Dr Julia Pitcher

Biography/ Background

Qualifications

• BAppSc(Ex&SpSc); BSc(Hons); PhD

Current Appointments

• M.S. McLeod Research Fellow (Paediatric Medicine)

• Research Program Leader, Neuromotor Plasticity and Development group

• Senior Lecturer

Research Overview

In 2009, the Developmental Neuromotor Physiology group headed by Dr Julia Pitcher and the Human Sensorimotor Plasticity group headed by Associate Professor Mike Ridding joined the Robinson Institute and formed the Neuromotor Plasticity and Development (NeuroPAD) research group. Mike is internationally-renowned for his pioneering work in human brain plasticity induction, and Julia is attracting increasing recognition for her novel use of neurophysiologic techniques to unravel the links between motor and cognitive development in preterm children. The research interests of the group encompass neuromotor development and neuroplasticity across the human lifespan, from prenatal and early postnatal factors influencing motor development, through to therapeutic uses of induced neuroplasticity in ageing and neuropathological disorders such as stroke and the dystonias. The aim of the group's research is to inform and develop therapeutic interventions to develop, maintain and rehabilitate human motor function. NeuroPAD collaborates widely with clinicians and scientists from a range of disciplines including motor control neuroscientists, neurologists, neonatologists, obstetricians, psychologists, paediatricians, anaesthetists, physiotherapists and clinical epidemiologists. NeuroPAD is housed in four new purpose-built laboratories in the Robinson Institute next to the Women's and Children's Hospital, and is fully equipped with state of the art transcranial magnetic brain stimulators with neuronavigation, high-density EEG and human neurophysiological recording systems.

NeuroPAD group members

Name	Position
Dr Julia Pitcher	Co-leader, M.S. McLeod Research Fellow
Associate Professor Michael Ridding	Co-leader, NH&MRC Senior Research Fellow
Dr Nicolette Hodyl	NH&MRC Peter Doherty Research Fellow
Dr Sebastian Doeltgen	NH&MRC Peter Doherty Research Fellow
Dr Luke Schneider	Post-doctoral Researcher
Dr Ann-Maree Vallence	Post-doctoral Researcher
Mr John Drysdale	Senior Paediatric Physiotherapist/Research Assistant
Mr Ruiting Yang	Biomedical Engineer/Research Assistant
Dr Ashleigh Smith	Research Assistant (p/t)
Ms Suzanne McAllister	Doctoral student
Ms Joanna Cole	MSc student
Mr Mitchell Goldsworthy	Doctoral student
Ms Kathryn Dansie	Honours student

Awards & Achievements

• 2009 NH&MRC Ten of the Best
  Awarded for one of the ten best research projects funded by the Australian National Health and Medical Research Council. http://www.nhmrc.gov.au/publications/synopses/r44-tenofthebest-syn.htm
• 2005 Young Tall Poppy of Science Award
  Australian Institute of Political Science, for outstanding scholarship of national and international standing by a young Australian scientist.
• 2004 NH&MRC Peter Doherty Research Fellowship
  
• 2003 Elizabeth Penfold Simpson Prize
  Awarded by the Australian Brain Foundation (SA Branch), for the most outstanding body of published clinical or basic neuroscience research in 2001 and 2002.

Current Research Projects

Motor and Cognitive Development in Children born Preterm (PREMOCODE)
For the past 20 years, much of the research concerning the long term neurological outcomes of preterm birth has concentrated on those children born very or extremely preterm (i.e. < 32 weeks gestation), with little interest in preterm children born 33-37 weeks. This is not surprising since the most preterm children are more likely to have profound disabilities. But a small number of recent studies suggested that even mildly and moderately preterm children also experience motor, learning and behavioural problems at school age. Across all gestations of preterm children, this motor and cognitive dysfunction usually co-occurs, suggesting that there is a common underlying origin. To test this hypothesis, the PREMOCODE (PREterm MOtor and COgnitive DEvelopment) study has been investigating the neurological development of a large cohort of children (now aged 12-14 years) who were born at the Women's and Children's Hospital after 24 - 41 weeks of gestation at a range of birthweights.
To date, we have found that abnormal development of the brain's motor control areas is not confined to the very preterm or very growth restricted, and for every week of reduced gestation (i.e. under 40 weeks), there is linear reduction in the excitability of the motor cortex that is clearly evident at the end of the first decade of life. In addition, for every percent an individual's actual birthweight is under their optimal predicted term birthweight (100%), there is a corresponding linear fall in the excitability of the motor cortex that is independent of the effects of gestation. Perhaps more importantly we have found quite strong associations between the underdevelopment of these motor areas and the level of cognitive dysfunction, specifically in those cognitive abilities related to language comprehension and reading. In fact, the development of the motor cortex is a much stronger predictor of cognitive abilities in these children than gestation. This is the first physiological evidence that the motor and cognitive dysfunction commonly experienced by preterm children when they reach school age probably has a common underlying origin(s) in the brain. This study is continuing and will elucidate the relationship between early postnatal health (including time spent in the NICU or SCBU) and socio-economic circumstances and the severity of this motor and cognitive dysfunction in preterm children.

Motor cortex excitability and speech perception in children born preterm
The PREMOCODE study (see above) has identified clear physiological alterations in the development of brain motor areas that correlates with dysfunction in specific cognitive abilities, particularly those concerned with language comprehension and reading. Several recent studies suggest that the motor cortex is involved not only in the production of speech (i.e. by activating muscles used to produce speech sounds) but also in its perception. In normal human adults, the output of the motor cortex is facilitated by listening to speech sounds and can be measured non-invasively. This motor facilitation is believed to reflect the motor centres of the brain contributing to decoding the meaning of the words, and is more pronounced when a greater effort is required to understand new or unfamiliar words. We have hypothesised that this motor facilitation is absent or abnormal in children born preterm, and contributes to their difficulties with language comprehension, auditory working memory and reading. The study involves the use of transcranial magnetic brain stimulation and surface electromyography techniques to measure motor facilitation during speech listening and to measure motor and sensory function in 12-13 year old children who are members of the PREMOCODE study cohort. The findings will guide future development and testing of interventions to improve motor and cognitive outcomes in preterm children.

Does preterm birth alter the capacity of the brain for neuroplasticity?
One outcome of preterm birth may be that the capacity of the brain to reorganise the strength of its connections may be altered. This may impair the preterm child's ability to compensate for their delay or dysfunction, by limiting the ability of their brain synapses and neurons to alter their strength (neuroplasticity) in response to experiences. Neuroplasticity underlies learning and memory of cognitive, motor and sensory abilities throughout life, but particularly during early childhood. Therefore the main aim of this study is to determine if neuroplasticity is impaired in premature children and contributes to their motor and cognitive deficits. The study utilises transcranial magnetic brain stimulation and surface electromyography techniques to induce motor plasticity and to measure motor and sensory function in 12-13 year old children who are members of the PREMOCODE study cohort. The findings will have implications for the way children born preterm learn, as well as therapeutic programs designed to assist motor and cognitive development in these children.

Motor cortex excitability and neurodevelopment following general anaesthesia in children
Studies in adult humans have shown that most commonly used general anaesthesias depress the excitability of the motor areas of the brain. However, the duration of this depression and whether it has any long-term effects on motor and/or brain function has not been examined. A number of recent studies on neurodevelopmental outcomes in children show that motor development is are delayed or altered after surgery. Since this appears to occur after surgery for quite different conditions, it suggests that is may be the anaesthetic and perhaps not condition for which the child had the surgery that influences subsequent motor development in these children. The influence of the type or duration of anaesthesia on motor cortex function has not been studied in either children or adults. The major aims of this project are to assess motor cortex neurophysiology and development of motor function, during and after surgeries involving general anaesthesia in children. Since nothing is known about long-term effects of general anaesthesia on motor cortex excitability in adults, we are concurrently performing a similar study in adults undergoing general anaesthesia for minor conditions. The aim is to identify if general anaesthesia has a long-term effect on motor cortex excitability (and motor development in children). If so, what are the characteristics that determine this i.e. type of drugs used, dosage, duration of anaesthesia, age of patient. The findings of the study will have immediate clinical significance in the selection of general anaesthetic agents and protocols for children and adults.

Research Funding

• National Health and Medical Research Foundation
• M.S. McLeod Trust
• Women's and Children's Hospital Research Foundation
• SA Channel 7 Children's Research Foundation

Publications

Pitcher JB, Riley AM, Kurylowicz L, Doeltgen SH, Rothwell JC, McAllister SM, Smith AE, Clow A, Kennaway DJ & Ridding MC (2012). Physiological evidence consistent with reduced neuroplasticity in human adolescents born preterm. Journal of Neuroscience (In press)

Pitcher JB, Schneider LA, Higgins RD, Drysdale JL, Burns NR, Nettelbeck TJ, Ridding MC, Haslam RR & Robinson JS (2012). Reduced corticomotor excitability and motor skills development in children born preterm. Journal of Physiology doi: 10.1113/jphysiol.2012.239269 (In press)

Goldsworthy MR, Pitcher JB & Ridding MC (2012). A comparison of two different continuous theta burst stimulation paradigms applied to the human primary motor cortex. Clinical Neurophysiology (In press)

Goldsworthy MR, Pitcher JB & Ridding MC (2012). Neuroplastic modulation of inhibitory motor cortical networks by spaced theta burst stimulation protocols. Brain Stimulation (In press)

Goldsworthy MR, Pitcher JB & Ridding MC (2012). The application of spaced rTMS protocols induces long-lasting neuroplastic changes on the human motor cortex. European Journal of Neuroscience 35(1): 125 - 134.

Pitcher JB, Schneider LA, Drysdale JL, Ridding MC & Owens JA (2011).Motor System Development of the Preterm and Low Birthweight Infant. Clinics in Perinatology; Developmental Care for the High Risk Neonate. 38(4): 605 - 625

Smith AE, Ridding MC, Higgins RD, Wittert GA & Pitcher JB (2011). Cutaneous afferent input does not modulate motor intracortical inhibition in ageing men. European Journal of Neuroscience 34(9):1461-1469 (Impact factor: 3.658)

Smith AE, Sale MV, Higgins RD, Wittert GA & Pitcher JB (2011). Male human motor cortex stimulus-response characteristics are not altered by ageing. Journal of Applied Physiology 110: 206-212. (Impact factor: 3.73)

Smith AE, Ridding MC, Higgins RD, Wittert GA & Pitcher JB (2009). Age-related changes in short latency motor cortex inhibition. Experimental Brain Research 198(4):489-500. (Impact factor: 2.027)

Pitcher JB, Robertson AL, Cockington RA & Moore VM (2009). Prenatal growth and early postnatal influences on adult motor cortical excitability. Pediatrics 124(1): e128-e136. (Impact factor: 4.473)

Pitcher JB, Henderson-Smart DJ & Robinson JS (2006). Prenatal programming of human motor function. Advances in Experimental Medicine & Biology 573:41-57.

Pitcher JB, Robertson AL, Clover EC & Jaberzadeh S (2004). Facilitation of cortically evoked potentials with motor imagery during post-exercise depression of motor cortex excitability. Experimental Brain Research 160(4): 409 - 417. (Impact factor: 2.304)

Pitcher JB, Ridding MC & Miles TS (2003). Bidirectional, frequency-dependent plasticity in the adult human motor cortex. Clinical Neurophysiology 114(7): 1265-1271. (Impact factor: 2.538)

Pitcher JB, Ogsten KM & Miles TS (2003). Age and sex differences in human motor cortex input-output characteristics. Journal of Physiology (London) 546(2): 605 - 613. (Impact factor: 4.346)

Pitcher JB & Miles TS (2002). Cortical excitability changes with imposed versus voluntary fatigue in human hand muscles. Journal of Applied Physiology. 92(5): 2131 - 2138. (Impact factor: 3.178)

Ridding MC, Brouwer B, Miles TS, Pitcher JB & Thompson PD (1999). Changes in muscle responses to stimulation of the motor cortex induced by peripheral nerve stimulation in human subjects. Experimental Brain Research 131: 135 - 143. (Impact factor: 2.304)

Pitcher JB & Miles TS (1997). The influence of muscle blood flow on fatigue during intermittent human hand-grip exercise and recovery. Clinical & Experimental Pharmacology & Physiology 24:471 - 476. (Impact factor: 1.78)

Entry last updated: Thursday, 15 Nov 2012