1. Experiment introduction.
The startle reflex is a brainstem reflex designed to protect vulnerable parts of the body such as the nape of the neck (generalized reflex), eyes (blink reflex), and accelerated evasion. The acoustic startle reflex (ASR) is an animal's response to a sudden onset of sound, which is generally thought to occur when the sound intensity reaches 80dB. Human startle reflex measurements are typically performed using electromyography, brain imaging, or PET, and in rodent laboratory animals, primarily by accelerometers or compression sensors.
The auditory startle reflex system (also known as shock conditioning system) provided by Shanghai Xinsoft detects the whole body shaking response of experimental animals through a gravity sensor. As sound stimuli are produced and enhanced, the animal's major muscle groups contract and relax. Anti-anxiety drugs reduce the intensity of this response, while anxiety-causing agents do the opposite. Prepulse inhibition (PPI) is one of the most commonly used applications. PPI refers to the phenomenon that a stimulus of a certain duration and intensity (a stimulus that does not cause the startle reflex) is given at an appropriate time before the startle stimulation (hence the pre-stimulation) to inhibit the startle reflex, so that the amplitude of the startle response is reduced and the latency period is prolonged. The PPI test can be used to observe the ability of the auditory system to process the prestimulus.
Two. System features:
The auditory startle reflex system adopts a general logical language structure, a graphical editing mode, and a free and flexible method of editing. Since there is no fixed restriction on the built-in method template, the experiment method can be edited arbitrarily
The software can run and control multiple experimental setups at the same time
Using high-power full-range horns and audio power amplifiers as sound stimuli, the sound pressure can reach up to 120dB;
The sound signal source is then the computer sound card, which can use any custom sound signal such as white noise and sine wave pure tone
Customized sensors are used to detect animal startle responses, and highly sensitive signal amplification modules are used to record the small movements of animals, which can be used for rats and mice respectively through different sensors
The system provides one analog signal acquisition (for analysis of startle reflection signals) and multiple switching signal controls, such as optical, electrical, gas, etc. (optional) for each experimental setup
The sensor can be gravity-corrected by software and used to accurately measure the actual gravity change of the animal's jumping;
By using a sound decibel meter, multiple decibels-volume curves can be created within the software, so that the sound volume can be controlled by specifying the decibel value directly in the method editor
The system sampling clock can be set up to 1ms, and the time accuracy is enough to detect the subtle beating reflections of animals.
Adopt a common data logging format for easy data analysis and export to Excel;
The experimental device is placed in a soundproof box to reduce mutual audiovisual interference;
Stimulation such as strong light and full electricity can be purchased
This system can be connected with other systems to create a special system that needs customers.
Three. Analyze metrics.
Shock Peak: Record the weight change 200 ms after each stimulus, and the maximum weight change in this 200 ms is the shock peak.
Mean Peak: The arithmetic mean of the peaks derived from all repeated stimuli at the same intensity is the mean peak, such as the mean of all 12 peaks at 98db.
Mean Shock Amplitude: An amplitude value is recorded every 1-2 ms, and the average value of each amplitude value is recorded over a period of time (e.g., 200 ms or 250 ms) after a strong stimulus.
Mean amplitude of the prepulse: An amplitude value is recorded every 1 ms, and the average value of each amplitude value is recorded for a period of time after the stimulation of the prepulse (e.g., 200 ms or 250 ms).
Prepulse Inhibition Rate: Formula: %ppi=(p-pp) p *100%, pp is the mean amplitude evoked by the prepulse (weak stimulus), and p is the mean amplitude evoked under strong stimulus conditions only.
Response latency: The time it takes to give a stimulus to a shock spike each time.
Others Shock pulse intensity, startle stimulus reactivity, adaptive reactivity (non-standard, customized parameters).