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Developmental Neuromotor Physiology
| Researchers: |
Dr. Julia Pitcher
Professor Jeffrey Robinson |
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| Email: |
julia.pitcher@adelaide.edu.au |
| Location: |
Level 5, Samuel Way Building,
Women’s and Children’s Hospital,
72 King William Road,
North Adelaide SA 5006. |
The Developmental Neuromotor Physiology group was established in 2004 to study
the fetal and early life developmental programming of human movement (motor) physiology
and function, how it is perturbed by adverse intrauterine and perinatal events
such as growth restriction and obstetric interventions, and how we might minimise
any negative long term impact these perturbations might have on the individual
in later life. We study motor control in children, adolescents and adults. We
also pursue research questions in basic human motor control, particularly in relation
to cortical plasticity, neuromuscular fatigue and motor skill learning. It is
a multidisciplinary team including neurophysiologists, obstetricians, neonatologists
and clinical epidemiologists.
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Tom has the hand area of his brain painlessly
stimulated. The coil is simply held gently against his head.
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Sticky electrodes over Tom’s index and little fingers
record the tiny electrical signals coming from his hand muscles.
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Tom’s mum Fiona watches while he has his brain stimulated
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* Tom and his parents gave us permission to
take and use these photographs.
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Staff
| Pitcher, Dr Julia |
8161 7480
Email
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NHMRC research Fellow |
| Higgins, Mr Ryan |
8161 7480
Email |
Research Associate |
| Pender, Ms Kay |
8161 7480
Email |
Study Co-ordinator |
| Robertson, Alexandra |
8161 7480
Email |
PhD Student |
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Collaborators:
Professor Timothy Miles (Physiology)
Dr. Michael Ridding (Physiology)
Dr. Vivienne Moore (Public Health)
Professor Caroline Crowther (Maternal & Perinatal Clinical Trials Unit, WCH)
Assoc. Prof. Ross Haslam (Neonatal Medicine, WCH
Current projects:
Neuromotor outcomes of fetal growth restriction.
Pitcher JB, Robertson AL, Moore VM, Cockington R & Miles TS.
We have been studying corticospinal function, fine motor skills, strength and
sensorimotor integration in a cohort of young adults whose birth characteristics
were recorded in detail. We are interested to know if size and weight at birth,
relative to gestational age, influences these neuromotor functions later in life.
Corticospinal function and neuromotor outcomes in children after prenatal
corticosteroid administration.
Pitcher JB, Haslam RR, Crowther CA & Robinson JS.
Despite widespread clinical use, evidence supported by findings from animal studies
suggests that repeat doses of prenatal corticosteroids, given to accelerate infant
lung maturity in women at risk of premature delivery, might adversely affect (among
other outcomes) infant birthweight, brain weight, myelination and neurological
development postnatally. The longer-term neurological consequences of prenatal
steroid treatment are unknown. We are trying to determine the effect, if any,
of single and repeat prenatal doses of corticosteroids on corticospinal and motor
function in children born prematurely who are now 8-10 years of age. These motor
outcomes are being compared with matched control children whose mothers were not
given antenatal corticosteroids. The overall aim is to determine which specific
aspects (if any) of corticospinal development and corticospinal function are perturbed
by antenatal corticosteroid administration and persist into childhood.
Mechanisms of homeostatic plasticity in human motor cortex
Pitcher JB & Ridding MC
We have recently shown for the first time that the human motor cortex is capable
of bi-directional plasticity by stimulating nerves in the body periphery. Its
excitability can be induced to either increase or decrease, depending on the stimulus
parameters. One of these parameters is stimulus frequency; low frequency stimulation
induces depression, while high frequency stimulation. However, homeostatic mechanisms
may limit the degree to which these changes can occur, to prevent neural assemblies
either saturating or failing to respond to incoming stimuli. In addition, there
may be distinct time windows during which any repeat of the novel stimulation
(for example) may “undo” the changes in synaptic strength induced
by the original stimulation. We are now examining the frequency and temporal characteristics
of repeated stimulation to determine how these homeostatic mechanisms work in
awake, performing humans. Longer term, these findings may help in the development
of therapies in which different types of plasticity are induced to overcome aberrant
motor function acquired perinatally, or help reinstate motor function lost due
to illnesses such as stroke and Parkinson’s Disease.
The functional significance of post-exercise depression of motor cortex
excitability
JB Pitcher, AL Robertson & TS Miles
Following a strong “fatiguing” muscle contraction, the excitability
of the motor cortex area of the human brain is depressed for up to an hour or
more. While this originates partly in the fatigued muscle, this reduced excitability
is only evident in the motor cortex, is not associated with a reduced ability
of the muscle to produce force. However, the functional significance of this depression
is unknown. Is it a manifestation of “central fatigue”, often associated
with an increased sense of effort when performing a task? Is it confined to the
motor cortex, or is the excitability of other brain areas involved in producing
voluntary movements also affected? Or is it related to changes in synaptic strength
associated with the learning and memory of motor skills? We have recently shown
that it does not appear to significantly affect the strength of the input to the
motor cortex from those areas of the brain responsible for the storage and generation
of internal representations of movement.
Some recent publications
Pitcher JB, Henderson-Smart DS & Robinson JS (2005). Prenatal programming
of human motor function. In: Early Life Origins of Health and Disease. Eds. M.
Coghlan-Wintour and JA Owens. Landes Bioscience (In press).
Pitcher JB, Robertson AL, Miles TS, Cockington RA & Moore VM (2004). The influence
of birthweight on neuromotor outcomes in adult humans. Proceedings of the 31st
Annual Meeting Fetal & Neonatal Physiological Society, Tuscany, Italy.
Pitcher JB, Moore VM, Robertson AL, Cockington RA & Miles TS (2004). Birthweight,
gestational age and neuromotor outcomes in adult humans. XVIIIth National Workshop
on Fetal and Neonatal Physiology, Sydney, Australia.
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 (In press).
Pitcher JB, Ridding MC & Miles TS (2003). Bidirectional, frequency-dependent
plasticity in the adult human motor cortex. Clinical Neurophysiology 114(7): 1265-1271.
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.
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.
Ridding MC, Brouwer B, Miles TS, Pitcher JB & Thompson PD (1999). Changes
induced in human motor cortex by peripheral nerve stimulation. Experimental Brain
Research 131: 135 - 143.
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.
Funding:
Our research is funded by:
National Health & Medical Research Council
Channel 7 Children’s Research Foundation Grant
Strategic Research Initiative Grant
Faculty of Health Sciences Research Establishment Grant
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