Dr Juanita Todd's studies into auditory brain responses could lead to earlier diagnosis and improved treatment of schizophrenia.
Early in her career, a colleague told Dr Juanita Todd that schizophrenia was considered the "graveyard of the neuroscientist", so intractable had the field proven to be for researchers. Undeterred by this discouraging perception, Todd launched into schizophrenia research regardless, motivated by a fascination with the workings of the brain and a desire to make a real contribution to determining the causes of this inscrutable disorder.
"I am intrigued, in the saddest way, by the element of this illness that makes people so detached from their prior selves," reflects Todd, who completed a Masters in clinical psychology after studying an undergraduate science degree. "I have worked with families of people with schizophrenia and they will often tell you the person they knew, the son or daughter that they had, is so different to the person they see before them now."
Todd's research focuses on detecting the earliest point at which that conversion starts to manifest and honing in on the neurological changes that may be taking place to cause those symptoms to appear. She studies a brain response called mismatch negativity, an indicator of a person's sensitivity to unexpected stimuli. This automatic brain response is smaller in people with schizophrenia, a finding first established two decades ago by an Australian research team that included Todd's PhD supervisor, longtime mentor and University of Newcastle colleague, Emeritus Professor Pat Michie.
Todd uses head caps with recording electrodes to measure response to sound stimuli, to study how the brain organises information and determine how the process might differ in people with schizophrenia.
"The brain quickly models anything repetitious and learns to expect that pattern to continue. Anything that interrupts that pattern – a different or sharper sound for instance – will produce mismatch negativity, even though that deviation may or may not enter a person's conscious awareness," Todd explains.
"This mismatch negativity is also called a 'prediction error signal'. In higher-order brain processes, prediction errors are highly influential in determining what we will learn about. So what I study is a very simple, very early form of prediction error that we think may be related to these higher levels of dysfunction in schizophrenia.
"I sometimes think that what I do is like a game of Chinese whispers, in that if you can trace something back to the point where it first goes wrong, perhaps everything else that happens afterwards will make more sense. If we can find the first point of dysfunction in prediction errors in schizophrenia, then it might be possible to better understand the processes of the disorder and be able to intervene earlier with treatments."
In the course of developing more sophisticated sound sequences for measuring auditory mismatch negativity, Todd has found evidence of apparent biases in the automatic process the brain uses to filter which sounds are relevant and which are not. Todd's findings were published in the journal Neuropsychologia last year and earlier this year she presented her research in this area to a conference on mismatch negativity in New York.
"To the field, this is an unpredicted finding so it is quite exciting and has opened up collaborations with people who work more generally in the field of how we learn," she states.
Todd and Michie, together with University of Newcastle colleague Professor Ulrich Schall, have received National Health and Medical Research Council funding to continue their research on mismatch negativity in schizophrenia. In another major project, Todd is collaborating with leading University of Newcastle clinical psychology researcher Professor Amanda Baker and researchers in Melbourne on a study of how nicotine use affects cognition in schizophrenia.
"The University of Newcastle is quite a force in schizophrenia research," Todd enthuses. "One of the things I have found very valuable is the range of very highly regarded researchers here with different specialties who are all working towards the same goals. It promotes a multidisciplinary approach and encourages you to step outside of your immediate field and think about things differently."
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