The dream of all neuroscientists is to get a tool to track the millions of real-time interactions between brain cells in animals, and even better - in humans. And if the subject is not fixed, but free to walk in natural conditions - it will be very interesting. The new technology developed at Rockefeller University is a major step towards this ambitious goal.
It is hoped that the discovery of scientists, whose report is published in the publication of "Natural Methods", will provide researchers with the technology to study the dynamic processes in the brain in a variety of animal behavior situations. Although he intended to experiment with rats, information obtained as a result of experiments may explain neuronal activity and in humans-people have much in common with animals.
The project leader is Alipasha Vaziri, who runs the Rockefeller University's Neurotechnology and Biophysics Laboratory. The authors hope that by using their findings, for example, it will be possible to better understand the physiological basis of many diseases that constitute brain disorders. These include common illnesses such as autism and schizophrenia.
Waziri said that the proposed tool will provide many discoveries in the future. While the animal moves in its natural state, some neurons provide spatial navigation, others receive sensory feedback from changes in body position or from the vision system. So far, no one has been able to observe these processes - how different neurons, located at different depths in the volume of brain tissue, dynamically interact with each other during the normal free movement of the body. Similarly, the tool can be used to record neural connections when two animals meet and begin to interact socially with each other.
Technically, this method consists of installing a small microscope to the head of a mouse, equipped with a special lens group. This lens allows the microscope to receive images from multiple angles, and using sensor chips creates three dimensional images of flashing and decaying neurons after passing them electrochemical impulses - with ordinary brain cell interactions.
In experiments, mouse neurons are genetically modified to provide luminescence during activation - this is a well-known and widely used technology. The coaxial cable attached to the top of the microscope transmits data to record to a computer. A microscope with a weight transmitter is only four grams - roughly equal to the amount that can be easily held by rats. Waziri suggests that they can improve the "helmet" and make it easier. Of course it is possible to transmit wireless data, thus limiting the free movement of experimental animals.
At a time when the array of microlens captures images of luminous neurons from the brain tissue volume, the next step is to process this array. The brain tissue is naturally not transparent, and this makes it difficult to determine the source of any outbreak of neurons. Waziri's team solved this problem by developing a new computer algorithm. The algorithm uses the statistical distribution of neurons in space and analyzes light scattering at each activity, allowing simultaneous and accurate detection of outbreaks in brain volume, regardless of the strong absorbent properties of the tissues.
As a result, a clear picture is obtained where individual neurons consistently blink, clearly indicating the interaction of different parts of the brain.
Waziri's laboratory previously used this algorithm, which they named SID, in a static study when a mouse's head was mounted in one position. After perfecting the technology, they became the first to successfully demonstrate the activity of neurons in the volumes of animals that move freely. To do this, they use a small microscope called Miniscope, which was developed in collaboration with scientists from the University of California, Los Angeles.
The technology in the case of widespread use will offer several advantages over conventional two-photon laser microscopes used by neurobiologists. Two-photon laser microscopy registers the activity of neurons only in separate focus plane - thin virtual "slices" of brain samples, then consecutively combined with each other to create three-dimensional images. In contrast, Waziri's method simultaneously captures data in three dimensions across all network volumes, making monitoring activity fast and efficient. Well, about the possibility of the phone wearing a "helmet" and needless to say.
Waziri's team plans to continue improving its unique instruments. The next task is to register the activity of neurons in the larger part of the brain, while this is a relatively limited area. Also, higher resolution and monitoring frequencies are required. Scientists hope that their work will ultimately lead to a deeper understanding of how the animal brain and one process the information that underlies individual behavior.
