Electrophysiological basis of reading related phonological impairment in Chinese speakers with schizophrenia: An ERP study

Unveiling the Associations between EEG Indices and Cognitive Deficits in Schizophrenia-Spectrum Disorders: A Systematic Review

Cognitive dysfunctions represent a core feature of schizophrenia-spectrum disorders due to their presence throughout different illness stages and their impact on functioning. Abnormalities in electrophysiology (EEG) measures are highly related to these impairments, but the use of EEG indices in clinical practice is still limited. A systematic review of articles using Pubmed, Scopus and PsychINFO was undertaken in November 2021 to provide an overview of the relationships between EEG indices and cognitive impairment in schizophrenia-spectrum disorders. Out of 2433 screened records, 135 studies were included in a qualitative review. Although the results were heterogeneous, some significant correlations were identified. In particular, abnormalities in alpha, theta and gamma activity, as well as in MMN and P300, were associated with impairments in cognitive domains such as attention, working memory, visual and verbal learning and executive functioning during at-risk mental states, early and chronic stages of schizophrenia-spectrum disorders. The review suggests that machine learning approaches together with a careful selection of validated EEG and cognitive indices and characterization of clinical phenotypes might contribute to increase the use of EEG-based measures in clinical settings.

Abnormalities in P300 components in depression: an ERP-sLORETA study

BACKGROUND

Alterations in P300 components occur in depressed patients, but the brain regions contributing to these changes remain unclear.

AIMS

Thus, the aim of the present study was to examine the underlying neural activation of P300 components in patients with depression to explore brain regions related to depression.

METHODS

P300 components were evoked by an oddball auditory paradigm and recorded from 30 patients with current depression, as well as 30 age-, gender-, and education level-matched healthy controls. The standardized Low-Resolution Brain Electromagnetic Tomography (sLORETA) method was used to explore the source activation of P300 components.

RESULTS

Compared with healthy controls, depressed patients tended to exhibit lower P200 and P300 amplitudes and prolonged P300 latency. In depressed patients, P200 source activations were reduced in the right insula, right precentral gyrus, left anterior cingulate, medial frontal gyrus, superior frontal gyrus, and middle frontal gyrus. Decreased source activations of P300 were identified in the right insula, postcentral gyrus, superior temporal gyrus, inferior parietal lobule, transverse temporal gyrus, cingulate gyrus, precentral gyrus, middle frontal gyrus, superior frontal gyrus, medial frontal gyrus, and paracentral gyrus.

CONCLUSIONS

Extensive dysfunction over the right hemisphere and bilateral prefrontal dysfunction may be involved in the pathophysiology of depression.

The P300 component decreases in a bimodal oddball task in individuals with depression: An event-related potentials study

OBJECTIVE

In this study, we investigated auditory-visual stimulation-induced P300 and examined whether P300 was differentially modulated between individuals with clinical depression and healthy controls. We hypothesized that the P300 component would significantly differ between individuals with depression and healthy individuals Specifically, we predicted that the P300 component induced by the bimodal oddball task would be significantly different from that induced by the unimodal task.

METHODS

Forty-five individuals with depression and forty-five healthy controls participated in this study. All participants were instructed to complete three oddball tasks-auditory (A), visual (V), and bimodal (AV)-while their electroencephalographic signals were recorded.

RESULTS

Individuals with depression had a lower P300 amplitude and a longer latency than controls in the bimodal task. P300 amplitudes in the bimodal task were significantly higher than in the auditory or visual tasks in both groups. In the depression group, the P300 amplitude was negatively correlated with Hamilton Depression Rating Scale (HAM-D) scores in the bimodal task.

CONCLUSIONS

Our results, which agree with those reported previously, suggest that there is a heightened P300 amplitude sensitivity in the bimodal task in individuals with depression. Our data also suggest that P300 amplitudes in the bimodal task may reflect the severity of depression.

SIGNIFICANCE

The reduced task-related ERP response in individuals with depression suggests significant impairments in these individuals in stimulus integration and response functions.

Abnormalities of P300 before and after antidepressant treatment in depression: an ERP-sLORETA study

Despite a wide range of reports on depression-induced P300 changes, it is still debatable whether P300 can return to a pattern characteristic of healthy individuals following antidepressant treatment. Thus, the present study aims to compare P300 and its underlying neural activation in depressed patients before and after antidepressant treatment to explore the brain regions related to pathogenesis and to evaluate the prognosis after treatment. P300 was evoked by the oddball auditory paradigm and collected from 14 sex-matched, age-matched, and education level-matched patients and controls. P300 was also collected in the same patients after treatment. sLORETA was used to explore the source activation of P300 components. Depressed patients before and after antidepressant treatment tended to show lower P300 amplitudes compared with healthy controls, and their P300 amplitudes of F3 electrodes were correlated negatively to their scores on the 24-item Hamilton Depression Rating Scale, the Snaith-Hamilton Pleasure Scale, and the nine-item Patient Health Questionnaire. P300 amplitudes of P4 electrodes were correlated negatively with their scores on the Dysfunctional Attitude Scale. P300 source activation of depressed patients before antidepressant treatment was reduced in the left superior parietal lobule and the precuneus compared with healthy controls and depressed patients after treatment. No difference was found between healthy controls and depressed patients after treatment. The left superior parietal lobule and the precuneus might be therapeutic targets of depression.