Images showing individual memory synapses in normal and Fragile X fly brains illustrate one of the syndrome's effects. Connections formed between sensory neurons and memory neurons located in a region of the brain called the calyx are shown in green. Normally, these connections are made on short branches away from the main axon (colored red), as indicated by the arrows. In Fragile X neurons, connections are made on top of the axon, as indicated by the white bar. Overall, fewer connections are formed between sensory and memory neurons, thereby disrupting the development of the olfactory circuit.