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Tim Vogels

 

Wednesday 22nd October 2014

Time: 4pm

 

Basement Seminar Room

Alexandra House, 17 Queen Square, London, WC1N 3AR

 

'The dance of excitation and inhibition (and some other interesting stories)'

 

The first part of my talk will investigate the electrical filtering abilities of dendritic spine necks.
Most excitatory inputs in the mammalian brain are made on dendritic spines. Spines are thought to compartmentalize calcium gradients, and have been hypothesized to serve also as electrical compartments. The latter hypothesis necessitates relatively high spine neck resistances. Due to its small size it is difficult to assess spine neck resistance directly in experiments, and has thus been discussed at somewhat above average temperatures in the field. I will show some modeling work that aims to deduce resistance estimates from two recent datasets showing negative correlations between spine neck length and somatically recorded EPSPs, and thus seem to imply high spine neck resistance. Using numerical simulations, we explore the parameter regimes for the spine neck resistance and other variables (such as synaptic conductance changes) necessary to explain these data sets.

Since we use NEURON for the above mentioned simulations, and NEURON, and its accompanying MODELDB database for previously published models is (sometimes) notoriously difficult to get comfortable with, I will show some recent meta-analysis on publicly available model ion channels. Our work visualizes the family relations of over 3000 unique models, and uses the similarity of their performance in standard protocols as a means to suggest a handful truly useful channels for everyday use.

The last part of my talk will visit the stabilizing performance of inhibitory synaptic plasticity in recurrent cortical networks and introduce a class of cortical architectures with very strong and random excitatory recurrence that is stabilized by intricate, fine-tuned inhibition. I will show that excitation and inhibition in such networks dance with each other to transiently amplify specific activity states that can be used to reliably execute multidimensional movement patterns. The intriguing similarity to recent experimental observations along with tightly balanced excitation and inhibition, suggest inhibitory control of complex excitatory recurrence as a generic organizational principle in cortex.

 

 

Bio

Tim Vogels studied physics at Technische Universität Berlin and neuroscience at Brandeis University. He received his PhD in 2007 in the laboratory of Larry Abbott. After a postdoctoral stay in experimental neuroscience with Rafael Yuste at Columbia University, he returned to computational work and to Europe as a Marie Curie Reintegration Fellow in the laboratory of Wulfram Gerstner at the École Polytechnique Fédérale de Lausanne (EPFL). Tim was awarded the Bernstein Award for Computational Neuroscience in 2012. in 2013 Tim moved to Oxford to establish a research group in theoretical neuroscience within the Centre of Neuroal Circuits and Behaviour. As a computational neuroscientist, he builds conceptual models to understand the fundamentals of neural systems at the cellular level. His research group is funded by a Sir Henry Dale Fellowship of the Wellcome Trust and the Royal Society."