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Optical Tracking of Zebrafish Neural Impulses


The brain of a zebrafish

Zebrafish are handy little critters, as far as neuroscience goes. These tiny, mostly transparent little fish have brains that whilst greatly simplified, have a structure remarkably similar in basic form, to our own. Add in that aforementioned near-transparency, and it becomes possible under the correct lighting conditions, to literally see right into their brains, to the point where you can practically watch as a thought takes place.

Researchers from Japan's National Institute of Genetics have now taken the final step in that logic train. Rather than practically being able to see thoughts, they have actually been able to follow individual thoughts as they progress through that brain. A tiny, single-electrode, highly-sensitive fluorescent probe inserted into the brain of a zebrafish that had been subjected to genetic therapy to render its neurons susceptible to light, resulted in essentially, a type of bio-luminescence, based as you might buy now suspect, on optogenetic brain interface techniques.

As lead researcher Koichi Kawakami put it: "Our work is the first to show brain activities in real time in an intact animal during that animal's natural behaviour. We can make the invisible visible; that's what is most important."

Essentially, the researchers place the fish in a specific scenario in its tank. Hunting for prey, or responding to perceived predators. It is exposed to the same scenario over and over again until the way it will react is known. Then the fluorescent probe is activated. Any neurons that are active at that moment, glow a bluish purple, in response to the probe. This means basically, that the active thought process becomes visible in normal light – and the researchers can track the thought in real-time as it moves through the brain.

Comparing the active thought processes to the current behaviour the fish is doing, lets the researchers know which brain regions are involved in any given behaviour, and in which order they are accessed. As you scale up from a zebrafish brain to a human brain, the complexity of these basic body-controlling brain regions increases dramatically, but their basic compartmentalisation does not. In other words, the hind-brain of a human is basically the same as that of a zebrafish, just with added complexity in each department – inter-departmental communication is still much the same.

So, by studying the communication in a zebrafish's brain, we are moving closer to understanding how the neurons interact with one another in the human hind-brain to control our bodies and instinctual behaviour.

As always, the more we learn in this critical area, the closer we are to effectively interfacing with this process- allowing for brain-controlled avatars of both virtual and physical types.

"In the future, we can interpret an animal's behaviour, including learning and memory, fear, joy, or anger, based on the activity of particular combinations of neurons," Kawakami said.


For the first time, researchers have been able to see a thought "swim" through the brain of a living fish. The new technology is a useful tool for studies of perception.

Credit: Current Biology, Muto et al.

 

References

This is what a fish thought looks like

Real-time visualization of neuronal activity during perception (Paper)

Stimulating brain cells with light

Staff Comments

 


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