Inhibitory sculpting of afferent signals in the thalamus is exerted by two types of neurons using gamma-amino butyric acid (GABA) as neurotransmitter. Of them, local-circuit neurons exert their functions via two outputs: axons and presynaptic dendrites. In this issue of Neuron, Govindaiah and Cox reveal that synaptic activation of metabotropic glutamate receptors selectively increases the output of presynaptic dendrites of local interneurons in rat visual thalamus, without affecting the axonal output.
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http://dx.doi.org/10.1016/s0896-6273(04)00076-5 | DOI Listing |
Eur J Neurosci
January 2025
Department of Pharmacology, University of Oxford, Oxford, UK.
Cannabinoid receptor 1 (CB1) regulates synaptic transmission through presynaptic receptors in nerve terminals, and its physiological roles are of clinical relevance. The cellular sources and synaptic targets of CB1-expressing terminals in the human cerebral cortex are undefined. We demonstrate a variable laminar pattern of CB1-immunoreactive axons and electron microscopically show that CB1-positive GABAergic terminals make type-2 synapses innervating dendritic shafts (69%), dendritic spines (20%) and somata (11%) in neocortical layers 2-3.
View Article and Find Full Text PDFBio Protoc
January 2025
Department of Biomedicine, University of Bergen, Bergen, Norway.
During neuronal synaptic transmission, the exocytotic release of neurotransmitters from synaptic vesicles in the presynaptic neuron evokes a change in conductance for one or more types of ligand-gated ion channels in the postsynaptic neuron. The standard method of investigation uses electrophysiological recordings of the postsynaptic response. However, electrophysiological recordings can directly quantify the presynaptic release of neurotransmitters with high temporal resolution by measuring the membrane capacitance before and after exocytosis, as fusion of the membrane of presynaptic vesicles with the plasma membrane increases the total capacitance.
View Article and Find Full Text PDFbioRxiv
December 2024
Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Fluorescent reporters for glutamate release and postsynaptic Ca signaling are essential tools for quantifying synapse functional heterogeneity across neurons and circuits. However, leveraging these probes for neuroscience requires scalable experimental frameworks. Here, we devised a high-throughput approach to efficiently collect and analyze hundreds of optical recordings of glutamate release activity at presynaptic boutons in cultured rat hippocampal neurons.
View Article and Find Full Text PDFFront Biosci (Landmark Ed)
December 2024
Department of Biological Sciences, Hunter College, City University of New York, New York, NY 10065, USA.
Background: Spatial-temporal control of mRNA translation in dendrites is important for synaptic plasticity. In response to pre-synaptic stimuli, local mRNA translation can be rapidly triggered near stimulated synapses to supply the necessary proteins for synapse maturation or elimination, and 3' untranslated regions (UTRs) are responsible for proper localization of mRNAs in dendrites. Although is a robust technique for analyzing RNA localization in fixed neurons, live-cell imaging of RNA dynamics remains challenging.
View Article and Find Full Text PDFJ Comp Neurol
December 2024
Wilkes Honors College, Florida Atlantic University, Jupiter, Florida, USA.
Neurons rely on mitochondria for an efficient supply of ATP and other metabolites. However, while neurons are highly elongated, mitochondria are discrete and limited in number. Due to the slow rates of metabolite diffusion over long distances, it follows that neurons would benefit from an ability to control the distribution of mitochondria to sites of high metabolic activity such as synapses.
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