summary: The mushroom body, a key region of the brain of insect-like arthropods, plays a key role in abstract behavioral decision-making.
Contrary to the long-held belief that insects respond purely on a stimulus-response basis, 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 in humans as well.
Important facts:
- The mushroom body in the arthropod brain encodes both memory formation and complex decision-making, challenging the traditional view that insects simply act on stimulus-response.
- The American cockroach was included in this study and was chosen because its relatively large brain facilitates the measurement and interpretation of neural signals and behavior in real time.
- The output neurons of the mushroom body also take into account the animal’s current state, such as whether it is hungry, so it can more accurately predict behavior.
sauce: University of Cologne
The mushroom body, the learning and memory region of the arthropod brain, is responsible for the insect’s ability to make abstract behavioral decisions, which are then executed by downstream motor networks.
This is the result of a study carried out by Professor Martin Paul Naurot and Dr. Cansu Arikan from the “Computational Systems Neuroscience” working group at the Institute of Zoology at the University of Cologne.
This study was reported as follows: current biology With the title “Mushroom somatic output encodes behavioral decisions during sensorimotor transformation.”
For a long time, researchers believed that insects respond like robots, following simple stimulus-response patterns, but this assumption has changed significantly over the past two decades. “Insects have simple cognitive skills such as memory formation and memorization.” In addition to remembering, they are also capable of decision-making that relies on experience. Despite their relatively small brains, they exhibit complex behavioral patterns,” Professor Naurot said.
Necessary nervous system processes in invertebrate insects, mammals, and humans alike follow similar basic principles in many respects. This involves rapid sensory processing of environmental conditions and their evaluation, comparison with acquired experience (and thus a reliable decision between possible action options), and finally the physical Includes execution.
15 years of brain circuit research
A key processing region in the center of the insect brain, known as the mushroom body due to 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 the mushroom somatic output.
Within the framework of the research group FOR 2705 “Dissection of brain circuits: structure, plasticity and behavioral functions of the Drosophila mushroom body”, which has received funding from the German Research Foundation since 2018, the team from Cologne led by Prof. Naroth also Contribute to this research field.
Insects may remember a particular stimulus as either previously remembered as positive (e.g., the smell promising food) or as negative (e.g., the smell of pathogenic substances such as harmful bacteria in food). determine whether it is.
Recent studies have also shown that mushroom body output neurons also evaluate sensory stimuli associated with innate, or non-experience-based, behaviors.
Explanation of new functions of mushroom body
In this latest study, lead author Dr. Kansu Arikan describes how they measured the activity of output neurons in the mushroom body of the American cockroach (Periplaneta Americana) In her experiment, she simultaneously filmed the animals’ feeding behavior.
This large insect species was chosen because it has a much larger brain than fruit flies, which are often used as model organisms in basic research.
This allows for electronic measurements of neural signals, simultaneously measuring both the stimulus activity of different food odors and the neural responses within the mushroom body, and ultimately the animal’s feeding behavior, as possible behavioral responses to the stimulus. It is now possible to measure and interpret. with high time precision.
The researchers found that output neurons in the mushroom’s body not only encode the valence of a particular odor, for example, comparing a food odor to a neutral odor, but also use this information to guide the performance of each feeding behavior. I observed them making decisions.
They do not make behavioral decisions based solely on this valence information. The current state of the animal is also important, for example, whether it is hungry at that moment. Therefore, on each trial, we were able to accurately predict whether the animal would exhibit feeding behavior after only about a tenth of a millisecond, based on its neural response pattern.
Similar to the motor cortex of the human brain’s cerebral cortex, the mushroom body makes initial behavioral decisions and sends abstract motor commands to the downstream motor network (in humans, this is the spinal cord), which are then executed . It works by activating the relevant muscles.
“This result challenges the prevailing view that the mushroom body is now thought to be the center of memory formation and behavioral decision-making. Research into insect brains has shown that the mushroom body is a more complex This is important because it is also relevant to understanding brain function,” Dr. Cansu Arikan 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 Oitneuer
sauce: University of Cologne
contact: Anna Oiteneuer – University of Cologne
image: Image credited to Neuroscience News
Original research: Open access.
“Mushroom somatic output encodes behavioral decisions during sensorimotor transformationWritten by Martin Paul Naurot et al. current biology
abstract
Mushroom somatic output encodes behavioral decisions during sensorimotor transformation
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 allow faithful prediction of behavior in a single trial
summary
Animals form behavioral decisions by evaluating the background of past experiences and sensory evidence about momentary motivational states. In insects, there is still a lack of understanding of how behavioral decisions are formed at which stages of the repetitive sensorimotor pathway.
The mushroom body (MB), a central structure in the brain of insects and crustaceans, connects various modalities of sensory input to internal states, behavioral states, and external sensory contexts through a large number of repetitive inputs (mainly neuromodulatory inputs). The case for the MB in state-dependent sensorimotor transformations suggests an integrated and functional role.
Many classical conditioning studies in honey bees and Drosophila have accumulated evidence that the MB encodes the valence of a sensory stimulus in terms of its behavioral relevance at the time of its output. Recent research has extended this concept of valence encoding to the context of innate behavior.
Here we jointly analyzed simultaneous extracellular single-unit recordings from cockroach MB output neurons (MBONs) in response to defined feeding behaviors and odor-based timed sensory stimuli. We showed that overt neural responses occurred almost exclusively during behavioral response tests.
Early MBON responses to sensory stimuli preceded feeding behavior and predicted the occurrence or non-occurrence of feeding behavior from single-trial population activity.
Our results therefore suggest that the MB does not simply encode the valence of sensory stimuli in its output. Instead, we hypothesize that the output of the MB represents an integrated signal of internal states, momentary environmental conditions, and experience-dependent memory to encode behavioral decisions.