The gamma rhythm as a guardian of brain health
- Transylvanian Institute of Neuroscience, Department of Experimental and Theoretical Neuroscience, Romania
- Preclinical MRI Center, Interdisciplinary Research Institute on Bio-Nano-Sciences, Babeș-Bolyai University, Romania
- Faculty of Biology and Geology, Babeș-Bolyai University, Romania
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Norway
- STAR-UBB Institute, Babeș-Bolyai University, Romania
Figures
Figure 1
Terminology relating gamma oscillations to stimulation.
Top box: Entrained oscillations do not require an internal generation mechanism, but simply activate in response to a periodic stimulation. (A) Entrained oscillations follow closely the stimulation frequency. Bottom box: Endogenous oscillations rely on the existence of an internal oscillation-generating mechanism. (B) Induced oscillations. (C) Spontaneous oscillations. From left to right: diagram of experimental design and stimulus delivery pattern (sketch); time-frequency representation (TFR); power spectral density (PSD; * - marks a visible peak); event-related potentials (ERP) for the trial segment marked on the spectrogram. Data was acquired from V1 of awake C57BL/6 mice during light flicker stimulation at 40 Hz (in panel A), and anesthetized C57BL/6 mice during presentation of oriented drifting gratings (panel B) and during absence of stimulation (panel C). Measures of amplitude and power are computed on z-scored normalized data. fs – stimulation frequency; fr – frequency of the response. Error bands represent s.d.
Figure 2
The spectrum (PSD) does not always reveal the presence of gamma oscillations in the signal.
(A) Vigorous gamma bursting across the time-frequency landscape. (B) Succession of bursts with linearly decreasing frequency. (C) Induced oscillation around 55 Hz. Toy data generated by inserting oscillatiory packets (Morlet atoms) into a pink noise signal. Error bands represent s.d. TFR, time-frequency representation; PSD, power spectral density.
Figure 3
Robust gamma bursting in spontaneous activity recorded in humans and mice.
(A) Resting state EEG (Oz electrode) recorded with eyes-closed in a human participant. (B) Same as in A, but on LFP recorded from an awake mouse. (C) Same as in B, but with spontaneous data recorded in an anesthetized mouse. Insets show time traces corresponding to gamma bursts outlined in the corresponding TFRs. TFRs were computed using superlets (Moca et al., 2021).
Figure 4
Vasomotor control by four major classes of interneurons in cortex (PV+, VIP+, SST+, NOS+).
These interneurons, with vasomotor properties, are known to act as local integrators promoting neurovascular coupling and enhancing arterial pulsatility – essential for cerebral autoregulation. VIP+ interneurons enhance arterial pulsatility through release of frequency-dependent neuropeptides, promoting vasodilation. Conversely, SST+ interneurons promote vasoconstriction, while NOS+ and PV+ cells exhibit both vasodilatory and vasoconstrictive properties. The interplay between these four classes of interneurons, along with their interactions with principal cells, support gamma rhythmogenesis which in turn, activates the glymphatic clearance. Gamma rhythmicity is essential for circuit maintenance and efficient waste removal through CSF-ISF exchange, contributing to homeostatic regulation.
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The gamma rhythm as a guardian of brain health
eLife 13:e100238.
https://doi.org/10.7554/eLife.100238
