Epileptic seizures are caused by excess electrical activity of neurons in the brain, and this electrical activity is generated by the flow of sodium, potassium and calcium ions into / out of the neuron. The ions enter and leave via structures known as ion channels, and once the current reaches a certain level, the electrical signal, now known as an action potential, travels to other neurons / cells via synapses.

Treatments for epilepsy are numerous and varied, and all have demonstrated effectiveness at controlling seizures. However whether it be medication, nerve stimulation or surgery, each is in some way invasive to the patient.

Ultrasound has a wide range of medical uses, including diagnostic and foetal imaging, physiotherapy, and even teeth cleaning. Over the past half century, several research groups have demonstrated that ultrasound can produce electrical changes in excitable tissues, such as nerve and/or muscle, but studies involving neurons at a cellular level have, until now, been lacking.

Scientists in Arizona, USA, have now successfully used low power ultrasound to stimulate neurons in the brain remotely, that is without any invasion to the body (such as the use of electrical conductors or introduction of chemicals).

Previous attempts to use ultrasound in this way failed, because the thickness of the skull proved too great a barrier. However the researchers in Arizona were able to achieve an intensity and frequency of ultrasound that could penetrate through to the brain tissue.

Having achieved this, they performed an experiment whereby they stimulated the brain using ultrasound, whilst simultaneously measuring the electrical activity in the neurons.

The group discovered that the ultrasound increased the activity of sodium and calcium channels in the neurons. This in turn and was able to stimulate both action potentials and the release of neurotransmitters from synapses.

The results of this study are exciting, because they suggest that ultrasound has the potential to become a powerful tool for controlling electrical activity in the brain. Clearly a lot more development and research is necessary, but if ultrasound could be applied to counteract the neuronal excitation seen in epilepsy, it could lead to a revolutionary form of non-invasive treatment.

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