summary: A key region of the insect-like arthropod brain, the mushroom body, plays a key role in abstract behavioral decision-making.
Contrary to longstanding beliefs that insects respond based purely on stimulus responses, this study shows that insects can actually make nuanced decisions based on experience. The researchers recorded feeding behavior along with neural signals.
This has implications not only for insect behavior, but also for our understanding of fundamental neurobiological principles that are similar in humans.
Important facts:
- Mushroom bodies in arthropod brains encode both memory formation and complex decision-making, challenging the conventional view that insects act solely on stimulus responses.
- The study included the American cockroach, which was chosen because its relatively large brain facilitates the measurement and interpretation of neural signals and behavior in real time.
- Mushroom body output neurons also take into account the animal’s current state, such as whether it is hungry or not, so they can predict behavior more accurately.
sauce: University of Cologne
The mushroom body (the learning and memory area of the arthropod brain) is responsible for the ability of insects to make abstract behavioral decisions, which are then carried out by downstream motor networks.
This is the result of a study carried out by Professor Martin-Paul Nawrott and Dr. Kansu Alikan of the “Computational Systems Neuroscience” working group at the Institute for Zoology, University of Cologne.
The study reported: biology today With the title “Mushroom body outputs encode behavioral decisions during sensorimotor transduction.”
Researchers have long believed that insects respond robotically to simple stimulus-response patterns, but this assumption has changed significantly in the last two decades. “Insects have simple cognitive skills such as memory formation and memory.” Despite their relatively small brains, they exhibit complex behavioral patterns,” said Professor Naurott.
Necessary nervous system processes in invertebrate insects and mammals, as well as humans, follow in many respects similar basic principles. This includes rapid sensory processing of environmental conditions and their evaluation, comparison with acquired experiences (thus making reliable decisions between possible behavioral alternatives), and ultimately physical Includes execution.
15 Years of Brain Circuit Research
A key processing area in the middle of the insect brain, known as the mushroom body because of its anatomical shape, is essential for memory formation. Over the past 15 years, various research efforts have shown that memory information is encoded by the valence of sensory stimuli in mushroom body outputs.
In the framework of the research group FOR 2705 “Dissection of brain circuits: structure, plasticity and behavioral function of the Drosophila mushroom body”, funded by the German Research Foundation since 2018, the Cologne team led by Prof. Naroth also Contribute to this research field.
Insects have previously remembered certain stimuli as positive (e.g., the scent that promises food) or as negative (e.g., the scent of pathogenic agents such as harmful bacteria in food). determine if it is
Recent studies have also shown that mushroom body output neurons also assess sensory stimuli associated with innate, or non-experience-based, behaviors.
Description of the new function of the mushroom body
In this latest study, lead author Dr. Kansu Alikan describes how he measured output neuron activity in the mushroom body of American cockroaches (periplaneta americana) in her experiment simultaneously filmed the feeding behavior of the animals.
This large insect species was chosen because it has a much larger brain than the fruit fly, which is often used as a model organism in basic research.
This allows for electronic measurements of neural signals, allowing simultaneous observation of both stimulatory activity by various food odors and neural responses within the mushroom body and, ultimately, feeding behavior in animals as possible behavioral responses to stimuli. It is now possible to measure and interpret. with high time accuracy.
The researchers found that output neurons in the body of mushrooms not only encode the valence of specific odors, such as food odors versus neutral odors, but also use this information to influence the execution of their respective feeding behaviors. Observed making a decision.
They do not base their behavioral decisions solely on this valence information. The current state of the animal is also important, for example, whether it is hungry at the moment. Therefore, in each test, we were able to accurately predict whether an animal would exhibit feeding behavior after only about a tenth of a millisecond, based on neural response patterns.
Similar to the motor cortex of the human brain, the mushroom body makes the initial action decisions and sends abstract motor commands to the downstream motor network (in humans, this is the spinal cord) for subsequent execution. . It works by activating the muscles involved.
“These results challenge the prevailing view that the mushroom body is now thought to be the center of memory formation and behavioral decision-making. Studies of insect brains are more complex.” This is important because it is also relevant for understanding brain function,” Dr. Kansu Alikan summarized the results.
Funding: This research was supported by funding from the German Research Foundation and the ‘iBehave’ network.
About this neuroscience research news
author: Anna Oituneur
sauce: University of Cologne
contact: Anna Outeneuer – University of Cologne
image: Image credited to Neuroscience News
Original research: open access.
“Mushroom body outputs encode behavioral decisions during sensorimotor transductionWritten by Martin Paul Naurot et al. biology today
abstract
Mushroom body outputs encode behavioral decisions during sensorimotor transduction
highlight
- Simultaneous Recording of Mushroom Body Output Neurons (MBON) and Behavior
- Innate feeding behavior is expressed only in response to food odors
- MBON responds almost exclusively with short latencies during behavioral testing.
- MBON responses enable faithful prediction of behavior in a single trial
summary
Animals shape their behavioral decisions by assessing the background of past experiences and sensory evidence about their momentary motivational state. In insects, it is still poorly understood how behavioral decisions are formed at which stages of the repetitive sensorimotor pathway.
The mushroom body (MB), a central structure in the brains of insects and crustaceans, transmits various modes of sensory input through internal, behavioral, and external sensory contexts and through numerous repetitive inputs (mainly neuromodulatory inputs). The case for MB in state-dependent sensorimotor transduction that is consolidating and suggests a functional role.
A number of classical conditioning studies in honeybees and Drosophila have accumulated evidence that MB encodes the valence of sensory stimuli in terms of their behavioral relevance during their output. Recent work has extended this concept of valence encoding to the context of innate behavior.
Here we jointly analyze defined feeding behaviors and simultaneous extracellular single-unit recordings from cockroach MB output neurons (MBONs) in response to timed sensory stimulation by odors. We have shown that overt neural responses occurred almost exclusively during behavioral response testing.
Early MBON responses to sensory stimuli preceded feeding behavior and predicted development or non-development of feeding behavior from single-trial collective activity.
Our results therefore suggest that MB does not merely encode the valence of sensory stimuli in its output. We instead hypothesize that MB outputs represent integrated signals of experience-dependent memory to encode internal states, instantaneous environmental conditions, and behavioral decisions.
