Broadband high-frequency activity (BHA; 70 to 150 Hz), also known as "high gamma," a key analytic signal in human intracranial (electrocorticographic) recordings, is often assumed to reflect local neural firing [multiunit activity (MUA)]. As the precise physiological substrates of BHA are unknown, this assumption remains controversial. Our analysis of laminar multielectrode data from V1 and A1 in monkeys outlines two components of stimulus-evoked BHA distributed across the cortical layers: an "early-deep" and "late-superficial" response. Early-deep BHA has a clear spatial and temporal overlap with MUA. Late-superficial BHA was more prominent and accounted for more of the BHA signal measured near the cortical pial surface. However, its association with local MUA is weak and often undetectable, consistent with the view that it reflects dendritic processes separable from local neuronal firing.
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http://dx.doi.org/10.1126/sciadv.abb0977 | DOI Listing |
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January 2025
Key Laboratory of Aerospace Materials and Performance (Ministry of Education) School of Materials Science and Engineering, Beihang University, No.37 Xueyuan Road, Beijing, 100191, P. R. China.
A reasonable construction of hollow structures to obtain high-performance absorbers is widely studied, but it is still a challenge to select suitable materials to improve the low-frequency attenuation performance. Here, the FeO@C@NiO nanoprisms with unique tip shapes, asymmetric multi-path hollow cavity, and core-shell heteroepitaxy structure are designed and synthesized based on anisotropy and intrinsic physical characteristics. Impressively, by changing the load of NiO, the composites achieve strong absorption, broadband, low-frequency absorption: the reflection loss of -55.
View Article and Find Full Text PDFPLoS One
December 2024
Xilinhot Earthquake Monitoring Center Station, Xilinhot, Inner Mongolia Autonomous Region, China.
Analysis of the continuous ambient noise data collected by a dense network of broadband seismic stations reveals the characteristics of ambient noise in densely populated urban areas. A study conducted in central Inner Mongolia utilized ten broadband stations to investigate two distinct repetitive and intense noise signals with predominant frequencies ranging from 1-20 Hz and 0.01-1 Hz.
View Article and Find Full Text PDFMicromachines (Basel)
November 2024
Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE), San Andrés Cholula 72840, Mexico.
A full characterization of multilayer ceramic capacitors including variations in capacitance, series resistance, and series inductance is accomplished by measuring their RF response while being submitted to mechanical stress. This allows for the first time quantifying the degradation of the device's RF performance when cracks form within its structure. In this regard, the main challenge is designing an interface for measuring the high-frequency response of a capacitor using a vector network analyzer as a bending test on a PCB in progress, which is achieved here by using a microstrip-based test fixture.
View Article and Find Full Text PDFJ Neurophysiol
January 2025
Department of Cellular Neuroscience, Leibniz Institute for Neurobiology, Magdeburg, Germany.
The high-frequency activity (HFA; 80-150 Hz) in human intracranial recordings shows a differential modulation to different degrees in contrast when stimuli are behaviorally relevant, indicating a feedforward process. However, the HFA is also significantly dominated by superficial layers and exhibits a peak before 200 ms, suggesting that it is more likely a feedback signal. Magnetoencephalographic (MEG) recordings are suited to reveal an HFA modulation similar to its modulation in intracranial recordings.
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