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Cell and Developmental Biology

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Seminar - Dr Vilaiwan Fernandes - 27 June 2017

Start: Jun 27, 2017 1:00:00 PM
End: Jun 27, 2017 2:00:00 PM

Speaker: Dr Vilaiwan Fernandes (New York University, Desplan Lab)
Title: "Glia relay differentiation cues to coordinate neuronal development in Drosophila"
Venue: Medawar Watson LT
Abstract:
Neuronal birth and specification must be coordinated across the developing brain to generate the neurons that constitute neural circuits. This is particularly true for sensory systems where topographic maps are built by connecting neurons at different levels of circuitry. I use the ordered Drosophila visual system to investigate how neuronal development is coordinated across different brain regions to establish retinotopy, a feature of all visual systems. Photoreceptors were believed to achieve retinotopy by inducing their target field in the optic lobe, the lamina composed of five neuron types, by a secreted differentiation cue (Epidermal Growth Factor; EGF). I will discuss my recent finding that communication between photoreceptors and lamina precursor cells is indirect, and requires a signaling relay through wrapping glia. Specifically, I have found that in response to EGF from photoreceptors, wrapping glia produce Insulin-like peptides, which in turn induce lamina neuronal differentiation. I propose that the signaling relay through glia is a strategy to translate an otherwise homogenous photoreceptor cue into a spatio-temporally graded one. Additionally, incorporating a relay via glia delays the differentiation cue to the lamina, thus ensuring that lamina unit assembly is completed prior to differentiation.

Seminar - Professor Jozsef Csicsvari - 27 June 2017

Start: Jun 27, 2017 3:00:00 PM
End: Jun 27, 2017 4:00:00 PM

Speaker: Professor Jozsef Csicsvari (Institute of Science and Technology Austria)
Title: "Does the content of hippocampal reactivation matter?"
Venue: H O Schild Pharmacology LT
Abstract:
I will present the results of two unpublished projects. The first part, work of Igor Gridchin, involves online identification of cell assemblies and the optogenetic disruption of a selective subgroup of them during reactivation using the Axona recording system. To this end, we trained animals to locate goals in two different environmental context (i.e. two cheeseboards at different location with different distal cues), with each associated with a different goal location. After learning we disrupted the reactivation of assemblies representing one of the goals using our online assembly detection procedure during rest/sleep. Following the disruption we observed a selective memory impairment with the disrupted goal but not with the other.
The second part, work of Haibing Xu, examined reactivated patterns during three different radial 8-arm maze spatial tasks. We found that waking reactivated trajectories at the decision point in the central stem predicted the future arm choice of the animal when the task had a reference memory component but not when it was a pure working memory task.