According to scientists at Columbia University, neurons in the brain can be programmed to operate in unison, meaning that an entire can be reactivated by simply stimulating only one neuron. Although the research is currently in its early stages, the team believes that these sets of brain cells could serve as major building blocks of memory and learning. Speaking about the breakthrough, Dr. Rafael Yuste, a professor of neuroscience at the university, said:

I always thought the brain was mostly hard-wired. But then I saw the results and said ‘Holy moly, this whole thing is plastic.’ We’re dealing with a plastic computer that’s constantly learning and changing.

The idea that neurons can be selectively reactivated was originally discussed by a psychologist named Donald Hebb back in the 1940s. For the current research, the scientists used advanced optogenetic tools to study and control the various processes of the brain in a living mouse. The team started by injecting a particular virus into the murine subject.

The virus, according to the researchers, contained special light-sensitive proteins that were genetically engineered to travel to specific brain cells. Upon reaching their destinations, the proteins inside the microorganisms allowed the team to activate the neurons remotely with the help of light. The scientists likened this step to the simple act of turning on a lamp or a television.

Through the experiments, the mouse was made to run on a treadmill, with its head held firmly under a powerful microscope. To activate its brain cells, the scientists fired a single laser beam at its skull. This, as explained by the researchers, resulted in the stimulation of a network of cells in the animal’s visual cortex. Following this, a second laser was beamed at the subject, allowing the team to observe the activities and record the increase in calcium levels in each of the neurons.

Technological advancements, particularly the development of optogenetic tools, in recent years have enabled neuroscientists to examine as well as manipulate the structure, functions and processes of the brain more non-invasively than ever before. The present project is part of a decade-long research, and is based on a 2003 study by Yuste that showed how nerve cells work in teams known as neural ensembles. A later research revealed these networks actually fire in sequential patterns with respect to time.

More recent studies have unraveled some of the many mysteries surrounding the brain. For instance, it is now believed that the neural ensembles operate without stimulation. Using data in these studies, the researchers developed a special mathematical algorithm that in turn allowed them to locate the visual cortex in the brain of living animals and, confirm their findings .

Recently published in the Science journal, the current research demonstrates that these brain can be remotely activated and replayed. With the help of a combination of two-photon calcium imaging technology and two-photon stimulation technique, the team was able to observe the neural networks’ response when exposed to light stimuli. Yuste added:

If you told me a year ago we could stimulate 20 neurons in a mouse brain of 100 million neurons and alter their behavior, I’d say no way. It’s like reconfiguring three grains of sand at the beach.

The breakthrough, according to the researchers, points to the possibility that human brain cells could be artificially reactivated and reprogrammed, as a way of enhancing the learning process or recovering lost memories. Luis Carrillo-Reid, the study’s chief author, was reported saying:

We think that these methods to read and write activity into the living brain will have a major impact in neuroscience and medicine.

Source: Columbia University