Frontiers in neuroscience
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Frontiers in neuroscience · Jan 2020
Beating Rate Variability of Isolated Mammal Sinoatrial Node Tissue: Insight Into Its Contribution to Heart Rate Variability.
Because of the complexity of the interaction between the internal pacemaker mechanisms, cell interconnected signals, and interaction with other body systems, study of the role of individual systems must be performed under in vivo and in situ conditions. The in situ approach is valuable when exploring the mechanisms that govern the beating rate and rhythm of the sinoatrial node (SAN), the heart's primary pacemaker. SAN beating rate changes on a beat-to-beat basis. However, to date, there are no standard methods and tools for beating rate variability (BRV) analysis from electrograms (EGMs) collected from different mammals, and there is no centralized public database with such recordings. ⋯ Our approach will enable standardization and reproducibility of BRV analysis in mammals. Different trends were found between beating rate and BRV or HRV in isolated SAN tissue vs. recordings collected under in vivo conditions, respectively, implying a complex interaction between the SAN and the autonomic nervous system in determining HRV in vivo.
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Frontiers in neuroscience · Jan 2020
Toward Establishing Internal Validity for Correlated Gene Expression Measures in Imaging Genomics of Functional Networks: Why Distance Corrections and External Face Validity Alone Fall Short. Reply to "Distance Is Not Everything in Imaging Genomics of Functional Networks: Reply to a Commentary on Correlated Gene Expression Supports Synchronous Activity in Brain Networks".
The primary claim of the Richiardi et al. (2015) Science article is that a measure of correlated gene expression, significant strength fraction (SSF), is related to resting state fMRI (rsfMRI) networks. However, there is still debate about this claim and whether spatial proximity, in the form of contiguous clusters, accounts entirely, or only partially, for SSF (Pantazatos and Li, 2017; Richiardi et al., 2017). Here, 13 distributed networks were simulated by combining 34 contiguous clusters randomly placed throughout cortex, with resulting edge distance distributions similar to rsfMRI networks. ⋯ In conclusion, SSF is unrelated to rsfMRI networks. The main conclusion of Richiardi et al. (2015) is based on a finding that is ∼50% likely to be a false positive, not <0.01% as originally reported in the article (Richiardi et al., 2015). We discuss why distance corrections alone and external face validity are insufficient to establish a trustworthy relationship between correlated gene expression measures and rsfMRI networks, and propose more rigorous approaches to preclude common pitfalls in related studies.
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Frontiers in neuroscience · Jan 2020
ReviewGABAergic Inhibitory Interneuron Deficits in Alzheimer's Disease: Implications for Treatment.
Alzheimer's disease (AD) is a neurodegenerative disorder characterized clinically by severe cognitive deficits and pathologically by amyloid plaques, neuronal loss, and neurofibrillary tangles. Abnormal amyloid β-protein (Aβ) deposition in the brain is often thought of as a major initiating factor in AD neuropathology. However, gamma-aminobutyric acid (GABA) inhibitory interneurons are resistant to Aβ deposition, and Aβ decreases synaptic glutamatergic transmission to decrease neural network activity. ⋯ Here we describe the roles played by excitatory neurons and GABA inhibitory interneurons in Aβ-induced cognitive deficits and how altered GABA interneurons regulate AD neuropathology. We also comprehensively review recent studies on how GABA interneurons and GABA receptors can be exploited for therapeutic benefit. GABA interneurons are an emerging therapeutic target in AD, with further clinical trials urgently warranted.
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Frontiers in neuroscience · Jan 2020
ReviewCircadian and Sleep Dysfunctions in Neurodegenerative Disorders-An Update.
Disruptions of sleep and circadian rhythms are among the most debilitating symptoms in patients with neurodegenerative diseases. Their underlying pathophysiology is multilayered and multifactorial. Recent evidence suggests that sleep and circadian disturbances may influence the neurodegenerative processes as well as be their consequence. In this perspective, we provide an update of the current understanding of sleep and circadian dysregulation in Alzheimer's, Parkinson's, and Huntington's diseases.
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Frontiers in neuroscience · Jan 2020
Safety and Efficacy of Magnetic Resonance-Guided Focused Ultrasound Surgery With Autofocusing Echo Imaging.
Magnetic resonance-guided focused ultrasound surgery (MRgFUS) lesioning is a new treatment for brain disorders. However, the skull is a major barrier of ultrasound sonication in MRgFUS because it has an irregular surface and varies its size and shape among individuals. We recently developed the concept of skull density ratio (SDR) to select candidates for MRgFUS from among patients with essential tremor (ET). However, SDR is not the only factor contributing to successful MRgFUS lesioning treatment-refining the target through exact measurement of the ultrasonic echo in the transducer also improves treatment efficacy. In the present study, we carried out MRgFUS lesioning using an autofocusing echo imaging technique. We aimed to evaluate the safety and efficacy of this new approach, especially in patients with low SDR in whom previous focusing methods have failed. ⋯ clinicaltrials.gov, identifier: NCT03935581.