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Mushroom bodies suppress locomotor activity in Drosophila melanogaster
J R Martin1, R Ernst, M Heisenberg
1Lehrstuhl für Genetik, Biozentrum, Würzburg, Germany.
Abstract:
Locomotor activity of single, freely walking flies in small tubes is analyzed in the time domain of several hours. To assess the influence of the mushroom bodies on walking activity, three independent noninvasive methods interfering with mushroom body function are applied: chemical ablation of the mushroom body precursor cells; a mutant affecting Kenyon cell differentiation (mushroom body miniature); and the targeted expression of the catalytic subunit of tetanus toxin in subsets of Kenyon cells. All groups of flies with mushroom body defects show an elevated level of total walking activity. This increase is attributable to the slower and less complete attenuation of activity during the experiment. Walking activity in normal and mushroom body-deficient flies is clustered in active phases (bouts) and rest periods (pauses). Neither the initiation nor the internal structure, but solely the termination of bouts seems to be affected by the mushroom body defects. How this finding relates to the well-documented role of the mushroom bodies in olfactory learning and memory remains to be understood.
Insights
Flies with mushroom body defects exhibit increased walking activity due to delayed activity decline. This impacts bout termination, not initiation, in fruit fly locomotion.
Area of Science:
- Neuroscience
- Animal Behavior
- Insect Physiology
Background:
- The mushroom bodies are crucial for learning and memory in insects.
- Locomotor activity patterns provide insights into neural function.
Purpose of the Study:
- To investigate the role of mushroom bodies in regulating locomotor activity in fruit flies.
- To determine how mushroom body defects affect walking behavior patterns.
Main Methods:
- Analysis of locomotor activity in freely walking flies over several hours.
- Noninvasive methods to interfere with mushroom body function: chemical ablation, Kenyon cell differentiation mutant (mushroom body miniature), and tetanus toxin expression in Kenyon cells.
Main Results:
- Flies with mushroom body defects displayed elevated total walking activity.
- This increase was linked to slower and incomplete attenuation of activity over time.
- Walking activity is organized into bouts and pauses; mushroom body defects primarily affected bout termination, not initiation or internal structure.
Conclusions:
- Mushroom body function is essential for the normal regulation of locomotor activity duration and decline.
- Defects in mushroom bodies alter the temporal dynamics of walking behavior, specifically affecting the cessation of activity bouts.
- The precise relationship between these observed motor control changes and the known roles of mushroom bodies in olfactory learning and memory requires further investigation.