The acoustic startle response is an unconditional reflex involving rapid facial and skeletal muscle movements triggered by sudden, startling stimuli like sound or light. Studying the acoustic startle response in mice is essential for gaining insights into the central nervous system (CNS), including classical conditioning, fear, habituation, and sensorimotor gating.
To quantify this response, scientists introduce a stimulus into a startle chamber and observe the mouse’s anxiety, fear, and stress levels. This article explores how the acoustic startle response in mice is quantified and highlights its significance.
Experimental setup
Researchers require multiple tools to accurately and efficiently monitor acoustic startle response in mice. A challenge in quantifying the acoustic startle response is that it occurs quickly, giving scientists only a brief window to capture the response. This setup ensures that the mice are closely monitored for safety and to ensure the accuracy of the results.
Image Credit: San Diego Instruments, Inc.
Startle chamber
The mouse is put inside a restraint within the startle chamber for safety. Startle chambers are equipped with speakers to deliver a loud sound as a stimulus and a transducer to quantity the response.
Acclimation period
Before testing begins, the mouse is given a short acclimation period to familiarize itself with the startle chamber. This reduces the risk of imprecise results and ensures the mouse reacts only to stimuli, not parts of the chamber.
Presentation of acoustic stimuli
After the acclimation period, various acoustic stimuli are activated over different intervals. The sound’s intensity is gradually increased, enabling scientists to determine the point at which the startle response is initiated.
Measurement of startle response and pre-pulse inhibition
At this stage, scientists may measure the startle response’s pre-pulse inhibition (PPI), another important feature for understanding the CNS. PPI frequently occurs in response to a softer sound before the startle-inducing noise, often reducing the startle response’s intensity.
A startle response is typically characterized by a rapid contraction of facial and skeletal muscles, which can look like a full-body flinch or forepaw and hind paw extension followed by a hunched posture or an alteration in facial expression or eyeblinks.
Once these steps are completed, scientists examine the experiment’s collected data.
Data analysis
Evaluating data from startle response experiments usually necessitates specialized software that produces reports based on each mouse or testing group’s startle response and PPI data.
After the data has been evaluated and presented, scientists use it to compare results between diverse mice or testing groups. This often occurs when one group has a genetic modification or receives certain drug treatments and is compared to another.
Quantifying acoustic startle response with San Diego Instruments
San Diego Instruments provides various products designed to monitor and measure the acoustic startle response in mice. The SR-LAB acoustic startle response system is commonly utilized to quantify acoustic startle response, fear-potentiated startle, and PPI in research environments.
The SR-LAB system is an all-in-one hardware and software solution for numerous startle response applications. Up to 16 stations can be added for high-throughput experiments. The SR-LAB software allows control of multiple stimuli, such as air puffs, background noise, foot shocks, lights, and noise bursts. Different test paradigms can be introduced without requiring additional software.
About San Diego Instruments, Inc.
For more than 30 years, San Diego Instruments has served the scientific community as a comprehensive resource for the design, manufacture and distribution of behavioral neuroscience research instruments used in human and animal studies. Utilized in laboratories and cited in research papers worldwide, SDI systems have come to represent the industry standard for quality and longevity. Our premier SR-LAB™ is the world’s most widely used startle response system. At SDI, our commitment to developing quality products that stand the test of time is matched only our dedication to excellent customer service. We take pride in our ever-growing core of loyal clientele.
SDI behavioral neuroscience research systems afford you the utmost in quality and performance, giving you the edge in an industry where Power, Flexibility and Ease of Use are everything.
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