Quantifying the Acoustic Startle Response in Mice Using Standard Digital Video

Abstract

The startle response is an unconditional reflex, characterized by the rapid contraction of facial and skeletal muscles, to a sudden and intense startling stimulus. It is an especially useful tool in translational research for its consistency across species, simple neural circuitry, and sensitivity to a variety of experimental manipulations. The rodent acoustic startle response is commonly used to study fundamental properties of the central nervous system, including habituation, sensitization, classical conditioning, fear and anxiety, sensorimotor gating, and drug effects. The rodent startle response is typically assessed in stabilimeter chambers, and while these systems are excellent at measuring startle, they are designed only for this sole purpose. In the present study, we used the VideoFreeze system-a widely used tool for studying Pavlovian fear conditioning-to assess the acoustic startle response in freely moving mice. We validated the use of this system to quantify startle response amplitude and prepulse inhibition of startle. This is the first demonstration to date of using standard video in the automated assessment of the acoustic startle response in rodents. We believe that researchers already using the VideoFreeze system will benefit from the additional ability to assess startle without the purchase of new equipment.

Research Progress in the Study of Startle Reflex to Disease States

“…Other novel measurement methods include the new optical non-invasive method, 9 mobile acoustic startle reflex monitoring system (MARS), 10 and video freeze monitoring system. 5 The Balogiannis team 9 believe that the new optical non-invasive method is simple and reliable, making it superior to traditional EMG systems in terms of effectiveness, accuracy, and reliability. MARS 10 is the first mobile phone-based monitoring system.…”

“…The diagnosis and monitoring of ASR in stroke, traumatic brain injury, and mood disorders has opened up new prospects and horizons, and the same went for that in remote or isolated conditions. The video freeze system 5 (Georgia Medical Association Co., Ltd., Vermont, USA) uses a standard digital camera to shoot videos and automatically evaluates the rodents’ shock response to sound. The system is also equipped with stimuli, such as sounds and lights, that are required for various startle modes, which is a new tool for studying startle reflex.…”

“…It has the characteristics of cross-species consistency, simple neural circuits, and sensitivity to experimental operations. 5 Throughout our review, we found that the degree of attention to the startle reflex has increased in the past five years, but review articles were mostly limited to the habituation, sensitization, pre-pulse inhibition (PPI), and sensorimotor gating of the startle reflex. Thereafter, we focused on summarizing the startle reflex in clinical disease states, and distinguishing the startle reflex from hyperekplexia.…”

“… 3 The startle reflex is considered a defensive (relative to directional) response, which is habitual. 5 As the number and frequency of startles increase, the body becomes habitual, and the degree of startle reflex decreases. This kind of reaction exists to a certain extent to protect the human body.…”

Fear Deficits in HypomyelinatedTpppKnock-Out Mice

“…Animals are then exposed to an auditory cue followed by a noxious stimulus (foot shock). Although at 85 dB this tone is not loud enough to stimulate an acoustic startle response (Pantoni et al, 2020), both wild-type and Tppp KO mice increase the percentage of time spent freezing. This indicates that Tppp KO mice can perceive the tone (i.e., are not deaf) and furthermore that they freeze acutely in response to the tone.…”