Researchers from the University of Toronto, working with Sunnybrook Research Institute and the Krembil Research Institute, have developed a miniature microscope that can be used to gather better insights into what causes epilepsy, potentially leading to more effective treatments.
Many cases of epilepsy are due to unknown causes, and while long-term drug therapy can treat the symptoms of epilepsy, there is currently no cure. In conducting further research into this disease, epilepsy researchers hope to monitor the brain function of rodents while the animal is awake and freely moving, because the drugs used to sedate the rodents affect brain function, while physically restraining the rats means not being able to image brain function that corresponds with motor behaviour.
To allow this, senior researcher Ofer Levi, a professor in the Institute of Biomaterials and Biomedical Engineering at the University of Toronto wanted to develop a solution that would be minimally-invasive, allowing for concurrent observations of brain activity and brain diseases over a period of time.
The research team designed and built a scaled-down optical microscope. This microscope, comprisong of a skull adapter plate, an imaging tube, and a laser light source, measured 40 mm in length and 12 mm in diameter, about the size of an AAA battery. The entire assembly weighed 15 g, which is less than five per cent of the rat's total body mass.
They then optimised the light source to fit several bright laser diodes, allowing different colours to be emitted from one small portable button-sized package. This allowed the microscope to change its illumination mode, from acting as a bright lamp, to performing like a coherent laser, allowing the researchers to track changes in brain physiology during a seizure.
“A lot of attention went into minimizing the size and weight of the microscope and optimising the surgical procedure for the cranial implant,” said lead researcher Iliya Sigal, a PhD student in the team.
“We had to ensure that the device was small and light enough to avoid discomfort and allow normal behaviour patterns without anaesthesia, while also being able to image the brain over several weeks in the same animal.”
Sigal and his colleagues were able to use their novel microscope to make a series of observations over a period of six weeks. The team was able to successfully record the brain during seizures and study its blood flow and metabolism without anaesthetic disruption.
According to the researchers, the miniature microscope technology, and the learnings from the experiment, could lead to implantable, wireless devices for monitoring human brain functions that provide early warning of epilepsy and provide opportunities to inhibit the disease.
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