Olfactory interneurons in the moth <i>Manduca sexta</i> : response characteristics and morphology of central neurons in the antennal lobes

TLDR

The antennal lobes of Manduca sexta contain local interneurons with multiglomerular dendrites and output neurons with uniglomerular dendrites, and exhibit sexual dimorphism with only males responding to female pheromone. Pheromone‑responsive neurons in male Manduca sexta have dendrites confined to the macroglomerular complex. Two morphologically and physiologically distinct pheromone‑responsive local interneurons and one output neuron type were identified in the macroglomerular complex.

Abstract

The antennal lobes of the moth Manduca sexta are composed of two distinct classes of central neurons: local interneurons, involved in sensory processing within the lobe, and output neurons, the relay elements carrying sensory information to higher neuropil centres in the brain. The different types of neurons in each class share many characteristics. All of the local interneurons have extensive multiglomerular dendritic arborizations and lack distinct axons while all of the output neurons have uniglomerular dendritic arborizations. In addition to these general characteristics the central neurons of the antennal lobes also possess a distinct sexual dimorphism. Only the male moth responds to the female sex pheromone. All of the central neurons in the antennal lobe of the male moth th at respond to pheromone have dendritic branches located in the macroglomerular complex, a male-specific neuropil region. Two types of pheromone-sensitive local interneurons have been described morphologically and physiologically while a single type of output neuron has been found that has a dendritic arborization in the macroglomerular complex.