Knowledge Base

Introduction

Optogenetics and EthoVision XT

In the last decade, a method was developed to specifically activate or even inhibit small groups of neurons with light. Today, scientists can insert light-sensitive receptor proteins (originally found in algae) into single mammalian neurons in vivo, making these neurons sensitive to activation by light of specific wavelengths. This allows scientists to control the activity of these neurons and study their downstream influence on a variety of biological processes.

Optogenetics is an important development for behavioral research. Not only can the actual influence of specific neurons on behavior more specifically be determined, but also, with the help of an automatic video tracking system such as EthoVision XT, behavior can be manipulated via optogenetic methods in real time. With the Trial & Hardware Control module, EthoVision XT can control light pulses given by a third party device, based on the behavior of the animal (for instance, presence in a trigger zone).

In this manual we focus on the optogenetics solution for rodents that combines EthoVision XT, PhenoTyper (as test environment) and the Prizmatix optogenetics devices. For how to conduct optogenetics experiments with zebrafish, see the DanioVision DVOC-0041 Reference Manual.

Examples

Place Preference

The animal is placed in an arena with two distinct sides - one of which is paired with optogenetic stimulation. Depending on whether this stimulation is activating or deactivating, and which neurons are affected, this can be a rewarding or aversive stimulus for the animal. If in further sessions the animal spends more time on the stimulated sides, it is fair to conclude the stimulus had a rewarding effect. If the animal avoids this side, the stimulus could then be considered aversive.

Operant Conditioning

In operant conditioning tests, the animal learns to perform an action in order to get a reward or avoid an aversive stimulus. The behavioral response can be recorded with EthoVision XT, either by detecting the animal (or its nose point) in a certain zone, such as the feeder, or by analyzing the external signal initiated by the nose poke or lever press. Following this action, EthoVision XT sends out the command for optogenetic stimulation.

Off-On-Off Stimulus Test

In an off-on-off stimulus test, you can program EthoVision XT to turn optogenetic stimulation on for a period of time during the test. For example, a 15 minute test during which continuous optogenetic stimulation takes place in the middle 5 minutes.

References

1. Guru, A., Post, R.J., Ho, Y., Warden, M. (2015). Making Sense of Optogenetics. International Journal of Neuropsychopharmacology, Aug 2015, 1–8.
2. Zalocusky, K., Deisseroth, K. (2013). Optogenetics in the behaving rat: integration of diverse new technologies in a vital animal model. Optogenetics 2013: 1-17.
3. Stamatakis, A.M., Stuber, G.D. (2012). Activation of lateral habenula inputs to the ventral midbrain promotes behavioral avoidance. Nature Neuroscience, (8), 1105-1107.
4. Kravitz, A.V., Tye, L.D., Kreitzer, A.C. (2012). Distinct roles for direct and indirect pathway striatal neurons in reinforcement. Nature Neuroscience, 816-818.

Source: EthoVision XT 18 - Application Manual, Noldus Information Technology