Page 25

SCIENCE 25

Epigenetic pattern spotted in individuals with autism Joshua Green

The researchers analysed post-mortem brain samples of individuals and found that 68% of the total sample shared a ‘common histone acetylation pattern’.

Kat Pooprasert

If this works, the training method could potentially be used for other for other forms of fear-based conditions.

A

New analysis possible due to “BrainSpan” technology

study published, in the November 17th issue of the journal Cell, suggests there are epigenetic modifications that are common between individuals of rare and common forms of autism. The study itself was headed by co-senior study authors Shyam Prabhakar (from the Genome Institute of Singapore) and Daniel Geschwind (from the David Geffen School of Medicine at UCLA). The study also opens up the idea that this common trait, seen in individuals with autism, could be the cause or basis of the diverse manifestations of autism. What what did they actually spot? The paper talks of a “epigenetic modification”. Something that is epigenetic, in a biological context, is something that ‘arises from non-genetic influences on gene expression’. It is known generally that environmental and genetic factors contribute to autistic spectrum disorders (ASD). Many studies have focused on looking at structural changes to the genome, for example, however there has been a shift in the studies which now focuses on factors that do not affect the DNA sequence of an individual. Epigenetic modifications are changes in genetic activity that does not alter DNA sequences. Researchers have been previously looking at a chemical modification of

DNA known as methylation. Methylation is an epigenetic mechanism that cells use to express genes. It can be used to ‘fix’ non-expressed genes from the “off” position. It is argued that this method ignores the complicated nature of gene expression associated with ASD conditions. In this new study the role of histone acetylation with ASD was explored. The study reports how the researchers focused on a ‘tag’ which is known as an acetylation mark. This tag, called H3K27ac, was used as a sign of gene activation. The researchers analysed postmortem brain samples of individuals and found that 68% of the total sample shared a ‘common histone acetylation pattern’ despite the other large amount of environmental factors and genetic factors causing a ASD condition affecting the samples. It was also found that a strong correlation, after 12 months from birth, linked gene activation in the brains to increased acetylation observed. This link that was established lends itself to the conclusion that acetylation has a significant role in the relevant genes, associated with ASD conditions, being expressed. This 12 month after birth analysis is possible due to researchers using ‘BrainSpan’ which is an ‘atlas’ of a developing brain. The authors are planning to follow

Pictured: Common epigenetic changes can explain for the complex (Photographer: hepingting)

up this study with further research questions. This study is seen to be powerful, however, it shows more about shared processes between autistic individuals rather than establishing causal links between the modifications and ASD conditions. There is speculation that, due to how these processes point

to specific genes and pathways in ASDindividual’s brains, new targets could be established for novel drug delivery. These drugs could be used to treat ASD conditions in some manner, however, there still needs to be much more extensive research.

Phobias can be conquered with the right training

T

ired of having phobias? A new way of curing phobias is underway and is aimed at nudging people into unconsciously thinking about their fears. This will help them to unlearn their associations of fear in a stress-free way. Conventionally, phobias are treated with ‘exposure therapy’, which involves showing someone the thing they are frightened of in a safe environment. This will teach them that they don’t need to be scared. Obviously, many people find this process too stressful and drop out, or is too apprehensive to sign up in the first place. Hakwan Lau from University of California, Los Angeles is one of the leaders of the team that is currently studying a new way to treat phobias. She describes how “we thought if we can do it unconsciously, there’s no unpleasantness”. Lau’s team uses software that can be trained to identify what people are looking at or imagining as they lie in fMRI brain scanners. This software can identify things that someone is thinking about unconsciously. With this software, the team has found a way to make people think about scary things without realising. In the study, the group recorded the patterns of brain activity that volunteers had when shown 40 images, some of which included common subjects of phobias such as spiders, snakes and dogs. They then set the team a task to do while an

Pictured: A common phobia (Photographer: Jamie Zeschke)

fRMI brain scanner. When unconscious patterns of activity in a person’s visual cortex matched that of a scary picture, that person was given positive feedback and a small cash reward. Thus, this ‘neurofeedback’ training encouraged subjects to think about the scary thing even more, but unconsciously. To see if this unconscious exposure technique can reduce phobiarelated stress, the team tried it on people whom they had conditioned to be scared of a pattern of colored

lines by giving them small electric shocks whenever they saw that pattern. Then the team asked 30 people to choose two pictures (from the set of 40) that they found most scary. After the neurofeedback training, however, the participants perspired less and even had reduced brain activity in the amygdala region (fear center). Such change did not occur on subjects who were not given neurofeedback training. To follow up, the team plans to

go back to the study participants in three months to ask if they still feel scared of their phobia animals. Only then will the success of the technique be known. Joe leDoux of New York University described that “selfreporting of fear is the gold standard for whether a person has been successfully treated or not”. If this works, the training method could potentially be used for other forms of fear-based conditions such as post-traumatic stress disorder and various anxiety disorders.

Gair Rhydd 1088 - 28th November 2016  
Gair Rhydd 1088 - 28th November 2016  
Advertisement