The Inhibitory Avoidance Apparatus was used by Gilvan Luiz Borba Filho et al. (2015). Its aim was to develop and standardize a new device for step-down inhibitory avoidance task, in which the applied electric current has the precise same intensity as the current passing through the subject’s paws, taking into consideration the subject’s bioimpedance; the stimulus frequency and intensity are controlled and recorded during the entire experiment.
The apparatus consists of a poly(methyl methacrylate) box and a control box. This box has a transparent acrylic window, a platform on the left facing a grid of a series of 20 pairs of stainless steel bars spaced within bars and each pair spaced apart.
Conductor software integrates Ethovision or ANY-Maze for seamless software integration without I/O boxes allowing for the configuration and execution of experiments (protocols) and view execution results.
Price & Dimensions
Mouse
$ 3900
+S&H- Chamber dimensions 30 x 20 x 30 cm (length x width x height)
- Walls: The front side is clear acrylic, the other three sides are black matte acrylic
- Platform: 7.9 x 20 x 3.3 cm, 3.3 cm (length x width x height) above the grid floor
- Diameter of stain steel bars: 1.3mm, Distance between bars: 0.66cm
- Shock Grid Included 22 x 20 cm (length x width)
- Smooth DC Shock Delivery
- Output Current: 0 – 4mA (adjustable in .1mA increments)
- Voltage: 163V (direct current)
- Current level can be controlled via our software or manually
- Feces and urine tray – removable for feces and urine cleaning
- No lid
Rats
$ 4900
+S&H- 50 x 25 x 30cm (length x width x height)
- Length of acrylic window: 48cm
- Width of acrylic window: 30cm
- 5cm x 12cmx 25cm (length x width x height) above the grid floor
- Diameter of stain steel bars: 2mm, Distance between bars: 1cm
- Shock Grid Included
- Smooth DC Shock Delivery
- Output Current: 0 – 4mA (adjustable in .1mA increments)
- Voltage: 163V (direct current)
Dimensions for the mouse Inhibitory Avoidance apparatus
Introduction
The inhibitory avoidance apparatus is a behavioral testing apparatus used in psychology and neuroscience research to study learning and memory processes in rodents. It is designed to assess a subject’s ability to remember and avoid an aversive or negative stimulus (a mild electric shock).
The apparatus consists of a platform and an electrified grid floor. The Grid floor is associated with an aversive stimulus (a mild electric shock). The subject is placed on the platform and due to its natural tendency is to explore its environment, leading it to touch the grid floor. During the training phase of the experiment, thesubject experiences a mild electric shock when it touchs the grid floor. This experience creates an association between the aversive grid floor snd the unpleasant stimulus, teaching the subject to avoid that area.The memory and learning aspect of this test come into play during the retention or testing phase, which occurs after a certain period of time has elapsed since the initial training. Researchers measure the latency or time it takes for the subject to touch the grid floor again. A longer latency period suggests better memory retention of the negative association and the subject’s ability to inhibit its natural tendency to explore the aversive chamber.
The Inhibitory Avoidance apparatus is used to study various aspects of learning and memory, including short-term memory, long-term memory, and the effects of different drugs or experimental manipulations on memory processes. It provides insights into the cognitive abilities of the subject and helps researchers understand the underlying neural mechanisms involved in memory formation and recall.
Apparatus and Equipment
The apparatus consists of a poly(methyl methacrylate) box and a control box. This box has a transparent acrylic window, a platform on the left facing a grid of a series of 20 pairs of stainless steel bars spaced within bars and each pair spaced apart. All bars have an insulating layer on the sides and bottom. Box, platform, and grid dimensions are available as rat and mouse models.
The control box uses Conductor software to integrate control of the apparatus with Ethovision or ANY-Maze for seamless software integration without I/O boxes allowing for the configuration and execution of experiments (protocols) and view execution results.
Take advantage of Neuralynx, Ethovision Integration, SMS and Email integration with the Conductor Science Software. No I/O Boxes Required
Training and Execution
Protocols as per Gilvan Luiz Borba Filho et al. (2015)
Inhibitory Avoidance Training:
- Stimulus Parameters:
- Electric shock stimulus: 0.35mA at 62Hz.
- This stimulus serves as an aversive experience for the subject.
- Initial Placement:
- Each subject is gently placed on the platform.
- The subject is positioned to face the rear left corner of the apparatus.
- Training Session:
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- When the subject steps down on the grid with all four paws, it completes the circuit and receives an electric footshock (0.35mA at 62Hz) for a duration of 3 seconds.
- The aversive stimulus creates an association between the grid and the unpleasant experience.
- Withdrawal:
- After receiving the footshock, the subject is immediately withdrawn from the apparatus.
- Test Session (24 hours later):
- Each subject is placed back on the platform inside the safe chamber.
- In this session, no electric shock is applied when the subject steps down on the grid.
- Behavioral Response:
- The time it takes for the subject to step down with all four paws onto the grid is recorded. This is known as the “step-down latency.”
- For the test session, the step-down latency is measured again when the subject enters the aversive chamber without receiving a shock,
- Time Parameters:
- A manual chronometer is used to measure the time intervals.
- In the training session, step-down latencies are recorded, but if an animal does not step down within 60 seconds, its latency is recorded as 60 seconds.
- In the test session, step-down latencies are recorded, but if an animal does not step down within 180 seconds, its latency is recorded as 180 seconds.
- Conclusion:
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- Longer step-down latencies during the test session compared to the training session indicate that the animal remembers the aversive experience and associates it with the grid in the aversive chamber.
This protocol outlines the training process for the inhibitory avoidance apparatus, focusing on the specific parameters used for stimulus delivery, animal placement, training session, test session, and the measurement of step-down latencies.
Inhibitory Avoidance Training with Escapable Footshock:
- Group Division:
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- The subjects are divided into 11 experimental groups based on the intensity and frequency of the footshock stimuli applied.
- Stimulus Parameters:
- The intensity and frequency of the electric footshock stimulus vary based on the specific experimental group.
- Stimuli groups:
- Group 1: 0.2mA; 20Hz, 62Hz, 125Hz.
- Group 2: 0.35mA; 10Hz, 20Hz, 40Hz, 62Hz, 125Hz.
- Group 3: 0.5mA; 20Hz, 62Hz, 125Hz.
- Initial Placement:
- Each subject is gently placed on the platform inside the safe chamber.
- The subject faces the rear left corner of the apparatus.
- Training Session:
- When the subject steps down on the grid with all four paws, it completes the circuit and receives a continuous scrambled footshock.
- The intensity and frequency of the footshock depend on the specific experimental group the subject belongs to.
- The footshock continues until the animal spontaneously steps back up onto the platform (latency to escape).
- Escape latency (time taken to step back up) is recorded and cut-off at 60 seconds.
- Withdrawal:
- After the subject escapes the footshock and returns to the platform, it is immediately withdrawn from the apparatus.
- Test Session (24 hours later):
- Similar to the test session in the first protocol, each animal is placed back on the platform in the safe chamber.
- No footshock is applied in this session when the animal steps down on the grid.
- Behavioral Response:
- Step-down latencies are measured during the test session as well as the training session, using a manual chronometer.
- As with the first protocol, step-down latencies are cut-off at 60 seconds during training and 180 seconds during the test session.
- Conclusion:
- Longer escape latencies during the test session compared to the training session indicate the animals’ ability to remember and avoid the aversive experience, based on the specific stimuli they received.
This protocol builds upon the first one by introducing the concept of escapable footshocks, where subjects learn to escape the aversive stimulus by returning to the safe platform. It also outlines the specific experimental groups based on the intensity and frequency of the footshock stimuli, providing a comprehensive framework for studying the effects of different parameters on learning and memory.
Passive Inhibitory Avoidance Training and Testing
- Stimulus Parameters:
- The intensity and frequency of the electric footshock stimulus vary based on the specific experimental group.
- Stimuli groups:
- Group 1: 0.2mA; 20Hz, 62Hz, 125Hz.
- Group 2: 0.35mA; 10Hz, 20Hz, 40Hz, 62Hz, 125Hz.
- Group 3: 0.5mA; 20Hz, 62Hz, 125Hz.
- Initial Placement and Training Session:
- Each subject is gently placed on the platform inside the safe chamber.
- The subject faces the rear left corner of the apparatus.
- When the subject steps down on the grid with all four paws, it receives continuous scrambled footshock based on its group’s specific stimulus parameters.
- The footshock continues until the animal spontaneously steps back up onto the platform (latency to escape).
- Escape latency (time taken to step back up) is recorded and cut-off at 60 seconds.
- Withdrawal and Test Session:
- After the subject escapes the footshock and returns to the platform, it is immediately withdrawn from the apparatus.
- After 24 hours, a test session is conducted similar to the first protocol, without any footshock.
- Behavioral Response:
- Step-down latencies and escape latencies are measured during both training and test sessions using a manual chronometer.
- Step-down latencies are cut-off at 60 seconds during training and 180 seconds during the test session.
- Group Division:
- The subject are divided into 11 experimental groups based on the intensity and frequency of the footshock stimuli applied.
- Passive Inhibitory Avoidance Performance Evaluation:
- Passive inhibitory avoidance performance is evaluated by measuring the latency to step-down in both training and test sessions.
- The memory performance is calculated by the difference between the latency to step-down during the test session and the latency to step-down in the training session.
- Equation for Performance Evaluation (f(t)):
-
- The equation f(t) is used to assess inhibitory avoidance performance (see below).
- It incorporates the step-down latency in the training session (SDT), latency to escape (SU), and step-down latency in the test session (SD24H)
f(t): IAT function
SDT: step-down latency in training session
SD24:step-down latency in test
SU: latency to escape
k1: 60s (maximum time in the platform during the training session)
k2: 3s (minimum time in the platform during the training session)
- Learning Measurement:
- Learning is measured by comparing the difference between step-down latency in the training and the step-down latency in the test session after 24 hours.
- Interpreting Equation Values:
-
- Values of the equation above indicate that the step-down latency in the test session (SD24H) is significantly higher than the step-down latency in the training session (SDT), regardless of the escape latency.
This protocol introduces a more comprehensive way to assess inhibitory avoidance performance, taking into account factors such as the latency to escape, step-down latency in both training and test sessions, and their differences. The provided equation f(t) offers a method to compare the effect of different treatments on learning and memory within the context of the inhibitory avoidance task.
References
Borba Filho, G. L., Zenki, K. C., Kalinine, E., Baggio, S., Pettenuzzo, L., Zimmer, E. R., Weis, S. N., & Calcagnotto, M. E. (2015). A New Device for Step-Down Inhibitory Avoidance Task—Effects of Low and High Frequency in a Novel Device for Passive Inhibitory Avoidance Task That Avoids Bioimpedance Variations. PLOS ONE, 10(2), e0116000. https://doi.org/10.1371/journal.pone.0116000