George S. Boyan

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Despite the importance of the insect nervous system for functional and developmental neuroscience, descriptions of insect brains have suffered from a lack of uniform nomenclature. Ambiguous definitions of brain regions and fiber bundles have contributed to the variation of names used to describe the same structure. The lack of clearly determined neuropil(More)
Understanding the cellular, molecular and genetic mechanisms involved in building the brain remains one of the most challenging problems of neurobiology. In this article, we review recent work on the developmental mechanisms that generate the embryonic brain in insects. We compare some of the early developmental events that occur in the insect brain with(More)
1. Auditory neurones in the brain (supraoesophageal ganglion) of the cricketGryllus bimaculatus (De Geer) were intracellularly recorded and stained with Cobalt or Lucifer. 2. The cell bodies and arborisations of all recorded neurones are contained entirely within the supraoesophageal ganglion. Further, the cells all have arborisations which overlap(More)
Our analysis of head segmentation in the locust embryo reveals that the labrum is not apical as often interpreted but constitutes the topologically fused appendicular pair of appendages of the third head metamere. Using molecular, immunocytochemical and retrograde axonal staining methods we show that this metamere, the intercalary segment, is innervated by(More)
We have investigated the ontogenetic basis of locustatachykinin-like expression in a group of cells located in the pars intercerebralis of the grasshopper midbrain. These cells project fibers to the protocerebral bridge and the central body via a characteristic set of fiber bundles called the w, x, y, z tracts. Lineage analyses associate the immunoreactive(More)
The central complex of the insect brain is a remarkably miniaturized but highly complex multimodal information-processing network. Recent work on central complex development in Drosophila and grasshopper reveals that the cells comprising its complex circuitry are generated by a surprisingly small number of primary progenitors. Of these, four identified(More)
1. The postembryonic development of three identified ascending interneurones in the auditory system ofLocusta migratoria was studied using intracellular recording and staining techniques. 2. The terminal arborisations in the brain of G, B and C neurones were identified in the adult, 5th and 4th instars, and for the G neurone in 3rd and 2nd instars as well(More)
Panarthropods are typified by disparate grades of neurological organization reflecting a complex evolutionary history. The fossil record offers a unique opportunity to reconstruct early character evolution of the nervous system via exceptional preservation in extinct representatives. Here we describe the neurological architecture of the ventral nerve cord(More)
1. The terminal ganglion ofLocusta migratoria contains a number of non-giant, wind-sensitive, ascending and local interneurones. Six ascending (Figs. 1, 2) and 6 local (Figs. 6, 7) interneurones have been identified morphologically on the basis of intracellular stains with Lucifer Yellow. 2. The physiological responses of the various cell types were(More)
The primary axon scaffold of the insect brain is established early in embryogenesis and comprises a preoral protocerebral commissure, a postoral tritocerebral commissure and longitudinal fiber pathways linking the two. In both grasshopper and fly its form is approximately orthogonal and is centered around the stomodeum. We show how pioneer fibers from the(More)