Constraints from functional magnetic resonance imaging (fMRI) were used to identify the sources of the visual P300 event-related potential (ERP). Healthy subjects performed a visual three-stimulus oddball paradigm with a difficult discrimination task while fMRI and high-density ERP data were acquired in separate sessions. This paradigm allowed us to differentiate the P3b component of the P300, which has been implicated in the detection of rare events in general (target and distractor), from the P3a component, which is mainly evoked by distractor events. The fMRI-constrained source model explained Ͼ99% of the variance of the scalp ERP for both components. The P3b was mainly produced by parietal and inferior temporal areas, whereas frontal areas and the insula contributed mainly to the P3a. This source model reveals that both higher visual and supramodal association areas contribute to the visual P3b and that the P3a has a strong frontal contribution, which is compatible with its more anterior distribution on the scalp. The results point to the involvement of distinct attentional subsystems in target and distractor processing.

Cortical functional connectivity, as indicated by the concurrent spontaneous activity of spatially segregated regions, is being studied increasingly because it may determine the reaction of the brain to external stimuli and task requirements and it is reportedly altered in many neurological and psychiatric disorders. In functional magnetic resonance imaging (fMRI), such functional connectivity is investigated commonly by correlating the time course of a chosen "seed voxel" with the remaining voxel time courses in a voxel-by-voxel manner. This approach is biased by the actual choice of the seed voxel, however, because it only shows functional connectivity for the chosen brain region while ignoring other potentially interesting patterns of coactivation. We used spatial independent component analysis (sICA) to assess cortical functional connectivity maps from resting state data. SICA does not depend on any chosen temporal profile of local brain activity. We hypothesized that sICA would be able to find functionally connected brain regions within sensory and motor regions in the absence of task-related brain activity. We also investigated functional connectivity patterns of several parietal regions including the superior parietal cortex and the posterior cingulate gyrus. The components of interest were selected in an automated fashion using predefined anatomical volumes of interest. SICA yielded connectivity maps of bilateral auditory, motor and visual cortices. Moreover, it showed that prefrontal and parietal areas are also functionally connected within and between hemispheres during the resting state. These connectivity maps showed an extremely high degree of consistency in spatial, temporal, and frequency parameters within and between subjects. These results are discussed in the context of the recent debate on the functional relevance of fluctuations of neural activity in the resting state.

The neuronal response patterns that are required for an adequate behavioural reaction to subjectively relevant changes in the environment are commonly studied by means of oddball paradigms, in which occasional 'target' stimuli have to be detected in a train of frequent 'non-target' stimuli. The detection of such task-relevant stimuli is accompanied by a parietocentral positive component of the event-related potential, the P300. We performed EEG recordings of visual and auditory event-related potentials and functional magnetic resonance imaging (fMRI) when healthy subjects performed an oddball task. Significant increases in fMRI signal for target versus non-target conditions were observed in the supramarginal gyrus, frontal operculum and insular cortex bilaterally, and in further circumscribed parietal and frontal regions. These effects were consistent over various stimulation and response modalities and can be regarded as specific for target detection in both the auditory and the visual modality. These results therefore contribute to the understanding of the target detection network in human cerebral cortex and impose constraints on attempts at localizing the neuronal P300 generator. This is of importance both from a neurobiological perspective and because of the widespread application of the physiological correlates of target detection in clinical P300 studies.

Background The cerebrospinal fluid (CSF) biomarkers amyloid β (Aβ)-42, total-tau (T-tau), and phosphorylated-tau (P-tau) demonstrate good diagnostic accuracy for Alzheimer’s disease (AD). However, there are large variations in biomarker measurements between studies, and between and within laboratories. The Alzheimer’s Association has initiated a global quality control program to estimate and monitor variability of measurements, quantify batch-to-batch assay variations, and identify sources of variability. In this article, we present the results from the first two rounds of the program. Methods The program is open for laboratories using commercially available kits for Aβ, T-tau, or P-tau. CSF samples (aliquots of pooled CSF) are sent for analysis several times a year from the Clinical Neurochemistry Laboratory at the Molndal campus of the University of Gothenburg, Sweden. Each round consists of three quality control samples. Results Forty laboratories participated. Twenty-six used INNOTESTenzyme-linked immunosorbent assay kits, 14 used Luminex xMAP with the INNO-BIA AlzBio3 kit (both measure Aβ-(1-42), P-tau(181P), and T-tau), and 5 used Meso Scale Discovery with the Aβ triplex (AβN-42, AβN-40, and AβN-38) or T-tau kits. The total coefficients of variation between the laboratories were 13% to 36%. Five laboratories analyzed the samples six times on different occasions. Within-laboratory precisions differed considerably between biomarkers within individual laboratories. Conclusions Measurements of CSF AD biomarkers show large between-laboratory variability, likely caused by factors related to analytical procedures and the analytical kits. Standardization of laboratory procedures and efforts by kit vendors to increase kit performance might lower variability, and will likely increase the usefulness of CSF AD biomarkers.

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Cognitive deficits are core symptoms in patients with schizophrenia (SZ) and major depressive disorder (MDD), but specific and approved treatments for cognitive deterioration are scarce. Experimental and clinical evidence suggests that aerobic exercise may help to reduce psychopathological symptoms and support cognitive performance, but this has not yet been systematically investigated. In the current study, we examined the effects of aerobic training on cognitive performance and symptom severity in psychiatric inpatients. To our knowledge, to date, no studies have been published that directly compare the effects of exercise across disease groups in order to acquire a better understanding of disease-specific versus general or overlapping effects of physical training intervention. Two disease groups (n=22 MDD patients, n=29 SZ patients) that were matched for age, gender, duration of disease and years of education received cognitive training combined either with aerobic physical exercise or with mental relaxation training. The interventions included 12 sessions (3 times a week) over a time period of 4 weeks, lasting each for 75 min (30 min of cognitive training+45 min of cardio training/mental relaxation training). Cognitive parameters and psychopathology scores of all participants were tested in pre- and post-testing sessions and were then compared with a waiting control group. In the total group of patients, the results indicate an increase in cognitive performance in the domains visual learning, working memory and speed of processing, a decrease in state anxiety and an increase in subjective quality of life between pre- and post-testing. The effects in SZ patients compared with MDD patients were stronger for cognitive performance, whereas there were stronger effects in MDD patients compared with SZ patients in individual psychopathology values. MDD patients showed a significant reduction in depressive symptoms and state anxiety values after the intervention period. SZ patients reduced their negative symptoms severity from pre- to post-testing. In sum, the effects for the combined training were superior to the other forms of treatment. Physical exercise may help to reduce psychopathological symptoms and improve cognitive skills. The intervention routines employed in this study promise to add the current psychopathological and medical treatment options and could aid the transition to a multidisciplinary approach. However, a limitation of the current study is the short time interval for interventions (6 weeks including pre- and post-testing).

One of the most consistent findings in the neuroscience of autism is hypoactivation of the fusiform gyrus (FG) during face processing. In this study the authors examined whether successful facial affect recognition training is associated with an increased activation of the FG in autism. The effect of a computer-based program to teach facial affect identification was examined in 10 individuals with high-functioning autism. Blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) changes in the FG and other regions of interest, as well as behavioral facial affect recognition measures, were assessed pre- and posttraining. No significant activation changes in the FG were observed. Trained participants showed behavioral improvements, which were accompanied by higher BOLD fMRI signals in the superior parietal lobule and maintained activation in the right medial occipital gyrus.