MICROSTATELAB: The EEGLAB Toolbox for Resting-State Microstate Analysis.

Microstate analysis is a multivariate method that enables investigations of the temporal dynamics of large-scale neural networks in EEG recordings of human brain activity. To meet the enormously increasing interest in this approach, we provide a thoroughly updated version of the first open source EEGLAB toolbox for the standardized identification, visualization, and quantification of microstates in resting-state EEG data. The toolbox allows scientists to (i) identify individual, mean, and grand mean microstate maps using topographical clustering approaches, (ii) check data quality and detect outlier maps, (iii) visualize, sort, and label individual, mean, and grand mean microstate maps according to published maps, (iv) compare topographical similarities of group and grand mean microstate maps and quantify shared variances, (v) obtain the temporal dynamics of the microstate classes in individual EEGs, (vi) export quantifications of these temporal dynamics of the microstates for statistical tests, and finally, (vii) test for topographical differences between groups and conditions using topographic analysis of variance (TANOVA). Here, we introduce the toolbox in a step-by-step tutorial, using a sample dataset of 34 resting-state EEG recordings that are publicly available to follow along with this tutorial. The goals of this manuscript are (a) to provide a standardized, freely available toolbox for resting-state microstate analysis to the scientific community, (b) to allow researchers to use best practices for microstate analysis by following a step-by-step tutorial, and (c) to improve the methodological standards of microstate research by providing previously unavailable functions and recommendations on critical decisions required in microstate analyses.

Examining Sensitivity to Developmental Changes on the Behavioral Inflexibility Scale.

PURPOSE: The study objective was to determine if the validated Behavioral Inflexibility Scale (BIS) is sensitive to the detection of developmental changes in inflexibility in a sample of autistic children. METHODS: Parents of autistic children (n = 146, 3-17 years) completed the BIS at two time points, one year apart, to examine change. RESULTS: The findings indicate the BIS is sensitive to the detection of developmental changes and that child-level variables are not associated with those changes. Children's Time 1 BIS scores predicted children's severity on an independent outcome measure. Finally, a relationship between total services children were receiving and change in BIS scores over time was not found. CONCLUSION: The findings suggest the BIS is a reasonable candidate for consideration as an outcome measure.

Children With Autism Produce a Unique Pattern of EEG Microstates During an Eyes Closed Resting-State Condition.

Although fMRI studies have produced considerable evidence for differences in the spatial connectivity of resting-state brain networks in persons with autism spectrum disorder (ASD) relative to typically developing (TD) peers, little is known about the temporal dynamics of these brain networks in ASD. The aim of this study was to examine the EEG microstate architecture in children with ASD as compared to TD at rest in two separate conditions - eyes-closed (EC) and eyes-open (EO). EEG microstate analysis was performed on resting-state data of 13 ASD and 13 TD children matched on age, gender, and IQ. We found that children with ASD and TD peers produced topographically similar canonical microstates at rest. Group differences in the duration and frequency of these microstates were found primarily in the EC resting-state condition. In line with previous fMRI findings that have reported differences in spatial connectivity within the salience network (previously correlated with the activity of microstate C) in ASD, we found that the duration of activation of microstate C was increased, and the frequency of microstate C was decreased in ASD as compared to TD in EC resting-state. Functionally, these results may be reflective of alterations in interoceptive processes in ASD. These results suggest a unique pattern of EEG microstate architecture in ASD relative to TD during resting-states and also that EEG microstate parameters in ASD are susceptible to differences in resting-state conditions.

Development of Intrathecal AAV9 Gene Therapy for Giant Axonal Neuropathy.

An NIH-sponsored phase I clinical trial is underway to test a potential treatment for giant axonal neuropathy (GAN) using viral-mediated GAN gene replacement (https://clinicaltrials.gov/ct2/show/NCT02362438). This trial marks the first instance of intrathecal (IT) adeno-associated viral (AAV) gene transfer in humans. GAN is a rare pediatric neurodegenerative disorder caused by autosomal recessive loss-of-function mutations in the GAN gene, which encodes the gigaxonin protein. Gigaxonin is involved in the regulation, turnover, and degradation of intermediate filaments (IFs). The pathologic signature of GAN is giant axonal swellings filled with disorganized accumulations of IFs. Herein, we describe the development and characterization of the AAV vector carrying a normal copy of the human GAN transgene (AAV9/JeT-GAN) currently employed in the clinical trial. Treatment with AAV/JeT-GAN restored the normal configuration of IFs in patient fibroblasts within days in cell culture and by 4 weeks in GAN KO mice. IT delivery of AAV9/JeT-GAN in aged GAN KO mice preserved sciatic nerve ultrastructure, reduced neuronal IF accumulations and attenuated rotarod dysfunction. This strategy conferred sustained wild-type gigaxonin expression across the PNS and CNS for at least 1 year in mice. These results support the clinical evaluation of AAV9/JeT-GAN for potential therapeutic outcomes and treatment for GAN patients.

Novel Vector Design and Hexosaminidase Variant Enabling Self-Complementary Adeno-Associated Virus for the Treatment of Tay-Sachs Disease.

GM2 gangliosidosis is a family of three genetic neurodegenerative disorders caused by the accumulation of GM2 ganglioside (GM2) in neuronal tissue. Two of these are due to the deficiency of the heterodimeric (α-ß), "A" isoenzyme of lysosomal ß-hexosaminidase (HexA). Mutations in the α-subunit (encoded by HEXA) lead to Tay-Sachs disease (TSD), whereas mutations in the ß-subunit (encoded by HEXB) lead to Sandhoff disease (SD). The third form results from a deficiency of the GM2 activator protein (GM2AP), a substrate-specific cofactor for HexA. In their infantile, acute forms, these diseases rapidly progress with mental and psychomotor deterioration resulting in death by approximately 4 years of age. After gene transfer that overexpresses one of the deficient subunits, the amount of HexA heterodimer formed would empirically be limited by the availability of the other endogenous Hex subunit. The present study used a new variant of the human HexA α-subunit, µ, incorporating critical sequences from the ß-subunit that produce a stable homodimer (HexM) and promote functional interactions with the GM2AP- GM2 complex. We report the design of a compact adeno-associated viral (AAV) genome using a synthetic promoter-intron combination to allow self-complementary (sc) packaging of the HEXM gene. Also, a previously published capsid mutant, AAV9.47, was used to deliver the gene to brain and spinal cord while having restricted biodistribution to the liver. The novel capsid and cassette design combination was characterized in vivo in TSD mice for its ability to efficiently transduce cells in the central nervous system when delivered intravenously in both adult and neonatal mice. This study demonstrates that the modified HexM is capable of degrading long-standing GM2 storage in mice, and it further demonstrates the potential of this novel scAAV vector design to facilitate widespread distribution of the HEXM gene or potentially other similar-sized genes to the nervous system.

Recent gene therapy advancements for neurological diseases.

The past few years have seen rapid advancements in vector-mediated gene transfer to the nervous system and modest successes in human gene therapy trials. The purpose of this review is to describe commonly-used viral gene transfer vectors and recent advancements towards producing meaningful gene-based treatments for central nervous system (CNS) disorders. Gene therapy trials for Canavan disease, Batten disease, adrenoleukodystrophy, and Parkinson's disease are discussed to illustrate the current state of clinical gene transfer to the CNS. Preclinical studies are under way for a number of diseases, primarily lysosomal storage disorders, using a newer generation of vectors and delivery strategies. Relevant studies in animal models are highlighted for Mucopolysaccharidosis IIIB and Krabbe disease to provide a prelude for what can be expected in the coming years for human gene transfer trials, using recent advancements in gene transfer technology. In conclusion, recent improvements in CNS gene transfer technology are expected to significantly increase the degree of disease rescue in future CNS-directed clinical trials, exceeding the modest clinical successes that have been observed so far.

Restoration of cytoskeleton homeostasis after gigaxonin gene transfer for giant axonal neuropathy.

Giant axonal neuropathy (GAN) is caused by loss of function of the gigaxonin protein. On a cellular level GAN is characterized by intermediate filament (IF) aggregation, leading to a progressive and fatal peripheral neuropathy in humans. This study sought to determine if re-introduction of the GAN gene into GAN-deficient cells and mice would restore proper cytoskeleton IF homeostasis. Treatment of primary skin fibroblast cultures from three different GAN patients with an adeno-associated virus type 2 (AAV2) vector containing a normal human GAN transgene significantly reduced the number of cells displaying vimentin IF aggregates. A proteomic analysis of these treated cells was also performed, wherein the abundance of 32 of 780 identified proteins significantly changed in response to gigaxonin gene transfer. While 29 of these responding proteins have not been directly described in association with gigaxonin, three were previously identified as being disregulated in GAN and were now shifted toward normal levels. To assess the potential application of this approach in vivo and eventually in humans, GAN mice received an intracisternal injection of an AAV9/GAN vector to globally deliver the GAN gene to the brainstem and spinal cord. The treated mice showed a nearly complete clearance of peripherin IF accumulations at 3 weeks post-injection. These studies demonstrate that gigaxonin gene transfer can reverse the cellular IF aggregate pathology associated with GAN.