Knowledge Base

Introduction

This document is intended for EthoVision users who record data with multiple arenas simultaneously, and want to apply different Trial Control protocols to different arenas.

Example: The camera points at two separate arenas, each with one animal. In arena 1, provide a foot shock 30 seconds from the start of the trial. In arena 2, provide a foot shock at a randomly chosen time between 0 and 90 seconds from the start.

Multiple Arenas in Your EthoVision Experiment

If you work with multiple arenas within an experiment, each arena is treated as an independent replicate. In most cases, you want to apply the same Trial Control protocol to all the arenas. Imagine that you create a Trial Control protocol that stops tracking when the subject has moved a certain distance. You define one Trial Control Settings profile and apply that profile for your trial.

Because subjects differ in their behavior, tracking will stop at different times for each of those arenas. That is because EthoVision XT uses multiple copies of the same Trial Control Settings, one for each arena.

Same Protocol, but Independent Processes

The Trial Control Settings are applied to each arena independently. Suppose that the protocol is "After starting the trial, switch on a light when the animal enters the zone named Food Zone." A light device has been installed on top of both arenas, and a zone named "Food Zone" has been defined in the Arena Settings for both arenas.

If the animal in Arena 1 enters its Food Zone, the corresponding light will be switched on. However, the light on top of Arena 2 won't be activated, unless the animal in Arena 2 enters its own Food Zone too. Although the protocol is the same, it is applied in two copies, one for each arena.

To implement this, select the different physical devices (Light 1 for Arena 1, Light 2 for Arena 2, etc.) on the same line in the Arena - Hardware Mapping window (Arena Settings). This way, different arenas refer to the same generic device name (e.g., "Light"). This "generic" name is then used in the instructions of the Trial Control protocol.

Another typical example is the PhenoTyper setup, where the same protocol is applied to a group of 4 or more cages. Conditions and actions are processed independently for each cage.

Different Protocols in Different Arenas

In some cases, two or more arenas may need different protocols. For example, your camera view includes three arenas:

• In Arena 1, a light (Light 1) is switched on at a specific time, for example at one minute after start.
• In Arena 2, the light (Light 2) is switched on at a moment randomly chosen between 30 seconds and 2 minutes.
• Arena 3 is used as a control, with no light stimuli presented.
• For all arenas, the trial lasts 3 minutes.

If the Trial Control procedure is based on an Arena - Hardware Mapping where the two light devices Light 1 and Light 2 are represented by the same device name, any instruction using that device name would be executed for both arenas. As a result, the light would be switched on in both arenas twice — once at 1 minute, and again at a random time between 30 seconds and 2 minutes. Similarly, if an action depends on the animal's behavior (for example, "Switch on the light when the animal is in the Food Zone"), the command would be executed in both arenas, producing incorrect results.

The solution is to map devices in a different way, by specifying one physical device in each row in the Arena - Hardware Mapping window.

Simple Case: Two Arenas

To illustrate the concept, we assume that we work with two arenas with one animal in each arena. The animals are subject to two different treatment protocols. In Arena 1, the stimulus is administered at a fixed time, while in Arena 2 the stimulus is administered at a randomly chosen time. Hardware devices are controlled through TTL commands.

Experiment Settings

1. Connect all hardware devices to the EthoVision XT computer via the appropriate TTL port in the Noldus USB-IO box.
2. In the Experiment Settings, under Trial Control Hardware, click Settings.
3. Choose Noldus USB-IO box.
4. In the Device Configuration window, assign a hardware device to a port of the USB-IO box. Select the device type in the Device type/Device column. This may be a standard device (such as the Top Unit Light for PhenoTyper) or a Custom Hardware device.

In the Device Configuration window, the Device ID indicates the name of each physical device. For example, Light 1 will be installed in Arena 1, Light 2 in Arena 2, and so on.

Arena Settings

1. In the Arena Settings, define and calibrate the arenas as usual. Next, click the Arena - Hardware Mapping button in the Arena Settings window.
2. In the Arena - Hardware Mapping window, click Add Device two or more times to create multiple rows — one row for each physical device that has to work independently.
3. For each arena, assign a device in a different row. Make sure that the other cells of the row show <No device allocated>.

Source: EthoVision XT 18 - THC - Trial and Hardware Control, Noldus Information Technology