Dr Hyojin Park is a cognitive neuroscientist and a part of the Centre for Human Brain Health (CHBH). Her research looks at how the brain processes information related to speech and memory with magnetoencephalography (MEG). Using thestate-of-the-art brain imaging technology, Dr Park is creating a comprehensive understanding of the neural mechanisms behind audio-visual processing..

What was your journey into magnetism?

When I was a PhD student, MEG research was just beginning. Back then, there were no ac- cessible resources to learn the physics behind it. Because it’s a very multidisciplinary area,

I struggled to find the right information. But then I went to conferences, met people and visited different labs. I learnt a lot by discuss- ing the mechanisms with experts. Now there’s so much more information, but the solution is the same - collaborating with physicists and engineers is key.

What is the goal of the centre, and how does your research fit into it?

The purpose of CHBH is to use all the different imaging modalities to develop a comprehen- sive understanding of the mechanisms in the human brain. This understanding is key to

the treatment of Alzheimer’s, developmental disorders, and more. MEG gives the precision and resolution to study fundamental cognition, which can be integrated into other techniques at the CHBH. Work on optically pumped mag- netometers is advancing MEG by improving the quality of measurements, reducing costs and expanding the applications.

What unexpected discoveries have you found in your research?

The motor cortex in the brain is activated for moving the body. However, we found that this can also be activated when comprehending speech, which implies an active sensing role in the brain. In a situation that’s noisy, the brain has to put more effort into listening and follow- ing the conversation. We now know that the motor cortex is involved in this, but the funda- mental mechanisms behind why and how are still to be determined.

How do you measure brain signals?

The neurons in the brain send electrical signals to communicate between different parts, creating small magnetic fields. MEG can detect these small femto-tesla (10-15 T) magnetic fields outside of the brain. We can measure these signals whilst people do certain tasks, which can tell us at the millisecond level how brain activity works. Most activity happens

at the surface of the brain, but sophisticat- ed mathematical algorithms can help us look deeper.

Why are you interested in studying speech?

I started by researching long-term memory, which led me to brain rhythms. My research used the same methods for studying memory, but applied them to natural speech and its complex, rich sounds. The brain processes speech at multiple levels: from the phonemes to the words, sentences, and phrases. And then on top of those, you have intonation, which carries meaning. Each component of speech has different rhythmic structures and is processed on different timescales. This com- bination is fascinating, and now I am trying to combine memory and speech into my research