Final answer:
Calcium ion flow into neurons is measured using patch-clamping, which detects ion flow and changes in potential across the membrane. Other neurons' activities are inferred from changes in neurotransmitter levels, membrane potentials, and synaptic receptor changes.
Step-by-step explanation:
The flow of calcium ions into neurons can be measured by a technique known as patch-clamping. This method enables the detection of specific ion flow and any resultant changes in potential difference across the neuron's membrane. When neurotransmitters bind to receptors, ion channels such as the ligand-gated NMDA receptors open, allowing an influx of ions like calcium. This disrupts the neuron's resting potential. During events like a stroke, these ion channels may become dysregulated, allowing excessive calcium to enter the neuron and initiate damaging processes.
To ascertain the activity of other neurons, researchers can look at signaling molecules such as neurotransmitters or changes in membrane potential. Additionally, certain techniques such as electrophysiology, which can include both patch-clamping and ophthalmic investigation, can be useful. In these practices, neuronal activity can be 'listened to' using a speaker that emits 'pops' each time an action potential occurs. Potentiation and depression of synaptic connections, elicited by calcium entry, affect the number and permeability of postsynaptic AMPA receptors, indicating synaptic activity and changes.
Scientific and educational tools like PHET neuron simulations can visualize the process of neuron stimulation and observe ions as they move across the neuron membrane, allowing students and researchers to study neuronal activity dynamically.