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Dr Steve Edgley

Reader in Sensorimotor Neuroscience
Tel: +44 (0)1223 333757, Fax: +44 (0)1223 333786, E-mail: sae1000@cam.ac.uk


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Motor Systems Neurophysiology Group

We are interested in how movements are controlled by neural circuits. Our everyday movements are performed with little conscious thought and are remarkably precise. Despite what the textbooks tell you, the neural mechanisms by which this is accomplished are poorly understood. We work at several levels, particularly at the spinal cord and cerebellum.

Research

Spinal Circuits

While spinal motoneurones have been extensively investigated, the intrinsic circuits of the spinal cord are much less well understood. Spinal premotor interneurones are the major source of inputs to spinal motoneurones and as such are major players in the control of movement, but relatively few groups of interneurones have been characterised. These are used in the control of movement by supraspinal systems as well as being involved in reflex activity and activity generated by intrinsic spinal circuits. Our work has focussed on the midlumbar segments of the spinal cord (L3-L5 in the cat, Th10-L1/2 in the rat). These segments are rostral to the motoneurone pools of the principal hindlimb muscles and communicate with motoneurones via short propriospinal neurones. This region of spinal cord was already seen as being particularly important for the coordination of more caudal segments 20 years ago, but has recently been the focus of a lot of interest as a leading region for locomotor-like motor patterns. Our work has involved a system of neurones with a characteristic input from hindlimb group II muscle afferents, which are principally the secondary endings from muscle spindles, which signal muscle stretch, although like all spinal interneurones studies, they have a multisensory input. Recent work has also examined the intercoordination between the 2 sides of the cord via commissural neurones, of which there are several different subgroups. Since the understanding of the function of the circuits is rudimentary, the particular questions asked at this stage are how the systems are organised in terms of input-output connectivity, how their activity is modulated by monoamines and by presynaptic inhibitory systems. Recent developments in immunocytochemistry have allowed the combination of electrophysiology (which can show connections) with morphology (which can show location and cell type) with chemical identity (which can show transmitter type, and neurotransmitter receptor expression patterns) in a single identified neuron

Cerebellar information processing

The cerebellum, in particular the cortex, is the most highly organised of all of the regions of the brain. As a result it is well studied in terms of intrinsic interconnectivity between neurones and the chemical/molecular properties of the constituent neurones. How information propagates through the system and what the structure actually does is understood in much less detail. Our work has used electrophysiological approaches to examine what inputs influence cerebellar neurones and how information is processed in the circuit. This work has examined how the climbing fibre system behaves and how Golgi cells are activated in relation to the local granule and Purkinje cells. In addition we have begun to investigate how cerebellar neuronal activity is modulated during the acquisition and performance of learned motor behaviour in the classically conditioned eyeblink response.

Corticospinal Systems

A third line of work has examined the corticospinal system, partly using non invasive stimulation and recording methods in man. These allow investigation of interesting processes like central fatigue and rhythmic changes in excitability.

People

Dr Tahl Holtzman (Research Associate)
Mr H J Room MA (Graduate Student)
Abteen Mostofi (Graduate Student)
Wei Xu (Graduate Student)

Main Collaborators

Prof Elzbieta Jankowska (Gothenburg, Sweden)
Prof David Maxwell (Glasgow)
Prof Christopher Yeo (UCL)
Prof Paul Dean (Sheffield)
Prof Richard Apps (Bristol)
Prof Stuart Baker (Newcastle)
Dr Stéphane Dieudonné (Ecole Normale SupĂ©rieure, France)

Former Colleagues

Dr Nick Riddle (Graduate Student, currently in clinical practice in Cambridge)
Mrs Amanda Grout (Research Assistant)
Dr S Chakrabarty (Graduate Student)
Dr Nick Aggelopoulos BSc PhD (Research Associate)
Dr Mark Baker MRCP (Graduate Student, currently in clinical practice in Newcastle)
Dr Kerry Elger (Graduate Student)

Publications

2000-present

Zaaimi B, Edgley SA, Soteropoulos DS, Baker SN. (2012) Changes in descending motor pathway connectivity after corticospinal tract lesion in macaque monkey. Brain. 135(Pt 7):2277-89. REF

Soteropoulos DS, Edgley SA, Baker SN. (2011) Lack of evidence for direct corticospinal contributions to control of the ipsilateral forelimb in monkey. Journal of Neuroscience. 31(31):11208-19. REF

Holtzman T, Sivam V, Zhao T, Frey O, van der Wal PD, de Rooij NF, Dalley JW, Edgley SA. Multiple extra-synaptic spillover mechanisms regulate prolonged activity in cerebellar Golgi cell-granule cell loops. (2011) J Physiol. 589(Pt 15):3837-54. REF

Jankowska E & Edgley SA (2010) Functional subdivision of feline spinal interneurons in reflex pathways from group Ib and II muscle afferents; an update. Eur. J Neurosci. (in the press). REF

Mostofi A Holtzman T Grout A Yeo CH Edgley SA (2010) Electrophysiological localisation of eyeblink-related microzones in rabbit cerebellar cortex J Neurosci. 30(26):8920-34. REF

Lemon RN, Edgley SA. (2010) Life without a cerebellum. Brain. 133(Pt 3):652-4. REF

Xu W & Edgley SA (2010) Cerebellar Golgi cells in the rat receive convergent peripheral inputs via a lateral reticular nucleus relay Eur J Neurosci 2010 32(4):591-7 REF

Riddle CN, Edgley SA & Baker SN. (2009) Direct and indirect connections with upper limb motoneurons from the primate reticulospinal tract. J Neurosci. 29(15):4993-9 REF

Holtzman T, Cerminara NL, Edgley SA & Apps R. (2009) Characterization in vivo of bilaterally branching pontocerebellar mossy fibre to Golgi cell inputs in the rat cerebellum. Eur J Neurosci. 29(2):328-39. REF

Xu W & Edgley SA. (2008) Climbing fibre dependent changes in Golgi cell responses to peripheral stimulation. J Physiol. 586(Pt 20):4951-9. REF

Aggelopoulos NC, Chakrabarty S & Edgley SA. (2008) Presynaptic control of transmission through group II muscle afferents in the midlumbar and sacral segments of the spinal cord is independent of corticospinal control. Exp Brain Res. 187(1):61-70. REF

Jankowska E, Stecina K, Cabaj A, Pettersson LG & Edgley SA.(2006) Neuronal relays in double-crossed pathways between feline motor cortex and ipsilateral hindlimb motoneurones. J Physiol. 575(Pt 2):527-41. REF

Holtzman T., Mostofi A., Phuah C.L. & Edgley S.A. (2006) Cerebellar Golgi cells receive multi-modal convergent peripheral inputs via the lateral funiculus of the spinal cord. J Physiol. 577(Pt 1):69-80; REF

Holtzman T, Rajapaksa T, Mostofi A & Edgley SA. (2006) Different responses of rat cerebellar Golgi cell and Purkinje cells evoked by somatosensory afferent inputs. J Physiol. 574(Pt 2):491-507 REF

Bannatyne BA, Edgley SA, Hammar I, Jankowska E & Maxwell DJ. (2006) Differential projections of excitatory and inhibitory dorsal horn interneurons relaying information from group II muscle afferents in the cat spinal cord. Journal of Neuroscience 26:2871-80. REF

Edgley SA & Aggelopoulos NC, (2006) Short Latency Crossed Inhibitory Reflex Actions Evoked From Cutaneous Afferents Exp Brain Res. 171: 541-50 REF

Jankowska E & Edgley SA. (2006) How can corticospinal tract neurons contribute to ipsilateral movements? A question with implications for recovery of motor functions. Neuroscientist. 12(1):67-79. REF

Baker MR & Edgley SA (2006) Non-uniform olivocerebellar conduction time in the vermis of the rat cerebellum. J Physiol. 570, 501-506 REF

Jankowska E, Edgley SA, Krutki P & Hammar I (2005) Functional differentiation and organization of feline midlumbar commissural interneurones Journal of Physiology 565:645-58 REF

Edgley SA, Jankowska E, and Hammar I (2004) Ipsilateral Actions of Feline Corticospinal Tract Neurons on Limb Motoneurons. Journal of Neuroscience, 24, 7804-13. REF

Edgley SA & Winter AP (2004) Different effects of fatiguing exercise on corticospinal and transcallosal excitability in human hand area motor cortex. Experimental Brain Research REF

Pardoe J, Edgley SA, Drew T & Apps R (2004) Changes In Excitability Of Ascending And Descending Inputs To Cerebellar Climbing Fibres During Locomotion. Journal of Neuroscience. 24, 2656-2666 REF

Hammar I, Bannatyne BA, Maxwell DJ, Edgley SA & Jankowska E (2004) The actions of monoamines and distribution of noradrenergic and serotoninergic contacts on different sub-populations of commissural interneurones in the spinal cord. European Journal of Neuroscience 19, 1305-1316 REF

Jankowska E, Hammar I, Slawinska U, Maleszak K & Edgley SA (2003) Neuronal basis of crossed actions from the reticular formation upon hindlimb motoneurones. Journal of Neuroscience 23: 1867-1878. REF

Krutki P, Jankowska E & Edgley SA (2003) Are crossed actions of reticulospinal and vestibulospinal neurons on motoneurons mediated by the same or separate commissural neurons? Journal of Neuroscience 23, 8041-8050 REF

Edgley SA, Jankowska E, Krutki P and Hammar I (2003) Both Dorsal Horn And Lamina VIII Interneurones Contribute To Crossed Reflexes From Group II Muscle Afferents. Journal of Physiology 552, 961-974 REF

B.A. Bannatyne, S.A. Edgley, I. Hammar, E. Jankowska & D.J. Maxwell, (2003) Networks of inhibitory and excitatory commissural interneurons mediating crossed reticulospinal actions. European Journal of Neuroscience 18, 2273-2284. REF

S. A. Edgley (2001) Organisation of inputs to spinal interneurone populations. Journal of Physiology 533: 51-56 REF

Baker M R, Javid M & Edgley S A (2001) Activation of cerebellar climbing fibres to rat cerebellar posterior lobe from motor cortical output pathways. Journal of Physiology 536, 825-839 REF

1990-1999

Edgley S A & Lemon R N (1999) Experiments using transcranial magnetic brain stimulation in man could reveal important new mechanisms in motor control Journal of Physiology 521, 565 REF

Armand, J., Olivier, E, Edgley S.A. & Lemon R.N. (1997) The postnatal development of corticospinal projections from motor cortex to the cervical enlargement. Journal of Neuroscience 17, 251-266 REF

Olivier, E. Edgley S.A., Armand, J & Lemon, R.N. (1997) An electrophysiological study of the postnatal development of the corticospinal system. Journal of Neuroscience 17, 267-276 REF

Aggelopoulos, N.C. Chakrabarty S & Edgley, S A (1997) Evoked excitability changes at the terminals of midlumbar premotor interneurones Journal of Neuroscience 17, 1512-1518. REF

Edgley SA, Eyre JA, Lemon RN, Miller S (1997) Comparison of activation of corticospinal neurons and spinal motor neurons by magnetic and electrical transcranial stimulation in the lumbosacral cord. Brain 120, 839-853 REF

Aggelopoulos, N.C., Bawa, P & Edgley, S.A (1996). Inputs to midlumbar interneurones from anterior hindlimb muscles. Journal of Physiology 497, 795-802.

Aggelopoulos, N.C., Burton, M.J., Clarke, R.W. & Edgley, S.A. (1995) Characterisation of a pathway which enables crossed group II inhibition in the spinal cord. Journal of Neuroscience 16, 723-729. REF

Aggelopoulos, N.C. & Edgley, S.A. (1995) Segmental localisation of the relays mediating crossed group II inhibition of motoneurones. Neuroscience Letters 185, 60-64.

Aggelopoulos, N.C., Duke, N.C. & Edgley, S.A. (1995) Non-uniform conduction time in the olivocerebellar pathway. Journal of Physiology 486, 763-768.

Davies, H.E. & Edgley, S.A. (1994) Projections to midlumbar neurones from descending motor pathways. Journal of Physiology 479 463-474.

Armand, J., Edgley, S.A., Lemon, R.N & Olivier, E. (1994) Protracted postnatal development of the corticospinal tract. Experimental Brain Research 101, 178-182.

Jankowska, E. & Edgley, S.A. (1993) Interactions between pathways controlling posture and gait at the level of the spinal cord. Progress in Brain Research 97, 161-170.

Bajwa, S. Edgley, S.A. & Harrison, P.J. (1992) Crossed actions on group II activated midlumbar propriospinal neurones. Journal of Physiology 455 205-217.

Edgley, S.A. & Grant, G.M. (1991) Inputs to spinocerebellar tract neurones located in Stilling's nucleus in the sacral segments of the rat spinal cord. Journal of Comparative Neurology 304, 130-138.

Arya, T., Bajwa, S & Edgley, S.A. (1991) Crossed reflex actions of group II afferents in the lumbar spinal cord. Journal of Physiology 444, 117-131.

Asif, M. & Edgley, S.A. (1991) Projections of group II activated spinocerebellar tract neurones to the region of nucleus Z. Journal of Physiology 448, 565-578.

Edgley, S.A., Eyre, J.A., Lemon, R.N. & Miller, S. (1990) Excitation of the corticospinal tract by electromagnetic and electrical stimulation of the scalp. Journal of Physiology 425 301-320.

1980-1989

Edgley, S.A. & Wallace, N.A. (1989). A short-latency crossed cutaneous reflex pathway to hindlimb motoneurones in the rat Journal of Physiology, 411, 469-480.

Edgley, S.A. & Jankowska, E. (1988). Information processed by dorsal horn spinocerebellar tract neurones. Journal of Physiology 397, 81-97.

Edgley, S.A. & Gallimore, C.M. (1988). Morphology and projections of dorsal horn spinocerebellar tract neurones. Journal of Physiology 397, 99-111.

Armstrong, D.M. & Edgley, S.A. (1988). Discharges of cerebellar neurones during locomotion under different conditions. Journal of Physiology 400, 425-446.

Armstrong, D.M., Edgley, S.A. & Lidierth, M. (1988). Complex spike discharges of cerebellar Purkinje cells during locomotion. Journal of Physiology 400, 405-415.

Edgley, S.A. & Lidierth, M. (1988). Step related discharges of Purkinje cells in the paravermal cortex of the cerebellar anterior lobe. Journal of Physiology 401, 399-416.

Edgley, S.A., Jankowska, E. & Shefchyk. S. (1988). Evidence that mid-lumbar neurones contribute to both reflexes from group II afferents and locomotion. Journal of Physiology 403, 57-72.

Edgley, S.A. & Jankowska, E. (1987). Field potentials evoked by group II muscle afferents in the mid-lumbar segments of the spinal cord. Journal of Physiology 385, 393-413.

Edgley, S.A. & Jankowska, E. (1987). An interneuronal relay for group I and II muscle afferents in the mid-lumbar segments of the spinal cord. Journal of Physiology 389, 647-674.

Cavalliari, P., Edgley, S.A. & Jankowska, E. (1987). Postsynaptic actions of mid-lumbar interneurones of hindlimb muscles. Journal of Physiology 389, 675-689.

Edgley, S.A. & Lidierth, M. (1987). Discharges of cerebellar Golgi cells during locomotion. Journal of Physiology 392, 315-332.

Edgley, S.A., Jankowska, E. & McCrea, D.M. (1985). The heteronymous monosynaptic actions of triceps surae group Ia afferents onto hip and knee extensor motoneurones. Experimental Brain Research 61, 443-446.

Armstrong, D.M. & Edgley, S.A. (1984). Discharges of nucleus interpositus neurones during locomotion. Journal of Physiology 351, 411-432.

Armstrong, D.M. & Edgley, S.A. (1984). Discharges of Purkinje cells in the paravermal part of the cerebellar anterior lobe during locomotion. Journal of Physiology 352, 403-424.

Armstrong, D.M., Campbell, N.C., Edgley, S.A., Schild, R.F. & Trott, J.R. (1982). Investigations of the olivo-cerebellar and spino-olivary pathways. In: The Cerebellum: New Vistas. Experimental Brain Research, supplement 6, 195-232.

Teaching

Part IB MVST Neurobiology and Human Behaviour

Neuroanatomy homepage (contains handbook chapters, posters from the DR, scans and specimens)

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Above: Dark field light micrograph of a juxtacellularly-filled cerebellar Golgi cell. In the middle of the picture is the cell body from which several principal dendrites emanate. Surrounding this is an extensively branching axonal tree containing many thousands of presynaptic swellings or boutons, a feature characteristic of Golgi cells. From The Journal of Physiology 574 (cover illustration).

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Above: Bilateral brain stimulation. The magnetic coils are fixed onto the motorbike helmet, one on each side. This is non-invasive and non-noxious!

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Above: A glutamate-releasing commissural interneuron in the spinal cord. The neuron was intracellularly filled with rhodamine (red), and the terminals co-localise the glutamate transporter VGlut2 (green). From European Journal of Neuroscience 18:2273 (2003).

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Above: A glycine-releasing commissural interneuron in the spinal cord. The neuron was intracellularly labelled with rhodamine (red). It has an axon that crosses the midline (top left diagram), and has terminals on the contralateral side of the spinal cord (bottom left). The confocal pictures on the right show that the labelled terminals (red) were always co-localised with the glycine transporter protein (green). From European Journal of Neuroscience 18:2273 (2003).