Author Interviews, Memory, PTSD / 17.08.2017
Weakening Neural Connections Can Eliminate Fearful Memories
MedicalResearch.com Interview with:
[caption id="attachment_36511" align="alignleft" width="197"]
Dr. Jun-Hyeong Cho[/caption]
Jun-Hyeong Cho MD PhD
Department of Molecular, Cell and Systems Biology
University of California, Riverside
Riverside, CA 92521
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: To survive in a dynamic environment, animals develop fear responses to dangerous situations. For these adaptive fear responses to be developed, the brain must discriminate between different sensory cues and associate only relevant stimuli with aversive events.
In our current study, we investigated the neural mechanism how the brain does this, using a mouse model of fear learning and memory. Our study demonstrates that the formation of fear memory associated with an auditory cue requires selective synaptic strengthening in neural pathways that convey the auditory signals to the amygdala, an essential brain area for fear learning and memory.
Dr. Jun-Hyeong Cho[/caption]
Jun-Hyeong Cho MD PhD
Department of Molecular, Cell and Systems Biology
University of California, Riverside
Riverside, CA 92521
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: To survive in a dynamic environment, animals develop fear responses to dangerous situations. For these adaptive fear responses to be developed, the brain must discriminate between different sensory cues and associate only relevant stimuli with aversive events.
In our current study, we investigated the neural mechanism how the brain does this, using a mouse model of fear learning and memory. Our study demonstrates that the formation of fear memory associated with an auditory cue requires selective synaptic strengthening in neural pathways that convey the auditory signals to the amygdala, an essential brain area for fear learning and memory.


















Dr. Susanne Asu Wolf[/caption]
Susanne Asu Wolf PhD
Max-Delbrueck-Center for Molecular Medicine
Berlin, Germany
MedicalResearch.com: What inspired you to research this link between Ly6Chi monocytes, antibiotics and neurogenesis?
Dr. Wolf: As a neuroimmunologist I research the communication between the immune system and the brain. Amongst other research groups we found almost 10 years ago that T cells are needed to maintain brain homeostasis and plasticity, namely neurogenesis. Since only activated T cells enter the brain, we were looking for a mouse model, where immune cells are not activated. My former supervisor Polly Matzinger (NIH), a well-known immunologist, suggested to use germ free mice, born and raised in an isolator without any contact to a pathogen or any bacteria. I did a pilot experiment with the germ free mice, but wanted to get closer to possible applications in humans. Since humans are rarely born and raised in a sterile environment, I was looking for another model. By chance I met with the group of Bereswill and Heimesaat (Berlin, Charite) who provided me with a model, where due to prolonged treatment with an antibiotic cocktail, the microbiota are below detection level and the mice are also virtually germ free. They got me into contact with the second senior author of the paper Ildiko Dunay (University of Magdeburg). Her expertise is the function of Ly6Chi monocytes during infection with malaria or toxoplasmosis.
Now we were ready to investigate the gut-immune-brain axis with the focus on neurogenesis and cognition. Meanwhile the impact of the microbiome on behavior was reported by several research groups using “sterile” germ free mice and I was also curious if we could see similar differences in our antibiotic treated mice.




Dr. Andrew Lim[/caption]
Dr. De Brito[/caption]
MedicalResearch.com Interview with:
Stephane De Brito, PhD
Birmingham Fellow
School of Psychology
Robert Aitken Building, Room 337a
University of Birmingham UK
Medical Research: What is the background for this study? What are the main findings?
Dr. De Brito: In the last decade, an increasing number of neuroimaging studies have used structural magnetic resonance imaging (sMRI) to examine the brains of youths who show behavioural problems that include antisocial and aggressive behaviour. Those studies have mostly relied on a method called voxel-based morphometry (or VBM), which is a whole-brain and automated technique that allows researchers to objectively assess the local composition of brain tissue, such as grey matter volume. The main problem is that the findings from those sMRI studies have been quite disparate and few have been replicated, partly due to differences in sample sizes and characteristics across studies. Therefore, we set out to carry out a meta-analysis of the available data to provide a clearer account of the literature on this topic. A particular strength of our meta-analysis is that we used the original brain imaging maps (also referred to as statistical parametric maps) from 11 of the 13 studies, which makes our analysis more accurate and reliable. The final sample comprised of 394 youths with behavioural problems and 350 typically developing youths, making it the largest study on this topic to date.
Our results showed that, compared to typically developing youths, those with behavioural problems show reduced grey matter volume in the amygdala, the insula, and the prefrontal cortex. These brain areas have been shown to be important for decision-making, empathic responses, processing facial expressions and emotion regulation; key cognitive and affective processes that are shown to be deficient in youths with behavioural problems.