4.2 Neurons, neurotransmitters and hormones

Other brain studies focus at the level of nerve cells or neurons and other microscopic components of the nervous system. The millions of neurons which transmit messages within the brain and nervous system form a dense network of connected fibres. One current idea is that the overall pattern of this connectivity is different in the autistic brain, with some areas being unusually densely connected, and others sparsely connected (Wolff, 2012, cited in Hughes, 2012).

Figure 8 Different areas of the brain are profusely connected by complex networks of neurons. The pattern of connectivity may be different in autism.

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This is an image giving an idea of the neuron network within the brain, which is speculated to vary structurally in the autistic brain.

Figure 8 Different areas of the brain are profusely connected by complex networks of neurons. The pattern of connectivity may be ...

There is also some evidence that the structure and functioning of synapses (the miniscule gaps between neurons) differs in autism. Messages are transmitted along nerve fibres by minute electric currents, but crossing the synaptic gaps involves chemical messengers called neurotransmitters.

Figure 9 Schematic image of a synapse with molecules of neurotransmitter carrying messages across the synaptic gap.

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This is a schematic image of a synapse with molecules of neurotransmitter carrying messages across the synaptic gap.

Figure 9 Schematic image of a synapse with molecules of neurotransmitter carrying messages across the synaptic gap.

Some studies suggest that some autistic people have higher than normal levels of a neurotransmitter called serotonin in their blood, suggesting an overproduction within the brain. Medical drugs which are known to influence serotonin uptake in the brain can have an impact on anger and repetitive behaviour in autism.

Finally, different levels of certain hormones have been reported. Hormones are another type of chemical messenger, which play an important role in bodily and brain function. For instance, when you experience a stressful situation, adrenaline is released which causes perspiration, raised heart rate and other ‘fight or flight’ reactions. Oxytocin is a hormone which is known to be important in social relations, and some studies report lower levels in children with autism. Some studies suggest that administering extra oxytocin to autistic people via a nasal spray may help with emotion recognition skills.

If you are interested to learn more about the brain and nervous system and how they are implicated in autism, you may like to look at parts of this optional interactive activity:

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