ABSTRACT
Functional near-infrared spectroscopy (fNIRS) is a relatively new technique that can measure the hemoglobin changes in brain tissue. Depending on the absorption for different wavelength, relative changes in the concentration of hemoglobin in brain can be measured, obtaining the hemodynamic characteristics of brain to understand the brain functional state in real-time. Compared with other neuroimaging techniques, it has some advantages and has been used in psychiatry rapidly. Schizophrenia is one of the most common mental disorders, researches on its pathogenesis have focused on collection of structural and functional alteration in brain. Existing techniques can provide only indirect evidence, while fNIRS can perform brain function monitoring in real-time. A number of studies have suggested that fNIRS signal could be used as a biomarker for schizophrenia identification and adjuvant diagnosis. This paper reviewed the research progress in the application of fNIRS in schizophrenia.
ABSTRACT
<p><b>BACKGROUND</b>Several studies using functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) have indicated that cognitive remediation therapy (CRT) might improve cognitive function by changing brain activations in patients with schizophrenia. However, the results were not consistent in these changed brain areas in different studies. The present activation likelihood estimation (ALE) meta-analysis was conducted to investigate whether cognitive function change was accompanied by the brain activation changes, and where the main areas most related to these changes were in schizophrenia patients after CRT. Analyses of whole-brain studies and whole-brain + region of interest (ROI) studies were compared to explore the effect of the different methodologies on the results.</p><p><b>METHODS</b>A computerized systematic search was conducted to collect fMRI and PET studies on brain activation changes in schizophrenia patients from pre- to post-CRT. Nine studies using fMRI techniques were included in the meta-analysis. Ginger ALE 2.3.1 was used to perform meta-analysis across these imaging studies.</p><p><b>RESULTS</b>The main areas with increased brain activation were in frontal and parietal lobe, including left medial frontal gyrus, left inferior frontal gyrus, right middle frontal gyrus, right postcentral gyrus, and inferior parietal lobule in patients after CRT, yet no decreased brain activation was found. Although similar increased activation brain areas were identified in ALE with or without ROI studies, analysis including ROI studies had a higher ALE value.</p><p><b>CONCLUSIONS</b>The current findings suggest that CRT might improve the cognition of schizophrenia patients by increasing activations of the frontal and parietal lobe. In addition, it might provide more evidence to confirm results by including ROI studies in ALE meta-analysis.</p>
Subject(s)
Humans , Brain , Cognition , Cognitive Remediation , Likelihood Functions , Magnetic Resonance Imaging , Positron-Emission Tomography , Schizophrenia , Diagnostic Imaging , TherapeuticsABSTRACT
<p><b>BACKGROUND</b>Few characteristic changes of linear electroencephalograph (EEG) have been reported in schizophrenia. The aim of the present study was to investigate the changes in temporal-spatial dimensional properties of EEG under different cognitive tasks in patients with schizophrenia.</p><p><b>METHODS</b>EEG was recorded by using EEG-1518K system and mapping system (Nihon Kohden Tomioka Corporation, Japan) in 45 schizophrenic patients and 47 healthy adults (normal control, NC) under five states: eyes closed, eyes open, mental arithmetic test with eyes closed, memory test with eyes open, and number cancellation test. Correlation dimension (D2) and point-wise correlation dimension (PD2) were calculated for all EEG analyses.</p><p><b>RESULTS</b>(1) There were no significant differences of D2 and PD2 between NC and schizophrenic patients under states of eyes open and closed. (2) Compared with NC, schizophrenic patients showed decreased performance of D2 in mental arithmetic test with eyes closed and number cancellation test (mental arithmetic test with eyes closed: Nc 5.9 ± 0.6, Sch 3.0 ± 0.8; number cancellation test: Nc 6.0 ± 0.6, Sch 4.4 ± 0.7; P < 0.05 or P < 0.01). (3) Schizophrenic patients also showed decrease performance of PD2 in mental arithmetic test with eyes closed, memory test with eyes open, and number cancellation test (mental arithmetic test with eyes closed: Nc 6.9 ± 0.7, Sch 4.0 ± 0.8; memory test with eyes open: Nc 6.6 ± 0.8, Sch 5.0 ± 0.9; number cancellation test: Nc 7.1 ± 0.7, Sch 4.8 ± 0.9; P < 0.05 or P < 0.01).</p><p><b>CONCLUSIONS</b>Nonlinear dynamic analysis provided a new approach in clinical investigation of EEG signals. It was helpful to further understand the cerebral mechanism in schizophrenic cognitive process.</p>
Subject(s)
Adult , Female , Humans , Male , Middle Aged , Cognition , Physiology , Electroencephalography , Nonlinear Dynamics , SchizophreniaABSTRACT
Objective: To study the differences of activated brain areas during brain error monitoring in schizophrenia patients. Methods: The latencies and amplitudes of error related negativity (ERN) were obtained in 16 patients with first episode schizophrenia and 25 normal controls by high-density event related potential (ERP) technique, and the activated areas were analyzed by low resolution electromagnetic tomography (LORETA). Results: The correct response rate was significantly lower in the schizophrenia participant group than in the control group (P<0.01), and the reaction periods of correct responses and incorrect responses were significantly longer in the schizophrenia group than in the control group (P<0.05, P<0.01). The ERN latencies in the schizophrenic patients were significantly longer on Cz and Pz electrodes compared with those in the control subjects (P<0.05) and ERN amplitudes were significantly smaller than those in the controls (P<0.05). The activation of insula, superior temporal gyrus, middle temporal gyrus, and inferior parietal lobule were obviously lower in the schizophrenic participants than in the controls. Conclusion: Some brain area, such as insular, may contribute to the dysfunction of error monitoring in schizophrenia patients.
ABSTRACT
<p><b>BACKGROUND</b>Prior research about N400 has been mainly based on English stimuli, while the cognitive processing of Chinese characters is still unclear. The aim of the present study was to further investigate the semantic processing of Chinese idioms.</p><p><b>METHODS</b>Event related potentials (ERP) component N400 was elicited by 38 pairs of matching (congruent) and mismatching (incongruent) ended Chinese idioms: ending words with same phoneme but different shape and meaning (sPdSdM), with similar shape but different phoneme and meaning (sSdPdM), with same meaning but different phoneme and shape (sMdPdS), and words with different phoneme, shape and meaning (dPdSdM) and recorded by Guangzhou Runjie WJ-1 ERP instruments. In 62 right-handed healthy adults (age 19 - 50 years), N400 amplitudes and latencies were compared between matching and mismatching conditions at Fz, Cz and Pz.</p><p><b>RESULTS</b>N400 showed a midline distribution and could be elicited in electrodes Fz, Cz and Pz. The mean values of N400 latencies and amplitudes were obtained for matching and mismatching ending words in healthy adults. Significant differences were found in N400 latencies and amplitudes in matching and mismatching ending-words idioms in healthy adults (P < 0.05). Compared with matching ending-words idioms, N400 latencies were prolonged and the amplitudes were increased in mismatching ones. N400s elicited by different types of stimuli showed different latencies and amplitudes, and longest N400 latency and largest N400 amplitude were elicited by ending-words with dPdSdM. No gender difference was found of N400 latency and amplitude in this study (P > 0.05).</p><p><b>CONCLUSIONS</b>Compared with English stimuli, Chinese ideographic words could provide more flexible stimuli for N400 research in that the words have 3-dimension changes - phoneme, shape and meaning. Features of N400 elicited by matching and mismatching ending words in Chinese idioms are mainly determined by the meaning of the word. Some issues of N400 elicited by Chinese characters deserve further research.</p>