A Micro-Electrode Array device coupled to a laser-based system for the local stimulation of neurons by optical release of glutamate

Diego Ghezzi, Andrea Menegon, Alessandra Pedrocchi, Flavia Valtorta, Giancarlo Ferrigno

Research output: Contribution to journalArticlepeer-review

Abstract

Optical stimulation is a promising approach to investigate the local dynamic responses of cultured neurons. In particular, flash photolysis of caged compounds offers the advantage of allowing the rapid change of concentration of either extracellular or intracellular molecules, such as neurotransmitters or second messengers, for the stimulation or modulation of neuronal activity. We describe here the use of an ultra-violet (UV) laser diode coupled to an optical fibre for the local activation of caged compounds combined with a Micro-Electrode Array (MEA) device. Local uncaging was achieved by UV irradiation through the optical fibre previously positioned by using a red laser diode. The size of the stimulation was determined using caged fluorescein, whereas its efficacy was tested by studying the effect of uncaging the neurotransmitter glutamate. Uncaged glutamate evoked neuronal responses that were recorded using either fluorescence measurements or electrophysiological recordings with MEAs, thus showing the ability of our system to induce local neuronal excitation. This method allows overcoming the limitations of the MEA system related to unfocused electrical stimulation and induction of electrical artefacts. In addition, the coupling of a UV laser diode to an optical fibre allows a precise local stimulation and a quick change of the stimulation point.

Original languageEnglish
Pages (from-to)70-78
Number of pages9
JournalJournal of Neuroscience Methods
Volume175
Issue number1
DOIs
Publication statusPublished - Oct 30 2008

Keywords

  • Caged compound
  • Flash photolysis
  • MEA
  • Neuronal excitation
  • Optical fiber
  • Uncaging

ASJC Scopus subject areas

  • Neuroscience(all)

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