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Background: Prefrontal repetitive Transcranial Magnetic Stimulation (rTMS) may improve negative symptoms in patients with schizophrenia, but few studies have investigated the underlying neural mechanism., Objective: This study aims to investigate changes in the levels of glutamate and glutamine (Glx, neurotransmitter and precursor) and N-Acetyl Aspartate (NAA) in the left dorsolateral prefrontal cortex of patients with schizophrenia treated with active bilateral prefrontal rTMS as compared to sham-rTMS, as measured with 1 H-Magnetic Resonance Spectroscopy ( 1 H-MRS)., Methods: Patients were randomized to a 3-week course of active or sham high-frequency rTMS. Pre-treatment and post-treatment 1 H-MRS data were available for 24 patients with schizophrenia with moderate to severe negative symptoms (Positive and Negative Syndrome Scale (PANSS) negative subscale ≥ 15). Absolute metabolite concentrations were calculated using LCModel with the water peak as reference. To explore the association between treatment condition and changes in concentration of Glx and NAA, we applied a linear regression model., Results: We observed an increase of Glx concentration in the active treatment group and a decrease of Glx concentration in the group receiving sham treatment. The association between changes in Glx concentration and treatment condition was significant. No significant associations between changes in NAA and treatment condition were found., Conclusions: Noninvasive neurostimulation with high-frequency bilateral prefrontal rTMS may influence Glx concentration in the prefrontal cortex of patients with schizophrenia. Larger studies are needed to confirm these findings and further elucidate the underlying neural working mechanism of rTMS., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Insight is impaired in most patients with psychosis and has been associated with poorer prognosis. The exact neural basis of impaired insight is still unknown, but it may involve disrupted prefrontal neural connectivity. Numerous studies have indeed found white matter (WM) abnormalities in psychosis. The association between prefrontal WM abnormalities and insight has not been studied yet by means of proton magnetic resonance spectroscopy ( 1 H-MRS). 1 H-MRS can be used to measure N-acetylaspartate (NAA), which is considered to be a marker of neuronal integrity. We measured insight with the Birchwood Insight Scale (BIS) as well as item G12 of the Positive and Negative Syndrome Scale (PANSS) in 88 patients with psychosis. Prefrontal WM concentrations of NAA and ratios of NAA to creatine (Cr) were assessed with 1 H-MRS. Nonparametric partial correlational analyses were conducted between NAA concentrations and insight controlling for illness duration, standardized antipsychotic dose, symptom scores, voxel grey matter content and voxel cerebrospinal fluid content. We found a significant correlation between reduced NAA/Cr ratios and poorer insight as measured with the BIS, which remained significant after additional correction for full width at half maximum, signal/noise and age. This is the first study reporting a relationship between lower prefrontal concentrations of a marker of neuronal integrity and impaired insight, providing further evidence that prefrontal pathology may play an important role in impaired insight in psychosis. This may be explained by the involvement of the prefrontal cortex in several executive and metacognitive functions, such as cognitive flexibility and perspective taking., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The majority of patients with traumatic brain injury (TBI) sustain a mild injury (mTBI). One out of 4 patients experiences persistent complaints, despite their often normal neuropsychological test results and the absence of structural brain damage on conventional neuroimaging. Susceptibility to develop persistent complaints is thought to be affected by interindividual differences in adaptation, which can also be influenced by preinjury psychological factors. Coping is a key construct of adaptation and refers to strategies to deal with new situations and serious life events. An important element of coping is the ability to regulate emotions and stress. The prefrontal cortex is a crucial area in this regulation process, given that it exerts a top-down influence on the amygdala and other subcortical structures involved in emotion processing. However, little is known about the role of the prefrontal cortex and associated brain networks in emotion regulation and adaptation post-mTBI. Especially, the influence of prefrontal dysfunction on development of persistent postconcussive complaints is poorly understood. In this article, we aim to integrate findings from functional and structural MRI studies on this topic. Alterations within the default mode, executive and salience network have been found in relation to complaints post-mTBI. Dysfunction of the medial prefrontal cortex may impair network dynamics for emotion regulation and adaptation post-mTBI, resulting in persistent post-concussive complaints.

Background: Prefrontal cortical dysfunction is frequently reported in schizophrenia and is thought to underlie negative symptoms of schizophrenia. Repetitive Transcranial Magnetic Stimulation (rTMS) can modulate neuronal activity and has been shown to improve negative symptoms in patients with schizophrenia, but the underlying neural mechanism is unknown., Objective: To examine whether 3weeks of 10Hz rTMS treatment of the bilateral dorsolateral prefrontal cortex (DLPFC) would improve frontal brain activation in patients with negative symptoms of schizophrenia, as measured by functional magnetic resonance imaging (fMRI) during the Tower of London (ToL) task., Methods: 24 patients with the diagnosis of schizophrenia with moderate to severe negative symptoms (Positive and Negative Syndrome Scale (PANSS) negative subscale≥15) participated. Patients were randomized to a 3-week (15day) course of active or sham rTMS. All patients performed the ToL task during fMRI scanning both pre-treatment and post-treatment. Differences in brain activation between the two groups were compared non-parametrically., Results: After rTMS treatment, brain activity in the active group increased in the right DLPFC and the right medial frontal gyrus as compared to the sham group. In addition, the groups significantly differed with regard to activation change in the left posterior cingulate, with decreased activation in the active and increased activation in the sham group., Conclusions: Treatment with rTMS over the DLPFC may have the potential for increasing task-related activation in frontal areas in patients with schizophrenia. Effects of different rTMS parameters and fMRI tasks targeting relevant brain circuitry deserve further investigation., Trial Registration: Nederlands Trial Register, registration number: NTR1261., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Decreased prefrontal activation (hypofrontality) in schizophrenia is thought to underlie negative symptoms and cognitive impairments, and may contribute to poor social outcome. Hypofrontality does not always improve during treatment with antipsychotics. We hypothesized that antipsychotics, which share antagonism at dopamine receptors, with a relatively low dopamine receptor affinity and high serotonin receptor affinity may have a sparing effect on prefrontal function compared to strong dopamine receptor antagonists. We systematically investigated the relation between serotonin and dopamine antagonism of antipsychotics and prefrontal functioning by reviewing neuroimaging studies. The weight of the evidence was consistent with our hypothesis that antipsychotics with low dopaminergic receptor affinity and moderate to high serotonergic affinity were associated with higher activation of the prefrontal cortex. However, clozapine, a weak dopamine and strong serotonin antagonist, was associated with decrease in prefrontal activation. Future studies should further elucidate the link between prefrontal activation and negative symptoms using prospective designs and advanced neuroimaging techniques, which may ultimately benefit the development of treatments for disabling negative symptoms., (Copyright © 2011 Elsevier B.V. All rights reserved.)