, further strengthened by no significant differences between patients and relatives. Altered processing of simultaneous ongoing events in patients and relatives can serve as state and trait-specific features of schizophrenia.

Altered parahippocampal gyrus activation and its connectivity with resting-state network areas in schizophrenia: An EEG study.

Synchronized and coherent activity in resting-networks during normal brain functioning could be altered in disconnection syndrome like schizophrenia. Study of neural oscillations as assessed by EEG appears to be a promising proposition to understand the pathophysiology of schizophrenia in patients and their first-degree relatives, where disturbances in neural oscillations point towards genetic predisposition. Therefore, present study aims at establishing EEG based biomarkers for early detection and management strategies. Thirty-two patients with schizophrenia, 28 first-degree relatives and 31 healthy controls (HC) participated in the study. Resting brain activity was recorded using 128-channel electroencephalography. After pre-processing and independent component analysis (ICA), an equivalent current dipole was estimated for each IC. Total of 1551 independent and localizable EEG components across all groups were used in subsequent analysis. Power spectral density and source coherence between IC clusters were computed. Patients and first-degree relatives displayed significantly higher power spectral density (PSD) than HC for all frequency bands in left parahippocampal gyrus (PHG) (-7, -26, 8; BA 27). Another region within left deep PHG (-4, -28, 1), however, distinguished patients from first-degree relatives and HC in terms of significantly lower PSD in higher frequency bands. Functional connectivity (FC) was found to be lower in patients and higher in relatives compared to HC between different resting-state network areas. In patients, connectivity was lower compared to first-degree relatives. Altered activity within left PHG and FC of primarily this with other areas in resting-state network can serve as state and trait markers of schizophrenia.

The 2019 Schizophrenia International Research Society Conference, 10-14 April, Orlando, Florida: A summary of topics and trends.

The Schizophrenia International Research Society (SIRS) recently held its first North American congress, which took place in Orlando, Florida from 10-14 April 2019. The overall theme of this year's congress was United in Progress - with the aim of cultivating a collaborative effort towards advancing the field of schizophrenia research. Student travel awardees provided reports of the oral sessions and concurrent symposia that took place during the congress. A collection of these reports is summarized and presented below and highlights the main themes and topics that emerged during the congress. In summary, the congress covered a broad range of topics relevant to the field of psychiatry today.

Pre-trial and pre-response EEG microstates in schizophrenia: An endophenotypic marker.

Cognitive deficits in Schizophrenia interfere with everyday functioning and social functioning. Strong familial associations in schizophrenia might serve to establish cognitive impairments as endophenotypic markers. Therefore, visuo-spatial working memory simulating day-to-day activities at high memory load was assessed in patients with schizophrenia, their first-degree relatives and healthy controls to explore pre-trial and pre-response EEG microstates and their intracranial generators. Twenty-eight patients with schizophrenia, first-degree relatives and matched healthy controls participated in the study. Brain activity during visuo-spatial working memory task was recorded using 128-channel electroencephalography. Pre-trial and pre-response microstate maps of correct and error trials were clustered across groups according to their topography. Microstate map parameters and underlying cortical sources were compared among groups. Pre-trial (correct) microstate Map 1 was significantly different between controls and patients which could qualify it as a state marker with its intracranial generator localized to right inferior frontal gyrus (rIFG). Pre-response (correct) microstate map was significantly different between controls and first-degree relatives which could be considered an endophenotypic marker for schizophrenia. No significant differences were observed for error trials between groups. rIFG which is involved in the execution of multi-component behaviour and selective inhibitory control could distinguish patients with schizophrenia from their first-degree relatives and healthy controls. Further, microstate based biomarkers have the potential to facilitate diagnosis of schizophrenia at a preclinical stage resulting in efficient diagnosis and better prognosis.

Hyperactivation of left inferior parietal lobule and left temporal gyri shortens resting EEG microstate in schizophrenia.

OBJECTIVE: The momentary spatial configuration of the brain electric field at the scalp reflects quasi-stable "functional microstates" caused by activity of different intracranial generators. There is paucity in literature on the intracranial generators of resting state EEG microstate alterations in stable patients with schizophrenia. The present study aimed to investigate resting state microstate alterations and their neural generators in patients with schizophrenia and their first-degree relatives as compared to healthy controls in an attempt to establish state and trait marker. METHOD: Thirty-four patients with schizophrenia (DSM-5 criteria), 29 first-degree relatives and 25 matched healthy controls participated in the study. Brain activity during eyes closed condition was recorded using 128 channel electroencephalography. Microstates were clustered into 5 maps across groups according to their topography. Microstate map parameters and their cortical sources were compared among groups. RESULTS: Map 5 mean duration (χ2(2) = 7.617, p = 0.022) was significantly lower in patients compared to controls (U = 256, p = 0.010). Maximum activation was seen in left inferior parietal lobule (MNI coordinates: -65, -35, 25, Log-Fmax = 0.748). Suprathreshold cortical voxels with increased activations were found localized at left temporal gyri. CONCLUSION: Hyperactivation in left inferior parietal lobule and temporal gyri might have shortened Map 5 duration at rest in patients with schizophrenia. This could imply microstate alterations as the potential state marker of schizophrenia.

A novel method for assessing patients with schizophrenia and their first-degree relatives by increasing cognitive load of visuo-spatial working memory.

INTRODUCTION: In patients with schizophrenia, social and functional outcome is determined by the cognitive impairment. Assessment of visuo-spatial working memory (VSWM) which can simulate the day-to-day activities by simultaneous involvement of various elements of working memory may reflect disorganized thinking and fragmentation of thoughts in schizophrenia. METHODS: Thirty-six patients with schizophrenia, 29 first-degree relatives of patients, and 25 healthy controls performed a VSWM task with three memory loads (comprising three pairs, six pairs, and eight pairs of abstract pictures). They were administered Hindi version of the Mini Mental State Examination, Scale for the Assessment of Negative Symptoms and Scale for the Assessment of Positive Symptoms, and Edinburgh handedness inventory. RESULTS: Patients (mean age 27.29(5.98) years) committed significantly higher number of errors than healthy controls (mean age 26.76(6.08) years) in load 3 (P = 0.012) and total errors (P = 0.018). Within all the groups, errors in load 3 were significantly higher than in load 2. Significant correlation was observed between years of education (r = -0.388, P = 0.021), treatment duration (r = -0.880, P < 0.001), negative symptoms scores (r = 0.345, P = 0.039), and the total errors committed by patients. DISCUSSION: Visuo-spatial working memory was impaired in schizophrenia with increasing cognitive load with no difference in search time between the groups.