Speakers > Jean-Marc Goaillard

Jean-Marc Goaillard

Institut de Neurosciences de la Timone, Marseille, France

Jean-Marc Goaillard is leading the SANE team at INT. After obtaining a PhD in Neuroscience in Paris studying the link between second-messenger signaling and ion channel modulation, Jean-Marc Goaillard joined the Marder lab to work on invertebrate neuronal networks. His work in the Marder lab helped demonstrating that ion channel expression levels are highly variable in neurons, although ion channels share strong correlations in their expression, defining co-expression modules that may underlie the stability of neuronal output. For the past 15 years, his group has been working on neuron-to-neuron variability in morphological, biophysical properties and ion channel expression in mammalian dopaminergic neurons, using electrophysiological, transcriptomics and computational approaches.

Degeneracy, cell-to-cell variability and co-variations in ion channel properties

Since the first mathematical description of ion channel function by Hodgkin and Huxley in the 1950s, our understanding of the biophysical mechanisms underlying neuronal activity has been constantly growing, feeding on the genetic identification of hundreds of ion channel genes, the crystallography-mediated deciphering of their structure-function relationships and many other discoveries. In spite of 70 years of multi-disciplinary collection of data, we are still unable to quantitatively understand how every neuronal type invariably achieves the unique electrophysiological phenotype sustaining its physiological function. This paradoxical lack of understanding may be explained by several factors that I will review in this talk: 1) Every neuronal type expresses many subtypes of ion channel with partially degenerate functions and 2) the expression levels and biophysical properties of any ion channel subtype display strong cell-to-cell variability, even in neurons with virtually identical patterns of activity. Recent findings made in invertebrate and vertebrate neurons suggest that this cell-to-cell variability may hide invariant relationships between ion channel properties, such as co-variations in expression levels. These co-variations may be genetically encoded to ensure that the neuron always reaches its “expected” pattern of activity.