Insects and Mammals Share Brain Secrets for Decision-Making

Insect Brains Unveiled: The ‘Mushroom Body’ Decides Behavior

Did you know insects have a brain region called the “mushroom body” that’s responsible for their ability to make thoughtful decisions? A team led by Professor Dr. Martin Paul Nawrot and Dr. Cansu Arican from the University of Cologne’s Institute of Zoology discovered this exciting finding. They studied how insects use this brain region to make complex choices and carry out actions. Their research was shared in the journal Current Biology under the title ‘The mushroom body output encodes behavioural decision during sensory-motor transformation’.

For a while, scientists thought insects behaved robotically, responding to simple patterns of stimuli. However, in the past two decades, this perception has drastically changed. “Insects possess simple cognitive skills like forming memories, recalling them, and making decisions based on their experiences. Despite their small brains, they display intricate behaviors,” explained Professor Nawrot.

Insects, like humans, follow similar neural processes when processing sensory information and making decisions. These steps include quickly evaluating their surroundings, comparing it with past experiences, and then executing a specific action.

Understanding the Mushroom Body

The mushroom body, located in the central brain of insects, is vital for memory formation. Over the past 15 years, researchers have discovered that the mushroom body encodes memory information based on the emotional value of sensory input. The University of Cologne team, part of the research group FOR 2705 ‘Dissection of a Brain Circuit,’ delved into this area. They found that insects can determine whether a stimulus is positive (like the scent of food) or negative (like the smell of harmful bacteria).

A New Discovery

In their latest study, Dr. Cansu Arican, the lead author, focused on the American cockroach. By measuring the activity of the mushroom body’s output neurons and observing the cockroach’s feeding behavior, she uncovered something intriguing. The mushroom body doesn’t just encode the emotional value of a smell; it also makes decisions based on this information. The brain region not only processes whether the smell is related to food or something neutral but also decides whether to perform feeding behavior based on the context. This context includes factors like the insect’s hunger level. Remarkably, the researchers could predict the feeding behavior within a fraction of a millisecond based on the neural response pattern.

The Takeaway

Similar to how the motor areas of the human brain guide actions, the mushroom body acts as the decision-maker for insects. It sends abstract commands to downstream motor networks that control actions. This finding challenges the previous understanding of the mushroom body and highlights its role in memory and behavior. Dr. Cansu Arican emphasized the significance of this discovery for understanding not only insect brains but also more complex ones.

This study was supported by the German Research Foundation and the “iBehave” network, shedding light on the fascinating world of insect brains and how they make decisions.

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