Individual fascicles of the paraspinal muscles are activated by discrete cortical networks in humans

OBJECTIVE To investigate whether functional specificity in different fascicles of the paraspinal muscles is associated with discrete organisation within the motor cortex. METHODS In 11 healthy volunteers, electromyographic (EMG) activity was recorded bilaterally using fine-wire intramuscular electrodes from the short and deep fibres of multifidus (DM) at L4, and the longer and more superficial fibres of longissimus erector spinae (LES) at L4 and L1. Surface electrodes were also placed over the right LES at L4 and L1. Organisation at the motor cortex associated with motor excitation was investigated using transcranial magnetic stimulation (TMS). RESULTS The results showed that motor cortical representation for DM was located posteriorly to that for LES. TMS maps from surface recordings of LES showed two optimal sites, which were located in proximity to the sites for DM and LES from intramuscular recordings. CONCLUSION Different fascicles of the paraspinal muscles are organised and thus could be controlled by discrete neuronal networks within the motor cortex. Further, TMS mapping from surface recordings of paraspinal muscles may be confounded by cross-talk from multiple underlying fascicles. SIGNIFICANCE Discrete organisation at the motor cortex appears consistent with differential activation of different fascicles of the paraspinal muscles with function.

[1]  J. Lorberbaum,et al.  The transcranial magnetic stimulation motor threshold depends on the distance from coil to underlying cortex: a replication in healthy adults comparing two methods of assessing the distance to cortex , 2001, Biological Psychiatry.

[2]  M Hallett,et al.  Dissociation of the pathways mediating ipsilateral and contralateral motor‐evoked potentials in human hand and arm muscles , 1999, The Journal of physiology.

[3]  P. Hodges,et al.  Concurrent excitation of the opposite motor cortex during transcranial magnetic stimulation to activate the abdominal muscles , 2008, Journal of Neuroscience Methods.

[4]  R. Töpper,et al.  Localization of the motor hand area using transcranial magnetic stimulation and functional magnetic resonance imaging , 1999, Clinical Neurophysiology.

[5]  G. Thickbroom,et al.  Transcranial magnetic stimulation mapping of the motor cortex in normal subjects The representation of two intrinsic hand muscles , 1993, Journal of the Neurological Sciences.

[6]  Annapoorna Kuppuswamy,et al.  Cortical control of erector spinae muscles during arm abduction in humans. , 2008, Gait & posture.

[7]  N. Bogduk,et al.  1987 Volvo Award in Basic Science: The Morphology of the Lumbar Erector Spinae , 1987, Spine.

[8]  N Bogduk,et al.  The biomechanics of the lumbar multifidus. , 1986, Clinical biomechanics.

[9]  J. Rothwell,et al.  Cortical projection to erector spinae muscles in man as assessed by focal transcranial magnetic stimulation. , 1992, Electroencephalography and clinical neurophysiology.

[10]  H Kalimo,et al.  Lumbar muscles: structure and function. , 1989, Annals of medicine.

[11]  N. Davey,et al.  Corticospinal Excitability in Patients With Chronic Low Back Pain , 2005, Journal of spinal disorders & techniques.

[12]  Paul W Hodges,et al.  External Perturbation of the Trunk in Standing Humans Differentially Activates Components of the Medial Back Muscles , 2003, The Journal of physiology.

[13]  M. Ridding,et al.  Stability of Maps of Human Motor Cortex Made with Transcranial Magnetic Stimulation , 2004, Brain Topography.

[14]  S. Gandevia,et al.  Comparison of human motor cortical projections to abdominal muscles and intrinsic muscles of the hand , 2004, Experimental Brain Research.

[15]  G. Thickbroom,et al.  A model of the effect of MEP amplitude variation on the accuracy of TMS mapping , 1999, Clinical Neurophysiology.

[16]  M. Stokes,et al.  Evidence of lumbar multifidus muscle wasting ipsilateral to symptoms in patients with acute/subacute low back pain. , 1994, Spine.

[17]  L M Harrison,et al.  Evidence for bilateral innervation of certain homologous motoneurone pools in man. , 1994, The Journal of physiology.

[18]  M. Merzenich,et al.  Neurophysiological correlates of hand preference in primary motor cortex of adult squirrel monkeys , 1992, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[19]  H. Jasper.  Report of the committee on methods of clinical examination in electroencephalography , 1958 .

[20]  J. Lorberbaum,et al.  How coil-cortex distance relates to age, motor threshold, and antidepressant response to repetitive transcranial magnetic stimulation. , 2000, The Journal of neuropsychiatry and clinical neurosciences.

[21]  A. Nowicky,et al.  Mapping the cortical representation of the lumbar paravertebral muscles , 2007, Clinical Neurophysiology.

[22]  M Arand,et al.  Stability Increase of the Lumbar Spine With Different Muscle Groups: A Biomechanical In Vitro Study , 1995, Spine.

[23]  Abbas Heydari,et al.  EMG analysis of lumbar paraspinal muscles as a predictor of the risk of low-back pain , 2010, European Spine Journal.

[24]  R. Lemon,et al.  Differences in the corticospinal projection from primary motor cortex and supplementary motor area to macaque upper limb motoneurons: an anatomical and electrophysiological study. , 2002, Cerebral cortex.

[25]  S. Gandevia,et al.  Deep and Superficial Fibers of the Lumbar Multifidus Muscle Are Differentially Active During Voluntary Arm Movements , 2002, Spine.

[26]  S. Wise,et al.  The motor cortex of the rat: Cytoarchitecture and microstimulation mapping , 1982, The Journal of comparative neurology.

[27]  P. Hodges,et al.  Rapid Atrophy of the Lumbar Multifidus Follows Experimental Disc or Nerve Root Injury , 2006, Spine.

[28]  P. Hodges,et al.  Corticomotor excitability of back muscles is affected by intervertebral disc lesion in pigs , 2009, The European journal of neuroscience.

[29]  Rupert Lanzenberger,et al.  Finger Somatotopy in Human Motor Cortex , 2001, NeuroImage.

[30]  K. Sakai,et al.  Preferential activation of different I waves by transcranial magnetic stimulation with a figure-of-eight-shaped coil , 2006, Experimental Brain Research.

[31]  N. Davey,et al.  Corticospinal Facilitation Studied During Voluntary Contraction of Human Abdominal Muscles , 2001, Experimental physiology.

[32]  M. L. Thompson,et al.  Corticomotor representation of the sternocleidomastoid muscle. , 1997, Brain : a journal of neurology.

[33]  T. Perneger.  What's wrong with Bonferroni adjustments , 1998, BMJ.

[34]  G. Vanderstraeten,et al.  Differences in electromyographic activity in the multifidus muscle and the iliocostalis lumborum between healthy subjects and patients with sub-acute and chronic low back pain , 2002, European Spine Journal.

[35]  N. Davey,et al.  Corticospinal activation of internal oblique muscles has a strong ipsilateral component and can be lateralised in man , 2004, Experimental Brain Research.

[36]  P. Strick,et al.  Motor areas in the frontal lobe of the primate , 2002, Physiology & Behavior.

[37]  W. Penfield,et al.  The Cerebral Cortex of Man: A Clinical Study of Localization of Function , 1968 .

[38]  W M Jenkins,et al.  A primate genesis model of focal dystonia and repetitive strain injury , 1996, Neurology.

[39]  Jejo D. Koola,et al.  Motor threshold in transcranial magnetic stimulation: The impact of white matter fiber orientation and skull‐to‐cortex distance , 2009, Human brain mapping.

[40]  M. Malcolm,et al.  Reliability of motor cortex transcranial magnetic stimulation in four muscle representations , 2006, Clinical Neurophysiology.

[41]  M J Pearcy,et al.  A Universal Model of the Lumbar Back Muscles in the Upright Position , 1992, Spine.

[42]  P. Hodges,et al.  Reorganization of the motor cortex is associated with postural control deficits in recurrent low back pain. , 2008, Brain : a journal of neurology.

[43]  T. Tani,et al.  Motor-evoked potentials elicited from human erector spinae muscles by transcranial magnetic stimulation. , 1999, Spine.

[44]  P. Hodges,et al.  A comparison of computer-based methods for the determination of onset of muscle contraction using electromyography. , 1996, Electroencephalography and clinical neurophysiology.

[45]  P. Hodges,et al.  Why do some patients keep hurting their back? Evidence of ongoing back muscle dysfunction during remission from recurrent back pain , 2009, PAIN®.

[46]  D. Hoffman,et al.  Muscle and movement representations in the primary motor cortex. , 1999, Science.

[47]  Paul W Hodges,et al.  The lumbar multifidus: does the evidence support clinical beliefs? , 2006, Manual therapy.

[48]  John P. Donoghue,et al.  Dynamic Motor Cortical Organization , 1997 .

[49]  N. Davey,et al.  Corticospinal control of human erector spinae muscles. , 2001, Motor control.

[50]  Shrawan Kumar,et al.  Torso muscle EMG profile differences between patients of back pain and control. , 2010, Clinical biomechanics.

[51]  M. Hallett,et al.  Noninvasive mapping of muscle representations in human motor cortex. , 1992, Electroencephalography and clinical neurophysiology.