Pessimistic rats are extra sensitive to negative feedback

Posted on July 2, 2016

The optimistic and pessimistic rats were trained and tested in a probabilistic reversal-learning (PRL) task, which essentially involves using negative or positive feedback to teach the animals to change or maintain a response that they’ve learned previously. Rygula and Popik determined how likely each rat was to switch its response after receiving negative feedback and to maintain its response following positive feedback.

The researchers found that the two groups did not differ in their responses to positive feedback, but that pessimistic rats were more sensitive to negative feedback than optimistic rats. That is, the pessimistic rats were much quicker to drop a previously learned response once it started to be met with negative feedback – you could see this as akin to a depressed human giving up more quickly in response to criticism.

This new finding builds on earlier research by Rygula and his colleagues, in which they demonstrated that the trait of pessimism can also influence rats’ motivation levels (the optimistic rats were more motivated than pessimistic rats to obtain a sip of sugary water), and their vulnerability to “stress-induced anhedonia” – after being restrained, which they find stressful, pessimistic rats showed a longer-lasting lost appetite for sugary water. This might represent a reduction in their ability to experience pleasure that is analogous to human anhedonia, which is another important symptom of depression.

This new study on sensitivity to negative feedback in pessimistic rats, in combination with Rygula’s two previous studies, supports the claim that rats that tend to be pessimistic are also more likely to demonstrate a variety of behavioral and cognitive processes that are linked with increased vulnerability to depression.

It’s hard to know how similar pessimistic rats are to depressed people, but studies like these certainly provide intriguing commonalities. Scientists use animals such as rats as models for human disorders like depression, and use such models to test new therapies and drugs. It seems that rats can display the same negative cognitive biases as people, tending to make negative judgments about events and interpreting ambiguous cues unfavorably. And these biases, in turn, affect both rats’ and humans’ sensitivity to negative feedback.

To read the full article, click the link below.


Category(s):Depression

Source material from Research Digest


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