Diagram of synaptic transmission

(1) A nerve impulse arrives. (2) This causes calcium ion channels to open, resulting in an influx of calcium ions in the terminal. (3) This causes synaptic vesicles to fuse with the terminal membrane, releasing neurotransmitter into the gap between neurons, known as the synaptic cleft. (4) The neurotransmitters bind to receptor sites on ion channels in the postsynaptic membrane, causing them to open. (5) Ions flow into the postsynaptic neuron, which generates an action potential when a threshold level is reached.

(1) A nerve impulse arrives. (2) This causes calcium ion channels to open, resulting in an influx of calcium ions in the terminal. (3) This causes synaptic vesicles to fuse with the terminal membrane, releasing neurotransmitter into the gap between neurons, known as the synaptic cleft. (4) The neurotransmitters bind to receptor sites on ion channels in the postsynaptic membrane, causing them to open. (5) Ions flow into the postsynaptic neuron, which generates an action potential when a threshold level is reached.

Date:
24 April 2020

Copyright OIST (Okinawa Institute of Science and Technology Graduate University, 沖縄科学技術大学院大学). Creative Commons Attribution 4.0 International License (CC BY 4.0).

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Correlation between connectivity and distance of neurons in the human cortex

This diagram shows correlation between connectivity and distance of neurons in the human cortex. There are approximately 100,000 neurons in a square millimeter of cortex, as illustrated in the center box. The red gradation shows neuronal connectivity, with dark red indicating denser connectivity through synapses. While half of the synapses connect to neurons close to them, the other half connect with distant neurons, as so illustrated in the boxed area on the far left of this diagram. The differences in connectivity and distance between neurons require whole brain simulation in order to understand brain function.