Representation of the brain's superior protocerebrum of the flesh fly, Neobellieria bullata, in the central body

Abstract

The central complex of the insect brain is a system of midline neuropils involved in transforming sensory information into behavioral outputs. Genetic studies focusing on nerve cells supplying the central complex from the protocerebrum propose that such neurons play key roles in circuits involved in learning the distinction of visual cues during operant conditioning. To better identify the possible sites of such circuits we used Bodian and anti-synapsin staining to resolve divisions of the superior protocerebrum into discrete neuropils. Here we show that in the fly Neobellieria bullata, the superior protocerebrum is composed of at least five clearly defined regions that correspond to those identified in Drosophila melanogaster. Intracellular dye fills and Golgi impregnations resolve “tangential neurons” that have intricate systems of branches in two of these regions. The branches are elaborate, decorated with specializations indicative of pre- and postsynaptic sites. The tangentially arranged terminals of these neurons extend across characteristic levels of the central complex’s fan-shaped body. In this and another blowfly species, we identify an asymmetric pair of neuropils situated deep in the fan-shaped body, called the asymmetric bodies because of their likely homology with similar elements in Drosophila. One of the pair of bodies receives collaterals from symmetric arrangements of tangential neuron terminals. Cobalt injections reveal that the superior protocerebrum is richly supplied with local interneurons that are likely participants in microcircuitry associated with the distal processes of tangential neurons. Understanding the morphologies and arrangements of these and other neurons is essential for correctly interpreting functional attributes of the central complex.

MicroRNA-133 Inhibits Behavioral Aggregation by Controlling Dopamine Synthesis in Locusts

“…We found that miR-133 and henna were only detected in the neuronal cell body of the locust protocerebrum (Figures 3A and Figure S3), which is an important region in determining the behavioral responses by output neurons from the mushroom body [26]. Pale was also widely expressed in the protocerebrum, including the mushroom body and the neuronal cell body.…”

Information flow through neural circuits for pheromone orientation

“…The medial portion of the protocerebrum in fruit fly, Drosophila melanogaster has been shown to receive an input from the subregion in the lateral horn, which receives an input from neurons processing the pheromone [49][50][51] . The superior protocerebrum was also shown to provide an input to the CX in the fly [52][53][54][55] . The input from the CX in the fly has been reported to converge on the lateral side of the inferior dorsofrontal protocerebra 55 , which roughly corresponds to the upper division of the LAL in the moth.…”

Principles of Insect Path Integration

“…route following and landmark navigation, are integrated with path integration. One region of the CX appears to be anatomically suited to serve as integration site for different strategies: The CBU (fan-shaped body) receives input from many different brain areas via a diverse set of input neurons [86,117,118]. These regions include areas that receive projections from the output cells of the mushroom body and thus could carry information controlling navigation strategies that require long-term memory (route following, landmark navigation, retrieval of averaged path integration vectors).…”