When a rat moves, grid cells in its entorhinal cortex become active in multiple regions of the external world that form a hexagonal lattice. As the animal traverses one such "firing field," spikes tend to occur at successively earlier theta phases of the local field potential. This phenomenon is called phase precession. Here, we show that spike phases provide 80% more spatial information than spike counts and that they improve position estimates from single neurons down to a few centimeters. To understand what limits the resolution and how variable spike phases are across different field traversals, we analyze spike trains run by run. We find that the multiple firing fields of a grid cell operate as independent elements for encoding physical space. In addition, phase precession is significantly stronger than the pooled-run data suggest. Despite the inherent stochasticity of grid-cell firing, phase precession is therefore a robust phenomenon at the single-trial level, making a theta-phase code for spatial navigation feasible.
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http://dx.doi.org/10.1073/pnas.1109599109 | DOI Listing |
Nanoscale
January 2025
School of Instrumentation and Optoelectronic Engineering, Beihang University, Beijing 100191, China.
Low-frequency noise in detection systems significantly affects the performance of ultrasensitive and ultracompact spin-exchange relaxation-free atomic magnetometers. High frequency modulation detection helps effectively suppress the 1/ noise and enhance the signal-to-noise ratio, but conventional modulators are bulky and restrict the development of integrated atomic magnetometer modulation-detection systems. Resonant metasurface-based thin-film lithium-niobate (TFLN) active optics can modulate free-space light within a compact configuration.
View Article and Find Full Text PDFNat Commun
January 2025
Neurobiology Department, School of Biological Sciences, University of California, San Diego, CA, USA.
The hippocampal CA3 subregion is a densely connected recurrent circuit that supports memory by generating and storing sequential neuronal activity patterns that reflect recent experience. While theta phase precession is thought to be critical for generating sequential activity during memory encoding, the circuit mechanisms that support this computation across hippocampal subregions are unknown. By analyzing CA3 network activity in the absence of each of its theta-modulated external excitatory inputs, we show necessary and unique contributions of the dentate gyrus (DG) and the medial entorhinal cortex (MEC) to phase precession.
View Article and Find Full Text PDFRadiographics
January 2025
From the Department of Radiology, Cardiovascular Imaging, Mayo Clinic, 200 1st St SW, Rochester, MN 559905 (P.S.R., P.A.A.); Department of Radiology, Division of Cardiothoracic Imaging, Jefferson University Hospitals, Philadelphia, Pa (B.S.); Department of Radiology, Baylor Health System, Dallas, Tex (P.R.); Department of Diagnostic Radiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong SAR (M.Y.N.); and Department of Diagnostic Radiology, Cleveland Clinic, Cleveland, Ohio (M.A.B.).
Cardiac MRI (CMR) is an important imaging modality in the evaluation of cardiovascular diseases. CMR image acquisition is technically challenging, which in some circumstances is associated with artifacts, both general as well as sequence specific. Recognizing imaging artifacts, understanding their causes, and applying effective approaches for artifact mitigation are critical for successful CMR.
View Article and Find Full Text PDFNeurosci Biobehav Rev
December 2024
Interdisciplinary Neuroscience Program, University of Nevada, Las Vegas, United States; Department of Psychology, University of Nevada, Las Vegas, United States.
This review highlights the crucial role of neuroelectrophysiology in illuminating the mechanisms underlying Alzheimer's disease (AD) pathogenesis and progression, emphasizing its potential to inform the development of effective treatments. Electrophysiological techniques provide unparalleled precision in exploring the intricate networks affected by AD, offering insights into the synaptic dysfunction, network alterations, and oscillatory abnormalities that characterize the disease. We discuss a range of electrophysiological methods, from non-invasive clinical techniques like electroencephalography and magnetoencephalography to invasive recordings in animal models.
View Article and Find Full Text PDFMagn Reson Med
December 2024
Department of Diagnostic, Interventional and Pediatric Radiology (DIPR), Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
Purpose: To develop and validate a novel analytical approach simplifying , , proton density (PD), and off-resonance quantifications from phase-cycled balanced steady-state free precession (bSSFP) data. Additionally, to introduce a method to correct aliasing effects in undersampled bSSFP profiles.
Theory And Methods: Off-resonant-encoded analytical parameter quantification using complex linearized equations (ORACLE) provides analytical solutions for bSSFP profiles.
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