Sensorimotor Research Laboratory

Principal Investigator

Prof. Mary Galea

General Overview

The laboratory is concerned with the investigation of some of the mechanisms involved in the control of voluntary movement by the nervous system, and its recovery following injury. Techniques used include: neuronal tracing, immunohistochemical labelling and movement analysis.

Major Projects

EphA4 receptor tyrosine kinase and regeneration following spinal cord injury

One member of the Eph family, EphA4, has been shown to be involved in the development of the corticospinal tract in mice. Mice lacking the EphA4 receptor exhibit pathfinding defects in the corticospinal spinal tract, especially at the level of the spinal cord where corticospinal axons  are mislocated within the grey matter and aberrantly cross the midline. The importance of EphA4 in regulating the correct targeting of axons within the spinal cord and its upregulation following injury has led us to test the hypothesis that EphA4 may be a key regulator of spinal cord regeneration. 

Density and distribution of muscle spindles

The abundance of muscle spindles in neck muscles suggests that they play a major role in neck position sense and an understanding of their location and morphology is important for understanding how neck posture is maintained, and how it can be affected by disorders of the cervical spine. We have conducted a study examining the density, distribution and variations in the morphology of receptors in longus colli and multifidus. This information has led to a clearer picture of the functional role of these muscles in controlling movement of the cervical spine.

The ability to contract muscles correctly is dependent on feedback normally provided by the muscle spindles. However the presence and distribution of muscle spindles in some muscle groups is unknown.  This is the case for pelvic floor muscles. In conjunction with a large randomised controlled trial of pelvic floor muscle training in elderly women with stress incontinence, we are undertaking a parallel study of the density and distribution of muscle spindles in the pelvic floor muscles.

Regeneration in the peripheral nervous system

Restoration of sensory and motor function following transection of a peripheral nerve depends on many factors, including the degree of neuronal death and the extent to which regeneration occurs and target tissue is reinnervated. Growth factors may be applied to a transected peripheral nerve to enhance regeneration of the nerve and reduce muscle atrophy. In this project we are concerned with evaluating the level of regeneration following such an intervention. Neuronal tracers applied before and after surgical repair of the nerve will label the somas of both motor and sensory neurons. Estimates of the numbers of the different types of surviving neurons will be made using modern stereological methods.

Key References

Dottori M, Hartley L, Galea M, Paxinos G, Kilpatrick T, Bartlett P, Murphy M, Kontgen, F & Boyd A (1998) EphA4 (Sek 1) receptor tyrosine kinase is required for the development of the corticospinal tract. Proceedings of the National Academy of Sciences, USA 95:13248-13253.

Sangster CLC, Galea MP, Fan R, Morrison WA & Messina A (1999) A method for processing fluorescent labelled tissue into methacrylate: a qualitative comparison of four tracers. Journal of Neuroscience Methods 89:159-165.

Boyd-Clark L, Galea MP, Briggs CA, Opeskin K  (2000) Monitoring age-related changes of collagen content and vascularity in ganglia using unbiased stereological methods. Journal of Microscopy. 200:284-290.

Coonan JR, Greferath U, Messenger J, Hartley L, Murphy M, Boyd AW, Dottori M, Galea MP, Bartlett PF (2001) The development and reorganization of corticospinal projections in EphA4 deficient mice. Journal of Comparative Neurology. 436:248-262.

Boyd-Clark L, Galea MP, Briggs CA (2001) Muscle fiber type composition in longus colli and multifidus of the cervical spine.  Journal of Anatomy. 199:709-16.

Boyd-Clark L, Briggs CA, Galea MP (2002) Muscle spindle distribution, morphology and density in longus colli and multifidus of the cervical spine. Spine. 27:694-701.

Byers CT, Fan R, Messina A, Morrison WA, Galea MP Comparing the efficacy of two fluorescent retrograde tracers in labeling the motor and sensory neuron populations of the rat sciatic nerve. Journal of Neuroscience Methods. 114:159-164

Coonan JR, Bartlett  PF,  Galea MP (2003) A role for EphA4 in defining the position of a motoneuron pool within the spinal cord. Journal of Comparative Neurology. 458:98-11.