T12 Flashcards
What triggers the entry of calcium into the presynaptic terminal?
Activation of voltage-gated calcium channels (VGCCs) due to an action potential allows Ca²⁺ ions to flow into the presynaptic terminal.
How does elevated Ca²⁺ lead to neurotransmitter release?
Increased Ca²⁺ in the presynaptic terminal binds to calcium-binding proteins (e.g., synaptotagmin), triggering synaptic vesicle fusion with the membrane and releasing neurotransmitters into the synaptic cleft.
What other pathways allow Ca²⁺ entry besides VGCCs?
Ca²⁺ can enter through ligand-gated ion channels, such as NMDA receptors, or be released from internal stores like the endoplasmic reticulum.
How is Ca²⁺ concentration regulated within neurons?
Ca²⁺ is regulated by buffering proteins (e.g., calbindin, parvalbumin) and by mechanisms like PMCA and NCX to prevent toxic buildup.
What role does Ca²⁺ play in synaptic plasticity?
Transient increases in Ca²⁺ are key to synaptic plasticity, promoting changes like long-term potentiation (LTP) or long-term depression (LTD), which are essential for learning and memory.
How does high-frequency stimulation of neurons affect Ca²⁺ levels and synaptic strength?
High-frequency stimulation raises Ca²⁺ in postsynaptic neurons, often leading to LTP, a strengthening of synaptic connections.
What is calcium imaging?
Calcium imaging is an optical technique to monitor calcium levels within cells using calcium-sensitive fluorescent dyes.
What is the significance of calcium dynamics in neuronal activity?
Calcium dynamics reflect the integration of synaptic inputs and postsynaptic activity, allowing the study of neuronal activity over time.
What types of indicators are used in calcium imaging?
Calcium dyes like Fura-2 and Fluo-4, and genetically encoded calcium indicators (GECIs) like GCaMP.
How does fluorescence microscopy relate to calcium imaging?
Calcium-bound indicators emit fluorescence, which is captured by microscopes like confocal or two-photon to measure calcium levels in real-time.
What is the first step in a calcium imaging experiment?
Preparing the sample, which includes culturing cells or tissue slices and using transgenics or viral vectors for genetic models if applicable.
What type of stimulus is used in calcium imaging?
Stimuli can be electrical, chemical, or optogenetic to trigger calcium changes during real-time imaging.
What software is commonly used for analyzing calcium imaging data?
Tools like ImageJ and MATLAB are used for detailed analysis and quantifying fluorescence changes.
How does Fura-2 dye work in calcium imaging?
Fura-2 is a calcium-sensitive fluorescent dye that binds intracellular Ca²⁺ and fluoresces, allowing measurement of calcium levels in neurons.
What techniques can be used to label neurons for calcium imaging?
Techniques include applying calcium dyes, viral transduction, and optogenetics for precise neuron labeling.
