Sonogenetics is the New Optogenetics

In our recent Neuroscience Seminar, Dr. Stephan Steidl presented his findings in optogenetics. His research entailed injecting certain neurons in an animal’s brain with a light sensitive virus.  The virus then makes the neuron sensitive to a certain wavelength of light.  So, a wire with a light at the end is placed in the animal’s brain right where the affected neurons are.  When the light is turned on, it excites the specific neurons.  In this way, a particular pathway of the brain can be studied.  If a pathway is known that relates to certain things, like the dopamine pathway studied by Dr. Steidl, that pathway can be activated on demand.  The dopamine pathway is related to rewards, a pleasing reaction.  So, when rats have the dopamine path triggered, they choose to keep that going even if it involves an unpleasant stimulus like being shocked.  This is an example of topics that can be studied with techniques that single out neuron pathways. 

            Optogenetics is very intriguing, but word on the street is that sonogenetics is the new optogenetics.  Ultrasound waves are starting to be used to trigger neurons in worms.  Sonogenetics is essentially using ultrasound waves instead of light.  Worms don’t have brains, but they do have neurons like us.  So in this study, they made a specific neuron sensitive to ultrasound waves.  Activation of this neuron causes a worm to turn around and move in the opposite direction.  When the worm was exposed to ultrasound waves, the neuron was excited and the worm turned around right away. This technique has advantages such as being safe and noninvasive because the waves penetrate tissues- no more wires hanging out of the brain!  

            The implications of this are huge.  The next step is testing this development in mice.  If it works in them, maybe a long way down the line, it could be used in humans.  This would be helpful in such cases as depression and other mental disorders.  People with depression can be medicated to either increase serotonin or norepinephrine in the synapse.  But with a system like this, a specific pathway that involves serotonin or norepinephrine could be identified and those neurons treated with substances that make them sensitive to ultrasound waves.  Then ultrasounds could be applied whenever a boost of serotonin or norepinephrine was needed.  This is noninvasive and would not have the side effects that medicines so often have!  That of course is a long way out, but the future is definitely bright for sonogenetics. 

http://www.nytimes.com/2015/09/29/science/testing-neurons-with-ultrasound.html?rref=collection%2Fundefined%2Fundefined&action=click&contentCollection=science&region=stream&module=stream_unit&version=search&contentPlacement=6&pgtype=sectionfront&_r=0