A revolutionary new microscope allows neuroscientists to observe and control neural activity on a cellular level with millisecond accuracy. Bringing together disparate technology, the new device will provide the most detailed peek at the inner workings of the brain to date.
The brain is the most complex organ in the body, by far.
It consists of an estimated 86 billion neurons, all able to fire independently or in patterned unison.
Neuroscience has advanced in leaps and bounds over the decades, but there are, of course, many questions still to be answered.
An organ capable of constructing a seamless internal representation of our environment from the cacophony of stimuli that it is presented with was always likely to be difficult to understand.
All of the brain’s impressive feats – memory, emotion, control of movement – are achieved by simple on/off signals running along neurons. Scientists have been able to observe these signals for many years, but to see them in context and see the “syntax” of the neural language has not been possible, until now.
Researcher Hillel Adesnik, PhD, assistant professor of neurobiology at the University of California-Berkeley, and his team have designed an incredible microscope that looks set to add another layer to our ever-growing understanding of the brain.
The microscope allows the researcher to watch the activity of the brain at the level of individual cells with millisecond accuracy; in addition to visualizing the brain’s activity in real-time, the device is also able to control activity in the individual neurons of a live rat. Adesnik explains:
“We have developed a prototype microscope that achieves the level of detail needed to actually understand the neural code.”
Adesnik has high hopes for future applications of the microscope: “After more refinements, this instrument may be able to function as a sort of Rosetta Stone to help us crack the neural code.”
The team’s research will be presented at the American Association of Anatomists Annual Meeting during Experimental Biology 2016 in San Diego, CA.
In their research, Adesnik and his team use mice with modified neurons that respond to light. The technique, known as optogenetics, allows investigators to turn individual neurons on or off with a simple pulse of light.
The researchers install a glass window in the rodent’s skull and place the microscope on top. This allows them to both observe the neural patterns and alter them.
In the same way that knocking out a gene in an animal and measuring the changes allows you to see what role that gene normally fulfills, this technology allows scientists to tinker with neural patterns and measure how the resulting behavior differs.
For instance, the team can map the brain activity during the wiggle of a whisker. This pattern can then be played back to the brain in the form of a laser-produced hologram, inducing the whisker wiggle. Alternatively, they can play back the signals but change minor elements to observe what difference is made to the final behavior.
In another series of ongoing tests, the team uses mice that are trained to push a specific lever when they see a certain shape; they plan to develop holograms that, when fired into the brain, can fool the mouse into seeing a shape where none exists.
Adesnik hopes that soon they will “be able to treat the brain as the keyboard of a piano […] and write in a sequence of activity that is needed to understand or correct brain function.” Initially, the microscope will be predominantly used on rat brains; he told Medical News Today:
“We don’t have plans to move beyond rodents at the moment, but in future collaborations with neuroscientists that work on non-human primates, there should be the possibility to address higher order cognitive processes.”
The creation of the microscope was a true meeting of minds with experts in various fields contributing to the final piece. As might be expected with such innovative work, there were many difficulties to face along the way.
When MNT asked Adesnik about the technical challenges, he mentioned problems with the optical tools and “overlap in their color sensitivity.” The team is presently collaborating with electrical engineers at Berkeley to address various obstacles and improve the functioning of the microscope ever further.
MNT asked Adesnik what the far future might hold for devices of this nature, and he said:
“We are currently working with a large team to design a miniature, implantable version of the microscope using several new technologies. Such a device will find use in neural prosthetics for patients with paralysis or amputations, but may also be useful for various neurological diseases.”
For now, Adesnik is focusing on rodent work, because “even in rodents there is much work to be done to understand sophisticated mental processes like the encoding and storage of memories.”
MNT recently covered another innovative microscope that uses smartphone technology to quickly detect blood parasites.