The use of two-photon microscopy allows for imaging of deep neural tissue in vivo. This paper examines frequency-based analysis to two-photon calcium fluorescence images with the goal of deriving smooth tuning curves. We present a multifrequency analysis approach for improved extraction of calcium responses in episodic stimulation experiments, that is, when the stimulus is applied for a number of frames, then turned off for the next few frames, and so on. Episodic orientation stimulus was applied while recording from the primary visual cortex of an anesthetized mouse. The multifrequency model demonstrated improved tuning curve descriptions of the neurons. It also offers perspective regarding the characteristics of calcium fluorescence imaging of the brain.
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http://dx.doi.org/10.1109/IEMBS.2011.6090826 | DOI Listing |
Proc Natl Acad Sci U S A
January 2025
Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390.
Neurotransmitter release is triggered in microseconds by Ca-binding to the Synaptotagmin-1 C-domains and by SNARE complexes that form four-helix bundles between synaptic vesicles and plasma membranes, but the coupling mechanism between Ca-sensing and membrane fusion is unknown. Release requires extension of SNARE helices into juxtamembrane linkers that precede transmembrane regions (linker zippering) and binding of the Synaptotagmin-1 CB domain to SNARE complexes through a "primary interface" comprising two regions (I and II). The Synaptotagmin-1 Ca-binding loops were believed to accelerate membrane fusion by inducing membrane curvature, perturbing lipid bilayers, or helping bridge the membranes, but SNARE complex binding through the primary interface orients the Ca-binding loops away from the fusion site, hindering these putative activities.
View Article and Find Full Text PDFCells
December 2024
Neural Dynamics Laboratory, Department of Medicine, The University of Melbourne, Melbourne, VIC 3052, Australia.
Neurological disorders (NDs), such as amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and schizophrenia, represent a complex and multifaceted health challenge that affects millions of people around the world. Growing evidence suggests that disrupted neuronal calcium signalling contributes to the pathophysiology of NDs. Additionally, calcium functions as a ubiquitous second messenger involved in diverse cellular processes, from synaptic activity to intercellular communication, making it a potential therapeutic target.
View Article and Find Full Text PDFJ Biophotonics
January 2025
Univ. Grenoble Alpes, CNRS, LIPhy, Grenoble, France.
A challenge in neuroimaging is acquiring frame sequences at high temporal resolution from the largest possible number of pixels. Measuring 1%-10% fluorescence changes normally requires 12-bit or higher bit depth, constraining the frame size allowing imaging in the kHz range. We resolved Ca or membrane potential signals from cell populations or single neurons in brain slices by acquiring fluorescence at 8-bit depth and by binning pixels offline, achieving unprecedented frame sizes at kHz rates.
View Article and Find Full Text PDFPflugers Arch
January 2025
Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky St, Kazan, 420111, RT, Russia.
Many synaptic vesicles undergo exocytosis in motor nerve terminals during neuromuscular communication. Endocytosis then recovers the synaptic vesicle pool and presynaptic membrane area. The kinetics of endocytosis may shape neuromuscular transmission, determining its long-term reliability.
View Article and Find Full Text PDFAnal Bioanal Chem
January 2025
School of Pharmacy, Guangdong Pharmaceutical University, Guangzhou, 510006, China.
Although fluorescence analysis methods are widely used in pesticide residue detection, improving their sensitivity and selectivity remains a challenge. This paper presents a novel ratio fluorescence sensor based on the molecular imprinting polymers (MIPs) and metal-enhanced fluorescence for visual detection of dicamba (DIC). Calcium fluoride (CaF) quantum dots (QDs) were immobilized on the surface of Ag@MIPs, resulting in a blue fluorescence response signal (Ag@MIPs-CaF).
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