16.12.14

***** Seminar *****

Gilad Wallach

M.Sc. student under the supervision of Prof. Yael Hanein

Glutamate Mediated Astrocytic Filtering of Neuronal Activity

Neuron-astrocyte communication is an important regulatory mechanism in various brain functions. The complexity and role of this communication are not yet fully understood and several recent models have been proposed. In this work we built, characterized and optimized a new in vitro experimental setup suitable for the investigation of the neuro-glia communication pathway. The electrical activity of neuron-astrocyte cultures on multi electrode arrays was mapped using  imaging while neurons were selectively activated using underlying micro-electrodes. Using this setup, we demonstrate, for the first time, the existence of a frequency dependent, glutamate-mediated signaling mechanism between neurons and astrocytes. By modifying the stimulation frequency and number of spikes, we revealed a clear onset of astrocytic activation at neuron firing rates around 3 Hz. Astrocytic activation by neurons, as evidenced by astrocytic intracellular free calcium ion concentration  transients, was abolished with glutamate receptor blockers, validating the glutamate-dependence of this neuron-to-astrocyte pathway. These experimental results are compared with a biophysical model of neuron-astrocyte intercellular signaling developed by Berry and colleagues, which further support a glutamate mediated frequency dependent neuro-astrocyte communication. The frequency dependent neuro-astrocytes communication presented here may play an important, task specific role in brain function.

Tuesday, 16 December 2014 at 11:00, Room 011, Kitot Building.