Gradual changing context Fear conditioning

The Gradual Changing Context Fear Conditioning (G2C) is our latest evolution of the Fear conditioning apparatus. Several components of the context may be modified in a continuous manner within an experimental session.

The main idea with this apparatus is to condition an animal to experience electric shocks in a context A, composed of an ensemble of elements (shape of the chamber, odor, lights, sound). At the beginning of the test session, another context B is defined with contextual elements, which are different from the elements of the fear-conditioned context A. Then each of the components of the context may be changed slowly one after the other, to analyze their involvement in the fear conditioning. In parallel, our apparatus can send electrical signals to synchronize behavioral events with electrophysiological recordings.

To combine technologies with behavior, use our movement compensator and rotary joints with the G2S.

Apparatus

The G2C is a very high-tech apparatus to analyze Fear conditioning, in which the different elements of the context can be adjusted continuously, contrarily to most other fear conditioning systems, in which elements are just activated or deactivated. These analog components are:

• the shape of the chamber. The chamber can switch from a square to a circle and vice-versa.
• the odor. An odor diffuser may diffuse two odors independently or a mix of odors in a proportion which is defined in the protocol by the experimenter.
• the lights. Two light sources give to the environment various lighting conditions.

The apparatus is composed of:

• a faradized, ventilated, sound-attenuated cubicle
• an infrared floor
• a digital video camera, to measure the animal activity and identify the freezing events
• a scrambled-shock generator
• a sound generator. This sound generator can play fast sequences of sounds or WAV files from the computer.
• synchronization kit (TTL signals)

All these upgrades allow changing the components of the context in a continuous way within an experimental session.

Software

The software that manages the G2C is similar to POLY_FEAR, which manages our classic Fear conditioning apparatus. POLY_G2C allows:

• creating, editing, loading task schedules,
• storing and dating all events: freezing, transformation of the shape of the chamber, emission of shocks, sounds, diffusion of odor, …
• following the proceedings of the experimental session, thanks to a graphical representation of the events and components

Le logiciel qui pilote l’appareil de G2C est similaire à celui qui pilote les appareils de Fear Conditioning classiques. Il possède en plus la possibilité de contrôler les composantes analogiques du contexte.

An additional software calculates output variables based on the raw data (which are accessible), for example:

• the number of freezing events, the duration of freezing, their kinetics
• the locomotor activity and rearings, their kinetics
• the delay between the diffusion of a sound and the start of the freezing
• etc…

The software extracts output variables in a Microsoft Excel data sheet.

Combination with other techniques

We developed a wide range of solutions to combine the analysis of behaviors in our apparatus with other techniques.

To combine with electrophysiology, we propose:

• rotary joints, embedded with our motorized movement compensator.
• the synchronization of behavioral events using TTL signals.

In order to control an optogenetic source, we propose:

• our moment compensator with which you can use your optic rotary joint, and even combine optogenetic stimulation with additional techniques,
• a high-frequency TTL generator. This tool sends TTL at 500Hz maximum according to the task schedule or to the animal as analyzed in real time during an experiment.