Hippocampal place cells represent the cellular substrate of episodic memory. Place cell ensembles reorganize to support learning but must also maintain stable representations to facilitate memory recall. Despite extensive research, the learning-related role of place cell dynamics in health and disease remains elusive.
View Article and Find Full Text PDFMossy cells in the hilus of the dentate gyrus constitute a major excitatory principal cell type in the mammalian hippocampus; however, it remains unknown how these cells behave in vivo. Here, we have used two-photon Ca imaging to monitor the activity of mossy cells in awake, behaving mice. We find that mossy cells are significantly more active than dentate granule cells in vivo, exhibit spatial tuning during head-fixed spatial navigation, and undergo robust remapping of their spatial representations in response to contextual manipulation.
View Article and Find Full Text PDFThe mammalian hippocampus is critical for spatial information processing and episodic memory. Its primary output cells, CA1 pyramidal cells (CA1 PCs), vary in genetics, morphology, connectivity, and electrophysiological properties. It is therefore possible that distinct CA1 PC subpopulations encode different features of the environment and differentially contribute to learning.
View Article and Find Full Text PDFAdult-born granule cells (abGCs) have been implicated in cognition and mood; however, it remains unknown how these cells behave in vivo. Here, we have used two-photon calcium imaging to monitor the activity of young abGCs in awake behaving mice. We find that young adult-born neurons fire at a higher rate in vivo but paradoxically exhibit less spatial tuning than their mature counterparts.
View Article and Find Full Text PDFThe transition of promising technologies for production of renewable chemicals from a laboratory scale to commercial scale is often difficult and expensive. As a result the timeframe estimated for commercialization is typically underestimated resulting in much slower penetration of these promising new methods and products into the chemical industries. The theme of 'sugar is the next oil' connects biological, chemical, and thermochemical conversions of renewable feedstocks to products that are drop-in replacements for petroleum derived chemicals or are new to market chemicals/materials.
View Article and Find Full Text PDFFluorescence imaging is a powerful method for monitoring dynamic signals in the nervous system. However, analysis of dynamic fluorescence imaging data remains burdensome, in part due to the shortage of available software tools. To address this need, we have developed SIMA, an open source Python package that facilitates common analysis tasks related to fluorescence imaging.
View Article and Find Full Text PDFCA1 pyramidal cells (PCs) are not homogeneous but rather can be grouped by molecular, morphological, and functional properties. However, less is known about synaptic sources differentiating PCs. Using paired recordings in vitro, two-photon Ca(2+) imaging in vivo, and computational modeling, we found that parvalbumin-expressing basket cells (PVBCs) evoked greater inhibition in CA1 PCs located in the deep compared to superficial layer of stratum pyramidale.
View Article and Find Full Text PDFFear memories guide adaptive behavior in contexts associated with aversive events. The hippocampus forms a neural representation of the context that predicts aversive events. Representations of context incorporate multisensory features of the environment, but must somehow exclude sensory features of the aversive event itself.
View Article and Find Full Text PDFThe beneficial effects of chronic and early pharmacological treatment with ethosuximide on epileptogenesis were studied in a genetic absence epilepsy model comorbid for depression. It was also investigated whether there is a critical treatment period and treatment length. Cortical excitability in the form of electrical evoked potentials, but also to cortico-thalamo-cortical network activity (spike-wave discharges, SWD and afterdischarges), white matter changes representing extra cortico-thalamic functions and depressive-like behavior were investigated.
View Article and Find Full Text PDFPurpose: Functional magnetic resonance imaging (fMRI)-based resting functional connectivity is well suited for measuring slow correlated activity throughout brain networks. Epilepsy involves chronic changes in normal brain networks, and recent work demonstrated enhanced resting fMRI connectivity between the hemispheres in childhood absence epilepsy. An animal model of this phenomenon would be valuable for investigating fundamental mechanisms and testing therapeutic interventions.
View Article and Find Full Text PDFChildhood absence epilepsy (CAE) has been recently linked to a number of cognitive, behavioral, and emotional disorders. Identification of affective disorders (anxiety and depression) presents unique challenges in pediatric populations, and successful early intervention may significantly improve long-term developmental outcomes. The current study examined the specific anxiety and depression symptoms children with CAE experience, and explored the role of disease factors in the severity of their presentation.
View Article and Find Full Text PDFThe default mode network has been hypothesized based on the observation that specific regions of the brain are consistently activated during the resting state and deactivated during engagement with task. The primary nodes of this network, which typically include the precuneus/posterior cingulate, the medial frontal and lateral parietal cortices, are thought to be involved in introspective and social cognitive functions. Interestingly, this same network has been shown to be selectively impaired during epileptic seizures associated with loss of consciousness.
View Article and Find Full Text PDFPatients with childhood absence epilepsy (CAE) often demonstrate impaired interictal attention, even with control of their seizures. No previous study has investigated the brain networks involved in this impairment. We used the continuous performance task (CPT) of attentional vigilance and the repetitive tapping task (RTT), a control motor task, to examine interictal attention in 26 children with CAE and 22 matched healthy controls.
View Article and Find Full Text PDFImpaired consciousness requires altered cortical function. This can occur either directly from disorders that impair widespread bilateral regions of the cortex or indirectly through effects on subcortical arousal systems. It has therefore long been puzzling why focal temporal lobe seizures so often impair consciousness.
View Article and Find Full Text PDFPurpose: Absence seizures cause transient impairment of consciousness. Typical absence seizures occur in children, and are accompanied by 3-4-Hz spike-wave discharges (SWDs) on electroencephalography (EEG). Prior EEG-functional magnetic resonance imaging (fMRI) studies of SWDs have shown a network of cortical and subcortical changes during these electrical events.
View Article and Find Full Text PDFPatients with epilepsy are at risk of traffic accidents when they have seizures while driving. However, driving is an essential part of normal daily life in many communities, and depriving patients of driving privileges can have profound consequences for their economic and social well-being. In the current study, we collected ictal performance data from a driving simulator and two other video games in patients undergoing continuous video/EEG monitoring.
View Article and Find Full Text PDFGeneralized tonic-clonic seizures cause widespread physiological changes throughout the cerebral cortex and subcortical structures in the brain. Using combined blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) at 9.4 T and electroencephalography (EEG), these changes can be characterized with high spatiotemporal resolution.
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