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Scholarly Works (2 results)

  • Thesis
  • Peer Reviewed
UCLA Electronic Theses and Dissertations (2015)

This work examines a variety of fundamental biological questions regarding the

central brain of D. melanogaster. These questions focus on topics relating to neurons

which form the neural circuits of the larval and adult brain. We focused specifically on

the neurons which form the central brain and are organized into developmental-structural units termed lineages. Through a combination of genetics and

immunohistochemical assays we were able to create a detailed atlas of lineages in the

early larval brain (made by embryonic-born primary neurons) and the adult brain (made

mostly by larval-born secondary neurons; Chapters 2 and 6); show that secondary

lineages are born in a strict temporal manner and how they develop during larval and

pupal stages (Chapters 3-5). By observing secondary lineages in both wild-type and

various mutant conditions we were able to show the following: pattern and timing of

secondary lineage axon tract extension in the larva; movement of cell body clusters due

to the growing central brain and optic lobe neuropils during metamorphosis; which

secondary lineages retain their entire cohort of neurons (many lose a hemilineage in the

pupa); and proper differentiation of secondary lineages relies on the presence of both

synaptic partners. Taken together, these studies make a significant contribution to our

understanding of Drosophila brain circuitry and development. They support the overall

goal of mapping all central brain lineages (primary and secondary components), from

their inception in the early embryo (when neuroblasts first appear) to their final mature

form in the adult.

    Cover page: An anatomical and developmental analysis of neural lineages, the fundamental units of circuitry in the central brain of Drosophila melanogaster
    • Article
    • Peer Reviewed
    UCLA Previously Published Works (2017)
    The Drosophila central brain consists of stereotyped neural lineages, developmental-structural units of macrocircuitry formed by the sibling neurons of single progenitors called neuroblasts. We demonstrate that the lineage principle guides the connectivity and function of neurons, providing input to the central complex, a collection of neuropil compartments important for visually guided behaviors. One of these compartments is the ellipsoid body (EB), a structure formed largely by the axons of ring (R) neurons, all of which are generated by a single lineage, DALv2. Two further lineages, DALcl1 and DALcl2, produce neurons that connect the anterior optic tubercle, a central brain visual center, with R neurons. Finally, DALcl1/2 receive input from visual projection neurons of the optic lobe medulla, completing a three-legged circuit that we call the anterior visual pathway (AVP). The AVP bears a fundamental resemblance to the sky-compass pathway, a visual navigation circuit described in other insects. Neuroanatomical analysis and two-photon calcium imaging demonstrate that DALcl1 and DALcl2 form two parallel channels, establishing connections with R neurons located in the peripheral and central domains of the EB, respectively. Although neurons of both lineages preferentially respond to bright objects, DALcl1 neurons have small ipsilateral, retinotopically ordered receptive fields, whereas DALcl2 neurons share a large excitatory receptive field in the contralateral hemifield. DALcl2 neurons become inhibited when the object enters the ipsilateral hemifield and display an additional excitation after the object leaves the field of view. Thus, the spatial position of a bright feature, such as a celestial body, may be encoded within this pathway.
      Cover page: Visual Input to the Drosophila Central Complex by Developmentally and Functionally Distinct Neuronal Populations
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