Researchers have uncovered how the brains of fruit flies transform memories of past rewards into executable behaviors, allowing them to find food. Specifically, a key region of the brain called the corpus callosum processes olfactory information and assigns values to different odors. However, it was unclear how these values influenced motor actions. This study identified a group of neurons called UpWiNs that play a crucial role in converting odor memories into wind-oriented movements.

Fruit flies, like other insects, turn in the direction of the wind to track odors and locate the source of attractive smells. The olfactory system in the fly’s brain detects and perceives these wind-borne odors, guiding the fly towards the reward. Researchers found that UpWiNs integrate inhibitory and excitatory inputs from different compartments of the corpus callosum, causing the fly to turn and move with the wind.

The corpus callosum in the fly’s brain processes and integrates olfactory information and assigns positive or negative values to different odors. Researchers discovered that memories formed in different compartments of the corpus callosum lead to distinct behaviors, with only some driving the fly’s wind-oriented movement. UpWiNs receive inhibitory and excitatory signals from these compartments, allowing the fly to effectively navigate towards the source of attractive odors.

This research provides insight into how learned positive and negative values are translated into concrete actions based on memory. UpWiNs also send excitatory signals to dopaminergic neurons for higher-order learning. Understanding these neural circuit mechanisms helps explain how parallel dopaminergic neurons and memory subsystems interact to guide memory-based actions and learning at the level of individual neural circuits.

Further studies on fruit flies may shed light on the role of memory in behavior and learning in both vertebrate and invertebrate brains.

Definitions:

• Corpus callosum: a region of the brain found in some insects that is responsible for processing olfactory information and assigning values to different odors.
• UpWiNs: a group of neurons that integrate inhibitory and excitatory signals from different compartments of the corpus callosum, guiding fruit flies to move with the wind towards attractive odors.

Sources:

• HHMI (Howard Hughes Medical Institute)
• Original research: “Neural circuit mechanisms for transforming learned olfactory valences into wind-oriented movement” by Yoshinori Aso et al. eLife.