Robust memories through neuron networks: How does the brain store information over a long period of time? Gonzalez et al. chronically implanted custom-built high-sensitivity microendoscopes and performed long-term imaging of neuronal activity in freely moving mutant mice. The majority of neurons were active on most days, but their firing rate changed across sessions and tasks. Although the responses of individual neurons changed, the responses of groups of neurons with synchronous activity were very stable across days and weeks. In addition, the network activity in hippocampal area CA1 recovered after an extended period without performing the task or even after abnormal activity induced by local lesions. These findings indicate the presence of attractor-like ensemble dynamics as a mechanism by which the representations of an environment are encoded in the brain. Science , this issue p. 821

There are no pharmacological disease-modifying treatments with an enduring effect to mitigate the seizures and comorbidities of established chronic temporal lobe epilepsy (TLE). This study aimed to evaluate for disease modifying effects of sodium selenate treatment in the chronically epileptic rat post-status epilepticus (SE) model of drug-resistant TLE. Wistar rats underwent kainic acid-induced SE or sham. Ten-weeks post-SE, animals received sodium selenate, levetiracetam, or vehicle subcutaneousinfusion continuously for 4 weeks. To evaluate the effects of the treatments, one week of continuous video-EEG was acquired before, during, and 4, 8 weeks post-treatment, followed by behavioral tests. Targeted and untargeted proteomics and metabolomics were performed on post-mortem brain tissue to identify potential pathways associated with modified disease outcomes. Telomere length was investigated as a novel surrogate marker of epilepsy disease severity in our current study. The results showed that sodium selenate treatment was associated with mitigation of measures of disease severity at 8 weeks post-treatment cessation; reducing the number of spontaneous seizures (p< 0.05), cognitive dysfunction (p< 0.05), and sensorimotor deficits (p< 0.01). Moreover, selenate treatment was associated with increased protein phosphatase 2A (PP2A) expression, reduced hyperphosphorylated tau, and reversed telomere length shortening (p< 0.05). Network medicine integration of multi-omics/pre-clinical outcomes identified protein-metabolite modules positively correlated with TLE. Our results provide evidence that treatment with sodium selenate results in a sustained disease-modifying effect in chronically epileptic rats in the post-KA SE model of TLE, including improved comorbid learning and memory deficits.

Absence epilepsy syndromes are part of the genetic generalized epilepsies, the pathogenesis of which remains poorly understood, although a polygenic architecture is presumed. Current focus on single molecule or gene identification to elucidate epileptogenic drivers is unable to fully capture the complex dysfunctional interactions occurring at a genetic/proteomic/metabolomic level. Here, we employ a multi-omic, network-based approach to characterize the molecular signature associated with absence epilepsy-like phenotype seen in a well validated rat model of genetic generalized epilepsy with absence seizures. Electroencephalographic and behavioral data was collected from Genetic Absence Epilepsy Rats from Strasbourg (GAERS, n = 6) and non-epileptic controls (NEC, n = 6), followed by proteomic and metabolomic profiling of the cortical and thalamic tissue of rats from both groups. The general framework of weighted correlation network analysis (WGCNA) was used to identify groups of highly correlated proteins and metabolites, which were then functionally annotated through joint pathway enrichment analysis. In both brain regions a large protein-metabolite module was found to be highly associated with the GAERS strain, absence seizures and associated anxiety and depressive-like phenotype. Quantitative pathway analysis indicated enrichment in oxidative pathways and a downregulation of the lysine degradation pathway in both brain regions. GSTM1 and ALDH2 were identified as central regulatory hubs of the seizure-associated module in the somatosensory cortex and thalamus, respectively. These enzymes are involved in lysine degradation and play important roles in maintaining oxidative balance. We conclude that the dysregulated pathways identified in the seizure-associated module may be involved in the aetiology and maintenance of absence seizure activity. This dysregulated activity could potentially be modulated by targeting one or both central regulatory hubs.

Heat shock protein 72 (Hsp72), a stress‐inducible member of the Hsp70 family, has been implicated in mitigating the pathogenic effects of amyloid‐beta (Aβ) and tau pathology; both key factors associated with the development and progression of Alzheimer's disease (AD). However, no in vivo study has been conducted to investigate the ability of Hsp72 to provide benefit when both Aβ and tau pathology are present concurrently. This study set out to utilize a genetic approach (transgenic overexpression) and a pharmacological validation approach (BGP‐15) to increase Hsp72 expression in mice exhibiting Aβ and tau pathology (5xFADxTg30 model). Our findings indicate that genetic Hsp72 overexpression did not significantly alter Aβ or tau burden, deficits in motor performance, or alterations to body composition in this model, but modestly improved survival rates (driven by findings in male mice) and altered anxiety‐like behavior (driven by findings in female mice). Similarly, BGP‐15 treatment was unable to rescue behavioral traits, motor deficits, body composition, or alleviate Aβ or tau accumulation, although this treatment also showed a trend towards enhancing survival (again in male mice) and altered anxiety‐like behavior (specifically in female mice). While the 5xFADxTg30 mice demonstrated seizure susceptibility compared to WT mice, BGP‐15 was unable to alleviate this trait. These findings were independent of any measurable increase in Hsp72 abundance in the brain in response to BGP‐15. Together, these findings suggest a limited impact of genetic overexpression and pharmacological targeting of Hsp72 protein abundance in this combined Aβ and tau model, although some sex‐specific differences are noted.