Kenyon cells
systemLearning and memoryspeciesD. melanogaster3D view10 of 626 cellssources6
Kenyon cells are the intrinsic neurons of the mushroom body, the fruit fly’s center for associative learning and memory. Each mushroom body contains about 2,000 of them, and their parallel axons form its lobes.
| Also known as | KCs · Mushroom body intrinsic neurons · γ, α′β′ and αβ neurons |
|---|---|
| Region | Mushroom body: calyx, peduncle and lobes |
| System | Learning and memory |
| In the display bundle | 10 of the 626 reconstructed neurons in the site’s MaleCNS display bundle, which shows 626 of the model’s 166,700 neurons: KCab 3, KCapbp-ap2 1, KCg-d 1, KCg-m 5 |
What they are
Each mushroom body is built from the parallel axons of about 2,000 Kenyon cells (Aso et al., 2014). There are three main classes, named for the lobes their axons enter: γ, α′β′ and αβ. Each mushroom body neuroblast generates them in sequence, γ neurons first and αβ neurons last (Lee et al., 1999).
Where they sit
Kenyon cell dendrites form the calyx, where they receive input from olfactory projection neurons of the antennal lobe; their axons run through the peduncle into the lobes (Turner et al., 2008; Aso et al., 2014). Not all Kenyon cells are olfactory: a small subset responds to visual but not olfactory stimulation and has its dendrites in a separate ventral accessory calyx (Vogt et al., 2016), and the mushroom body connectome revealed extensive visual input (Li et al., 2020).
What they do
Kenyon cells respond to odors sparsely. Each cell receives input from only about 10 projection neurons on average and has a high firing threshold, so it responds to few odors, and the representations of different odors become less correlated than in earlier stages of the olfactory system (Turner et al., 2008).
Twenty-one types of mushroom body output neurons (MBONs) divide the lobes into 15 compartments, and each of 20 types of dopaminergic neurons projects to one or at most two of them. Dopaminergic input converging on the compartmentalized Kenyon cell to MBON synapses provides a substrate for learning to assign value to sensory representations (Aso et al., 2014).
Behavior
Behavioral, molecular and genetic studies identified the mushroom body as essential for forming and retrieving olfactory memories (Turner et al., 2008; Heisenberg, 2003).