If a piece of electronics isn’t working, going to the root of the problem frequently includes probing the flow of electricity through the different components of the circuit to find any defective parts.
Stanford bioengineer and neuroscientist Jin Hyung Lee, who studies Parkinson’s disease, has adapted that plan to brain diseases, creating a new way to turn on specific types of neurons so as to see how this affects the whole brain. The work is described in the Jan. 26 issue of Neuron.
Lee, who trained as an electrical engineer before turning into a brain specialist, needed to provide neuroscientists an approach to probe brain diseases like how engineers troubleshoot faulty electronics. “Electrical engineers try to figure out how individual components affect the overall circuit to guide repairs,” Lee said.
For the time being, her technique should help improve treatments for Parkinson’s disease. Over the long haul, it provides a methodology to identify, map and ultimately repair neural circuits related to other brain diseases.
Seeing the Circuit
Lee’s circuit-mapping approach consolidates two experimental tools with a computational method. The first experimental tool is optogenetics. Spearheaded by Stanford bioengineer Karl Deisseroth, optogenetics alters specific types of neurons – the basic working parts of the mind – so they can be turned on in response of light. The second experimental tool is called functional MRI, or fMRI, which measures blood flow in the brain. Increased blood flow is related to increased activity. Using optogenetics to turn on a specific type of neuron, and fMRI to see how different regions of the mind responded, Lee at that point used computational analysis to map the entire neural circuit and furthermore determine its function.
Controlling Parkinson’s Tremors
One sign of Parkinson’s disease are wild tremors. Neuroscientists believe that these tremors are brought about by malfunctions in the neural pathways that control motion. They know that various regions of the brain are always forming circuits to do tasks, regardless of whether motion or speech. Be that as it may, preceding Lee’s technique, scientists had no real way to show how activating a particular sort of neuron may make a particular circuit to form in the whole brain.
Testing her approach on rodents, Lee probed two different types of neurons known to be associated with Parkinson’s disease – despite the fact that it wasn’t known precisely how. Her team found that one type of neuron activated a pathway that called for greater motion while the other enacted a signal for less motion. Lee’s team then designed a computational approach to draw circuit diagrams that underlie these neuron-specific brain circuit functions.
Lee said the findings in this paper should improve treatments for Parkinson’s disease. Neurosurgeons are already using a technique called deep brain stimulation (DBS) to calm Parkinson’s tremors in their patients. DBS delivers tiny electric jolts to neurons thought to be in charge of the tremors. A more precise understanding of how those neurons work to control motion could help guide more effective stimulation.
In any case, more comprehensively, Lee believes that her strategy – optogenetic fMRI combined with computational modeling – gives scientists another approach to figure out the functions of the many different types of neurons in the brain and the bafflingly diverse array of neural circuits formed to do various commands.