Impact of volume and expression time in an AAV-delivered channelrhodopsin

Sanaz Ansarifar, Gabija Andreikė, Milad Nazari, Rodrigo Labouriau, Sadegh Nabavi, Andrea Moreno*

*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review


Optogenetics has revolutionised neuroscience research, but at the same time has brought a plethora of new variables to consider when designing an experiment with AAV-based targeted gene delivery. Some concerns have been raised regarding the impact of AAV injection volume and expression time in relation to longitudinal experimental designs. In this study, we investigated the efficiency of optically evoked post-synaptic responses in connection to two variables: the volume of the injected virus and the expression time of the virus. For this purpose, we expressed the blue-shifted ChR2, oChIEF, employing a widely used AAV vector delivery strategy. We found that the volume of the injected virus has a minimal impact on the efficiency of optically-evoked postsynaptic population responses. The expression time, on the other hand, has a pronounced effect, with a gradual reduction in the population responses beyond 4 weeks of expression. We strongly advise to monitor time-dependent expression profiles when planning or conducting long-term experiments that depend on successful and stable channelrhodopsin expression.

Original languageEnglish
Article number77
JournalMolecular Brain
Number of pages5
Publication statusPublished - Dec 2023


  • AAV
  • Channelrhodopsin
  • EPSP
  • Expression time
  • In vivo electrophysiology
  • Longitudinal
  • oChIEF
  • Optogenetics
  • Volume


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