Effects of Visual Game Experience on Auditory Processing Speed.

Games are one of the fastest growing and most exciting forms of entertainment. Whether casual mobile game playing has a cognitive, physiological, or behavioral effect on players whose game use is not pathological is unknown. Here we explored whether preattentive auditory processing is linked to the behavioral inhibition system (BIS) in frequent and infrequent game players. A total of 74 subjects who were enrolled in our study were divided into two groups, 40 subjects were frequent gamers and 34 subjects were age-, gender-, IQ-, and education-matched infrequent gamers. All participants underwent a passive auditory oddball paradigm and completed the behavioral inhibition/behavioral activation system scales. The mismatch negativity (MMN) latency was shorter for the frequent gamers relative to the infrequent gamers, whereas no difference in MMN amplitude was found between groups. MMN amplitude was negatively associated with the degree of behavioral inhibition in the frequent and infrequent gaming group. We also found that those who frequently play games show an enhanced processing speed, which could be an effect of game practice. Greater behavioral inhibition induces increased vigilance, and this may have enhanced the MMN amplitude in the infrequent gamers. This differential pattern of correlations suggests that differences in the BIS could lead to different approaches to auditory information processing.

Intraindividual neurophysiological variability in ultra-high-risk for psychosis and schizophrenia patients: single-trial analysis.

BACKGROUND: Intraindividual variability in neurophysiological responses is an important factor in the study of schizophrenia. Interestingly, this variability strongly predicts individual differences in cognitive processing. Neurobiological abnormalities that present during the prodromal phase of schizophrenia are not well characterized. However, these symptoms may provide insight into the key circuits involved in the disorder. AIMS: To investigate the variability in magnetoencephalographic responses at ultrahigh risk and schizophrenia patients. METHODS: Twenty-four ultrahigh risk, 21 patients with schizophrenia and 28 healthy controls were evaluated. The intraindividual variability was estimated by calculating the s.d. of the across-trial amplitude in responses to deviant and standard stimuli. The degree of phase locking across trials was calculated by intertrial coherence. RESULTS: Greater variability in the responses to deviant and standard tones was noted in the schizophrenia and ultrahigh risk groups compared with controls. Variability in response to standard stimuli was positively correlated with the amplitude for the standard stimuli in all of the groups. Moreover, schizophrenia patients displayed lower alpha and theta intertrial coherence compared with ultrahigh risk and controls. Mismatch negativity amplitude was correlated with the alpha intertrial coherence in all groups. Taken together, the augmented variability and reduced inter-trial coherence provide empirical evidence for increased amplitude and phase inconsistencies in schizophrenia and ultrahigh risk. CONCLUSIONS: The results implicate widespread dysfunction in amplitude modulation and phase concentration in schizophrenia and ultrahigh risk, as well as evidence for early amplitude and phase disruption. These finding suggest intraindividual variability and intertrial coherence appear to be important indicators of pathophysiological processing.

Power spectral aspects of the default mode network in schizophrenia: an MEG study.

BACKGROUND: Symptoms of schizophrenia are related to deficits in self-monitoring function, which may be a consequence of irregularity in aspects of the default mode network (DMN). Schizophrenia can also be characterized by a functional abnormality of the brain activity that is reflected in the resting state. Oscillatory analysis provides an important understanding of resting brain activity. However, conventional methods using electroencephalography are restricted because of low spatial resolution, despite their excellent temporal resolution.The aim of this study was to investigate resting brain oscillation and the default mode network based on a source space in various frequency bands such as theta, alpha, beta, and gamma using magnetoencephalography. In addition, we investigated whether these resting and DMN activities could distinguish schizophrenia patients from normal controls. To do this, the power spectral density of each frequency band at rest was imaged and compared on a spatially normalized brain template in 20 patients and 20 controls. RESULTS: The spatial distribution of DMN activity in the alpha band was similar to that found in previous fMRI studies. The posterior cingulate cortex (PCC) and lateral inferior parietal cortex were activated at rest, while the medial prefrontal cortex (MPFC) was deactivated at rest rather than during the task. Although the MPFC and PCC regions exhibited contrasting activation patterns, these two regions were significantly coherent at rest. The DMN and resting activities of the PCC were increased in schizophrenia patients, predominantly in the theta and alpha bands. CONCLUSIONS: By using MEG to identify the DMN regions, predominantly in the alpha band, we found that both resting and DMN activities were augmented in the posterior cingulate in schizophrenia patients. Furthermore, schizophrenia patients exhibited decreased coherence between the PCC and MPFC in the gamma band at rest.

Impaired mismatch negativity is associated with current functional status rather than genetic vulnerability to schizophrenia.

The aim of this study is to investigate whether mismatch negativity (MMN) is associated with functional status or is a state-independent trait for schizophrenia. We assessed MMN in 26 patients with schizophrenia, 20 healthy subjects with high genetic loading, and 48 healthy controls. Repeated measures analysis of variance and Pearson׳s correlations were used to test the hypothesis that MMN is not state-independent. We found a significant main effect of group, indicating differences in the peak amplitudes of the MMN among the three groups. Post-hoc analyses revealed that schizophrenia patients showed a significant reduction in the peak amplitude of MMN, but subjects at high genetic risk and healthy controls did not. Additionally, significant correlations between Global Assessment of Functioning scores and MMN peak amplitude at Fz and Cz were found in patients with schizophrenia. These findings suggest that MMN may reflect current functional status rather than a genetic risk for schizophrenia.

Abnormal corticostriatal-limbic functional connectivity in obsessive-compulsive disorder during reward processing and resting-state.

Compulsive behaviors in obsessive-compulsive disorder (OCD) may be related to deficits in reward processing mediated by corticostriatal circuitry, a brain network implicated in the pathophysiology of OCD. Performing compulsive actions can be perceived as a reward to OCD patients because it temporarily reduces the anxiety provoked by obsessions. Although most OCD literature provides evidence of altered regional activity in these corticostriatal circuits, very little is known about the connectivity between individual regions of the corticostriatal-limbic circuits, including the cognitive and affective neural circuitry associated with OCD. Thus, this study investigated the differences in functional connectivity (FC) patterns in this network during resting-state and incentive processing. Nineteen patients with OCD and 18 well-matched healthy controls were scanned during resting-state and a monetary incentive delay task (task state). FC was assessed using both voxel-wise and region-of-interest (ROI)-wise analyses. Voxel-wise FC analysis with the nucleus accumbens seed revealed that patients with OCD exhibited increased FC between the nucleus accumbens and the lateral orbitofrontal cortex during resting-state. Additionally, these patients showed decreased FC between the nucleus accumbens and limbic areas such as the amygdala during incentive processing. Exploratory ROI-wise FC analysis revealed that OCD patients demonstrated enhanced FC between the nucleus accumbens and the lateral orbitofrontal cortex and increased total connectivity of the lateral orbitofrontal cortex during resting-state. Additionally, patients showed alterations in FC between resting and task state. This study provides evidence that patients with OCD have altered FC in the corticostriatal-limbic network, particularly in striatal-amygdala and striatal-orbitofrontal circuitry, during incentive processing and resting-state. These findings also emphasize that functional connections in the network are modulated by affective/motivational states and further suggest that OCD patients may have abnormalities of such modulation in this network.

Impaired coupling of local and global functional feedbacks underlies abnormal synchronization and negative symptoms of schizophrenia.

BACKGROUND: Abnormal synchronization of brain oscillations is found to be associated with various core symptoms of schizophrenia. However, the underlying mechanism of this association remains yet to be elucidated. RESULTS: In this study, we found that coupled local and global feedback (CLGF) circuits in the cortical functional network are related to the abnormal synchronization and also correlated to the negative symptom of schizophrenia. Analysis of the magnetoencephalography data obtained from patients with chronic schizophrenia during rest revealed an increase in beta band synchronization and a reduction in gamma band power compared to healthy controls. Using a feedback identification method based on non-causal impulse responses, we constructed functional feedback networks and found that CLGF circuits were significantly reduced in schizophrenia. From computational analysis on the basis of the Wilson-Cowan model, we unraveled that the CLGF circuits are critically involved in the abnormal synchronization and the dynamical switching between beta and gamma bands power in schizophrenia. Moreover, we found that the abundance of CLGF circuits was negatively correlated with the development of negative symptoms of schizophrenia, suggesting that the negative symptom is closely related to the impairment of this circuit. CONCLUSIONS: Our study implicates that patients with schizophrenia might have the impaired coupling of inter- and intra-regional functional feedbacks and that the CLGF circuit might serve as a critical bridge between abnormal synchronization and the negative symptoms of schizophrenia.

Neuromagnetic auditory response and its relation to cortical thickness in ultra-high-risk for psychosis.

BACKGROUND: Higher cognitive dysfunction, lower perceptual disturbance and its relation to the structures that implicate such processes have been considered as key features in patients with schizophrenia. However, little is known about the relationship between perceptual processing and structural deficits in ultra-high-risk for psychosis. METHODS: We investigated the dipole moment of M100 auditory evoked response using a magnetoencephalography in 18 patients with schizophrenia, 16 ultra-high-risk for psychosis and 16 healthy controls, and their relation to cortical thinning on Heschl's gyrus and planum temporale. RESULTS: The auditory evoked M100 dipole moment was decreased in the ultra-high-risk subjects and in the patients with schizophrenia. Ultra-high-risk subjects showed impaired right M100 dipole magnitude, similar to patients with schizophrenia. Robust correlations between the cortical thickness of left Heschl's gyrus and the left M100 dipole moment were found in patients with schizophrenia. Moreover, correlations were also evident between right Heschl's gyrus and right M100 in subjects at ultra-high-risk for psychosis. CONCLUSIONS: The primary feature of auditory perception in ultra-high-risk subjects and schizophrenia patients is an encoding deficit that manifests as a reduced M100 dipole moment. The relationship between abnormal M100, thinning of cortical generators and their symptomatology were shown to exist prior to the onset of overt psychosis and progressively worsen over time. Therefore, they may be a potential indicator of the development of schizophrenia.

Aberrant auditory processing in schizophrenia and in subjects at ultra-high-risk for psychosis.

The N1 and the mismatch negativity (MMN) responses observed in electroencephalographic and magnetoencephalographic (MEG) recordings reflect sensory processing, sensory memory, and adaptation and are usually abnormal in patients with schizophrenia. However, their differential sensitivity to ultra-high-risk (UHR) status is controversial. The current study evaluated the sensitivity of MEG N1m, N1m adaptation, and magnetic counterpart of MMN (MMNm) in 16 UHR subjects, 15 schizophrenia patients, and 18 healthy controls (HCs) during a passive auditory oddball task. N1m adaptation was assessed using the difference in N1m dipole moment between the first and last standard tones in a standard stimulus sequence. N1m adaptation occurred in HCs, whereas neither the UHR nor the schizophrenia groups showed adaptation to the standard tone on repeated presentations. The UHR group had values between those for HCs and schizophrenia patients. Additionally, MMNm dipole moment was reduced in both the UHR and patient groups compared with HCs, whereas the UHR and schizophrenia groups did not differ from each other. These findings indicated that both N1m adaptation and MMNm were altered in UHR subjects and in schizophrenia patients, despite unaffected N1m dipole moment to the first standard tones. Moreover, both UHR and schizophrenia groups failed to show adaptation of the N1m to repeated standard tones. This failure in adaptation was more severe in patients than UHR subjects, suggesting that auditory adaptation may be sensitive to the progression of the illness and be an early biomarker of UHR for psychosis. Deficits in auditory sensory memory, on the other hand, may be similarly impaired in both groups.

An MEG study of alpha modulation in patients with schizophrenia and in subjects at high risk of developing psychosis.

BACKGROUND: Selective attention involves a dynamic interaction between attentional control systems and brain oscillations. In auditory processing, selective attention toward task-relevant stimuli and the inhibition of irrelevant information can be considered as aspects of top-down attentional control. Oscillatory rhythms in the alpha band have been found to play an important role during top-down processing. Because attention deficits have been noted in patients with schizophrenia, we examined alpha oscillations in schizophrenia and in the prodromal phase of psychosis. METHODS: The present study compared alpha oscillations using measures of both spectral power and inter-trial coherence in 17 subjects at ultra-high-risk, 10 patients with schizophrenia, and 18 matched normal control subjects. Whole-head magnetoencephalography (MEG) was conducted during an auditory oddball task to investigate alpha brain activity related to selective attention to target stimuli and selective inhibition of irrelevant stimuli. RESULTS: Patients with schizophrenia showed diminished alpha event-related desynchronization compared with the control subjects, while the ultra-high-risk subjects had values intermediate between the control subjects and schizophrenia patients. Similarly, alpha inter-trial phase coherence was lower in the schizophrenia patients than the ultra-high-risk subjects, and lower in the ultra-high-risk subjects than the normal control subjects. Furthermore, alpha band activity in the parieto-occipital region was more severely depressed in the schizophrenia patients than the ultra-high-risk subjects. CONCLUSIONS: The altered alpha band activity in the ultra-high-risk group indicates that a deficit in top-down attentional control exists before the onset of psychosis. The alpha event-related desynchronization and inter-trial coherence may reflect a functional decline in the prodromal phase of schizophrenia.

Combining halogen bonding and chirality in a two-dimensional organic metal (EDT-TTF-I2)2(D-camphorsulfonate).H2O.

A chiral organic conductor with metallic conductivity has been obtained by electrocrystallisation of a diiodotetrathiafulvalene derivative and enantiopure D-camphorsulfonate anion, associated in the solid state by halogen bonding interactions.

Pre-attentive auditory processing in ultra-high-risk for schizophrenia with magnetoencephalography.

BACKGROUND: It is uncertain whether the neurobiological abnormalities in schizophrenia emerge at the first episode of the disorder or are present during the prodromal phase. Recent neuroimaging studies indicate that some brain abnormalities are present in subjects at ultra-high-risk (UHR) for schizophrenia. Pre-attentive auditory deficits, which represent a core feature of schizophrenia, were investigated in individuals at UHR for schizophrenia. METHODS: We assessed early auditory processing indexed by the magnetoencephalographic mismatch negativity magnetic counterpart (MMNm) component elicited during a passive oddball paradigm in UHR individuals. Sixteen individuals at UHR for schizophrenia on the basis of clinical criteria and 18 healthy control subjects matched for age, gender, and education participated. A duration-deviant oddball paradigm was used to obtain MMNm dipole moment, which was measured with cortical source modeling. RESULTS: The UHR group showed a smaller right MMNm dipole moment than those of the control group. Group difference was observed in MMNm dipole latency, suggestive of slowed processing. The left MMNm dipole moment was negatively correlated with clinical symptoms measured by the Comprehensive Assessment of At-Risk Mental States positive symptom score. CONCLUSIONS: Our findings suggest that deficits in the early stage of auditory processing in individuals at UHR for schizophrenia exist before the onset of psychosis. The MMNm dipole moment might reflect the functional decline at the prodromal stage of schizophrenia.

Neuropsychological correlates of N400 anomalies in patients with schizophrenia: A preliminary report.

We investigated N400 anomalies and their relationship with neuropsychological disturbance of schizophrenia. Twelve patients with schizophrenia and 12 normal controls, matched for age, sex, education and handedness underwent both the neuropsychological test and the electrophysiological recordings employing semantic violation sentence paradigm. The patients with schizophrenia showed a reduced N400 amplitude and worse performance in the frontal lobe function test compared to healthy participants. Furthermore, statistically significant positive correlations were found between N400 amplitude and neuropsychological performances on the Stroop Task and Wisconsin Card Sorting Test in patients with schizophrenia. Our results suggest the possibility that N400 anomalies reflect the disturbed integrity of the fronto-temporal network in schizophrenia evidenced by neuropsychological deficits. In addition, we concluded that the N400 amplitude is a candidate for an endophenotype marker of schizophrenia by revealing its relationship to neuropsychological deficits.

Neuropsychological correlates of error negativity and positivity in schizophrenia patients.

The purpose of the present paper was to determine error-monitoring ability and its relationship with executive function in patients with schizophrenia. In order to evaluate error-monitoring ability, the error negativity (Ne) and error positivity (Pe) were measured using the Stroop task. The correct-related negativity (CRN) and positivity (Pc) were also measured. In addition, neuropsychological tests were administered in order to evaluate executive function. The patients with schizophrenia had significantly reduced Ne and augmented CRN amplitudes, but the Pe and Pc amplitudes of the patients were comparable to those of the controls. In addition, the Ne amplitude, measured at Fcz was positively correlated with the Trail Making Test (TMT), part B response time, and the categories achieved on the Wisconsin Card Sorting Test (WCST) in patients with schizophrenia. No significant correlations were found between Ne amplitude and performance on the neuropsychological tests in the controls. And no associations were detected between CRN, Pe, Pc amplitudes and neuropsychological performance, in either the patients with schizophrenia or the controls. Reduced Ne amplitudes and augmented CRN amplitudes in patients with schizophrenia suggest the dysfunctional behavior-monitoring system in these patients. The functional significances of Ne and Pe are discussed.