Pre-pulse inhibition of the acoustic startle response as a behavioral assay for sound localization abilities of the Mongolian gerbil

Abstract

The Mongolian gerbil (Meriones unguiculatus) has been used to investigate mechanisms of binaural and spatial hearing. However, behavior assays used to test gerbil spatial hearing using operant conditioning are very time consuming. Pre-pulse inhibition (PPI) of the acoustic startle response offers a method that requires no training and is thus high throughput. Here, we examine whether PPI can be used to assess spatial hearing in gerbils. In eight gerbils, we presented a continuous broadband noise that swapped speaker locations as a pre-pulse prior to a startle stimulus and found PPI increased with wider angles of swaps. Swap angles at 30° (±15° re: midline) or higher showed significantly higher PPI compared to baseline for swaps across midline and in each hemifield. We also performed speaker swap with a low- (0.5 kHz) and high-pass (4 kHz) filter and found that PPI increased at wider angles for both conditions. PPI also increased at wider angles and lower intensity of a spatial broadband masker to a broadband chirp pre-pulse. We successfully demonstrate the gerbil’s sound localization abilities and show that PPI paradigms are capable of quickly testing large numbers of gerbils and reveal performance similar to operant conditioning methods. [Work supported by R01-DC017924.]