A structure-function mechanism for schizophrenia

Individual and simultaneous treatment with antipsychotic aripiprazole and antidepressant trazodone inhibit sterol biosynthesis in the adult brain

Polypharmacy, or the simultaneous use of multiple drugs to treat a single patient, is a common practice in psychiatry. Unfortunately, data on the health effects of commonly used combinations of medications are very limited. In this study, we therefore investigated the effects and interactions between two commonly prescribed psychotropic medications with sterol inhibiting side effects, trazodone (TRZ), an antidepressant, and aripiprazole (ARI), an antipsychotic. In vitro cell culture experiments revealed that both medications alone disrupted neuronal and astroglial sterol biosynthesis in dose-dependent manners. Furthermore, when ARI and TRZ were combined, exposure resulted in an additive 7-dehydrocholesterol (7-DHC) increase, as well as desmosterol (DES) and cholesterol decreases in both cell types. In adult mice, at baseline, we found that the three investigated sterols showed significant differences in distribution across the eight assessed brain regions. Furthermore, experimental mice treated with ARI or TRZ, or a combination of both medications for 8 days, showed strong sterol disruption across all brain regions. We show ARI or TRZ alone elevated 7-DHC and decreased DES levels in all brain regions, but with regional differences. However, the combined utilization of these two medications for 8 days did not lead to additive changes in sterol disturbances. Based on the complex roles of 7-DHC derived oxysterols, we conclude that individual and potentially simultaneous use of medications with sterol biosynthesis-inhibiting properties might have undesired side effects on the adult brain, with as yet unknown long-term consequences on mental or physical health.

From cells to sensations: A window to the physics of mind

Principles of methods for studying particles and fields that cannot be sensed by third-person observers by routine methods can be used to understand the physics of first-person properties of mind. Accordingly, whenever a system exhibits disparate features at multiple levels, unique combination of constraints offered by them direct us towards a solution that will be the first principle of that system. Using this method, it was possible to arrive at a third-person observable solution-point of brain-mind interface. Examination of this location identified a set of unique features that can allow an associatively learned (cue) stimulus to spark hallucinations that form units of first-person internal (inner) sensations reminiscent of stimuli from the associatively learned second item in timescales of milliseconds. It allows us to peep into a virtual space of mind where different modifications and integrations of units of internal sensations generate their different net conformations ranging from perception to an inner sense of hidden relationships that form a hypothesis. Since sparking of inner sensations of the late arriving (when far away) or non-arriving (when hidden) features of items started providing survival advantage, the focus of evolution might have been to optimize this property. Hence, the circuity that generates it can be considered as the primary circuitry of the system. The solution provides several testable predictions. By taking readers through the process of deriving the solution and by explaining how it interconnects disparate findings, it is hoped that the factors determining the physics of mind will become evident.

Prenatal zinc supplementation attenuates lipopolysaccharide-induced behavioral impairments in maternal immune activation model

Maternal infection during pregnancy is considered a key risk factor for developing schizophrenia in offspring. There is evidence that maternal exposure to infectious agents is associated with fetal zinc deficiency. Due to the essential role of zinc in brain function and development, in the present study, we activated maternal immune system using lipopolysaccharide (LPS) as a model of schizophrenia to examine whether zinc supplementation throughout pregnancy can reverse LPS-induced deleterious effects. To test the hypothesis, pregnant rats were treated with intraperitoneal injection of either saline or LPS (0.5 mg/kg) at gestational day 15 and 16, and zinc supplementation (30 mg/kg) was administered throughout pregnancy by gavage. At postnatal day 60, Y-maze was used to evaluate working memory of offspring. Moreover, the expression levels of catechol O-methyltransferase (COMT) and glutamate decarboxylase 67 (GAD67) were measured in the frontal cortex of the brain samples. Only male offspring prenatally exposed to LPS showed a significant impairment in working memory. In addition, prenatal LPS exposure causes a moderate decrease in GAD67 expression level in the male pups, while COMT expression was found unchanged. Interestingly, zinc supplementation restored the alterations in working memory as well as GAD67 mRNA level in the male rats. No alteration was detected for neither working memory nor COMT/GAD67 genes expression in female offspring. This study demonstrates that zinc supplementation during pregnancy can attenuate LPS-induced impairments in male pups. These results support the idea to consume zinc supplementation during pregnancy to limit neurodevelopmental deficits induced by infections in offspring.

Reading the (functional) writing on the (structural) wall: Multimodal fusion of brain structure and function via a deep neural network based translation approach reveals novel impairments in schizophrenia

This work presents a novel approach to finding linkage/association between multimodal brain imaging data, such as structural MRI (sMRI) and functional MRI (fMRI). Motivated by the machine translation domain, we employ a deep learning model, and consider two different imaging views of the same brain like two different languages conveying some common facts. That analogy enables finding linkages between two modalities. The proposed translation-based fusion model contains a computing layer that learns "alignments" (or links) between dynamic connectivity features from fMRI data and static gray matter patterns from sMRI data. The approach is evaluated on a multi-site dataset consisting of eyes-closed resting state imaging data collected from 298 subjects (age- and gender matched 154 healthy controls and 144 patients with schizophrenia). Results are further confirmed on an independent dataset consisting of eyes-open resting state imaging data from 189 subjects (age- and gender matched 91 healthy controls and 98 patients with schizophrenia). We used dynamic functional connectivity (dFNC) states as the functional features and ICA-based sources from gray matter densities as the structural features. The dFNC states characterized by weakly correlated intrinsic connectivity networks (ICNs) were found to have stronger association with putamen and insular gray matter pattern, while the dFNC states of profuse strongly correlated ICNs exhibited stronger links with the gray matter pattern in precuneus, posterior cingulate cortex (PCC), and temporal cortex. Further investigation with the estimated link strength (or alignment score) showed significant group differences between healthy controls and patients with schizophrenia in several key regions including temporal lobe, and linked these to connectivity states showing less occupancy in healthy controls. Moreover, this novel approach revealed significant correlation between a cognitive score (attention/vigilance) and the function/structure alignment score that was not detected when data modalities were considered separately.

Neurodegenerative disorders share common features of "loss of function" states of a proposed mechanism of nervous system functions

Neurodegenerative disorders are highly heterogeneous for the locations affected and the nature of the aggregated proteins. Nearly 80% of the neurodegenerative disorders occur sporadically, indicating that certain factors must combine to initiate the degenerative changes. The contiguous extension of degenerative changes from cell to cell, the association with viral fusion proteins, loss of dendritic spines (postsynaptic terminals), and the eventual degeneration of cells indicate the presence of a unique mechanism for inter-cellular spread of pathology. It is not known whether the "loss of function" states of the still unknown normal nervous system operations can lead to neurodegenerative disorders. Here, the possible loss of function states of a proposed normal nervous system function are examined. A reversible inter-postsynaptic functional LINK (IPL) mechanism, consisting of transient inter-postsynaptic membrane (IPM) hydration exclusion and partial to complete IPM hemifusions, was proposed as a critical step necessary for the binding process and the induction of internal sensations of higher brain functions. When various findings from different neurodegenerative disorders are systematically organized and examined, disease features match the effects of loss of function states of different IPLs. Changes in membrane composition, enlargement of dendritic spines by dopamine and viral fusion proteins are capable of altering the IPLs to form IPM fusion. The latter can lead to the observed lateral spread of pathology, inter-neuronal cytoplasmic content mixing and abnormal protein aggregation. Since both the normal mechanism of reversible IPM hydration exclusion and the pathological process of transient IPM fusion can evade detection, testing their occurrence may provide preventive and therapeutic opportunities for these disorders.

Rapid chain generation of interpostsynaptic functional LINKs can trigger seizure generation: Evidence for potential interconnections from pathology to behavior

The experimental finding that a paroxysmal depolarizing shift (PDS), an electrophysiological correlate of seizure activity, is a giant excitatory postsynaptic potential (EPSP) necessitates a mechanism for spatially summating several EPSPs at the level of the postsynaptic terminals (dendritic spines). In this context, we will examine reversible interpostsynaptic functional LINKs (IPLs), a proposed mechanism for inducing first-person virtual internal sensations of higher brain functions concurrent with triggering behavioral motor activity for possible pathological changes that may contribute to seizures. Pathological conditions can trigger a rapid chain generation and propagation of different forms of IPLs leading to seizure generation. A large number of observations made at different levels during both ictal and interictal periods are explained by this mechanism, including the tonic and clonic motor activity, different types of hallucinations, loss of consciousness, gradual worsening of cognitive abilities, a relationship with kindling (which uses an augmented stimulation protocol than that used for inducing long-term potentiation (LTP), which is an electrophysiological correlate of behavioral makers of internal sensation of memory), effect of a ketogenic diet on seizure prevention, dendritic spine loss in seizure disorders, neurodegenerative changes, and associated behavioral changes. The interconnectable nature of these findings is explained as loss of function states of a proposed normal functioning of the nervous system.

A supplementary circuit rule-set for the neuronal wiring

Limitations of known anatomical circuit rules necessitate the identification of supplementary rules. This is essential for explaining how associative sensory stimuli induce nervous system changes that generate internal sensations of memory, concurrent with triggering specific motor activities in response to specific cue stimuli. A candidate mechanism is rapidly reversible, yet stabilizable membrane hemi-fusion formed between the closely apposed postsynaptic membranes of different neurons at locations of convergence of sensory inputs during associative learning. The lateral entry of activity from the cue stimulus-activated postsynapse re-activates the opposite postsynapse through the hemi-fused area and induces the basic units of internal sensation (namely, semblions) as a systems property. Working, short-term and long-term memories can be viewed as functions of the number of re-activatible hemi-fusions present at the time of memory retrieval. Blocking membrane hemi-fusion either by the insertion of the herpes simplex virus (HSV) glycoproteins or by the deposition of insoluble intermediates of amyloid protein in the inter-postsynaptic extracellular matrix (ECM) space leads to cognitive impairments, supporting this mechanism. The introduction of membrane fusion blockers into the postsynaptic cell cytoplasm that attenuates long-term potentiation (LTP), a correlate of behavioral motor activities in response to memory retrieval, provides further support. The lateral spread of activity through the inter-postsynaptic membrane is capable of contributing to oscillating neuronal activity at certain neuronal orders. At the resting state these oscillations provide sub-threshold activation to many neurons at higher orders, including motor neurons maintaining them at a low initiation threshold for motor activity.