Active & Passive Avoidance Learning in Mice: What's the Difference?

Avoidance learning can be described as a component of an organism’s survival instinct, as they develop a response to avoid a harmful or unpleasant stimulus before it occurs. Once the organism has experienced an unpleasant stimulus, it can begin to recognize when it is about to happen and escape the situation or determine which behaviors can prevent the unwanted impact. For example, if a human notices a specific setting is too loud, they may wear earplugs before entering or avoid the place altogether. In mice, if a shock follows a specific noise, eventually, they will learn to escape as soon as they hear the noise.

Although humans and animals have the capacity for avoidance learning, moving forward, we will only discuss avoidance learning in mice. We will look at the differences between active and passive avoidance learning, their key features and why it is essential for research in this area to continue.

Avoidance Learning

Avoidance learning is when voluntary behavior is learnt to prevent a negative stimulus before it occurs or avoid it altogether. These responses can only be developed after the avoidance response has been learnt, which requires a mouse to have experienced the aversive event previously. Many parts of avoidance learning are natural and essential for avoiding danger, but excessive or unnecessary avoidance behaviors can suggest anxiety disorders, thus making it an essential area of study in psychology. Avoidance learning and behaviors are commonly studied using mice in a laboratory setting.

Active Avoidance Learning in Mice

Active avoidance learning occurs when a mouse learns to respond to an unpleasant stimulus in a specific way. In mice, the most common way to observe avoidance behaviors is by using a shuttle box apparatus, which includes two sections with a barrier between them. During the study, a light or noise stimulus is presented, followed by a non-harmful shock or stimulation of the paws. Over time, and through trial and error, the mouse must learn to move to the other compartment to escape from the unpleasant stimulus by recognizing the light or noise stimulus, also known as the conditioned stimulus.1

The key features of active avoidance learning include presenting behaviors that would not occur without the negative stimulus. This is learnt through Pavlovian conditioning as the fear of an unconditioned stimulus forces the mouse to develop behaviors to avoid the unpleasant stimuli. The mouse model must also actively engage in the learning process that helps them escape exposure to the stimuli, which naturally would be part of their survival instinct in the wild.

It is, however, important to note that active avoidance learning and the fear response can vary between individuals, as some learn quickly and others do not. There are many reasons why some organisms do not engage in avoidance learning, including limited acquisition and retention of experience.1

Passive Avoidance Learning in Mice

Passive avoidance learning refers to behaviors that involve a mouse not engaging in certain behaviors to avoid an unpleasant experience.2 As the name suggests, passive avoidance training is a more passive process, unlike active avoidance learning, in which subjects must actively engage to avoid a stimulus.

The method of studying passive avoidance learning is to use the step-through apparatus. Like the active avoidance chambers, a mouse will be placed in an apparatus with two compartments and a barrier in the middle. Firstly, into a brightly lit compartment and as they move into a dimly lit compartment, a paw stimulation, or shock, is activated.3 Over time, the mouse is trained to inhibit a natural response. Its avoidance learning is monitored by measuring its reluctance to enter the darker compartment, which would be a natural instinct.

Passive avoidance learning is simpler as it requires the mouse to do less. Although rodents naturally seek out darker environments, through this model, they will learn to avoid the darker compartment as they remember the shock administered.

Differences Between Active and Passive Avoidance Learning

Although we have mentioned some of the differences between active and passive avoidance learning theories throughout this blog post, we will summarize the key features of each learning style in this section.

Active Avoidance Learning

Measured based on the occurrence of a specific response
Requires active engagement from subject
The subject learns to prevent an aversive stimulus

Passive Avoidance Learning

Measured based on the non-occurrence of a response
Passive engagement from subject
The subject learns to avoid an environment where they have experienced an unpleasant situation

Both active and passive avoidance learning is studied to understand better how organisms respond to anxiety, fear, trauma and other disorders. In the field of psychology, studying active avoidance learning is crucial to learn more about the neural and behavioral mechanisms behind anxiety disorders and support the development of new treatments. Using mice models in these studies help researchers gain valuable information about these disorders and how they can be impacted by genetics and the environment.

San Diego Instruments

San Diego Instruments design and develop a range of life science instruments for behavioral neuroscience research. The GEMINI active and passive avoidance system is designed to accurately and reliably monitor learning and memory in rodent subjects for avoidance learning.

The GEMINI allows up to 8 independent avoidance chambers and provides cues such as non-heating LED house lights, standard cue lights, and various auditory stimuli. For unconditioned stimulus, it offers an air puff or shock option.

Contact a member of San Diego Instruments today to learn more about active and passive avoidance learning and the apparatus we provide for enhancing your studies.

Active & Passive Avoidance Learning in Mice: What’s the Difference?