summary: Researchers present a new system that uses photons instead of chemical neurotransmitters to control neural activity.
Our brain consists of billions of neurons that are connected in complex networks. They communicate with each other by sending electrical signals known as action potentials and chemical signals known as neurotransmitters in a process called synaptic transmission.
Chemical neurotransmitters are released from one neuron, diffuse to other neurons, reach target cells, and produce signals that excite, inhibit, or modulate cellular activity. The timing and intensity of these signals are critical for the brain to process and interpret sensory information, make decisions, and generate behavior.
Controlling the connections between neurons allows us to understand and treat neurological disorders, rewire or repair dysfunctional neural circuits after injury, improve learning capacity, or extend the continuum of behavior. There are several ways to control neuronal activity.
One possible way is to use drugs that alter levels of chemical neurotransmitters in the brain and affect neuronal activity. Another approach is to use electrical stimulation applied to specific brain regions to activate or inhibit neurons. A third possibility is to use light to control neural activity.
Using photons to control neuronal activity
Using light to manipulate neuronal activity is a relatively new technique that has been investigated in the past. This involves genetically modifying neurons to express light-sensitive proteins, ion channels, pumps, or specific enzymes within target cells. This technique allows researchers to precisely control the activity of specific populations of neurons with greater precision.
However, there are some limitations. Because light scatters in brain tissue, it must be delivered very close to neurons to achieve sufficient resolution at the synaptic level. Therefore, they are often invasive and require external intervention. Additionally, the intensity required to reach target cells can be detrimental to them.
To overcome these challenges, ICFO’s team of researchers nature’s way A system that uses photons instead of chemical neurotransmitters as a strategy to control neural activity.
ICFO researchers Montserrat Porta, Adriana Carolina Gonzalez, Nois Sanferiu Serdán, Shadi Karimi, Nawafat Maraiwong, Alexandra Pide, Luis Felipe Morales and Sala González Bolivar developed the method led by Prof. Michael Krieg with Pablo Fernández and Cedric Haas . Using luciferase, a luciferase, and a light-sensitive ion channel he connects two neurons.
They developed and tested a system named PhAST (short for Photon as Synaptic Transmitter) in roundworms. Caenorhabditis elegans, widely used model organisms to study specific biological processes. Similar to how bioluminescent animals communicate using photons, PhAST uses the enzyme luciferase to send photons rather than chemicals as the messenger between neurons.
Replace chemical neurotransmitters with photons
To test whether photons can codify and transmit activity states between two neurons, the team genetically modified roundworms to have defects in their neurotransmitters, making them insensitive to mechanical stimuli. I made it They aimed to overcome these shortcomings using the PhAST system. They then designed the luciferase luciferase and selected ion channels that are sensitive to light.
To follow the flow of information, they developed a device that subjects the animal’s nose to mechanical stress while simultaneously measuring calcium activity in sensory neurons, one of the most important ions and intracellular transmitters. .
To be able to study bioluminescence by looking at photons, the team previously simplified a fluorescence microscope, removing all unnecessary optical elements such as filters, mirrors and the laser itself, and using machine learning to reduce noise. I was designing a new microscope. Comes from an external light source.
The researchers then tested the PhAST system to work in several experiments, successfully using photons to communicate the state of neurons. They were able to establish a new transmission between two of her cells that were not connected and restore neurotransmission in the defective circuit.
They also suppressed animal responses to painful stimuli, changed responses to olfactory stimuli from attractive to aversive behavior, and studied calcium dynamics during oviposition.
These results demonstrate that photons indeed act as neurotransmitters, enabling communication between neurons, and that the PhAST system enables synthetic modification of animal behavior.
Possibilities of light as a messenger
Light as a messenger offers a wide range of potential future applications. Because photons can be used in other types of cells and in some animal species, they have broad implications for both basic research and clinical applications in neuroscience.
Using light to control and monitor neuronal activity could help researchers better understand the mechanisms underlying brain function and complex behavior, and how different brain regions communicate with each other. useful and provide new ways to image and map brain activity with higher spatial and temporal resolution. It could also help researchers develop new treatments, such as helping to repair damaged brain connections without invasive surgery.
However, there are still some limitations to the widespread use of the technique, and further improvements in engineering bioluminescent enzymes and ion channels or targeting molecules could lead to non-invasive and more specific optical control of neuronal function. Allows and accuracy.
About this neuroscience research news
author: Alina Hirschmann
contact: Alina Hirschman – ICFO
image: Image credited to ICFO
Original research: closed access.
“Neuroengineering with Photons as Synaptic TransmittersMontserrat Porta de la Riva etc. nature’s way
Neuroengineering with Photons as Synaptic Transmitters
Neuron computation is achieved by connecting individual neurons into a larger network. To expand the repertoire of endogenous cellular communication, we developed a synthetic photon-assisted synaptic transfer (PhAST) system.
PhAST is based on luciferase and channelrhodopsin, which use photons as neurotransmitters to enable the transmission of neuronal states across space.
PhAST overcomes synaptic barriers and rescues behavioral deficits in glutamate mutants. Caenorhabditis elegans Nociceptive avoidance circuit.
To demonstrate versatility and flexibility, we generated de novo synaptic transmission between two unconnected cells within a sexually dimorphic neural circuit and endogenous nociception through activation of the anion channelrhodopsin. It suppressed defensive responses and switched the attraction to aversive behavior in the olfactory circuit.
Finally, we applied PhAST to analyze the calcium dynamics of the temporal pattern generator in the oviposition motor circuit. In summary, we have established photon-based synaptic transmission that facilitates behavioral modification in animals.