Explaining Delusions: Reducing Uncertainty Through Basic and Computational Neuroscience.

Delusions, the fixed false beliefs characteristic of psychotic illness, have long defied understanding despite their response to pharmacological treatments (e.g., D2 receptor antagonists). However, it can be challenging to discern what makes beliefs delusional compared with other unusual or erroneous beliefs. We suggest mapping the putative biology to clinical phenomenology with a cognitive psychology of belief, culminating in a teleological approach to beliefs and brain function supported by animal and computational models. We argue that organisms strive to minimize uncertainty about their future states by forming and maintaining a set of beliefs (about the organism and the world) that are robust, but flexible. If uncertainty is generated endogenously, beliefs begin to depart from consensual reality and can manifest into delusions. Central to this scheme is the notion that formal associative learning theory can provide an explanation for the development and persistence of delusions. Beliefs, in animals and humans, may be associations between representations (e.g., of cause and effect) that are formed by minimizing uncertainty via new learning and attentional allocation. Animal research has equipped us with a deep mechanistic basis of these processes, which is now being applied to delusions. This work offers the exciting possibility of completing revolutions of translation, from the bedside to the bench and back again. The more we learn about animal beliefs, the more we may be able to apply to human beliefs and their aberrations, enabling a deeper mechanistic understanding.

The value of muscle biopsies in Pompe disease: identifying lipofuscin inclusions in juvenile- and adult-onset patients.

BACKGROUND: Pompe disease, an inherited deficiency of lysosomal acid alpha-glucosidase (GAA), is a metabolic myopathy with heterogeneous clinical presentations. Late-onset Pompe disease (LOPD) is a debilitating progressive muscle disorder that can occur anytime from early childhood to late adulthood. Enzyme replacement therapy (ERT) with recombinant human GAA is currently available for Pompe patients. Although ERT shows some benefits, the reversal of skeletal muscle pathology - lysosomal glycogen accumulation and autophagic buildup - remains a challenge. In this study, we examined the clinical status and muscle pathology of 22 LOPD patients and one atypical infantile patient on ERT to understand the reasons for muscle resistance to ERT. RESULTS: The patients were divided into three groups for analysis, based on the age of onset and diagnosis: adult-onset patients, juvenile-onset patients, and those identified through newborn screening (NBS). The areas of autophagic buildup found in patients' biopsies of all three groups, contained large autofluorescent inclusions which we show are made of lipofuscin, an indigestible intralysosomal material typically associated with ageing. These inclusions, analysed by staining, spectral analysis, time-resolved Fluorescence Lifetime Imaging (FLIM), and Second Harmonic Generation (SHG) imaging, were the major pathology remaining in many fibers after ERT. The best outcome of ERT both clinically and morphologically was observed in the NBS patients. CONCLUSIONS: The muscle biopsy, in spite of its shortcomings, allowed us to recognize an underreported, ERT-resistant pathology in LOPD; numerous lysosomes and autolysosomes loaded with lipofuscin appear to be a hallmark of LOPD skeletal muscle. Lipofuscin accumulation - a result of inefficient lysosomal degradation - may in turn exacerbate both lysosomal and autophagic abnormalities.

Skeletal muscle pathology of infantile Pompe disease during long-term enzyme replacement therapy.

BACKGROUND: Pompe disease is an autosomal recessive metabolic neuromuscular disorder caused by a deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA). It has long been believed that the underlying pathology leading to tissue damage is caused by the enlargement and rupture of glycogen-filled lysosomes. Recent studies have also implicated autophagy, an intracellular lysosome-dependent degradation system, in the disease pathogenesis. In this study, we characterize the long-term impact of enzyme replacement therapy (ERT) with recombinant human GAA (rhGAA) on lysosomal glycogen accumulation and autophagy in some of the oldest survivors with classic infantile Pompe disease (IPD). METHODS: Muscle biopsies from 8 [4 female, 4 male; 6 cross-reactive immunologic material (CRIM)-positive, 2 CRIM-negative] patients with a confirmed diagnosis of classic IPD were examined using standard histopathological approaches. In addition, muscle biopsies were evaluated by immunostaining for lysosomal marker (lysosomal-associated membrane protein-2; LAMP2), autophagosomal marker (microtubule-associated protein 1 light chain 3; LC3), and acid and alkaline ATPases. All patients received rhGAA by infusion at cumulative biweekly doses of 20-40 mg/kg. RESULTS: Median age at diagnosis of classic IPD was 3.4 months (range: 0 to 6.5 months; n = 8). At the time of muscle biopsy, the patients' ages ranged from 1 to 103 months and ERT duration ranged from 0 (i.e., baseline, pre-ERT) to 96 months. The response to therapy varied considerably among the patients: some patients demonstrated motor gains while others experienced deterioration of motor function, either with or without a period of initial clinical benefit. Skeletal muscle pathology included fiber destruction, lysosomal vacuolation, and autophagic abnormalities (i.e., buildup), particularly in fibers with minimal lysosomal enlargement. Overall, the pathology reflected clinical status. CONCLUSIONS: This is the first study to investigate the impact of rhGAA ERT on lysosomal glycogen accumulation and autophagic buildup in patients with classic IPD beyond 18 months of treatment. Our findings indicate that ERT does not fully halt or reverse the underlying skeletal muscle pathology in IPD. The best outcomes were observed in the two patients who began therapy early, namely at 0.5 and 1.1 months of age.

Immunohistochemical characterization of axonal sprouting in mice.

PURPOSE: Transgenic manipulation of mouse physiology facilitates the preclinical study of genetic risk factors, neural plasticity, and reactive processes accompanying Alzheimer's disease. Alternatively, entorhinal cortex lesions (ECLs) model pathophysiological denervation and axonal sprouting in rat. Given reports of anatomical differences between the mouse and rat hippocampus, application of the ECL paradigm to transgenic mice first requires comprehensive characterization of axonal sprouting in the wild-type. METHODS: Adult male C57BL/6 mice sustained unilateral transections of the perforant pathway. Subjects were sacrificed at 1, 4, 10, 18, and 28 days postlesion, and hippocampal sections were stained for AChE, the postsynaptic terminal marker drebrin, and the presynaptic terminal proteins SNAP-25, GAP-43, synapsin, and synaptophysin. To examine synaptic turnover and reinnervation, ipsilateral-to-contralateral staining densities were determined within the dentate molecular layer, and shrinkage-corrected ratios were compared to 28 day-yoked sham cases. RESULTS: At 28 days postlesion, ipsilateral terminal marker densities exhibited significant depression. In contrast, qualitative analyses at earlier time points suggested altered AChE staining patterns and increased SNAP-25 and synapsin immunoreactivity in the inner molecular layer (IML) of the dentate gyrus. CONCLUSIONS: C57BL/6 mice exhibit synaptic reorganization following perforant path transections. The IML may provide a key target for evaluation and intervention in ECL mouse models.

What else is in store for autophagy? Exocytosis of autolysosomes as a mechanism of TFEB-mediated cellular clearance in Pompe disease.

It is hard to find an area of biology in which autophagy is not involved. In fact, the topic extends beyond scientific research to stimulate intellectual exercise and entertainment-autophagy has found its way into a crossword puzzle (Klionsky, 2013). We have found yet another function of autophagy while searching for a better treatment for Pompe disease, a devastating metabolic myopathy resulting from excessive lysosomal glycogen storage. To relieve this glycogen burden, we stimulated lysosomal exocytosis through upregulation of transcription factor EB (TFEB). Overexpression of TFEB in Pompe muscle clears the cells of enlarged lysosomes, reduces glycogen levels, and alleviates autophagic buildup, the major secondary abnormality in Pompe disease. Unexpectedly, the process of exocytosis does not seem to be a purely lysosomal event; vesicles arranged along the plasma membrane are double-labeled with the lysosomal marker LAMP1 and the autophagosomal marker LC3, indicating that TFEB induces the exocytosis of autolysosomes. Furthermore, the effects of TFEB are almost abrogated in autophagy-deficient Pompe mice, suggesting a previously unrecognized role of autophagy in TFEB-mediated cellular clearance.