Dr Paul Sowman
Dr Paul Sowman - World First in Childhood Stuttering Research
Stuttering can emerge in children aged two to five years but for 70% the problem resolves spontaneously before puberty. For 1% of the population, however, stuttering becomes chronic.
“Stuttering occurs as children move from using individual words to constructing sentences but in most cases brain development catches up and stuttering disappears,” explains Dr Paul Sowman, a member of Macquarie University’s Centre for Cognitive Sciences.
“A lot of stuttering studies have been done with adults, particularly in the US and Finland, but the brain changes over time so the original issue may be masked,” he said.
“Speech can contain six syllables per second and involve up to 100 muscles in the tongue, neck, jaws, chest and diaphragm. Then there’s the feedback from the ears. It’s an amazing feat of coordination.”
In a world first, Dr Sowman and his colleagues are using a unique MEG or magnetoencephalography system designed specifically for young children. The brain imaging technique measures the magnetic field generated whenever information is processed by the brain – in this case as a child watches and responds to a series of pictures in short sessions.
The MEG captures measurements every 1/1000 second even though the brain’s magnetic fields are 100 million times smaller than the earth’s and 1 million times smaller those produced in an urban environment. To guarantee accuracy the MEG system is located in a multi-tonne, shielded room with thick walls specially constructed to block out external magnetic fields. “It’s been likened to trying to pick up the footsteps of an ant at a rock concert,” said Paul.
To make the child MEG experience more friendly from the outset, the researchers have created a “Space Adventure” with the children boarding a space ship, “wearing” a helmet and travelling to another planet. Their mission is to listen to the instructions from ground control through earphones within the space ship while observed at all times by a video camera. Parents are invited to accompany them but many children prefer to “travel” with a substitute teddy after the initial visit.
The youngest child to slip into the MEG space helmet to date was aged two years but researchers have found children aged three or more have a better attention span and are more likely to remain still enough for the required data collection over two sessions. Four and five year olds usually require only one session of 15 minutes.
Dr Sowman originally trained as a physiotherapist but over the past seven years his focus has moved from the clinical to the neurosciences. His PhD looked at the links between teeth and facial motor control and was followed by research at universities in Adelaide, Denmark and Turkey into neuromuscular control and sensory motor interactions.
Now an NHMRC Postdoctoral Training Fellow at Macquarie, Dr Sowman is investigating how cortex networks in very young children integrate sounds (auditory input) and speech motor output. An additional university grant over three years is funding his work on brain anomalies in stuttering using transcranial magnetic stimulation (TMS) to transiently block brain areas implicated by brain scans in impaired speech function.
Brain scans of stutterers show that the amount of activation and the timing is slightly different to those in control groups, said Dr Sowman.
“The MEG system is a 'passive' device and completely safe and non-invasive. The research proposal was closely scrutinised by the University’s Ethics Committee before we began.
“Unlike electroencephalography (EEG) which depends on electrodes placed on the scalp to measure electrical activity produced by the brain, MEG uses a helmet-like device with extremely sensitive sensors. We can see how a child's brain responds when she or he is looking at pictures or reading.”
“The child MEG system allows us to explore language acquisition and auditory processing in children who are too young to participate in behavioural studies. We now have a window of opportunity to learn more about the earlier stages of development when the brain is most plastic.”
The child MEG system was developed by the Kanazawa Institute of Technology (KIT) in Japan, which also jointly funded the development of the KIT Macquarie Brain Research Laboratory, and a second MEG system designed for adults. The child MEG system is the first of its kind in the world and the MEG facility at Macquarie University is the only one in Australia .
Fellow collaborators with Dr Sowman in the multidisciplinary research are Brain Research Laboratory Director, Professor Stephen Crain; MEG specialist Dr Blake Johnson, research assistant Melanie Reid and speech pathologist Dr Elisabeth Harrison.