Practical Tools and Wise Quotes on All Matters Creative
7.3.1. How We Think: Reaching Out to Communicate
Although they come in many shapes and sizes, a magnified single neuron (Fig 6.2) looks like an alien from another planet. From its central cell body, an axon stretches out as a long-distance nerve fibre, communicating with other neurons, muscles or glands through its set of terminal buttons. Other protuberances are called dendrites, reaching out to listen to other neurons, ready to connect up in the vast Internet of the mind.
Fig. 7.2 A neuron
Neurons communicate with one another through a combination of electricity and chemistry. A neuron at rest has a net negative charge. This attracts the (mostly) sodium ions outside the neuron into it. This causes another change which results, about one millisecond later, with the ions being pumped back outside. The voltage on the cell thus swings up and down and is the ‘firing’ that is the basis of communication between neurons.
When a terminal button of a neuron gets close to the receptor areas on a dendrite of a second neuron, it does not quite touch, but leaves a gap known as a synapse. When the first neuron fires, the electrical charge causes little containers in the terminal button called synaptic vesticules to expel the chemical they contain across the synapse and into receptor cells on the second neuron, as in Fig. 7.3.
Fig. 7.3 Neurons connecting
There are two types of chemical that can be transmitted across the synapse: exciters and inhibitors. Exciters stimulate the second neuron, increasing the chance of it firing and inhibitors decrease the chance of it firing. If the second neuron fires, then it will stimulate a further chain of neurons to fire, creating a thought pattern in the brain.
There are various chemicals that are used as transmitter substances, such as acetylcholine and norepinephrine. Just to complicate matters a little, a single chemical can be either an exciter or an inhibitor, depending on where it is being used.
Just for interest: mind altering drugs often work by playing around with this synaptic connection. Cocaine and amphetamines, for example, prevent the re-absorption of norepinephrine, resulting in an extended period of stimulation as the brain fills up with incomplete synaptic transmissions.
Other parts of this section:
The other sections in this chapter: