Knowledge Base

Problem

A laboratory that previously triggered single-channel optogenetic devices via EthoVision now needs to trigger two independent optogenetic channels, each activated when an animal enters a different zone in an open-field arena.

Details

Applies to EthoVision XT versions that support hardware TTL output and custom hardware device configuration (XT 13 and later). Requires a USB I/O box or compatible TTL output device with at least two independent output ports. The solution uses EthoVision's hardware mapping and Trial Control rule system.

Solution

1. Go to Setup > Experiment Settings. Under Hardware, add two Custom Hardware devices. Name them (e.g., Pulser 1 and Pulser 2) for easy identification.
2. Assign each device to a different TTL output port: Pulser 1 → Output 1, Pulser 2 → Output 2.
3. Go to Setup > Arena Settings. Click the Arena-Hardware Mapping button. Add both devices and map them to the same arena (they share the same camera/arena context).
4. Define your two target zones in Arena Settings (e.g., Zone A and Zone B).
5. In Trial Control, create a rule for Zone A entry: Condition = Subject in Zone A; Action = Activate Pulser 1 (TTL Output 1 ON). Add a paired rule for Zone A exit to turn Output 1 OFF.
6. Create a second rule for Zone B entry: Condition = Subject in Zone B; Action = Activate Pulser 2 (TTL Output 2 ON). Add a paired rule for Zone B exit to turn Output 2 OFF.
7. Test the configuration with a sample trial to confirm each zone triggers only its assigned output and that outputs turn off correctly on exit.
8. Adjust pulse duration or pattern in the hardware device settings if your optogenetic stimulator requires a specific pulse width.