Be afraid, be very afraid, if you learned to

A new study on rats has identified a part of the brain's cortex that controls learned but not innate fear responses.

The results suggest that hyperactivity in a region of the prefrontal cortex might contribute to disorders of learned fear in humans, such as post-traumatic stress disorder and other anxiety disorders, say authors Kevin A. Corcoran, PhD, and Gregory Quirk, PhD, of the Ponce School of Medicine in Puerto Rico. Their report appears in the January 24 issue of The Journal of Neuroscience.

While building on previous findings, this study contradicts prior thinking that the amygdala, which plays a central role in emotional learning, is sufficient for processing and expressing fear, and it opens the potential for new avenues of treatment, the researchers say.

“This is the first paper demonstrating that a region of the cortex is involved in learned fear but not in innate fear,” says Markus Fendt, PhD, of the Novartis Institutes for Biomedical Research in Basel, Switzerland, who is not connected with the study.

In their study, Corcoran and Quirk taught rats to associate a 30-second tone with a shock to the foot at the end of the tone. Upon hearing the same tone the next day, rats spent nearly 70 percent of the time of the tone frozen, a typical fear response.

In another group of rats, the researchers chemically blocked activity in the prelimbic cortex, which is located near the front of the brain and close to the midline between the two hemispheres. These rats spent only 14 percent of the time freezing to the sound of the tone.

Yet the rats' innate, or natural, fears seemed unaffected by blocking the prelimbic cortex; they froze as much in response to seeing a cat or being placed in a large open area as they did to hearing the tone. Furthermore, when the team trained rats with the tone after chemically inactivating the prelimbic cortex, and then tested them drug-free the next day, the rats showed a normal fear response, indicating that inactivating the prelimbic cortex did not prevent them from learning to fear the tone.

The prelimbic cortex is connected to the amygdala, and, based on their findings, Corcoran and Quirk speculate that “by modulating amygdala activity, the prelimbic cortex is important for determining the circumstances in which it is appropriate to convey learned fears.” In contrast, they propose that fear responses to innate threats are automatic and do not require cortical involvement.

“Corcoran and Quirk's work raises the question of whether learned fear is more controllable–for example, by higher brain functions–than innate fear,” says Fendt.

Media Contact

Sara Harris EurekAlert!

Weitere Informationen:

http://www.sfn.org

Alle Nachrichten aus der Kategorie: Studies and Analyses

innovations-report maintains a wealth of in-depth studies and analyses from a variety of subject areas including business and finance, medicine and pharmacology, ecology and the environment, energy, communications and media, transportation, work, family and leisure.

Zurück zur Startseite

Kommentare (0)

Schreib Kommentar

Neueste Beiträge

High-thermoresistant biopolyimides become water-soluble like starch

This is the first report for the syntheses of water-soluble polyimides which are Interestingly derived from bio-based resources, showing high transparency, tunable mechanical strength and the highest thermoresistance in water-soluble…

Land management in forest and grasslands

How much can we intensify? A first assessment of the effects of land management on the links between biodiversity, ecosystem functions and ecosystem services. Ecosystem services are crucial for human…

A molecular break for root growth

The dynamic change in root growth of plants plays an important role in their adjustment to soil conditions. Depending on the location, nutrients or moisture can be found in higher…

By continuing to use the site, you agree to the use of cookies. more information

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.

Close