How flies turn memories into downwind hunts for food

summary: Researchers have revealed how the fruit fly brain converts memories of past rewards into actionable behaviors, directing the fly toward food. One key brain region, the mushroom body, integrates olfactory information and assigns values ​​to odors, but the link to motor actions has not been clear.

This study identifies a group of neurons, called UpWiNs, that process these signals, prompting the fly to move upwind toward the source of attractive odors. These insights provide a deeper understanding of how memories influence behavior through complex neural circuits.

Key facts:

  1. Fruit flies head upwind to track odors, guided by memories of past rewards.
  2. The mushroom body in the fly’s brain processes odors, assigning them positive or negative values.
  3. A newly identified group of neurons, UpWiNs, plays a pivotal role in converting odor memories into upwind movements.

source: My concern

New research by Janelia scientists and her collaborators at the University of North Carolina at Chapel Hill shows how a group of neurons in the fruit fly brain turns memories about past rewards into action, helping the fly navigate to find food.

Like other insects, flies turn into the wind, or against the direction of the wind, to locate the source of attractive odors. The fly’s olfactory system detects and senses odors carried by the wind, directing the fly toward the reward.

The study identifies a group of neurons — upwind neurons, or UpWiNs — that integrate inhibitory and excitatory inputs from these parts, causing the fly to turn and move downwind. Credit: Neuroscience News

In the fly, an area of ​​the brain called the mushroom body processes and integrates olfactory information. Multiple parts of the mushroom body work in parallel to assign positive or negative values ​​to odor stimuli, but how these signals are translated into motor actions is unknown.

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New research shows that reward memories formed in different parts of the mushroom’s body trigger distinct behaviors, with only some driving the fly’s downwind movement. The study identifies a group of neurons — upwind neurons, or UpWiNs — that integrate inhibitory and excitatory inputs from these parts, causing the fly to turn and move downwind.

New research provides insight into how learned positive and negative values ​​are gradually transformed into concrete, memory-based actions. UpWiNs also send excitatory signals to dopaminergic neurons for higher-level learning, according to the researchers.

These findings help explain how parallel dopaminergic neurons and memory subsystems interact to direct memory-based actions and learning at the level of individual neural circuits.

About this neuroscience research news

author: Nancy Pompey
source: My concern
communication: Nancy Pompey – HHMI
picture: Image credited to Neuroscience News

Original search: Open access.
Neural circuit mechanisms for converting acquired olfactory valence into wind-directed movement“By Yoshinori Aso et al. eLife


a summary

Neural circuit mechanisms for converting acquired olfactory valence into wind-directed movement

How the brain uses memories to guide future action is not well understood. In olfactory associative learning in Drosophila, multiple parts of the mushroom body work in parallel to assign valence to a stimulus.

Here we show that appetitive memories stored in different compartments stimulate different levels of downwind movement.

Using a photoactivation screen of a novel set of discrete GAL4 drivers and EM connections, we have identified a population of postsynaptic neurons of mushroom body output neurons (MBONs) that can give rise to robust downwind guidance.

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These UpWind neurons (UpWiNs) integrate inhibitory and excitatory synaptic inputs from MBONs of appetitive and aversive memory compartments, respectively. After appetitive memory formation, UpWiNs acquire an enhanced response to odors that predict reward as the presynaptic inhibitory MBON response undergoes depression.

Impaired appetitive memory blocking of UpWiNs results in decreased downwind movement during retrieval. Photoactivation of UpWiNs also increased the chance of returning to the location where activation was terminated, suggesting an additional role in olfactory navigation.

Thus, our results provide insight into how acquired abstract valences are gradually transformed into concrete, memory-based actions through divergent and convergent networks, a neural architecture typically found in vertebrate and invertebrate brains.

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