Associate Professor, Department of Biology
Ph.D. Universita di Padova, Italy
B.Sc. Imperial College London, UK
Research Interests: Molecular mechanisms of synapse formation
Overview: Information is exchanged between neurons at synapses, which are essentially specialized sites of cell-cell adhesion . A mature synapse is defined as an accumulation of synaptic vesicles within the axon, in close apposition to a dendritic membrane studded with receptors (see figure)which are held in place by a submembranous scaffold (Sheng and Kim, 2002). The formation of such an intercellular structure requires spatially and temporally controlled changes in morphology and molecular content at sites of contacts. Recent advances in subcellular fluorescence microscopy have revealed that this process involves the rapid recruitment and stabilization of both pre- and postsynaptic elements. These studies have shown that major components of the synaptic vesicle and active zone machinery travel in clusters together with other presynaptic proteins, such as calcium channels, and are rapidly recruited to new sites of contact (Ahmari et al., 2000; Zhai et al., 2001; Washbourne et al., 2002) .
On the postsynaptic side, receptor subunits and components of the scaffold or post-synaptic density (PSD) are recruited separately and with distinct time courses within minutes to hours after initial contact (Friedman et al., 2000; Bresler et al., 2001; Washbourne et al., 2002; Bresler et al., 2004)
Despite these advances the basic mechanisms by which synapse formation is induced at discrete locations and by which the molecular machinery is recruited to sites of contact remain elusive. We are currently using both mammalian primary neuronal cultures and zebrafish embryos to investigate molecules that are involved in the mechanisms of synapse formation. Techniques currently employed are live confocal imaging of fluorescently-tagged synaptic components, electron microscopy, biochemistry and molecular biology.
Forebrain Control of Behaviorally Driven Social Orienting in Zebrafish.
Curr Biol. 2018 Jul 21;:
Authors: Stednitz SJ, McDermott EM, Ncube D, Tallafuss A, Eisen JS, Washbourne P
Deficits in social engagement are diagnostic of multiple neurodevelopmental disorders, including autism and schizophrenia . Genetically tractable animal models like zebrafish (Danio rerio) could provide valuable insight into developmental factors underlying these social impairments, but this approach is predicated on the ability to accurately and reliably quantify subtle behavioral changes. Similarly, characterizing local molecular and morphological phenotypes requires knowledge of the neuroanatomical correlates of social behavior. We leveraged behavioral and genetic tools in zebrafish to both refine our understanding of social behavior and identify brain regions important for driving it. We characterized visual social interactions between pairs of adult zebrafish and discovered that they perform a stereotyped orienting behavior that reflects social attention . Furthermore, in pairs of fish, the orienting behavior of one individual is the primary factor driving the same behavior in the other individual. We used manual and genetic lesions to investigate the forebrain contribution to this behavior and identified a population of neurons in the ventral telencephalon whose ablation suppresses social interactions, while sparing other locomotor and visual behaviors. These neurons are cholinergic and express the gene encoding the transcription factor Lhx8a, which is required for development of cholinergic neurons in the mouse forebrain . The neuronal population identified in zebrafish lies in a region homologous to mammalian forebrain regions implicated in social behavior such as the lateral septum . Our data suggest that an evolutionarily conserved population of neurons controls social orienting in zebrafish.
PMID: 30057306 [PubMed - as supplied by publisher]