In order to become active, the total input must reach a threshold at which excitation outweighs inhibition enough.

This is a process called synaptic integration, which determines whether a neuron becomes active. These inputs add and subtract in a constantly evolving pattern, depending on what the brain is thinking. A given neuron receives hundreds of inputs, almost exclusively on its dendrites and cell body. Neuronal communication is exquisitely regulated as a balance between excitatory and inhibitory influences (Fig 2).

Dopamine (the loss of which leads to Parkinson’s Disease)Īction potentials and synapses: in depth More excitation than inhibition.

Most of these (~80%) release the excitatory transmitter glutamate, which promotes spiking in target neurons, whereas other neurons release GABA, an inhibitory neurotransmitter that functions to prevent spiking. Although some research has revealed exceptions, the vast majority of neurons are currently thought to be monolingual-they can only release one type of neurotransmitter. What do these neurons hear as they listen to other neurons talking? That depends on the language being spoken-or the identity of the neurotransmitter that is released. Image credit: Dr Alan Woodruff, Queensland Brain Institute. This work is licensed under a Creative Commons Attribution 4.0 International License. The neurotransmitter travels across the gap to activate receptors on the receiving neuron. An action potential here (yellow lightning) causes neurotransmitters to be released. Figure 1: Synapses are tiny gaps between neurons, across which the neurons talk to each other. Any time a neuron spikes, neurotransmitters are released from hundreds of its synapses, resulting in communication with hundreds of other neurons. When a neuron spikes it releases a neurotransmitter, a chemical that travels a tiny distance across a synapse before reaching other neurons (Fig 1). They allow neurons to communicate with each other, computations to be performed, and information to be processed.

Nerve impulses are the basic currency of the brain. This means that they produce electrical events called action potentials, which are also known as nerve impulses, or spikes. The key difference between neurons and glia is that neurons are ‘excitable’.

How many neurons in the human brain