Fear memory reduction without consciousness: a novel application of decoded neurofeedback.
Ironically, one common way to overcome fear memory is to face it. Repetitive exposure to the reminders of fear memory may eventually alleviate your fear response to them. Yet, this exposure may stress you out before fear gets alleviated.
An alternative, less-stressful, procedure to reduce fear memory was recently reported in a study published in Nature Human Behaviour, led by an international collaboration teams with ATR (Japan), NICT (Japan), UCLA, and Cambridge University.
Dr. Ai Koizumi, a lead author, used a decoded neurofeedback (DecNef), which is a hybrid of a real-time fMRI neurofeedback and the analysis of spatial (multi-voxel) pattern of brain activity.
Dr. Mitsuo Kawato, an inventor of DecNef and one of the authors of this study explains “DecNef allows you to estimate the similarity between a participant’s current brain activation patterns and his or her activation patterns evoked when physically presented with the visual fear reminders. With this technique, whenever the participants’ brain “represented” the fear reminders, they received monetary reward.”
Dr. Ben Seymour, of the University of Cambridge’s Engineering Department, was one of the authors on the study. He explained how this was done:
"The way information is represented in the brain is very complicated, but the use of artificial intelligence (AI) image recognition methods allowed us to identify specific features of the content of that information. When we induced a mild fear memory in the brain, we were able to develop a fast and accurate method of reading it by using AI algorithms. The challenge then was to find a way to reduce or remove the fear memory, without ever consciously evoking it".
Importantly, participants did not consciously experience the fear reminders during DecNef. This is possible, because the activation patterns are induced only locally in a portion of the visual cortex, which barely spread across the rest of brain. Confirming this, analyses revealed neither the conscious awareness of the reminder nor the apparent fear response towards the fear reminder which was induced as the activation patterns.
Strikingly, despite such absence of aversive experience of the fear reminder, DecNef led to significant reduction of fear response towards the fear reminder when tested afterwards. Such reduction was reported both in terms of physiological response (skin conductance) and of neuronal response (amygdala activity). This fear reduction effect was selectively observed with the fear reminder which was paired with reward during DecNef, and was not observed with another fear reminder which served as a control.
Further analyses suggested that a different neural mechanism may reduce fear memory with DecNef, compared with a conventional procedure involving direct exposure. That is, a conventional procedure may only allow you to inhibit the fear memory, without modifying such memory itself. This inhibitory mechanism may not tolerate the changes in time or locations, such that your fear may easily return when you see the fear reminders in a novel location. While ventromedial prefrontal cortex (VMPFC) is a key brain region in this inhibitory mechanism, its involvement was barely observed during DecNef. Instead, the striatal area was actively involved, an area related with the reinforcement learning.
These results suggest that, in the absence of VMPFC, DecNef may have allowed the original fear memory to get overwritten instead of simply inhibited. One possible mechanism might be that the fear memory may have been overwritten with a positive one, through the counter-conditioning of the fear reminder patterns and the reward.
“This is an early stage, as we are not dealing with patients yet,” said Professor Hakwan Lau from UCLA, the last author of the paper. “The participants were only afraid of the relevant images because we had paired the images with mild electric shocks. But in actual cases of severe phobia and PTSD, patient dropout is a real issue, because it is very difficult for them to face the feared objects or to relive the dreadful experiences. Perhaps by going directly into the brain, bypassing consciousness, we have a potential solution to this problem here.”
Although DecNef has a potential to help alleviate some fear related disorders including post-traumatic stress disorder (PTSD) and phobia, the authors carefully note that such clinical application should await further basic research.
The paper, “Fear reduction without fear through reinforcement of neural activity that bypasses conscious exposure” by Ai Koizumi, Kaoru Amano, Aurelio Cortese, Kazuhisa Shibata, Wako Yoshida, Ben Seymour, Mitsuo Kawato and Hakwan Lau is published in Nature Human Behaviour . DOI: 10.1038/s41562-016-0006 (2016).
Contact detailsSatoko Fujimura
Research Communications Officer,
Advanced Telecommunications Research Institute International
Dept. of Psychology, UCLA
Brain Research Institute, UCLA
Tel: +1-347-867-8528 (or +852-68597283 until Nov 21, 2016)
Research Communications Officer,
University of Cambridge