Source Paper
Ventral pallidum GABA neuron inhibition augments context-appropriate defensive responses to learned threat cues
Ramirez EM, Martinez MX, Rokerya RK, Vera VA, Ruiz CM et al.
Neurobiol Stress • 2026
Shock Probe Fear Expression Test
Objective: To test effects of VP GABA inhibition on expression of defensive responses directed at a threatening probe which previously delivered shock
Protocol Steps
Habituation
Habituate rats to plexiglass tub cage with corncob bedding for 30 minutes on two consecutive days
View evidence from paper
“Rats were first habituated for 30min on two days to a specific plexiglass tub cage”
Shock probe acquisition session
Place rats in chamber with electrified copper-wrapped probe (1.5 mA) inserted 8cm above floor, continue for 20min after first shock
View evidence from paper
“shock probe acquisition session continued for 20min after the first rat-initiated shock”
Re-acquisition session
Conduct short 5-minute session with re-electrified probe, ensuring all rats receive at least one shock
View evidence from paper
“they underwent a short (5min) shock probe fear "re-acquisition" session, where the probe was re-electrified”
Drug injection
Inject VEH or CNO intraperitoneally 30 minutes before expression test
View evidence from paper
“Vehicle (VEH) or CNO was injected IP 30min prior to commencement of all behavioral tests”
First expression test
Place rats in chamber with inactive probe for 20 minutes and record behavior
View evidence from paper
“rats received VEH or CNO injection, then were placed into the chamber with the inactive probe for 20min”
Second expression test
Repeat expression test after 48 hours with counterbalanced drug treatment (VEH/CNO)
View evidence from paper
“they received the alternative injection (VEH/CNO) prior to the session”