Knowledge Base

Introduction

Startle Pre-Pulse Inhibition (PPI) is an experimental paradigm to study sensorimotor gating. With this term we intend the ability of the brain to filter out irrelevant sensory stimuli to suppress or decrease a motor response, in this case, a startle response.

The Startle PPI paradigm has been widely used in rodents, such as mice and rats, to study sensorimotor gating deficits in different animal models. In a typical PPI experiment, a startle baseline is measured as a response to a loud sound, or a light or air-puff. A pre-pulse stimulus is delivered shortly before the loud stimulus. That is supposed to decrease the startle reaction.

This section refers to the Ugo Basile system for the Pre-Pulse Inhibition of the Startle Reflex. You can have this system send TTL signals to EthoVision XT when a pulse is fired or terminated, and when an environmental output is activated or deactivated. This way the EthoVision XT tracking information is synchronized with the main events generated by the PPI system.

Connection Scheme

For this you need the Ugo Basile PPI Startle Reflex Interface. This Interface box is connected to the PPI Startle Reflex system through a flat cable and has two additional output connectors, OUT 1 and OUT 2. You can connect one or both outputs to TTL ports of the USB-IO box. Contact Noldus if you need the proper adapter cables.

• OUT 1 can be enabled with each stimulus pulse (or pre-pulse). The status is ON while the pulse is fired and OFF when the pulse is terminated.
• OUT 2 can send out "environment" signals, like that for the visible light, the infrared light or the fan that can be turned ON or OFF at a specific time during the trial.

See also the Ugo Basile Pre-Pulse Inhibition of Startle Reflex (PPI) User Guide.

EthoVision XT

1. In the Experiment Settings, define the TTL ports as Custom Hardware.
2. In the Arena Settings, click the Arena - Hardware Mapping button and define the devices for each arena.
3. In the Analysis Profile, define a Hardware State variable for example to visualize the pulses together with the tracking data.

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