Summary: Scientists have discovered how serotonergic neurons in the visual information of the Larval Cebra Fish process linked to the movement to determine when and how much serotonin releasing. This neuromodulator adjusts the swimming effort of the fish, adjusting the behavior based on the effectiveness of past actions.
Neurons in a key brain region only admit visual entry after an explosion of swimming ends, using a “door” mechanism that opens after the cemetery to process relevant feedback. This selective purchase allows the system to learn which actions lead to the desired results, essentially assigning credit for success.
Key facts:
Modulation -based modulation: serotonergic neurons adjust the vigor of swimming based on visual feedback after each movement. Temporary Guration: A neural “door” admits sensory information only after a swimming ends, optimizing the credit allocation. Neuronal overflows: the suppression of activity during swimming is followed by an excitatory rebound that increases the liberation of serotonin.
Source: HHMI
Janelia researchers are decoding how neurons carry out the calculations carefully calibrated with the movement and environment of an animal to precisely regulate the release of neuromodulators, chemicals that afflict brain activity and allow us to adapt to new situations.
The new findings could help scientists better understand how the brain allows flexible behavior and provide information on mood disorders such as depression.
Unlike neurotransmitters, which allow rapid communication between neurons, neuromodulators regulate groups of neurons through slower time scales. These chemicals adjust how our brain responds to messages and help shape our behavior, mood and thought.
In the Larval Cebbus fish, the neuromodulator serotonin controls how difficult the fish swim as changes in the environment or their own body alter the effectiveness of their effort.
Previous research of the Ahrens laboratory in Janelia found that serotonergic neurons in a region of the brain called the nucleus of the dorsal raphe use visual clues to assess the effectiveness of the swimming of the fish to discover how much effort should exercise in the future, releasing serotonin to adjust the swim vigor of the fish.
In a new investigation, a team led by the Ahrens laboratory sought to understand how these neurons discovered when and how much serotonin secretaries. While much research has focused on how neuromodulators affect neuronal circuits, less about how the neuromodulator system itself processes information.
As the fish swam in a virtual reality configuration, the researchers tracked the activity in the RAFE using voltage sensors and imaging tools of neurotransmitters developed in Janelia.
The zebra fish swam in a staccato pattern, which provides and coast, and found serotonergic neurons in the RAFE only integrate information about their perceived movement just after a swimming period.
Ahrens and his team determined that a “door” allows visual information to enter the RAFE: it is closed if the fish has not swam and opens just after it.
This process allows the RAFE cells to use visual information associated with the fish’s swimming effort to adjust the fish’s actions while filtering irrelevant visual signals. In general, this type of credit allocation, to correctly associate actions with the results, is in the heart of how a system learns from experience and is an active research field in neuroscience and automatic learning.
Then, the team examined how this activation works. Surprisingly, they discovered that swimming initially suppresses the activity in serotonergic neurons in the RAFE. But, once the fish stops swimming and enters the period of the coast, suppression is eliminated.
This causes a rebound effect, increases neuronal activity, such as pushing down on a balloon on a table and then releasing it, which causes it to go up. During this rebound phase, the door opens and visual information can reach the RAFE.
These visual signals add to the excitation of neurons and make cells fire in proportion to visual speed, releasing serotonin that adjusts the fish vigor of the fish.
The new findings provide information on how neuromodulation works in the RAFE, a region of the brain that is also found in human brains, and potentially sheds light on the processes involved in other neuromodulatory systems in the brain, according to researchers.
On this serotonin and visual neuroscience research news
Author: Nanci Bompeyo
Source: HHMI
Contact: Nanci Bompeyo – HHMI
Image: The image is accredited to Neuroscience News
Original research: open access.
“Voltage images reveal circuit calculations in the RAFE underlying the learning of serotonin -mediated engine” by Misha B. Ahrens et al. Neuron
Abstract
The voltage image reveals circuit calculations in the RAFE underlying the learning of the serotonin -mediated engine
As animals adapt to new situations, neuromodulation is a powerful way to alter behavior, however, the mechanisms by which neuromodulatory nuclei calculate during behavior do not apply.
The serotonergic RAFE supports motor learning in the Larval Cebra fish by visually detecting the distance traveled during the swimming, coding the effectiveness of the action and modular motor vigor.
We trace the RAFE input calculations on the millisecond time scales using voltage and neurotransmitter images and discover that swimming opens a door for visual entrance to cause peaks in serotonergic neurons, allowing the coding of the results of the action and the filtration of visual signals of unbeatable learning.
Specifically, SWIM commands initially inhibited serotonergic neurons through γ-aminobutiric acid (GABA). Immediately afterwards, the membrane voltage increased through the inhibitor’s subsequent rebound, which allows swimming visual movement to evoke the shot through glutamate, which triggers the release of serotonin to modulate the future vigor of the engine.
Subbing local gabaergic neurons affected RAFE coding and motor learning.
Therefore, serotonergic neuromodulation arises from the detection of the coincidence of the action of the action within the rafe.
