Australian researchers led by Dr Timothy Bredy of the University of Queensland’s Queensland Brain Institute say they may have found a way to silence the gene that feeds fear.

Their study, published in the Proceedings of the National Academy of Sciences, sheds new light on the processes involved in loosening the grip of fear-related memories, particularly those implicated in conditions such as phobia and post-traumatic stress disorder.

The team discovered a novel mechanism of gene regulation associated with fear extinction, an inhibitory learning process thought to be critical for controlling fear when the response was no longer required.

“Rather than being static, the way genes function is incredibly dynamic and can be altered by our daily life experiences, with emotionally relevant events having a pronounced impact,” Dr Bredy said.

“By understanding the fundamental relationship between the way in which DNA functions without a change in the underlying sequence, future targets for therapeutic intervention in fear-related anxiety disorders could be developed.”

This may be achieved through the selective enhancement of memory for fear extinction by targeting genes that are subject to this novel mode of epigenetic regulation.

“Fear extinction was a clear example of rapid behavioral adaptation, and that impairments in this process were critically involved in the development of fear-related anxiety disorders,” added Xiang Li, a PhD candidate at Queensland Brain Institute and the first author on the study.

“What is most exciting is that we have revealed an epigenetic state that appears to be quite specific for fear extinction.”

This was the first comprehensive analysis of how fear extinction was influenced by modifying DNA. It highlights the adaptive significance of experience-dependent changes in the chromatin landscape in the adult brain.

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Xiang Li et al. Neocortical Tet3-mediated accumulation of 5-hydroxymethylcytosine promotes rapid behavioral adaptation. PNAS, published online April 22, 2014; doi: 10.1073/pnas.1318906111